The crustal evolution of the Rudall Province from an ...

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Mar 27, 2013 - Subjects: Soil crusting--Western Australia--Rudall Province. ...... Hickman AH, 1978, Nullagine, Western Australia, 1:250 000 Geological.
Department of

Mines and Petroleum Government of Western Australia

REPORT 122

THE CRUSTAL EVOLUTION OF THE RUDALL PROVINCE FROM AN ISOTOPIC PERSPECTIVE by CL Kirkland, SP Johnson, RH Smithies, JA Hollis, MTD Wingate,IM Tyler, AH Hickman, JB Cliff, EA Belousova, RC Murphy, and S Tessalina

Geological Survey of Western Australia

REPORT 122

THE CRUSTAL EVOLUTION OF THE RUDALL PROVINCE FROM AN ISOTOPIC PERSPECTIVE by

CL Kirkland, SP Johnson, RH Smithies, JA Hollis, MTD Wingate, IM Tyler, AH Hickman, JB Cliff, EA Belousova1, RC Murphy1, and S Tessalina2

1

GEMOC, Department of Earth & Planetary Sciences, Macquarie University, Sydney NSW 2109

2

John De Laeter Centre for Isotope Research, GPO Box U1987, Perth WA 6845

Perth 2013

Geological Survey of Western Australia

MINISTER FOR MINES AND PETROLEUM Hon. Bill Marmion MLA DIRECTOR GENERAL, DEPARTMENT OF MINES AND PETROLEUM Richard Sellers EXECUTIVE DIRECTOR, GEOLOGICAL SURVEY OF WESTERN AUSTRALIA Rick Rogerson

REFERENCE The recommended reference for this publication is: Kirkland CL, Johnson SP, Smithies RH, Hollis JA, Wingate MTD, Tyler IM, Hickman AH, Cliff JB, Belousova EA, Murphy RC and Tessalina S 2013, The crustal evolution of the Rudall Province from an isotopic perspective: Geological Survey of Western Australia, Report 122, 30p.

National Library of Australia Cataloguing-in-Publication entry Author:

Kirkland, C. L., author.

Title:

The crustal evolution of the Rudall province from an isotopic perspective / C. L. Kirkland [and ten others]

ISBN:

9781741684995 (ebook)

Subjects:

Soil crusting--Western Australia--Rudall Province. Earth (Planet)--Crust. Isotopes.

Other Authors/Contributors: Dewey Number:

Geological Survey of Western Australia, issuing body

551.1409941

ISSN 0508–4741

U–Pb measurements were conducted using the SHRIMP II ion microprobes at the John de Laeter Centre of Isotope Research at Curtin University in Perth, Australia. Isotope analyses were funded in part by the Western Australian Government Exploration Incentive Scheme (EIS). Lu–Hf measurements were conducted using LA-ICPMS at the ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC), via the ARC Centre of Excellence in Core to Crust Fluid Systems (CCFS), based in the Department of Earth and Planetary Sciences at Macquarie University, Australia. Copy editor: K Coyle Cartography: M Prause Desktop publishing: RL Hitchings Printed by Images on Paper, Perth, Western Australia Published 2013 by Geological Survey of Western Australia This Report is published in digital format (PDF), as part of a digital dataset, and is available online at .

Further details of geological publications and maps produced by the Geological Survey of Western Australia are available from: Information Centre Department of Mines and Petroleum 100 Plain Street EAST PERTH WESTERN AUSTRALIA 6004 Telephone: +61 8 9222 3459 Facsimile: +61 8 9222 3444 www.dmp.wa.gov.au/GSWApublications Cover photograph: Bouguer gravity anomaly map of central Western Australia. The image highlights the Anketell Regional Gravity Ridge which approximately outlines the location of the Paterson Orogen. The Rudall Province lies within this gravity feature.

Contents Abstract ..................................................................................................................................................................1 Introduction ............................................................................................................................................................1 Geological setting of the Rudall Province .............................................................................................................2 The Talbot Terrane ..........................................................................................................................................2 The Connaughton Terrane ...............................................................................................................................4 The Tabletop Terrane.......................................................................................................................................4 Structural evolution .........................................................................................................................................4 Lu–Hf and oxygen isotopes, and reinterpreted SHRIMP U–Pb geochronology ...................................................5 Analytical methodology ..................................................................................................................................5 Lu–Hf isotopes .........................................................................................................................................5 Oxygen isotopes .....................................................................................................................................14 Talbot Terrane ...............................................................................................................................................14 Kalkan Supersuite ..................................................................................................................................14 GSWA 112379: biotite monzogranite (augen) gneiss, Split Rock ..................................................14 GSWA 104981: biotite–muscovite monzogranite gneiss, southern part of Graphite Valley ..........14 GSWA 111854: biotite–muscovite granodiorite gneiss, Poonemerlarra Creek west......................14 GSWA 112341: micromonzogranite (meta-aplite) dyke, Rudall airstrip .......................................16 GSWA 110056: biotite–hornblende granodiorite gneiss, Rooney Creek .......................................17 GSWA 112101: biotite-epidote monzogranite gneiss, Larry Creek ...............................................17 GSWA 111843: biotite–muscovite monzogranite gneiss, Poynton Creek......................................17 GSWA 104980: monzogranite gneiss, Graphite Valley ..................................................................17 GSWA 112310: granodiorite gneiss, Dunn Creek west ..................................................................18 GSWA 112397: coarse-grained porphyritic biotite monzogranite (augen) gneiss, Watrara Inlier ..................................................................................................................................18 Eastern Association ................................................................................................................................18 GSWA 104989: muscovite quartzite, Fingoon Quartzite................................................................18 Mesoproterozoic granites .......................................................................................................................18 GSWA 112102: seriate biotite metamonzogranite, southern part of the Watrara Inlier .................18 Connaughton Terrane ....................................................................................................................................18 Kalkan Supersuite ..................................................................................................................................18 GSWA 113035: orthogneiss, east of South Rudall Dome ..............................................................18 GSWA 113002: granodiorite gneiss, Cotton Creek ........................................................................18 Unassigned gneissic rocks .....................................................................................................................19 GSWA 112160: garnet microgneiss, Harbutt Range ......................................................................19 Tabletop Terrane.....................................................................................................................................19 GSWA 118914: foliated granite, north of Harbutt Range...............................................................19 Discussion ............................................................................................................................................................19 Hf isotope signatures of Paleoproterozoic Australia .....................................................................................19 Capricorn Orogen...................................................................................................................................19 Pilbara Craton ........................................................................................................................................21 Arunta Orogen........................................................................................................................................21 Musgrave Province.................................................................................................................................21 Inherited and detrital zircons of the Rudall Province....................................................................................22 Hf isotopic signature of the Rudall Province ...............................................................................................23 Crust formation and underplating at 1900 Ma .......................................................................................23 Constraints on the tectonic evolution of the Rudall Province ......................................................................25 Implications for terrane boundaries .............................................................................................................26 Conclusions ...................................................................................................................................................26 References ............................................................................................................................................................27

iii

Figures 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Simplified geological map indicating the location of the Rudall Province relative to other Proterozoic orogens and Archean cratons in Western Australia...................................................................3 Simplified geological map of the Rudall Province, indicating the main geological features and the distribution of terranes .....................................................................................................................3 a) and b): Stacked concordia diagrams showing U–Pb zircon analytical data for zircons from Rudall Province samples analysed by SHRIMP ion microprobe ...............................................................15 HHf evolution diagrams for Rudall Province samples compared to potential source regions ....................17 Initial 176Hf/177Hf evolution diagram for samples from the Rudall Province compared to potential source regions ..............................................................................................................................20 İHf evolution diagram for inherited zircons from Rudall Province intrusive rocks compared to potential West Australian Craton source regions........................................................................................22 Magmatic crystallization ages and two-stage Hf model ages for zircons from Rudall Province magmatic rocks ............................................................................................................................................. 24 Oxygen isotope analyses of zircons from Mesoproterozoic metamonzogranite sample GSWA 112102............................................................................................................................................24 Comparison of 176Yb/177Hf ratios for zircons from two Mesoproterozoic magmatic rocks with those from other Rudall Province magmatic rocks of Paleoproterozoic age ............................................24 Time-space diagrams showing magmatic and metamorphic U–Pb ages for the Gascoyne Province, Rudall Province, and Arunta Orogen .........................................................................................25

Tables 1. 2. 3.

Lu–Hf isotopic measurement of zircons from the Rudall Province .............................................................6 Oxygen isotope analyses from zircons of sample GSWA 112102 .............................................................12 Summary of U-Pb SIMS dates for Rudall Province ..................................................................................13

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The crustal evolution of the Rudall Province from an isotopic perspectiveby by CL Kirkland, SP Johnson, RH Smithies, JA Hollis, MTD Wingate, IM Tyler, AH Hickman, JB Cliff, EA Belousova1, RC Murphy1, and S Tessalina2

Abstract The Rudall Province, in the Paterson Orogen, is part of the West Australian Craton (WAC) and now lies to the east of the Archean East Pilbara Terrane. Components within the Rudall Province have previously been linked to the Arunta Orogen of the North Australian Craton based on similarities in timing of magmatism, deformation, and metamorphism and hence have been regarded as exotic terranes on the margin of the WAC. The Rudall Province is divided into three lithotectonic elements known as the Talbot, Connaughton, and Tabletop Terranes. The southern two terranes (Talbot and Connaughton) were affected by magmatism related to collision between the West and North Australian Cratons during the 1800–1765 Ma Yapungku Orogeny. Zircons within the Talbot Terrane and Connaughton Terrane indicate crustal residence ages of 3.4 – 2.4 Ga, with strong isotopic and, in the case of inheritance, temporal affinity to detritus that originated from Capricorn Orogen basement sources (e.g. 2005–1970 Ma Dalgaringa Supersuite of the Glenburgh Terrane). Furthermore, the range of Hf isotopic compositions in c. 1800 Ma magmatic zircons in the Rudall Province has similarity to that in the c. 1800 Ma Bridget Suite, which has an undisputed association to the Pilbara Craton. Hence, sources for all isotopic compositions preserved within the Rudall Province are present within the proximal West Australian Craton. There is no necessity to invoke transfer of exotic North Australian Craton lithotectonic units to the West Australian Craton margin and to suggest an accretionary style of orogenesis for the Rudall Province. The Tabletop Terrane has been regarded as a different far-travelled block with crust unique to the other components of the Rudall Province. This inference was based on the resemblance of magmatism in this terrane to that in the northern Gawler and Musgrave regions. However, the similarity of source compositions throughout all three terranes of the Rudall Province implies that the Tabletop Terrane was derived from crust of similar composition to the Connaughton and Talbot terranes. A phase of crust formation at 1.9 Ga is indicated by zircons within a Talbot Terrane c. 1450 Ma monzogranite, which have mantle-like oxygen isotope ratios. This timing of crust formation is distinctive and implies an affinity to a major deep lithospheric source of similar age documented in the Musgrave Province and could indicate a regional underplate of this age. These data indicate that the major suture between the North and West Australian Cratons lies to the east of the Rudall Province (present-day coordinates). KEYWORDS: continental accretion, crustal evolution, earth crust, hafnium isotopes, lutetium isotopes, oxygen isotopes, radiometric dating, structural evolution, zircon, zircon dating

Introduction

2.2 – 2.1 Ga Ophthalmian Orogeny, and second, this combined cratonic block collided with the Yilgarn Craton during the c. 1.9 Ga Glenburgh Orogeny (Johnson et al., 2012). Subsequent tectono-magmatic events include the 1820–1770 Ma Capricorn Orogeny and the 1800–1765 Ma Yapungku Orogeny; the latter recorded within the Rudall Province of the Paterson Orogen along the eastern margin of the West Australian Craton (all directions refer to present-day coordinates). In the Rudall Province, deformation, metamorphism, and magmatism during the Yapungku Orogeny have been interpreted as a response to either accretional events that sutured exotic terranes to the craton margin (Bagas, 2004), or to the collision and amalgamation of the North and West Australian Cratons (Bagas and Smithies, 1997; Tyler, 2000; Li et al., 2008). Deformation and magmatism associated with the Capricorn Orogeny is interpreted as an intraplate response to these far-field plate-margin events (Sheppard et al.,

Precambrian Australia comprises three main cratonic entities — the North, South, and West Australian Cratons — each of which was assembled and stabilized during the Paleoproterozoic. The West Australian Craton, which includes the Pilbara and Yilgarn Cratons and a wedge of exotic Archean to Paleoproterozoic continental crust known as the Glenburgh Terrane (Johnson et al., 2011a, 2012), was assembled along the Capricorn Orogen during two separate and distinct tectonic events. First, the Pilbara Craton and Glenburgh Terrane were sutured during the

1

GEMOC, Department of Earth & Planetary Sciences, Macquarie University, Sydney NSW 2109

2

John De Laeter Centre for Isotope Research, GPO Box U1987, Perth WA 6845 1

Kirkland et al.

pronounced gravity high, known as the Anketell Regional Gravity Ridge (GSWA, 2012). Metasedimentary and igneous rocks within the two provinces were deformed and metamorphosed at medium to high metamorphic grades during the Proterozoic. However, the timing of tectono-magmatic events in the two regions is distinctly different, with events in the Rudall Province dominated by the 1800–1765 Ma Yapungku Orogeny (Bagas, 2004), and those in the Musgrave Province by the 1345–1293 Ma Mount West Orogeny, the 1220–1150 Ma Musgrave Orogeny, and the 1085–1040 Ma Giles Event (Smithies et al., 2011). However, both provinces (including parts of the Centralian Superbasin), were reworked at low to medium metamorphic grades during the c. 550 Ma Paterson/Petermann Orogeny, implying that juxtaposition of the Musgrave and the Rudall regions may have occurred during latest Neoproterozoic to Cambrian time (Williams and Myers, 1990).

2010a; Johnson et al., 2012). Understanding the tectonic setting of the Rudall Province is important because this province may record the collision between the North and West Australian Cratons and preserve a major crustal suture related to the Proterozoic assembly of Australia. Furthermore, within the region, a range of Neoproterozoic mineral systems exist, including Zn–Pb (Warrabarty; Smith, 1996), Cu (Nifty; Huston et al., 2007), U (Kintyre; Cross et al., 2011) and Au–Cu (Telfer; Maidment et al., 2008; 2010). The isotopic signature of units characterized in this report may be of significance for constraining the influence and role of crystalline basement on these younger mineralizing systems. This report uses time-constrained Lu–Hf isotope analyses to evaluate the tectonic and crustal evolution of the Rudall Province, including: 1.

2.

whether the 1800–1765 Ma Yapungku Orogeny records the collision between the North and West Australian Cratons, or the assembly of exotic lithotectonic units to the West Australian Craton margin during accretionary orogenesis

whether terranes within the Rudall Province are exotic entities that:

The Rudall Province is divided into three major lithotectonic elements: the Talbot, Connaughton, and Tabletop Terranes (Hickman et al., 1994; Hickman and Bagas, 1995, 1999a; Bagas and Smithies, 1997; Fig. 2). The Talbot and Connaughton Terranes contain Paleoproterozoic intrusive rocks that formed during the Yapungku Orogeny, whereas the Tabletop Terrane consists of younger Mesoproterozoic granites. The three terranes are bounded by major faults that have been considered a response to terrane juxtaposition during the Yapungku Orogeny, or the c. 650 Ma Miles Orogeny, or both (Bagas and Smithies, 1997; Bagas, 2004).

a. formed part of the opposing North Australian Craton margin, being juxtaposed with the West Australian Craton during collisional orogenesis

The Talbot Terrane

whether terranes within the Rudall Province are (para) autochthonous and related to the thickening of a Proterozoic margin of the Pilbara Craton or, alternatively,

3.

The Talbot Terrane occupies the western parts of the Rudall Province (Fig. 2), and consists of multiply deformed and metamorphosed supracrustal and felsic intrusive rocks (Bagas and Smithies, 1997; Hickman and Bagas, 1999b, 1999a). The depositional setting of the siliciclastic rocks has been interpreted as a deltaic to moderately deep-water marine basin on the southeastern margin of the Pilbara Craton (Hickman et al., 1994).

or b. have an entirely exotic source (e.g. part of the northern Gawler and Musgrave regions; (Cassidy et al., 2006), having been accreted to the West Australian Craton margin during accretionary or collisional orogenesis.

Basement to the supracrustal rocks is not exposed, although a syenogranite gneiss from the Sundowner drillhole was interpreted to have crystallized at c. 2015 Ma (GSWA 104932; Nelson, 1995a). However, it is possible that the granitic protolith to the gneiss is much younger, and contains only inherited zircons. Major zircon age components, at 2715–2577, 2010, and 1960 Ma, are also present in this gneiss (Nelson, 1995a).

Geological setting of the Rudall Province The ~2000 km long Paterson/Petermann Orogens of Western Australia extend along the eastern margin of the Archean Pilbara Craton, beneath younger sedimentary rocks, and into Central Australia (Fig. 1). The orogen includes Paleoproterozoic to Mesoproterozoic metasedimentary and igneous rocks of the Rudall and Musgrave Provinces, and Neoproterozoic to Paleozoic sedimentary rocks of the Centralian Superbasin (Myers and Hocking, 1988; Williams and Myers, 1990; Clarke, 1991; Bagas and Lubieniecki, 2000; Bagas et al., 2001; Haines et al., 2001; Bagas, 2004; Cawood and Korsch, 2008; Smithies et al., 2011; Reading et al., 2012). The Rudall and Musgrave Provinces are separated by younger sedimentary rocks of the Yeneena, northwest Officer, and Canning Basins, but appear to be connected via a

The metasedimentary rocks of the Talbot Terrane are divided into a western association of quartzite, amphibolite, serpentinite, and banded iron-formation, and an extensive eastern association containing nearly 5 km of siliciclastic sedimentary rocks. The eastern association consists of quartz-feldspar-mica paragneisses of the Larry Formation, conformably overlain by a succession of quartzite and minor mica schist known as the Fingoon Quartzite (Hickman et al., 1994; Bagas and Smithies, 1998). Quartz-muscovite schist, iron-rich graphitic pelitic schist, banded iron-formation, and chert of the 2

GSWA Report 122

The crustal evolution of the Rudall Province from an isotopic perspective 115°

120°

20°

SO R

TE PA

Canning Basin O RO 0

ton

Phanerozoic

Basin Officer Basin 2000

GT 3000

Narryer Terrane

Southern Cross Domain

27.03.13

Figure 1.

Simplified geological map indicating the location of the Rudall Province relative to other Proterozoic orogens and Archean cratons in Western Australia (modified after Sheppard et al., 2010a). Red dashed line indicates the approximate coverage of an extensive basin system during the 1820–1770 Ma Capricorn Orogeny. Inset map (top right) shows the location of the main map as a red rectangle and the WAC (West Australian Craton) in the context of other tectonic entities. Abbreviations used in figure: CG — Capricorn Group, GC — Gawler Craton, GT — Glenburgh Terrane, KC — Kimberley Craton, LRF — Lyons River Fault, NAC — North Australian Craton, PC — Pilbara Craton, SAC — South Australian Craton, YC — Yilgarn Craton, WAC — West Australian Craton.

Yandagooge Formation rest conformably on the Fingoon Quartzite. The Yandagooge Formation is overlain by banded paragneiss and minor amphibole-chlorite schist of the Butler Creek Formation, and quartzite and quartzfeldspar-mica gneiss of the Poynton Formation. Detrital zircon age data for the Fingoon Quartzite indicate a unimodal zircon age component at 1791 ± 10 Ma (Nelson, 1995e), which also provides a maximum depositional age for the sedimentary protolith to the quartzite and for the lowermost part of the eastern association.

123°

Permian

Camel–Tabletop Fault Zone

CANNING BASIN

Late granitic rocks Tabletop Terrane

Talbot Terrane

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we s

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Mc

Ka

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Throssell Group & Lamil Group undivided Tabletop Terrane Talbot Terrane Connaughton Terrane

Rudall Province

Tarcunyah Group

Paterson Orogen

Based on the presence of western association xenoliths within strongly deformed orthogneisses with c. 2015 and c. 1972 Ma zircon age components, the western association has generally been regarded as considerably older than the eastern association (Bagas, 2004). However, it is possible that the protoliths to the orthogneisses are much younger, containing only inherited zircons, and thus the two sequences may be of comparable age (Neumann and Fraser, 2007).

y Fa ul t

CLK80

Figure 2.

Archean

200 km

Eastern Goldfields Superterane

CLK88

So

Palaeoproterozoic

4000

YILGARN CRATON Murchison Domain

Mesoproterozoic

igneous and metamorphic

Collier Basin in OROGEN

Edmund Bas

sedimentary andvolcanic

Neoproterozoic 1000

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Carnarvon Basin

122°

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granitegreenstone

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Fortescue, Hamersley, and Turee Creek Basins

As

Gascoyne Province

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East Pilbara Terrane

CG

Arunta Musgraves

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PILBARA CRATON

Fault Thrust Normal fault

Metasedimentary rocks in both the eastern and western associations of the Talbot Terrane have been intruded by voluminous granites of the 1800–1765 Ma Kalkan Supersuite (Budd et al., 2002). These granitic rocks are characterized by high-K, metaluminous, calc-alkaline chemistry, with large K-feldspar phenocrysts and

Simplified geological map of the Rudall Province, indicating the main geological features and the distribution of terranes (modified after Bagas and Smithies, 1997; Smithies and Bagas, 1997).

3

Kirkland et al.

Sr  depleted, Y-undepleted trace-element patterns typical of many Australian Proterozoic granite suites (Wyborn, 2001). These granites have crystallization ages between c. 1800 and c. 1760 Ma (Nelson, 1995i, 1995k), which provide a younger limit for deposition of the protoliths to both metasedimentary associations in the Rudall Province. Compressional shear zones within the Talbot Terrane contain enclaves of deformed ultramafic and mafic rocks, interpreted to represent slivers of dismembered ophiolite (Carr, 1989).

rocks of the Krackatinny Suite, with minor quartzite, mafic and ultramafic schists, amphibolite, and banded iron-formation (Bagas et al., 1999). Unpublished geochronology reported in Neumann and Fraser (2007) indicates that most of the felsic and mafic intrusive rocks of the Krackatinny Suite away from the Camel–Tabletop Fault were emplaced between c. 1590 and c. 1550 Ma. Other felsic intrusive rocks in this terrane have been dated at 1476 ± 10 Ma (unpublished result referred to in Bagas, 2004) and 1310 ± 4 Ma (Nelson, 1996e).

The Talbot Terrane also records minor magmatic episodes during the Mesoproterozoic, including a 1453 ± 10 Ma monzogranite that crosscuts fabrics associated with the Yapungku Orogeny (Nelson, 1996b) and a 1291 ± 10 Ma pegmatite close to the Camel–Tabletop Fault (Nelson, 1995b).

Available geochronology suggests that the magmatic history of the Tabletop Terrane is distinctly different from that in the Talbot and Connaughton Terranes, which share a common structural, magmatic, and deformational history (Bagas, 2004). The Tabletop Terrane does not appear to contain evidence for 1800–1760 Ma magmatism, whereas the Talbot and Connaughton Terranes lack 1590–1550 Ma magmatism, possibly implying that the Camel–Tabletop Fault (Fig. 2), which separates these terranes, is a major crustal boundary (Hickman et al., 1994; Bagas and Lubieniecki, 2000).

The Connaughton Terrane The Connaughton Terrane (Fig. 2), within the southeastern part of the province, comprises a series of poorly dated metavolcanic and metasedimentary rocks. This terrane contains a significantly higher proportion of amphibolite than the Talbot Terrane (Bagas and Smithies, 1998). The amphibolite is interlayered with banded iron-formation, quartzite, pelitic metasedimentary rocks, chert, and ultramafic rocks (Hickman et al., 1994). In a situation similar to the Talbot Terrane, basement rocks are not exposed. Importantly, all rocks within the Connaughton Terrane were metamorphosed at upper amphibolite to granulite facies conditions (peak 800°C, 12 kbar) during the Yapungku Orogeny (Smithies and Bagas, 1997).

Structural evolution The Talbot and Connaughton Terranes share a similar structural history, including two high-grade tectonomagmatic events during the Paleoproterozoic Yapungku Orogeny (Clarke, 1991; Hickman et al., 1994; Bagas and Smithies, 1997; Hickman and Bagas, 1999b; Bagas, 2004). The timing and duration of the Yapungku Orogeny is defined by the age of the oldest and youngest granitic components at c. 1800 and c. 1760 Ma, respectively (Smithies and Bagas, 1997; Bagas, 2004). In the Talbot Terrane, both tectonothermal events occurred prior to c. 1778 Ma, as constrained by the age of undeformed aplite dykes (Nelson, 1995j) that crosscut the major tectonic fabrics. The main phase of deformation and metamorphism in the Connaughton Terrane is not well established, but has been interpreted to be coeval with lower-pressure metamorphism (M2) in the Talbot Terrane (Bagas and Smithies, 1997; Bagas, 2004).

Preliminary U–Pb geochronology of detrital zircons in quartzite provides a maximum depositional age of c. 2300 Ma, and a provenance signature (age spectrum) significantly different from that of the Fingoon Quartzite of the Talbot Terrane (Maidment et al., in prep. reported in Neumann and Fraser, 2007). Insufficient geochronological data from metasedimentary rocks from both the Talbot and Connaughton Terranes makes it difficult to determine if they had different sedimentary source regions or depositional ages, or both.

The first deformation event (D1) is preserved as beddingparallel fabrics in the Talbot Terrane (Clarke, 1991; Bagas and Smithies, 1998). Associated metamorphic features indicate low-pressure metamorphism at amphibolite facies. The timing of D1 in the Talbot Terrane is constrained to be older than 1802 ± 14 Ma, the age of a K-feldspar porphyritic granite that crosscuts D1 fabrics (Nelson, 1995i). Evidence for D1 and M1 in the Connaughton Terrane is preserved only as inclusion trails of epidote, titanite, and amphibole within garnet porphyroblasts (Smithies and Bagas, 1997).

Granitic rocks of the 1800–1765 Ma Kalkan Supersuite (Nelson, 1995m; 1996d) form a major component of the Connaughton Terrane. This terrane may also have been subject to minor Mesoproterozoic magmatic activity. A garnet-bearing gneiss, south of Harbutt Range in the Connaughton Terrane, yielded zircon age components at c. 1800, 1672, and 1222 Ma (Nelson, 1996c), with the youngest group interpreted to date crystallization of the felsic intrusive protolith. However, the c. 1222 Ma date was obtained from zircon rims that have elevated thorium and common Pb contents and may have grown during metamorphism.

The D2 event produced north–south isoclinal folding, faulting, and crustal thickening in the Talbot and Connaughton Terranes, and was coeval with thrusting and the emplacement of granitic, mafic, and ultramafic (peridotite–dunite) rocks in the Talbot Terrane (Hickman and Bagas, 1995, 1999b). Geochronology of syn-D2 granitic rocks in the Talbot Terrane indicates that the D2 event occurred between c. 1801 and c. 1765 Ma

The Tabletop Terrane The Tabletop Terrane (Fig. 2) is dominated by weakly deformed and metamorphosed felsic and mafic igneous 4

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The crustal evolution of the Rudall Province from an isotopic perspective

Analytical methodology

(Nelson, 1995i, 1995k, 1995c; Bagas, 2004). In the Connaughton Terrane, peak regional M2 metamorphism was synchronous with, but outlasted, D2 deformation in the Talbot Terrane (Hickman et al., 1994). Pelitic schists within the Talbot Terrane contain peak M2 mineral assemblages of kyanite + garnet + staurolite, which are indicative of metamorphism in the mid-amphibolite facies (Smithies and Bagas, 1997; Bagas, 2004). In the Connaughton Terrane, peak M2 metamorphism is characterized by the presence of amphibolites and mafic granulites that were metamorphosed at high pressures (≤ 1200 MPa) close to the amphibolite–granulite facies transition, indicating that crust from depths of up to 40 km is now exposed at the surface (Smithies and Bagas, 1997). These conditions also imply that the deformation and metamorphism assigned to D2/M2 were in response to crustal thickening in which the Connaughton Terrane was thrust westwards over the Talbot Terrane (Bagas, 2004).

Lu–Hf isotopes Hafnium isotope analyses were conducted on previously dated zircons using a New Wave/Merchantek LUV213 laser-ablation microprobe attached to a Nu Plasma multicollector inductively coupled plasma mass spectrometer (LA-MC-ICPMS). The analyses employed a beam diameter of c. 40 µm and a 5 Hz repetition rate, and energies of 0.6 – 1.3 mJ per pulse, which resulted in ablation pits typically 40–60 µm deep during a 30–120 second analysis. Total Hf signals were between 1 x 10-11 and 6 x 10-11 amperes. The ablated sample material was transported from the laser cell to the ICPMS torch by a helium carrier gas. Interference of 176Lu on 176Hf was corrected by measurement of interference-free 175Lu, and using the invariant 176Lu/175Lu correction factor of 0.02669 (Debievre and Taylor, 1993). The measurement of accurate 176Hf/177Hf ratios in zircon requires correction of the isobaric interferences of 176Lu and 176Yb on 176Hf. The interference of 176Yb on 176Hf was corrected by measuring the interference-free 172Yb isotope and using the 176Yb/172Yb ratio to calculate the intensity of 176Yb. The appropriate value of 176Yb/172Yb (0.5865) was determined by successively doping a JMC475 Hf standard (100 ppb solution) with various amounts of Yb, and determining the value of 176Yb/172Yb required to yield the value of 176 Hf/177Hf in the undoped solution.

The Rudall Province has also been subject to several Neoproterozoic deformation events (Bagas, 2004). Northwesterly trending folds and north-northeasterly trending faults ascribed to D3/4 were developed during the c. 650 Ma Miles Orogeny (Bagas and Smithies, 1998; Hickman and Bagas, 1999b). Lower-greenschist facies metamorphism prevailed during northeasterly to southwesterly oriented shortening associated with the D4 event. An enigmatic D5 event is believed to be a response to northwest-directed shortening against the Pilbara Craton. The late Neoproterozoic (550 Ma) Paterson Orogeny, ascribed to D6, was responsible for easterly trending transpressional folds (Bagas, 2004).

Twenty-three zircons from the Mud Tank carbonatite locality were analysed, together with the samples, as a measure of the accuracy of the results. Most of the data and the mean 176Hf/177Hf value (0.282530 ± 0.000022; n = 23) are within two standard deviations (SD) of the recommended value (0.282522 ± 0.000042 (2V; Griffin, 2007). Temora-2 zircon was run as an independent check on the accuracy of the Yb correction. Temora zircon has an average 176Yb/177Hf ratio of 0.037, which is similar to the average 176Yb/177Hf ratio of Rudall zircon of 0.039. The average 176Hf/177Hf ratio for Temora-2 is 0.282683 ± 0.000022 (1V), which is consistent with the published value for the Temora-2 standard (0.282686 ± 8, solution ICPMS, Woodhead and Hergt, 2005; 0.282687 ± 24, LA-ICPMS, Hawkesworth and Kemp, 2006).

Lu–Hf and oxygen isotopes, and reinterpreted SHRIMP U–Pb geochronology This section presents new Lu–Hf (Table 1) and oxygen isotope data (Table 2) for previously dated samples from the Rudall Province. The geochemical characteristics of many of these samples have previously been discussed in Wyborn (2001). We calculate concordia ages from the previously published SHRIMP U–Pb geochronology data for these rocks. Where the location of the mean U–Pb composition can be assumed to fall on the concordia curve (i.e. the zircons have not undergone modern or ancient radiogenic-Pb loss), the ‘concordia age’ makes the optimum use of both 207Pb*/206Pb* and 238U/206Pb* ratios (Ludwig, 1998)1. This approach generally yields a more precise mean age than can be obtained using either ratio alone, and also yields an objective and quantitative measure of concordance. In cases where the U–Pb data do not fall on concordia, it is likely that the zircons have undergone modern or ancient radiogenic-Pb loss. Where the distribution of U–Pb data are consistent with mainly geologically-recent loss of radiogenic Pb, we calculate the weighted mean 207Pb*/206Pb* date. Weighted mean and concordia ages are reported below with 95% confidence intervals. A summary of the U–Pb geochronology is presented in Table 3. 1

Calculation of initial 176Hf/177Hf (e.g. 176Hf/177Hfi) is based on the 176Lu decay constant of Scherer et al. (2001; 1.867 x 10-11 yr-1). Since 176Hf/177Hf departures from the CHUR evolution line are very small, the epsilon notation is used whereby one epsilon unit represents a one part per 10 000 deviation from the CHUR composition. HHf values employ the present-day chondritic measurement of Blichert-Toft and Albarède (1997; 0.282772). Calculation of model ages (TDM) is based on a depleted-mantle source with 176 Hf/177Hfi = 0.279718 at 4.56 Ga and 176Lu/177Hf = 0.0384 (Griffin et al., 2004). Measured isotope compositions are referred to model bulk-Earth Hf reservoirs, including Depleted Mantle (DM; Griffin et al., 2000, 2004) and Chondritic Uniform Reservoir (CHUR; Blichert-Toft and Albarède 1997).

Pb* refers to radiogenic Pb produced by the in-situ decay of uranium. 5

Pb*/206Pb* (Ma)

1872

1831

1873

1764

1684

1771

1772

1629

1274

1144

1820

1677

1769

1787

112160-1.1

112160-2.1

112160-3.1

112160-4.1

112160-5.1

112160-6.1

112160-7.1

112160-8.1

112160-9.1

112160-9.2

112160-10.1

112160-11.1

113002-01.1

113002-02.1

1770

1762

1780

1742

1773

1772

1777

1760

1765

1763

1765

1788

1785

1756

1791

1771

1265

1495

113002-03.1

113002-05.1

113002-06.1

113002-08.1

113002-09.1

113002-10.1

113002-12.1

113002-14.1

113035-06.1

113035-07.1

113035-08.1

113035-09.1

113035-10.1

113035-11.1

113035-12.1

113035-13.1

118914-01.1

118914-02.1

207

Analysis No.

Hf/177Hf

6

0.281729

0.281903

0.281648

0.281608

0.281623

0.281631

0.281618

0.281642

0.281696

0.281580

0.281541

0.281583

0.281572

0.281546

0.281553

0.281536

0.281539

0.281519

0.281531

0.281531

0.281287

0.281504

0.281410

0.281369

0.281436

0.281338

0.281369

0.281406

0.281370

0.281438

0.281358

0.281396

176

0.000013

0.000014

0.000011

0.000009

0.000009

0.000017

0.000015

0.000014

0.000013

0.000011

0.000009

0.000007

0.000008

0.000009

0.000009

0.000007

0.000009

0.000008

0.000010

0.000009

0.000017

0.000020

0.000011

0.000013

0.000015

0.000011

0.000014

0.000049

0.000017

0.000018

0.000015

0.000009

1 SE

Table 1.

Lu/177Hf

0.003623

0.003001

0.000993

0.000802

0.000650

0.000787

0.000588

0.000792

0.000780

0.000478

0.000763

0.000667

0.000872

0.000559

0.000708

0.000436

0.000827

0.000660

0.000859

0.000901

0.001220

0.003659

0.000747

0.001463

0.000802

0.001255

0.002759

0.001672

0.000955

0.001286

0.000699

0.000492

176

0.141091

0.097656

0.034988

0.024706

0.019905

0.028304

0.019982

0.024360

0.022821

0.015547

0.024464

0.020670

0.026520

0.017819

0.022819

0.012568

0.025361

0.019636

0.024997

0.026661

0.036139

0.148092

0.029041

0.055740

0.023592

0.036494

0.098871

0.050077

0.028749

0.036350

0.020583

0.014042

Yb/177Hf

176

0.281627

0.281831

0.281615

0.281581

0.281601

0.281604

0.281598

0.281616

0.281670

0.281564

0.281516

0.281561

0.281543

0.281527

0.281530

0.281521

0.281511

0.281497

0.281502

0.281501

0.281248

0.281378

0.281394

0.281334

0.281411

0.281296

0.281276

0.281353

0.281338

0.281392

0.281334

0.281379

Hf/177Hfi

176

-7.3

-5.3

-1.5

-2.3

-2.3

-1.6

-1.7

-1.6

0.3

-3.4

-5.3

-3.3

-4.0

-4.6

-5.2

-4.6

-5.4

-5.7

-5.1

-5.6

-16.6

-8.8

-23.5

-22.7

-11.9

-12.8

-13.5

-12.8

-11.5

-7.1

-10.1

-7.6

İHf

Lu–Hf isotopic measurement of zircons from the Rudall Province

0.46

0.49

0.39

0.32

0.32

0.60

0.53

0.49

0.46

0.39

0.33

0.26

0.27

0.30

0.32

0.25

0.30

0.29

0.35

0.31

0.60

0.70

0.39

0.46

0.53

0.39

0.49

1.72

0.60

0.63

0.53

0.32

1 SE

2.30

2.00

2.25

2.29

2.26

2.26

2.27

2.24

2.17

2.31

2.38

2.32

2.35

2.36

2.36

2.37

2.39

2.40

2.40

2.40

2.76

2.63

2.56

2.66

2.53

2.69

2.76

2.63

2.63

2.56

2.63

2.56

TDM

2.72

2.41

2.56

2.62

2.60

2.57

2.59

2.56

2.44

2.68

2.79

2.68

2.72

2.76

2.77

2.76

2.80

2.83

2.80

2.82

3.44

3.06

3.45

3.50

3.11

3.27

3.32

3.20

3.19

2.99

3.15

3.02

TDM2

Tabletop

Tabletop

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Connaughton

Terrane

Kirkland et al.

Pb*/206Pb* (Ma)

1320

1315

1312

1324

1312

1194

1241

1298

1297

1287

1308

1311

1311

1311

1475

1453

1452

1435

1414

1426

1460

1453

1755

1810

1814

1796

1784

1790

1799

1781

1777

118914-03.1

118914-04.1

118914-05.1

118914-06.1

118914-07.1

118914-08.1

118914-09.1

118914-10.1

118914-11.1

118914-12.1

118914-15.1

118914-16.1

118914-17.1

118914-19.1

112102-4.1

112102-5.1

112102-6.1

112102-7.1

112102-8.1

112102-9.1

112102-10.1

112102-11.1

112101-01.2

112101-03.1

112101-04.1

112101-05.1

112101-06.1

112101-07.1

112101-08.1

112101-16.1

112101-17.1

207

Analysis No.

Hf/177Hf

7

0.281597

0.281591

0.281598

0.281572

0.281513

0.281575

0.281472

0.281463

0.281442

0.282094

0.282068

0.282054

0.282013

0.282031

0.282040

0.282033

0.282035

0.281764

0.281764

0.281798

0.281765

0.281776

0.281742

0.281780

0.281798

0.281766

0.281826

0.281771

0.281791

0.281802

0.281803

176

0.000010

0.000012

0.000015

0.000013

0.000012

0.000013

0.000008

0.000005

0.000008

0.000012

0.000025

0.000014

0.000011

0.000028

0.000013

0.000013

0.000014

0.000005

0.000010

0.000020

0.000008

0.000032

0.000018

0.000011

0.000016

0.000013

0.000014

0.000017

0.000021

0.000011

0.000011

1 SE

Lu/177Hf

0.000891

0.001056

0.001044

0.000766

0.001788

0.001341

0.000818

0.000698

0.000968

0.002730

0.002270

0.002922

0.002157

0.002243

0.002475

0.002009

0.002520

0.002445

0.002958

0.002938

0.002726

0.002247

0.004097

0.002835

0.003229

0.003034

0.003057

0.002295

0.002184

0.002427

0.002519

176

continued

0.033306

0.043864

0.042037

0.026506

0.075706

0.051304

0.031265

0.025322

0.037094

0.100553

0.084062

0.095044

0.071807

0.079450

0.093336

0.065885

0.090435

0.082733

0.101949

0.113409

0.100720

0.081515

0.157883

0.100851

0.093079

0.101863

0.101681

0.076764

0.073725

0.088281

0.085458

Yb/177Hf

176

Table 1.

0.281567

0.281555

0.281562

0.281546

0.281453

0.281529

0.281444

0.281439

0.281410

0.282019

0.282005

0.281975

0.281955

0.281970

0.281972

0.281978

0.281965

0.281703

0.281691

0.281725

0.281698

0.281721

0.281642

0.281711

0.281722

0.281698

0.281750

0.281714

0.281737

0.281742

0.281740

Hf/177Hfi

176

-3.1

-3.4

-2.7

-3.5

-7.0

-4.0

-6.6

-6.9

-9.1

5.6

5.3

3.5

2.5

3.5

4.0

4.2

4.2

-8.8

-9.2

-8.0

-9.0

-8.7

-11.3

-8.8

-9.7

-11.6

-7.1

-8.1

-7.5

-7.3

-7.2

İHf

0.34

0.42

0.53

0.46

0.42

0.46

0.27

0.19

0.27

0.42

0.88

0.49

0.39

0.98

0.46

0.46

0.49

0.19

0.34

0.70

0.28

1.12

0.63

0.39

0.56

0.46

0.49

0.60

0.74

0.39

0.39

1 SE

2.31

2.33

2.32

2.34

2.49

2.37

2.48

2.48

2.53

1.71

1.73

1.78

1.80

1.78

1.78

1.76

1.79

2.17

2.20

2.15

2.19

2.14

2.31

2.17

2.17

2.20

2.12

2.15

2.12

2.12

2.12

TDM

2.66

2.69

2.66

2.70

2.92

2.74

2.92

2.93

3.03

1.86

1.88

1.97

2.03

1.98

1.96

1.95

1.97

2.66

2.69

2.61

2.68

2.64

2.81

2.65

2.66

2.75

2.56

2.63

2.59

2.57

2.57

TDM2

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Tabletop

Tabletop

Tabletop

Tabletop

Tabletop

Tabletop

Tabletop

Tabletop

Tabletop

Tabletop

Tabletop

Tabletop

Tabletop

Tabletop

Terrane

GSWA Report 122 The crustal evolution of the Rudall Province from an isotopic perspective

Pb*/206Pb* (Ma)

1717

1804

1800

1801

1795

1809

1799

1794

1786

1772

1806

1797

1788

1760

1727

1612

1765

1703

1786

1754

1739

1717

1778

1877

1790

2102

1715

1756

1807

1723

1790

1809

104980-02.1

104980-03.1

104980-05.1

104980-06.1

104980-07.1

104980-08.1

104980-09.1

104980-12.1

104980-13.1

112341-02.1

112341-03.1

112341-04.1

112341-05.1

112341-06.1

112341-07.1

112341-09.1

112341-10.1

112341-11.1

112341-12.1

112341-13.1

112341-14.1

112341-15.1

111843-01.1

111843-01.2

111843-02.1

111843-03.1

111843-04.1

111843-07.1

111843-07.2

111843-08.1

111843-09.1

111843-10.1

207

Analysis No.

Hf/177Hf

8

0.281459

0.281354

0.281430

0.281498

0.281450

0.281477

0.281309

0.281483

0.281488

0.281554

0.281526

0.281518

0.281524

0.281535

0.281509

0.281490

0.281572

0.281515

0.281502

0.281518

0.281536

0.281572

0.281564

0.281444

0.281442

0.281457

0.281453

0.281448

0.281451

0.281467

0.281466

0.281569

176

0.000016

0.000010

0.000008

0.000015

0.000018

0.000009

0.000016

0.000012

0.000010

0.000014

0.000014

0.000011

0.000011

0.000011

0.000010

0.000009

0.000009

0.000011

0.000009

0.000011

0.000012

0.000006

0.000027

0.000008

0.000009

0.000010

0.000018

0.000006

0.000008

0.000021

0.000015

0.000023

1 SE

Lu/177Hf

0.001151

0.001373

0.001284

0.001065

0.000935

0.000788

0.000587

0.000822

0.000891

0.000900

0.001290

0.001365

0.001152

0.001213

0.001197

0.001027

0.000877

0.001399

0.000788

0.001534

0.001143

0.001141

0.006793

0.001045

0.001271

0.001302

0.001201

0.001312

0.001196

0.001061

0.001407

0.001825

176

0.035119

0.046598

0.038480

0.035546

0.028499

0.025412

0.018820

0.024279

0.025788

0.026260

0.063274

0.069148

0.043213

0.061997

0.065563

0.043101

0.036724

0.070912

0.037669

0.075168

0.056483

0.045455

0.257677

0.049180

0.064207

0.061824

0.056860

0.058224

0.051647

0.049399

0.065622

0.091936

Hf/177Hfi

0.281420

0.281307

0.281388

0.281462

0.281419

0.281451

0.281286

0.281455

0.281456

0.281524

0.281484

0.281473

0.281486

0.281494

0.281470

0.281456

0.281545

0.281469

0.281476

0.281466

0.281497

0.281533

0.281336

0.281409

0.281399

0.281413

0.281412

0.281403

0.281410

0.281431

0.281418

0.281510

176

continued

Yb/177Hf

176

Table 1.

-7.6

-12.0

-10.6

-6.1

-8.8

-8.6

-5.7

-6.7

-4.7

-4.6

-7.4

-7.3

-6.5

-5.5

-8.2

-7.3

-7.6

-7.7

-6.7

-6.4

-5.1

-3.6

-11.4

-8.5

-8.7

-8.0

-7.8

-8.5

-8.1

-7.4

-7.7

-6.5

İHf

0.56

0.35

0.26

0.53

0.63

0.31

0.56

0.42

0.35

0.49

0.49

0.39

0.39

0.39

0.34

0.30

0.30

0.39

0.33

0.39

0.42

0.22

0.95

0.26

0.33

0.34

0.63

0.21

0.26

0.74

0.53

0.81

1 SE

2.52

2.68

2.57

2.46

2.52

2.47

2.68

2.46

2.46

2.37

2.43

2.45

2.43

2.42

2.45

2.47

2.35

2.46

2.44

2.46

2.41

2.36

2.79

2.53

2.55

2.53

2.53

2.54

2.53

2.50

2.53

2.41

TDM

2.97

3.24

3.10

2.88

3.01

2.96

3.08

2.91

2.85

2.76

2.89

2.90

2.86

2.82

2.93

2.92

2.82

2.92

2.88

2.88

2.81

2.72

3.19

3.01

3.03

3.00

2.99

3.02

3.00

2.95

2.98

2.83

TDM2

Talbot

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Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

Talbot

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Terrane

Kirkland et al.

Pb*/206Pb* (Ma)

1810

1928

1777

1791

1796

1816

1817

1815

1791

1810

1804

1777

1791

1786

1777

1775

1955

1805

1801

1761

1794

1785

1755

2327

1784

1746

1749

1778

1792

1977

1811

111843-10.2

111843-11.1

104989-01.1

104989-02.1

104989-03.1

104989-04.1

104989-05.1

104989-06.1

104989-07.1

104989-08.1

104989-09.1

104989-10.1

104989-11.1

104989-12.1

104989-13.1

104989-14.1

104989-16.1

104989-17.1

104989-18.1

104989-19.1

111854-01.1

111854-02.1

111854-04.1

111854-05.1

111854-06.1

111854-08.1

111854-09.1

111854-11.1

111854-12.1

112310-01.1

112310-02.1

207

Analysis No.

Hf/177Hf

9

0.281512

0.281544

0.281421

0.281452

0.281498

0.281478

0.281538

0.281402

0.281504

0.281533

0.281495

0.281556

0.281517

0.281573

0.281316

0.281469

0.281489

0.281497

0.281490

0.281589

0.281499

0.281504

0.281467

0.281587

0.281488

0.281284

0.281495

0.281478

0.281589

0.281253

0.281475

176

0.000008

0.000005

0.000009

0.000012

0.000008

0.000008

0.000009

0.000010

0.000027

0.000011

0.000007

0.000011

0.000011

0.000013

0.000009

0.000011

0.000007

0.000013

0.000011

0.000009

0.000013

0.000015

0.000010

0.000013

0.000009

0.000013

0.000011

0.000012

0.000013

0.000008

0.000009

1 SE

Lu/177Hf

0.000754

0.001536

0.001333

0.000651

0.001013

0.001210

0.001433

0.001028

0.002128

0.001225

0.001483

0.000577

0.000724

0.000832

0.000764

0.002715

0.000698

0.000701

0.001177

0.000884

0.001676

0.001058

0.002499

0.001550

0.000966

0.000306

0.000957

0.001125

0.001618

0.000901

0.000916

176

0.021541

0.044432

0.048240

0.029702

0.044439

0.055630

0.061732

0.045938

0.091238

0.054238

0.059610

0.018483

0.024356

0.026043

0.025557

0.107964

0.022938

0.024107

0.045774

0.028606

0.060606

0.033601

0.098945

0.049102

0.030227

0.012546

0.034130

0.039609

0.052245

0.028782

0.028391

Hf/177Hfi

0.281486

0.281486

0.281376

0.281430

0.281464

0.281438

0.281490

0.281356

0.281433

0.281492

0.281445

0.281537

0.281492

0.281545

0.281288

0.281378

0.281465

0.281473

0.281450

0.281559

0.281442

0.281468

0.281382

0.281534

0.281455

0.281273

0.281462

0.281440

0.281534

0.281220

0.281444

176

continued

Yb/177Hf

176

Table 1.

-5.2

-1.4

-9.5

-7.9

-7.3

-8.3

-5.7

2.0

-8.3

-5.6

-7.0

-4.5

-5.2

-3.2

-8.9

-9.8

-6.7

-6.2

-6.9

-3.3

-6.9

-5.8

-9.3

-3.4

-6.1

-12.6

-6.3

-7.3

-4.2

-12.0

-6.7

İHf

0.27

0.19

0.33

0.42

0.29

0.28

0.31

0.35

0.95

0.39

0.26

0.39

0.39

0.46

0.30

0.39

0.25

0.46

0.39

0.31

0.46

0.53

0.35

0.46

0.32

0.46

0.39

0.42

0.46

0.29

0.32

1 SE

2.42

2.43

2.58

2.49

2.46

2.50

2.43

2.59

2.52

2.42

2.49

2.35

2.41

2.34

2.69

2.61

2.45

2.44

2.48

2.32

2.50

2.45

2.60

2.37

2.47

2.70

2.46

2.49

2.37

2.78

2.48

TDM

2.82

2.71

3.08

2.97

2.91

2.97

2.83

2.76

2.98

2.83

2.93

2.74

2.82

2.70

3.17

3.09

2.89

2.87

2.92

2.68

2.93

2.86

3.07

2.71

2.89

3.30

2.89

2.94

2.74

3.34

2.92

TDM2

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Terrane

GSWA Report 122 The crustal evolution of the Rudall Province from an isotopic perspective

Pb*/206Pb* (Ma)

1963

1797

1816

1972

1780

1974

1975

1975

1932

1980

1958

1937

1810

1760

112310-03.1

112310-04.1

112310-05.1

112310-06.1

112310-07.1

112310-08.1

112310-09.1

112310-10.1

112310-14.1

112310-16.1

112310-17.1

112310-18.1

112379-01.1

112379-03.1

1763

1775

1752

1788

1741

1802

1794

1741

1746

1682

1785

1784

1768

1771

1793

1780

1796

1817

112379-04.1

112379-05.1

112379-06.1

112379-07.1

112379-08.1

112379-14.1

112379-15.1

112379-17.1

112379-18.1

112379-19.1

112397-01.1

112397-02.1

112397-03.1

112397-04.1

112397-05.1

112397-06.1

112397-07.1

112397-08.1

207

Analysis No.

Hf/177Hf

10

0.281448

0.281484

0.281468

0.281499

0.281489

0.281480

0.281454

0.281469

0.281478

0.281442

0.281477

0.281445

0.281477

0.281421

0.281455

0.281474

0.281455

0.281527

0.281485

0.281499

0.281548

0.281554

0.281569

0.281564

0.281601

0.281504

0.281584

0.281419

0.281537

0.281475

0.281481

0.281555

176

0.000009

0.000011

0.000010

0.000016

0.000010

0.000009

0.000010

0.000009

0.000009

0.000009

0.000013

0.000011

0.000011

0.000009

0.000007

0.000010

0.000011

0.000022

0.000016

0.000020

0.000011

0.000011

0.000009

0.000009

0.000008

0.000018

0.000018

0.000020

0.000013

0.000021

0.000014

0.000015

1 SE

Lu/177Hf

0.000702

0.000694

0.000614

0.000543

0.000736

0.000601

0.000503

0.000511

0.000562

0.000701

0.000948

0.000748

0.000920

0.000612

0.000642

0.001369

0.000668

0.000579

0.000821

0.000730

0.000958

0.001144

0.000703

0.001409

0.001479

0.001800

0.001598

0.001023

0.001642

0.000977

0.001473

0.001174

176

0.032289

0.021747

0.021757

0.019933

0.017932

0.023483

0.018630

0.016207

0.015599

0.017870

0.022225

0.031823

0.025452

0.030384

0.019913

0.021521

0.045031

0.021022

0.019052

0.025499

0.020896

0.023614

0.032714

0.018597

0.040725

0.046078

0.048291

0.047092

0.028099

0.047882

0.027342

0.043455

Hf/177Hfi

0.281424

0.281460

0.281447

0.281481

0.281464

0.281460

0.281437

0.281452

0.281460

0.281419

0.281446

0.281420

0.281446

0.281401

0.281433

0.281429

0.281433

0.281508

0.281458

0.281474

0.281513

0.281511

0.281543

0.281512

0.281545

0.281436

0.281524

0.281384

0.281475

0.281441

0.281431

0.281511

176

continued

Yb/177Hf

176

Table 1.

-7.2

-6.4

-7.2

-5.8

-6.8

-7.1

-7.5

-7.0

-9.0

-9.0

-8.2

-7.9

-6.8

-9.8

-7.6

-8.5

-7.9

-5.5

-7.3

-5.6

-1.3

-0.9

0.7

-1.5

0.7

-3.2

-0.1

-9.5

-1.9

-6.6

-7.4

-0.8

İHf

0.33

0.39

0.35

0.56

0.35

0.31

0.34

0.30

0.30

0.30

0.46

0.39

0.39

0.32

0.26

0.35

0.39

0.77

0.56

0.70

0.39

0.39

0.30

0.33

0.27

0.63

0.63

0.70

0.46

0.74

0.49

0.53

1 SE

2.50

2.45

2.47

2.42

2.45

2.45

2.48

2.46

2.45

2.51

2.48

2.51

2.48

2.53

2.49

2.51

2.49

2.39

2.46

2.44

2.38

2.39

2.34

2.39

2.34

2.50

2.37

2.56

2.44

2.48

2.51

2.39

TDM

2.96

2.89

2.93

2.85

2.90

2.91

2.95

2.92

2.97

3.02

2.96

2.98

2.92

3.06

2.96

2.99

2.97

2.81

2.92

2.85

2.68

2.67

2.58

2.68

2.58

2.82

2.63

3.07

2.74

2.92

2.96

2.66

TDM2

Talbot

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Terrane

Kirkland et al.

11

1781

1792

1786

1785

1784

1766

1799

1761

1748

1795

1764

1770

1785

1883

1805

1761

1745

1915

2422

1806

1994

1767

2078

1856

2192

1759

2433

1774

2005

112397-09.1

112397-11.1

112397-13.1

112397-15.1

104981-3.1

104981-5.1

104981-6.1

104981-7.1

104981-8.1

104981-9.1

104981-11.1

104981-12.1

104981-13.1

104981-14.1

104981-17.1

104981-18.1

104981-19.1

110056-1.1

110056-2.1

110056-4.1

110056-7.1

110056-10.1

110056-12.1

110056-14.1

110056-15.1

110056-16.1

110056-17.1

110056-18.1

110056-19.1

NOTE:

Pb*/206Pb* (Ma)

Hf/177Hf

0.281447

0.281548

0.281237

0.281468

0.281402

0.281449

0.281495

0.281586

0.281479

0.281461

0.281424

0.281535

0.281473

0.281514

0.281485

0.281516

0.281545

0.281518

0.281538

0.281460

0.281482

0.281553

0.281519

0.281538

0.281547

0.281478

0.281486

0.281544

0.281416

176

0.000019

0.000018

0.000023

0.000012

0.000018

0.000021

0.000025

0.000022

0.000013

0.000012

0.000023

0.000018

0.000018

0.000019

0.000017

0.000023

0.000021

0.000021

0.000019

0.000023

0.000020

0.000018

0.000024

0.000013

0.000017

0.000010

0.000011

0.000010

0.000009

1 SE

Lu/177Hf

0.000523

0.000444

0.000505

0.000262

0.001062

0.001262

0.001142

0.001962

0.000548

0.000639

0.001607

0.002267

0.001073

0.000893

0.000480

0.000755

0.001139

0.001645

0.001010

0.001064

0.000934

0.000832

0.001149

0.000966

0.000860

0.000767

0.000584

0.000357

0.000597

176

0.016706

0.013959

0.015520

0.008467

0.033707

0.043539

0.034862

0.067551

0.017724

0.020933

0.053790

0.078992

0.031655

0.021338

0.012879

0.020557

0.031677

0.045562

0.027168

0.025921

0.023567

0.020366

0.031103

0.026083

0.023949

0.026662

0.018977

0.010884

0.018800

Yb/177Hf

176

207

Hf/177Hfi

-2.8

-4.3

-0.6

-7.3

-1.0

-7.0

-0.4

-4.9

-2.0

-6.9

4.0

-4.0

-8.4

-6.4

-5.9

-3.4

-5.0

-6.9

-5.6

-7.7

-7.8

-4.9

-5.7

-5.5

-4.6

-7.0

-6.4

-4.0

-9.0

İHf

0.67

0.63

0.81

0.42

0.63

0.74

0.88

0.77

0.46

0.42

0.81

0.63

0.63

0.67

0.60

0.81

0.74

0.74

0.67

0.81

0.70

0.63

0.84

0.46

0.60

0.35

0.39

0.35

0.31

1 SE

2.49

2.35

2.78

2.45

2.59

2.54

2.47

2.39

2.45

2.48

2.60

2.49

2.49

2.43

2.44

2.41

2.40

2.47

2.40

2.51

2.47

2.37

2.44

2.40

2.38

2.47

2.44

2.35

2.54

TDM

2.83

2.74

3.01

2.92

2.85

2.98

2.72

2.78

2.76

2.93

2.71

2.83

2.98

2.86

2.87

2.77

2.79

2.90

2.81

2.97

2.94

2.77

2.85

2.81

2.77

2.92

2.88

2.73

3.05

TDM2

Pb*/206Pb* age of grain. TDM2 is calculated using a two-stage evolution assuming a mean

0.281427

0.281533

0.281214

0.281459

0.281358

0.281405

0.281450

0.281520

0.281458

0.281439

0.281350

0.281453

0.281437

0.281484

0.281469

0.281489

0.281506

0.281463

0.281504

0.281424

0.281451

0.281525

0.281480

0.281506

0.281518

0.281452

0.281466

0.281532

0.281396

176

continued

The Analysis No. is the sample number '-' grain number '.' spot number. 176Hf/177Hfi, HHf and TDM of zircons are calculated using the TDM and TDM2 are in Ga.

207

Analysis No.

Table 1.

176

Lu/177Hf ratio of crust = 0.015.

Talbot

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Terrane

GSWA Report 122 The crustal evolution of the Rudall Province from an isotopic perspective

Kirkland et al. Table 2.

Oxygen isotope analyses from zircons of sample GSWA 112102

Sample id

Background corrected 18O/16O(a)

į18O(b)

1V

Excluded

Penglai@1

0.0020144

0.006

5.24

0.12

std

Penglai@2

0.0020145

0.020

5.27

0.40

std

Penglai@3

0.0020148

0.007

5.40

0.13

std

Penglai@4

0.0020145

0.007

5.28

0.14

std

Penglai@5

0.0020145

0.006

5.25

0.11

std

Penglai@6

0.0020144

0.006

5.24

0.12

std

112102@1

0.0020146

0.006

5.31

0.11

112102@02

0.0020146

0.008

5.32

0.16

112102@03

0.0020188

0.007

7.42

0.14

112102@04

0.0020147

0.008

5.39

0.15

112102@05

0.0020246

0.014

10.30

0.28

yes

112102@06

0.0020186

0.017

7.28

0.34

yes

112102@07

0.0020138

0.005

4.94

0.10

112102@08

0.0020182

0.009

7.09

0.18

112102@09

0.0020148

0.008

5.40

0.15

112102@10

0.0020149

0.007

5.48

0.14

112102@11

0.0020144

0.007

5.25

0.13

112102@12

0.0020208

0.009

8.40

0.18

112102@13

0.0020138

0.010

4.94

0.19

112102@14

0.0020147

0.011

5.35

0.21

112102@15

0.0020217

0.006

8.86

0.12

112102@16

0.0020151

0.007

5.57

0.14

112102@17

0.0020142

0.006

5.11

0.12

112102@18

0.0020144

0.008

5.21

0.15

112102@19

0.0020172

0.007

6.62

0.14

112102@20

0.0020138

0.008

4.94

0.16

112102@21

0.0020146

0.013

5.33

0.26

Penglai@7

0.0020144

0.008

5.20

0.16

std

Penglai@8

0.0020145

0.006

5.29

0.12

std

Penglai@9

0.0020147

0.006

5.37

0.12

std

yes

yes

yes

yes

yes

Penglai@10

0.0020144

0.012

5.24

0.23

std

Penglai@11

0.0020148

0.010

5.44

0.19

std

NOTES: Each į18O uncertainty (1ı) represents the sum of counting statistics errors for each individual spot and the external error based on all standards analysed during the session, which were added in quadrature. Table is in sequential order of analyses. (a) Raw ratios corrected for measured Faraday offsets and yields. (b) Normalized to a Penglai value of 5.3 per mil. Excluded analyses were located on fractures or overlapped inclusions. Accepted analyses are from grains interpreted to preserve magmatic values. Std denotes standard analysis

12

13

Kalkan Supersuite

Kalkan Supersuite

Kalkan Supersuite

Kalkan Supersuite

Kalkan Supersuite

Kalkan Supersuite

Kalkan Supersuite

Kalkan Supersuite

Kalkan Supersuite

Eastern Association

Mesoproterozoic granites

111854

112341

110056

112101

111843

104980

112310

112397

104989

112102

Kalkan Supersuite

Unassigned granitic rocks

113002

112160

NOTE:

Mesoproterozoic granites

Foliated granite

Garnet grantic gneiss

Granodiorite gneiss

Orthogneiss

Seriate biotite metamonzogranite

Muscovite quartzite

Biotite monzogranite (augen) gneiss

Granodiorite gneiss

Monzogranite gneiss

Biotite–muscovite monzogranite gneiss

Biotite-epidote monzogranite gneiss

Biotite–hornblende granodiorite gneiss

Micromonzogranite (meta-aplite) dyke

Biotite–muscovite granodiorite gneiss

Biotite–muscovite monzogranite gneiss

Biotite monzogranite (augen) gneiss

Lithology

-22.78452

-22.84800

-22.80147

-22.89508

-22.62091

-22.67750

-22.46946

-22.56113

-22.73233

-22.57140

-22.61702

-22.56808

-22.55919

-22.59918

-22.77444

-22.53752

Latitude

122.85445

122.85672

122.57583

122.61305

122.12083

122.31389

122.06106

122.28161

122.30067

122.31717

122.29166

122.35800

122.17411

122.28633

122.25917

122.18105

Longitude

Summary of U-Pb SIMS dates for Rudall Province

1310

5

7

6

10

6

12

3

16

8

12

15

12

13

13

2V

Magmatic

c. 1200

1768

1777

1453

1783

1801

1800

1789

1793

1795

1773

1782

1764

1762

Age

c. 1700, 1873–1764

3123

2433–1915

>2327

Age(s)

Inheritance

1791, 1955

Age(s)

Detrital

Summary of U–Pb SIMS geochronology for Rudall Province samples investigated in this work. U–Pb geochronology for these sample is published in Nelson (1995 to 1996) and is available online at . All ages are in Ma.

118914

Tabletop Terrane

Kalkan Supersuite

113035

Connaughton Terrane

Kalkan Supersuite

104981

Unit

112379

Talbot Terrane

Sample id

Table 3.

GSWA Report 122 The crustal evolution of the Rudall Province from an isotopic perspective

Kirkland et al.

Talbot Terrane

Model ages 2, (T DM), which are calculated using the measured 176Lu/ 177Hf of the zircon, provide only a minimum age for the source material of the magma from which the zircon crystallized, because the 176Lu/177Hf ratio of zircon is much lower than the 176Lu/177Hf ratio of all reasonable reservoirs for Hf. Therefore, we have calculated two-stage model ages (TDM2), which assumes that the parental magma was produced from an average continental crust (176Lu/177Hf = 0.015) that originally was derived from the depleted mantle (Griffin et al., 2004).

Kalkan Supersuite GSWA 112379: biotite monzogranite (augen) gneiss, Split Rock This sample was dated by Nelson (1995k). Zircons isolated from this sample are colourless to yellow, euhedral, and have aspect ratios up to 5:1. Both transmitted and reflected-light images imply that there are no inherited cores within this zircon sample. Excluding one U–Pb analysis that is 14% discordant and has lost radiogenic Pb, the remaining 20 analyses yield a concordia age of 1762 ± 13 Ma (MSWD = 1.8; Fig. 3a), interpreted as the igneous crystallization age of the granite protolith. This result is slightly younger than the 1765 ± 15 Ma date proposed by Nelson (1995k). Hf isotope measurements of 12 zircons yield HHf(t) values that range from –5.5 to –9.8 and are more unradiogenic than CHUR (Fig. 4). The Hf isotope data are well grouped and indicate a TDM2 of c. 2.8 Ga.

In the following text, the term ‘array’ is used to indicate variable 176Hf/177Hfi values at a single point in time, as could be due to mixing of isotopically distinct sources. The term ‘evolution’ refers to the variation of 176Hf/177Hfi values through time, consistent with the increase in daughter isotopes by decay of 176Lu within crust having a specific 176Lu/177Hf ratio.

Oxygen isotopes Oxygen isotope ratios (18O/16O) were determined using a Cameca IMS 1280 multi-collector ion microprobe located at the Centre for Microscopy, Characterisation and Analysis (CMCA) at the University of Western Australia. Analytical conditions were similar to those outlined in detail by Kita et al. (2009). A static ~3 nA Cs+ beam with an impact energy of 20 keV was focused to a 15 μm spot on the sample surface. Instrument parameters included a magnification of 130x between the sample and field aperture, 400 μm contrast aperture, 4000 μm field aperture, 120 μm entrance slit, 500 μm exit slits, and a 40 eV band pass for the energy slit with a 5 eV gap. Secondary O- ions were accelerated to 10 keV and analysed with a mass resolving power of approximately 2400 using dual Faraday Cup detectors. A normal-incidence electron gun was used to provide charge compensation.

GSWA 104981: biotite–muscovite monzogranite gneiss, southern part of Graphite Valley The geochronology of this sample was reported by Nelson (1995d). Zircons from this sample are colourless to dark brown, euhedral to subhedral, typically fractured, and have aspect ratios up to 5:1. Transmitted-light images indicate potentially older cores within several zircons, although most crystals are apparently homogeneous. The U–Pb analyses are concordant to strongly discordant. Five analyses >10% discordant are not considered further. Thirteen analyses yield a concordia age of 1764  ±  13  Ma (MSWD = 2.0; Fig. 3a), interpreted as the age of magmatic crystallization of the protolith to the gneiss. This date is younger than the 1775 ± 10 Ma date reported by Nelson (1995d). One analysis yields a 207 Pb*/206Pb* date (1V) of 1883 ± 47 Ma, interpreted as the age of an inherited component (Nelson, 1995d). Hf isotope measurements of 13 zircons yield HHf(t) values of –3.4 to –8.4, and are more unradiogenic than CHUR (Fig. 4). The Hf isotope data define an array indicating a maximum TDM2 of c. 3.0 Ga.

Each analysis spot was pre-sputtered for 10 seconds prior to automated peak-centering using secondary deflectors DTFA-X, DTFA-Y, and DTCA-X. Each analysis consisted of 20 four-second cycles through the mass stations, which gave an average internal precision of 0.17 ‰ (1 SDmean). Bracketing of standards permits instrumental mass fractionation (IMF) and drift to be assessed and corrected. IMF was corrected using the Penglai zircon standard (5.31  ± 0.10‰ 2V, (Li et al., 2010). A single block of 21 sample analyses of GSWA 112102 was bracketed by 11 standard analyses and IMF was calculated using a correction scheme similar to that described by Kita et al. (2009) with propagation of uncertainty as outlined in Appendix A1 of Kirkland et al. (2012). The spot-to-spot reproducibility (external precision) for standard spots on Penglai zircons was 0.08‰ (1 SDext, n=11). Corrected 18 O/16O ratios are reported in 18O notation, in per mil variations relative to Vienna Standard Mean Ocean Water (VSMOW).

2

GSWA 111854: biotite–muscovite granodiorite gneiss, Poonemerlarra Creek west This sample was dated by Nelson (1995h). Zircons from this sample are colourless to yellow, euhedral, and equant to elongate, with aspect ratios up to 6:1. Transmittedlight images suggest that most crystals are homogeneous with no inherited cores. Four analyses greater than 5% discordant have probably lost radiogenic Pb and are not considered further. One of these discordant analyses is of an inherited core that indicated a minimum age of 2327  Ma. The remaining eight analyses yield a concordia age of 1782 ± 12 Ma (MSWD = 1.6; Fig. 3a), interpreted as the age of magmatic crystallization of the protolith to the gneiss. This date is slightly older than the 1778 ± 17 Ma date reported by Nelson (1995h). Hf isotope

A model age, in its simplest form, is the time at which a sample was separated from its source in the mantle, assuming the source is not a mixture. More specifically, it is the time at which the isotopic signature of the sample was the same as that of a model reservoir 14

GSWA Report 122

The crustal evolution of the Rudall Province from an isotopic perspective

Te rra n

e

GSWA 112397: coarse-grained porphyritic biotite monzogranite (augen) gneiss, Watrara Inlier

Ta lb

ot

GSWA 112310: granodiorite gneiss, Dunn Creek west

GSWA 104980: monzogranite gneiss, Graphite Valley

GSWA 111843: biotitemuscovite monzogranite gneiss, Poynton Creek

GSWA 112101: biotite-epidote monzogranite gneiss, Larry Creek

GSWA 110056: biotite-hornblende granodiorite gneiss, Rooney Creek

GSWA 112341: micromonzogranite (meta-aplite) dyke, Rudall airstrip

0.16

2200

GSWA 111854: biotite-muscovite granodiorite gneiss, Poonemerlarra Creek west 2000

0.12

207

Pb*/206Pb*

0.14

GSWA 104981: biotite-muscovite monzogranite gneiss, southern part of Graphite Valley

1800 0.10

1600 1400 0.08 2.0

1200 2.4

CLK83_1

2.8

3.2 238

3.6 206

U/ Pb*

4.0

4.4

4.8 GSWA 112379: biotite monzogranite (augen) gneiss, Split Rock 27.03.13

Figure 3a. Stacked concordia diagrams showing U–Pb zircon analytical data for zircons from Rudall Province samples analysed by SHRIMP ion microprobe. Error crosses are shown at the 2-sigma level. All data (see Nelson et al. in the reference list) are available online (www.dmp.wa.gov.au/geochron). Yellow squares indicate magmatic zircon; red squares indicate inherited / detrital zircon; blue squares indicate youngest detrital zircon; green squares indicate metamorphic zircon; grey squares indicate discordant analyses; black squares indicate concordant analyses interpreted to have undergone radiogenic-Pb loss.

15

Co nn au gh ton

Ta ble top

Kirkland et al.

Ta lbo t

GSWA 118914: foliated granite, north of Harbutt Range

GSWA 112160: garnet microgneiss, Harbutt Range

GSWA 113002: granodiorite gneiss, Cotton Creek

0.16

2200 GSWA 113035: orthogneiss, east of South Rudall Dome 2000

0.12

207

Pb*/206Pb*

0.14

1800

GSWA 112102: seriate biotite metamonzogranite, southern part of the Watrara Inlier

0.10

1600 1400 0.08 2.0

2.4

CLK83_2

2.8

3.2 238

3.6

U/206Pb*

4.0

1200 4.8 GSWA 104989: muscovite

4.4

27.03.13

quartzite, Fingoon Quartzite

Figure 3b. Stacked concordia diagrams showing U–Pb zircon analytical data for zircons from Rudall Province samples analysed by SHRIMP ion microprobe. Error crosses are shown at the 2-sigma level. All data (see Nelson et al. in the reference list) are available online . Yellow squares indicate magmatic zircon; red squares indicate inherited / detrital zircon; blue squares indicate youngest detrital zircon; green squares indicate metamorphic zircon; grey squares indicate discordant analyses; black squares indicate concordant analyses interpreted to have undergone radiogenic-Pb loss.

measurements of 11 zircons yield HHf(t) values ranging from –5.6 to –9.5, and form an array that is slightly to strongly more unradiogenic than CHUR (Fig. 4), and define a maximum TDM2 of c. 3.4 Ga. The single discordant core yields an HHf(t) value of +2.

younger analysis, 15 analyses yield a concordia age of 1773 ± 15 Ma (MSWD = 1.0; Fig. 3a), interpreted as the age of magmatic crystallization of the dyke. This date is slightly younger than the 1778 ± 16 Ma date reported by Nelson (1995j). The single excluded analysis yields a 207Pb*/206Pb* date of 1612 ± 44 Ma (1V), interpreted by Nelson (1995j) to reflect disturbance by younger metamorphic events. Hf isotope measurements of 13 zircons yield HHf(t) values ranging from –3.6 to –11.4, plot as an array that is slightly to strongly more unradiogenic than CHUR (Fig. 4), and indicate a maximum TDM2 of c. 3.1 Ga.

GSWA 112341: micromonzogranite (meta-aplite) dyke, Rudall airstrip This sample, dated by Nelson (1995j), yielded zircons that are yellow to brown, subhedral to anhedral, and have aspect ratios up to 4:1. Transmitted-light images do not indicate any obvious cores. Excluding one 16

GSWA Report 122

The crustal evolution of the Rudall Province from an isotopic perspective

GSWA 110056: biotite–hornblende granodiorite gneiss, Rooney Creek

-30

Tabletop Terrane 10

This sample was dated by Nelson (1995f), and yielded zircons that are brown to black, euhedral to subhedral, and have aspect ratios up to 5:1. Transmitted-light images reveal that many crystals contain apparently older cores. Excluding seven analyses of inherited zircon cores, five analyses >5% discordant, and one analysis with high common Pb (>10% common 206Pb), six analyses yield a concordia age of 1795 ± 12 Ma (MSWD = 1.04; Fig. 3a), interpreted as the age of magmatic crystallization of the protolith to the gneiss. This date is slightly older than the 1790 ± 17 Ma date reported by Nelson (1995f). Inherited cores yield 207Pb*/206Pb* dates of 2433–1915 Ma. Hf isotope measurements of five zircons from the magmatic component in this sample yield HHf(t) values of –0.6 to –7.3, and seven analyses of inherited zircon cores yield HHf(t) values ranging from –0.4 to –4.0 (Fig. 4). The Hf isotope data define an evolution trend from a source with a maximum TDM2 of 3.0 Ga.

0

-10

D -20

EPT

GT

-30

Connaughton Terrane

Epsilon Hf

10

0

-10

D -20

EPT

GT

GSWA 112101: biotite-epidote monzogranite gneiss, Larry Creek

Talbot Terrane

The geochronology of this sample was reported by Nelson (1996a). Zircons from this sample are yellow to dark brown, euhedral, and have aspect ratios up to 5:1. Transmitted-light images reveal concentric zoning made visible by variable degrees of radiation damage. Several crystals contain apparently older cores. Seventeen analyses yield a weighted mean 207Pb*/206Pb* date of 1793 ± 8 Ma (MSWD = 1.02; Fig. 3a), interpreted as the age of magmatic crystallization of the protolith. This date is similar to the 1792 ± 9 Ma result reported by Nelson (1996a). A single analysis located on a xenocrystic core yields a 207Pb*/206Pb* date of 3123 ± 16 Ma (1V) (Fig. 3a). Hf isotope measurements on 10 magmatic zircons yield HHf(t) values of –2.7 to –9.1 (Fig. 4) and define an array with a maximum TDM2 of 3.0 Ga.

10

M 0

-10

D -20

-30 1000

1200

CLK82a

Figure 4.

GSWA 111843: biotite–muscovite monzogranite gneiss, Poynton Creek This sample was dated by Nelson (1995g), and yielded zircons that are colourless to black, euhedral, and have aspect ratios up to 5:1. Many crystals contain apparently older cores. Excluding two analyses >10% discordant, 10 analyses yield a concordia age of 1789 ±  16 Ma (MSWD  =  0.81; Fig. 3a), interpreted as the age of magmatic crystallization of the protolith. This date is slightly younger that the 1795 ± 17 Ma date reported by Nelson (1995g). Four other analyses yield dates of 2102– 1877 Ma, interpreted as xenocrystic components (Fig. 3a). Hf isotope measurements of 12 zircons yield HHf(t) values of –4.6 to –12.0 (Fig. 4), and define an array with a maximum TDM2 of 3.3 Ga. The older inherited zircons yield Hf isotope signatures consistent with evolution from the same source as the c. 1789 Ma magmatism (Fig. 4).

EPT

GT

1400

1600

1800

Age (Ma)

2000

2200

2400 14.01.13

İHf evolution diagrams for Rudall Province samples (circles, this study) compared to potential source regions. Shaded fields illustrate normal crustal evolution of Hf along a 176Lu/177Hf slope of 0.015. Abbreviations used in figure: EPT — East Pilbara Terrane, GT — Glenburgh Terrane (Capricorn Orogen basement), D — Dalgaringa Supersuite intrusive rocks. Red line is the depleted mantle model of Griffin et al. (2000) and the blue line is CHUR.

GSWA 104980: monzogranite gneiss, Graphite Valley This sample was dated by Nelson (1995c). Zircons from this sample are colourless to brown, euhedral, elongate to equant, and have aspect ratios up to 5:1. No cores are apparent in transmitted-light images. Fourteen analyses yield a concordia age of 1800 ± 3 Ma (MSWD = 0.84; Fig. 3a), interpreted as the age of magmatic crystallization of the protolith, and identical to the result reported by Nelson (1995c). Hf isotope measurements of 10 zircons yield HHf(t) values ranging from –6.5 to –8.7 (Fig. 4), and indicate a maximum TDM2 of 3.0 Ga.

17

Kirkland et al.

GSWA 112310: granodiorite gneiss, Dunn Creek west

Mesoproterozoic granites

This sample was dated by Nelson (1995i). Zircons from this sample are colourless to dark brown, euhedral, elongate and have aspect ratios up to 6:1. Idiomorphic zoning is ubiquitous and apparently older cores are visible in transmitted light. Excluding one analysis >10% discordant, four analyses yield a concordia age of 1801 ± 12 Ma (MSWD = 1.8; Fig. 3a), interpreted as the age of magmatic crystallization of the granite protolith. This date is identical to that reported by Nelson (1995i). A further 13 analyses from this sample yield 207Pb*/206Pb* dates of 1980–1932 Ma, interpreted as the ages of inherited components. A significant age component at 1967 ± 10 Ma (MSWD = 2.2; Fig. 3a), was interpreted by Nelson (1995i) as the age of an older granitic component within the orthogneiss. Hf isotope measurements of 14 zircons yield HHf(t) values ranging from +0.7 to –9.5 (Fig. 4). The Hf data from the c. 1800 Ma component define an array with a maximum TDM2 of 3.0 Ga, whereas the older c.  1970  Ma component defines a more radiogenic array with a maximum TDM2 of 2.8 Ga (Fig. 4).

GSWA 112102: seriate biotite metamonzogranite, southern part of the Watrara Inlier Geochronology of this sample was reported by Nelson (1996b). The zircons are colourless to yellow or brown, euhedral, and predominantly equant with aspect ratios up to 4:1. Transmitted and reflected light images do not indicate the presence of older cores. Eleven analyses indicate variable recent radiogenic-Pb loss and yield a weighted mean 207Pb*/206Pb* date of 1453 ± 10 Ma (MSWD = 0.68; Fig. 3b), interpreted as the igneous crystallization age of the granite (Nelson, 1996b). Hf isotope measurements of eight zircons yield HHf(t) values of +2.5 to +5.6, and plot between CHUR and DM (Fig. 4). The Hf isotope data are well grouped and indicate a TDM2 of c. 1.9 Ga. Oxygen isotopes were measured in 21 zircons, and include six analyses that ablated through cracks and one analysis that incorporated limonite adhered to the grain margin. These seven analyses yield heavy į18O values of >6.6 ‰ and are considered to represent modified į18O values. The remaining 14 analyses yield į18O values from 4.9 to 5.6 ‰, with a weighted mean of 5.23 ± 0.12 ‰ (MSWD = 2.1; Table 2).

GSWA 112397: coarse-grained porphyritic biotite monzogranite (augen) gneiss, Watrara Inlier This sample was dated by Nelson (1995l). Zircons from this sample are colourless, euhedral, and elongate, with aspect ratios up to 6:1. No older cores are apparent in transmitted light. Fifteen analyses yield a concordia age of 1783 ± 6 Ma (MSWD = 1.3; Fig. 3a), interpreted as the age of magmatic crystallization of the granite protolith. This date is slightly younger than the 1787 ± 5 Ma date reported by Nelson (1995l). Hf isotope measurements of 14 zircons yield HHf(t) values of –3.4 to –9.0 (Fig. 4), and define an array with a maximum TDM2 of 3.0 Ga.

Connaughton Terrane Kalkan Supersuite GSWA 113035: orthogneiss, east of South Rudall Dome This sample was dated by Nelson (1996d). Zircons from this sample are yellow to brown, euhedral, and have aspect ratios up to 5:1. No older cores are apparent in transmitted light. The analyses are slightly reversely discordant. The zircons have relatively low uranium (1% common 206Pb), and four analyses interpreted to have undergone minor ancient radiogenic-Pb loss, the remaining 13 analyses yield a weighted mean 207Pb*/206Pb* date of 1310 ± 5 Ma (MSWD = 1.4; Fig. 3b), essentially identical to that reported by Nelson (1996e), and interpreted as the age of magmatic crystallization. Hf isotope measurements of 16 zircons yield HHf(t) values ranging from –5.3 to –11.6 (Fig. 4). The Hf isotope data are well grouped and yield an average TDM2 of 2.6 Ga, although one analysis indicates a value of 2.8 Ga.

The Glenburgh Terrane, which forms the basement to the Gascoyne Province, comprises 2555–2430 Ma granitic gneisses of the Halfway Gneiss, mid-Paleoproterozoic metasedimentary rocks, and an arc-related granitic batholith of the 2005–1970 Ma Dalgaringa Supersuite (Johnson et al., 2012). The Hf isotope compositions of zircons within the Glenburgh Terrane indicate a major period of crustal growth between c. 2730 and c. 2600 Ma, although much of this material was reworked during 19

Kirkland et al. 0.2823 Talbot

MP

Connaughton

0.2821

Tabletop

0.2819

Capricorn Orogen basins Dalgaringa Supersuite

West Arunta

D

Halfway Gneiss

0.2817

0.2815

East Pilbara Terrane Arunta wholerock Nd

GT rim

0.2813

176

Hf/177 Hf initial

Bridget Suite

EPT 0.2811

0.2809

0.2807

0.2805 1000

1500

2000

CLK75a

Figure 5.

2500 Age (Ma)

3000

3500 15.08.12

Initial 176Hf/177Hf evolution diagram for samples from the Rudall Province (circles, this study) compared to potential source regions. Shaded fields illustrate normal crustal evolution of Hf along a 176Lu/177Hf slope of 0.015. Hf data are from . Whole-rock Nd data for the Arunta Orogen are converted to Hf values assuming a terrestrial array relationship. Abbreviation in figure: MP — Musgrave Province basement. Other notes as in Figure 4.

tectono-magmatic events between c. 2555 and c. 2430 Ma (Johnson et al., 2011a). Both the crystallization history and crustal source of the Halfway Gneiss is somewhat dissimilar to the Pilbara and Yilgarn Cratons, which led Johnson et al. (2012) to infer that the Glenburgh Terrane was an element exotic to both these cratons. The Glenburgh Terrane is envisaged to have collided with the Pilbara Craton during the 2215–2145 Ma Ophthalmian Orogeny, and the combined Pilbara Craton–Glenburgh Terrane (‘Pilboyne Craton’) collided with the Yilgarn Craton during the 2005–1950 Ma Glenburgh Orogeny (Johnson et al., 2012).

Metamorphics (Sheppard et al., 2010b) in the Gascoyne Province (Fig. 1). These sedimentary rocks were deposited in response to the onset of the 1820–1770 Ma Capricorn Orogeny, possibly in a foreland basin setting (Thorne and Seymour, 1991; Sircombe, 2002; Evans et al., 2003). The upper Wyloo Group, including the Ashburton Formation, is mostly a turbiditic deep-marine succession (Thorne and Seymour, 1991). These sedimentary rocks were deformed once, and unconformably overlain by terrestrial, lacustrine to shallow-marine sedimentary rocks of the Capricorn Group (Thorne and Seymour, 1991). Paleocurrent directions in both the Ashburton Formation (Thorne and Seymour, 1991) and Capricorn Group (Thorne and Seymour, 1991; Hall et al., 2001) imply that the sediments were supplied from the southeast and southwest, respectively. The U–Pb age spectrum and Lu–Hf isotopic composition of detrital zircons within both sedimentary successions (Sircombe, 2002; GSWA, unpublished data), combined with the paleocurrent data, indicate that the southern part of the Gascoyne Province was a major source for the sedimentary detritus (Nelson, 2004a,b). In particular, the 2555–2430 Ma Halfway Gneiss and 2005–1970 Ma Dalgaringa Supersuite of the Glenburgh Terrane, and the early c. 1820 to c. 1800 Ma Moorarie Supersuite granites, appear to dominate the detrital signatures.

The 1820–1770 Ma Capricorn Orogeny took place during a similar time interval to the 1800–1765 Ma Yapungku Orogeny in the Rudall Province, the effects of which are recognized throughout most of the Capricorn Orogen (Sheppard et al., 2010b). The orogeny is associated with low- to medium-grade metamorphism and intense structural reworking, the intrusion of voluminous granitic magmas of the 1820–1775 Ma Moorarie Supersuite, and deposition of sedimentary rocks of the upper Wyloo Group (Ashburton Basin), including the c. 1800 Ma Ashburton Formation (Evans et al., 2003; Sircombe, 2003), the c.  1800 Ma Capricorn Group (Blair Basin; Hall et al., 2001), and the 1840–1810 Ma Leake Spring 20

GSWA Report 122

The crustal evolution of the Rudall Province from an isotopic perspective

The 1840–1810 Ma Leake Spring Metamorphics are a package of low- to medium-metamorphic grade siliciclastic metasedimentary rocks that were deposited across much of the Gascoyne Province, including the Glenburgh Terrane (Sheppard et al., 2010). These sedimentary rocks are thought to pass, with decreasing metamorphic grade, into the Ashburton Formation to the north (Williams, 1986). These metasedimentary rocks were also sourced from the southern part of the Gascoyne Province (Sheppard et al., 2010b).

and has been divided into a southern Warumpi Province, generally inferred to be exotic, and an autochthonous Aileron Province (Scrimgeour et al., 2005). The Aileron Province had on its southern margin a north-dipping subduction zone during the 1810–1790 Ma Stafford Event (Claoue-Long and Hoatson, 2005). After the Stafford Event, an active margin/back-arc setting developed with several tectono-magmatic events including the c. 1780 Ma Yambah, 1760–1740 Ma Inkamulia, and 1690–1670 Ma Strangways Events (Collins and Williams, 1995; ClaoueLong and Hoatson, 2005).

Pilbara Craton

The 1810–1790 Ma Stafford Event (Claoue-Long and Hoatson, 2005) is coeval with intrusion of the 1800–1765 Ma Kalkan Supersuite in the Rudall Province. Only limited deformation was associated with the Stafford Event, and metamorphism during this event was driven by magmatic heat advection (Claoue-Long and Hoatson, 2005). The c. 1780 Ma Yambah Event in the Arunta Orogen (Collins and Shaw, 1995; Scrimgeour, 2003; Claoue-Long et al., 2008) was also near-synchronous with the youngest components of the Kalkan Supersuite in the Rudall Province. The Yambah Event does not appear to correspond to major crustal thickening (Scrimgeour, 2003) but has been associated with northeast–southwest shortening (Hand and Buick, 2001).

The boundary between the Pilbara Craton (including the East Pilbara Terrane and the overlying Fortescue, Hamersley, and Turee Creek Basins) and the Rudall Province to the east is covered by unconformably overlying Meso- to Neoproterozoic sedimentary rocks (Fig. 1). During the Archean and prior to 2800 Ma, the Pilbara Craton was dominated by the construction of granite–greenstone terranes (Smithies et al., 1999; Hickman, 2004; Van Kranendonk et al., 2004). These rocks are unconformably overlain by the late Archean to Paleoproterozoic volcanic and sedimentary rocks of the Fortescue, Hamersley, and Turee Creek Groups (Thorne and Trendall, 2001) which in turn are unconformably overlain by siliciclastic rocks of the c. 2200 Ma lower Wyloo Group and the c. 1800 Ma upper Wyloo Group (Thorne and Seymour, 1991). A minor suite of eastnortheast-trending kimberlite dykes intruded the eastern Pilbara Craton at c. 1870 Ma (Wyatt et al., 2002).

The Warumpi Province records two Paleoproterozoic magmatic events: high-K calc-alkaline magmatism during the 1690–1670 Ma Argilke Event, and magmatism associated with a 1640–1635 Ma accretion event known as the Liebig Orogeny (Scrimgeour et al., 2005). The Argilke event is thought not to have affected the North Australian Craton and has been attributed to an outboard magmatic arc that was subsequently accreted onto the Aileron Province during the 1640–1635 Ma Liebig Orogeny (Scrimgeour et al., 2005). In the westernmost extent of the Arunta Orogen, however, Hf isotope data for a 1690 Ma granite suggests both juvenile input and an Archean source component identical to the Aileron Province (Kirkland et al., 2009). This could imply a situation in which the Warumpi Province developed within proximity to the western Aileron Province during the Argilke Event, either as an autochthonous block that was never substantially displaced or as a rifted fragment that was significantly displaced but subsequently re-accreted onto the southern margin of the Aileron Province during north-directed subduction.

Calc-alkaline, lamprophyric syenite to monzodiorite granitic rocks of the c. 1800 Ma Bridget Suite (Hickman, 1978; Collins et al., 1988; Budd et al., 2002) form a north-northwest-trending belt within the East Pilbara Terrane and younger parts of the Pilbara Craton, adjacent and subparallel to the northwest−southeast trend of the Paterson Orogen. The rocks have Sr-undepleted, Y-depleted, fractionated compositions. Emplacement of the suite has been interpreted to be a far-field response to continent-continent collision during the Yapungku Orogeny. The crystallization age of a monzodiorite from this suite was dated at 1803 ± 19 Ma (GSWA 169030; Nelson, 2002), and a trondhjemitic pegmatite at 1793  ±  17  Ma (GSWA 178232; Bodorkos et al., 2006). Magmatic zircons from the monzodiorite (GSWA 169030) yield a range of HHf values, from –13.65 to –21.22, while those from the pegmatite yielded a range of HHf, from –4.67 to –7.50 (Fig. 5). Xenocrystic zircon cores dated between c. 3520 to c. 2841 Ma in both samples yielded HHf values from +4.10 to –7.47 (Fig. 5). The ages and Hf isotopic signatures of the inherited zircons in these magmatic rocks are consistent with incorporation of East Pilbara Terrane crust into Bridget Suite magmas.

The Hf isotope signature of 1810–1670 Ma zircons from the west Arunta region indicates crustal source regions dominated by components that formed between 2.7 and 2.0 Ga (Fig. 5; Kirkland et al., 2013). Whole-rock Nd isotope data from granites in the central and eastern Arunta imply similar crustal sources, dominated by components formed through mantle extraction at 2.5 – 2.2 Ga (Zhao and McCulloch, 1995).

Arunta Orogen

Musgrave Province

The Proterozoic Arunta Orogen lies along the southern margin of the North Australian Craton (Fig. 1; Collins and Shaw, 1995; Dunlap and Teyssier, 1995; Sun et al., 1995; Zhao and Bennett, 1995; Zhao and McCulloch, 1995; Claoue-Long and Hoatson, 2005; Scrimgeour et al., 2005)

The Musgrave Province lies at the junction of the North, South, and West Australian Cratons. Crystalline basement rocks, dated at 1600–1500 Ma and c. 1400 Ma (Edgoose et al., 2004; Wade et al., 2006; Wade et al., 2008; Kirkland 21

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et al., 2013), are subordinate to 1345–1293 Ma magmatic rocks of the Mount West Orogeny (Howard et al., 2011a; Howard et al., 2011b). The 1220–1150 Ma Musgrave Orogeny, and the 1085–1040 Ma Giles Event are younger, possibly intracontinental, tectono-magmatic events (Evins et al., 2010; Smithies et al., 2010; Smithies et al., 2011). Although the nature of Musgrave Province basement is cryptic, the Nd and Hf isotope evolution of nearly all rocks in the Musgrave Province requires the presence of sources derived from Archean, c. 1900 Ma, and c. 1600 Ma crust with subsequent juvenile additions after c. 1220 Ma. Although there are no physical remnants of c. 1900 Ma juvenile material, radiogenic addition into the crust at this time is required to account for the correspondence between mantle extraction ages and reworking of Archean material, and is indicated by mantle-like oxygen isotope ratios in zircons with c. 1900 Ma Hf model ages (Fig. 5; Kirkland et al., 2013).

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Inherited and detrital zircons of the Rudall Province In order to appropriately interpret the zircon Hf isotope data with respect to the regional evolution of the Rudall Province and the potential exotic (e.g. North Australian Craton) or endemic (West Australian Craton) nature of basement terranes, an important step is to consider the origin of the inherited zircons in the 1800–1765 Ma Kalkan Supersuite granitic rocks. The zircons may be of local provenance, having been entrained within the granites from basement terranes. In this case, the Hf isotopic evolution of the magmatic and inherited zircons will provide critical information on the nature and origin of the Rudall Province basement. If, however, the zircons are distally-derived (as part of a regionally-sourced sedimentary sequence, having been entrained within the granites during the emplacement of the magmas into the sedimentary succession), little information can be gained on the nature of the local basement, as these data reflect the geological development of all the distal sources of detritus in the region (e.g. the eastern Pilbara margin and Gascoyne Province).

Capricorn Orogen Basins

Rudall inheritance 27.03.13

İHf evolution diagram for inherited zircons from Rudall Province intrusive rocks (green circles) compared to potential West Australian Craton source regions (yellow and blue triangles). The histogram shows 207Pb*/206Pb* ages of inherited zircons from Rudall Province intrusive rocks. The isotopic signature of the inherited material is consistent with generation from crust similar to that in the Capricorn Orogen. Lines define fields for evolution of a source with similar composition to zircons in basins of the Capricorn Orogen (dash) and Dalgaringa Supersuite (dash-dot). The red line is model depleted mantle and the blue line is CHUR.

the province, here reinterpreted as a Kalkan Supersuite granite with abundant c. 2015 Ma-aged inherited zircons, led Clark (1991) and Bagas (2004) to suggest that the Glenburgh Terrane of the Gascoyne Province may form basement to the Talbot Terrane, since rocks of this age have not been documented in the Arunta Province. A recent deep crustal seismic reflection survey through the western part of the Capricorn Orogen (Johnson et al., 2011b), however, indicates that the Glenburgh Terrane is sutured to the southern margin of the Pilbara Craton along a southeast-trending, south-dipping suture zone (Fig. 1; the Lyons River – Minga Bar – Minnie Creek Fault System). The orientation of this suture means that the Glenburgh Terrane is progressively truncated toward the east against the northern margin of the Yilgarn Craton, making it highly unlikely that this terrane forms basement to any part of the Rudall Province.

In the eastern association, siliciclastic paragneiss contains c. 1790 Ma detrital zircons (Nelson, 1995e), and is intruded by the 1800–1765 Ma Kalkan Supersuite granites (Bagas, 2004). This indicates deposition of the eastern sedimentary association close to c. 1790 Ma, which is in a similar timeframe for the deposition of sedimentary rocks in the Capricorn Orogen to the west, specifically the c. 1800 Ma Ashburton Formation (Evans et al., 2003; Sircombe, 2003), the c. 1800 Ma Capricorn Group (Hall et al., 2001), and the 1840–1810 Ma Leake Spring Metamorphics (Sheppard et al., 2010b) (Fig. 1). The U–Pb age modes and Lu–Hf isotope composition of inherited zircons within the Kalkan Supersuite granitic rocks from both the Talbot and Connaughton Terranes are similar (Fig. 6). The granitic rocks are dominated by isotopically evolved (HHf between 0 and –20) zircon with discrete age modes at c. 1800 Ma and c. 2000 Ma, similar to the zircon detritus within the Capricorn Orogen basins (Fig. 6). The presence of a c. 2015 Ma granitic rock in

The similarity in isotopic composition and age of inherited zircons within granitic rocks of the Kalkan Supersuite with detrital zircons in sedimentary rocks in the Capricorn Orogen (Fig. 6) suggests that the Kalkan Supersuite granites may have assimilated similar sedimentary material during their emplacement into the upper crust. The sedimentary rocks of the eastern association of the Talbot Terrane were deposited in a similar timeframe to those in the Capricorn Orogen. The similar timing of basin formation during the early stages (c. 1820 to c. 1800 Ma) 22

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The crustal evolution of the Rudall Province from an isotopic perspective

The magmatic zircons from c. 1300 Ma granitic rocks of the Tabletop Terrane are dominated by mildly evolved compositions with model ages of 2.6 Ga. The average 176 Yb/177Hf value of zircons from Tabletop Terrane granite sample GSWA 118914 are high to extreme (176Yb/177Hf = 0.100 ± 0.022). However, the average stable 178Hf/177Hf ratio is 1.467241 ± 0.000047 (1SD; n=16), which is within the range of values reported by Thirlwall and Anczkiewicz (2004). The elevated 176Yb/177Hf ratio in this sample, as compared to other typical crustal melts, suggests crystallization either from a strongly fractionated magma or by direct melting of a garnet-bearing source. The Hf isotopic range of the magmatic zircon from the Tabletop Terrane granites is similar to that for the Kalkan Supersuite in the Connaughton Terrane, implying derivation from a similar crustal source.

of the Capricorn Orogeny imply the development of a single large basin — or a series of smaller linked basins — around the southern and eastern margins of the Pilbara Craton (Fig. 1). Synchronous regional-scale uplift along the southern margin of the Gascoyne Province provided abundant sedimentary detritus that was transported northward into the developing basin(s). Considering the data presented above, we suggest that: r JOIFSJUFE[JSDPOXJUIJOUIF,BMLBO4VQFSTVJUFHSBOJUFT were derived by the assimilation of sedimentary material during emplacement of the granites into the upper crust r UIF 3VEBMM TFEJNFOUBSZ TVDDFTTJPOT NBZ GPSN QBSU of a wider, regional-scale Capricorn Orogeny-aged basin(s), the detritus for which was derived from upland areas in the southern part of the Gascoyne Province

Crust formation and underplating at 1900 Ma

r UIF3VEBMMTFEJNFOUBSZTVDDFTTJPOTBSFBVUPDIUIPOPVT to the eastern Pilbara Craton margin (e.g. Hickman et al., 1994), consistent with the view presented by Reading et al. (2012) that thinned and extended Pilbara Craton crust occurs as basement beneath the Talbot Terrane

A post-D2 metamonzogranite in the southern part of the Watrara Inlier in the Talbot Terrane is dated at c. 1450 Ma (GSWA 112102; Nelson, 1996b), and contains zircon crystals with the least evolved Hf isotopic signature in the Rudall Province. The Hf isotopic data indicate that either the granitic material was extracted from the mantle at 1.96 Ga or that it represents a homogenized mix of sources with a component younger than 1.96 Ga. However, oxygen isotopes can be used to determine whether the parental magma from which these zircons grew contained a contribution from near-surface rocks (e.g. those with į18OVSMOW >6.3 ‰). This provides a means to screen the corresponding Hf model age for supracrustal contamination into the magma and to identify a model age that represents a mixing of source materials rather than a discrete crust-forming episode. Whereas zircon in equilibrium with mantle-derived melts has a į18OVSMOW value of 5.3 ± 0.6 ‰ (2 SD; Valley, 2003), incorporation of high-į18O material (i.e. rocks or minerals altered by low-temperature near-surface processes) will increase the į18O value of a melt, so that zircons crystallized from such melts will also have elevated į18O values. Oxygen isotope values for all zircons from this sample (Table 2) are within the mantle zircon field (Fig. 8); hence, the 1.96 Ga model age likely reflects a crust-forming fractionation event in the lithosphere.

r UIF )G JTPUPQJD FWPMVUJPO PG JOIFSJUFE BOE NBHNBUJD zircons within the Kalkan Supersuite granites are largely influenced by a variety of autochthonous source regions, including the sedimentary successions into which they were intruded.

Hf isotopic signature of the Rudall Province The Talbot and Connaughton Terranes are dominated by granitic rocks of the 1800–1765 Ma Kalkan Supersuite. In the Talbot Terrane, magmatic zircon crystals from these rocks show a range of isotopically evolved compositions with model ages (TDM2) between 3.4 and 2.6 Ga (Fig. 7), whereas in the Connaughton Terrane model ages (TDM2) range between 3.4 and 2.4 Ga (Fig. 7). The granites contain abundant inherited zircon cores (that were most likely derived from the sedimentary succession into which the magmas were intruded) that have contributed significantly to the isotopic composition of the granitic magmas. The inherited zircons are interpreted to have been derived from the Glenburgh Terrane (specifically the Halfway Gneiss and Dalgaringa Supersuite) of the Gascoyne Province, and the isotopic compositional range of the granites is also comparable to that for the Glenburgh Terrane (Figs. 5 and 6). The most evolved magmatic grains (those with HHf c. –17), however, are also comparable with the isotopic composition of the East Pilbara Terrane, including the granitic rocks of the Bridget Suite (Fig. 5). The lack of East Pilbara Terrane-aged (3500–3200 Ma) inherited zircons within the Kalkan Supersuite indicates that the most evolved isotopic component of the granites may not have been derived as an inherited sedimentary component, but reflect a contribution directly from the underlying Talbot Terrane basement, with an evolved isotopic signature identical to that of the East Pilbara Terrane.

Further constraint on the location of this fractionation event can be placed by examining the isotopic signature of this sample. The average 176Yb/177Hf values of zircon crystals from GSWA 112102 are high (176Yb/177Hf = 0.085 ± 0.012; Fig. 9). However, during the course of the analysis of this sample, the average 178Hf/177Hf ratio was 1.467168 ± 0.000051 (1SD; n=8), which is in the range of values reported by Thirlwall and Anczkiewicz (2004), indicating that Yb interference has been satisfactorily dealt with. Hence, the elevated 176Yb/177Hf ratio in these zircon crystals could imply anatexis of residual garnet (Fig. 9). There is only limited additional evidence for crust formation at c. 1.9 Ga in the West Australian Craton and its marginal terranes. Magmatic and metasedimentary rocks of the Musgrave Province are dominated by two major juvenile Proterozoic crust formation events — 23

Kirkland et al. 12

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Magmatic crystallization ages (left) and two-stage Hf model ages (right) for zircons from Rudall Province magmatic rocks. Crystallization age data are colour-coded according to İHf value. Although the timing of magmatism in the Tabletop Terrane is different from that in the Connaughton and Talbot terranes, the Hf isotopic signatures of all three are broadly similar, implying that each originated from the same, or a similar, crustal source.

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Oxygen isotope analyses of zircons from Mesoproterozoic metamonzogranite sample GSWA 112102 (Nelson, 1996b). Error bars are 2ı. Analyses located on fractures or inclusions are excluded.The line indicates the weighted mean į18O value for the analysed zircons; the grey field represents the range of values expected from zircon crystallized in equilibrium with the mantle (5.3 ± 0.6 ‰ (2 SD), e.g. Valley, 2003).

Figure 9.

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Comparison of 176Yb/177Hf ratios for zircons from two Mesoproterozoic magmatic rocks (circles) with those from other Rudall Province magmatic rocks of Paleoproterozoic age (squares). The zircons in Mesoproterozoic rocks have elevated Yb contents compared to most of those in Paleoproterozoic rocks.

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The crustal evolution of the Rudall Province from an isotopic perspective

Arunta Orogen

The Edmund Basin is an intracratonic sedimentary basin of early Mesoproterozoic age located between the Pilbara and Yilgarn Cratons (Fig. 1). Metasedimentary strata of the Edmund Group are intruded by voluminous mafic sills of the c. 1465 Ma Narimbunna Dolerite (Martin and Thorne, 2004). Hf isotopes in baddeleyite and zircon crystals from this magmatic suite consistently suggest a juvenile source component formed at 1950–1900 Ma (GSWA, unpublished data). Whole-rock Nd isotopes from these rocks also yield model ages (TCHUR) with a mode of 1.9 Ga (Morris and Pirajno, 2005).

Aileron Province

one at 1600–1550 Ma and a more significant event at 1950– 1900 Ma (Kirkland et al., 2013). Although no juvenile rocks or minerals are known from c. 1900 Ma in the Musgrave Province, addition of radiogenic material into the crust at this time is required to account for consistent Nd and Hf evolution patterns that show no indication of mixing processes, and mantle-like oxygen isotope signatures in zircons with 1.9 Ga model ages (Kirkland et al., 2013).

West

Warumpi Province

Yaya

Isotope data for c. 1450 Ma magmatic zircons in Talbot Terrane monzogranite sample GSWA 112102 fall directly on a normal-crustal evolution line from a c. 1900 Ma crust-formation event. This is also the case for isotope evolution in rocks of the Musgrave Province and the Edmund Basin. At c. 1.9 Ga, the timing of this crust formation event is unusual within Proterozoic Australia and supports the idea of an extensive 1.9 Ga underplate beneath these regions.

Kintore

Haasts Bluff

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Table Top

Constraints on the tectonic evolution of the Rudall Province Metasedimentary rocks of the eastern association in the Talbot and Connaughton Terranes have a similar structural and metamorphic history to the northern and central Arunta Orogen (Collins and Shaw, 1995; Bagas, 2004; Claoue-Long and Hoatson, 2005), and this has been considered as evidence that the Rudall Province and Arunta Orogen formed part of the North Australian Craton prior to the Yapungku Orogeny (Bagas, 2004; Fig. 10). However, it appears that the Rudall Province has more in common with a Capricorn Orogen source than it does with the Arunta Orogen.

Camel–Tabletop Fault Zone Connaughton Vines–Southwest–Mckay Faults Talbot

Boora Boora Zone

Gascoyne Province

Margaroon Zone

The Arunta Orogen contains 1690–1670 Ma magmatic rocks, whereas those in the Rudall Province are dominated by the 1800–1765 Ma Kalkan Supersuite. With regard to the age of crustal residence within these terranes, only the Connaughton Terrane has somewhat similar model ages to the Aileron Province of the Arunta Orogen (Kirkland et al., 2013), implying that this terrane could have a North Australian Craton heritage. However, the U–Pb age and Hf isotopic signature of inherited

Lime Juice Zone

Mutherbukin Zone Mooloo Zone Paradise Zone

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CLK79

Arunta Chewings Event Liebig Orogeny Strangways Event Yambah Event Stafford Event Argilke lgneous Event

Figure 10. Time-space diagrams showing magmatic and metamorphic U–Pb ages for the Gascoyne Province, Rudall Province, and Arunta Orogen. Data include all GSWA U–Pb zircon and baddeleyite ages and Arunta Orogen data compiled in Neumann and Fraser, (2007).

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14.06.13

Rudall Yapungku Orogeny Tectonic domains Magmatic Metamorphic

Kirkland et al.

Implications for terrane boundaries

zircons within all the Kalkan Supersuite granites, from both terranes, are most similar to sources in the West Australian Craton, in particular the Glenburgh Terrane in the southern part of the Gascoyne Province (Fig. 1). The presence of 2.0 and 1.8 Ga inherited zircons are consistent with the magmatic rocks of the Kalkan Supersuite having incorporated material from metasedimentary rocks of the eastern association, which was deposited in a similar timeframe to the Capricorn Orogeny-aged basins. The presence of 2715–2577 Ma-aged inherited zircons in a syenogranitic gneiss of the Talbot Terrane (GSWA 104932, Nelson, 1995a) are consistent with their derivation from the Fortescue and Hamersley Groups of the Pilbara Craton. The Hf isotopic evolution of granitic rocks within the Talbot and Connaughton Terranes also implies the involvement of unradiogenic crust, probably as basement to the sediments of the eastern succession (Fig. 5). This crust likely had a composition similar to that of the East Pilbara Terrane, consistent with the recent results of passive seismic study across the province, which suggests that thinned East Pilbara Terrane crust extends as basement beneath the western part of the Rudall Province (Reading et al., 2012), thus implying an autochthonous setting for the Talbot Terrane.

The 1800–1765 Ma Yapungku Orogeny is considered to represent collision of the North Australian Craton with the West Australian Craton. Isotope data demonstrate that the Rudall Province is a (para)autochthonous assemblage that developed on the eastern margin of the Pilbara Craton. Such a finding is consistent with the initial interpretation, based on regional 1:250 000 scale geological mapping, that the >5-km-thick clastic succession of the Talbot Terrane was deposited on the eastern margin of the Pilbara Craton, and immediately thereafter was intruded by the Kalkan Supersuite during southwest-directed thrusting (Hickman et al., 1994; Hickman and Bagas, 1995; Bagas and Smithies, 1997; Hickman and Bagas, 1999a). Therefore, the suture zone between the North and West Australian Cratons should be located to the east (in present-day coordinates) of the province. The Connaughton Terrane was thrust westwards over the Talbot Terrane during the latter stages of the Yapungku Orogeny (Bagas, 2004). The Camel–Tabletop Fault (Bagas and Lubieniecki, 2000) is a post-Yapungku structure, along which pieces of the same crustal block were reorganized. The timing of reworking in the Tabletop Terrane is similar to that of Mesoproterozoic events in the Musgrave Province. Magmatism at c. 1450 Ma in the Talbot Terrane appears to have tapped a more radiogenic source, in contrast to all other magmas of the Rudall Province. This radiogenic source shares similarities to the isotopic signature of the Musgrave Province, with a dominant isotopic crust formation age of c. 1900 Ma. Narimbunna Dolerites in the Mesoproterozoic Edmund Basin of the Capricorn Orogen (Fig. 1), also indicate a juvenile source formed at 1950–1900 Ma. The potential of a c. 1900 Ma source in the basement of the Rudall Province, Edmund Basin and Musgrave Province could support a regional underplate of this age in the deep geology of the West Australian Craton. Such a structure could indicate a c. 1950–1900 Ma subduction zone dipping and underplating oceanic crust towards the present-day southwest. Nonetheless, the crustal source of the Kalkan Supersuite is vastly different from the crust of the Musgrave Province, which implies at least some dissimilar basement components within these two regions.

The Tabletop Terrane has been regarded as geologically distinct from the Connaughton and Talbot Terranes (Bagas, 2004). However, crust within the Tabletop Terrane appears to have been generated at the same time as that in the Connaughton Terrane and also from a similar source to inheritance in the Talbot Terrane (Fig. 7). It has, however, a distinct magmatic and overprinting history. In addition, the Paleoproterozoic isotope evolution of the Rudall Province is different from that of the Musgrave Province (Fig. 5). The isotopic composition of the Rudall Province lies mainly in the gap between the 3.0 and 1.9 – 1.6 Ga crustal evolution lines that are characteristic of the Musgrave Province, implying that the crust of the two provinces is broadly dissimilar (Fig. 5). The Archean source within the Musgrave Province is unidentified, although it could be the Gawler Craton (Kirkland et al., 2013). This Archean component overlaps the array from the most unradiogenic components of the Talbot and Connaughton Terranes, although such a signature is common to many Archean crustal blocks. These data imply an autochthonous setting for the Rudall Province on the margin of the East Pilbara Terrane, and do not necessitate any connection to the Arunta Orogen, the North Australian Craton or the Musgrave Province. Therefore, a model of suturing at 1800–1765  Ma of an allochthonous block (Arunta Orogen) of the North Australian Craton to the Pilbara Craton margin is inconsistent with the distinctly different post-1765 Ma tectonic histories of these two regions (Neumann and Fraser, 2007). Such a model predicts a shared history of post-suturing events. Although the Arunta Orogen records late Paleoproterozoic tectonic events such as the 1680– 1650 Ma Argilke tectonic event and the 1620– 1580  Ma Chewings Orogeny (Claoue-Long and Hoatson, 2005), no contemporaneous events are known in the Rudall Province.

Conclusions The U–Pb age and Hf isotopic composition of inherited zircons within Kalkan Supersuite granitic rocks throughout the Rudall Province are consistent with these magmas incorporating material from sedimentary rocks that were sourced from the Glenburgh Terrane of the Gascoyne Province. The >5-km-thick eastern association of sedimentary rocks in the Talbot Terrane were deposited at c. 1790 Ma, in a similar timeframe to other sedimentary rocks in the Capricorn Orogen, which were also sourced from the Glenburgh Terrane. This suggests that during the 1800–1765 Ma Yapungku Orogeny and 1820–1770 Ma

26

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Capricorn Orogeny, the southern margin of the Gascoyne Province was uplifted to supply detritus into an extended sedimentary basin, or series of linked basins, that wrapped around the southern and eastern margins of the Pilbara Craton.

Budd, AR, Wyborn, LAI and Bastrakova, IV 2002, The metallogenic potential of Australian Proterozoic granites: Geoscience Australia, Record 2001/12, 152p. Carr, HW 1989, The geochemistry and platinum group element distribution of the Rudall River ultramafic bodies, Paterson Province, Western Australia: University of Western Australia, honours thesis (unpublished).

The Hf isotopic composition of magmatic zircons in the Kalkan Supersuite has similarity to components within the c. 1800 Ma Bridget Supersuite of the East Pilbara Terrane. This implies that the East Pilbara Terrane extends eastward to form basement to the Talbot and Connaughton Terranes, a view supported by a recent passive seismic study of the area (Reading et al., 2012).

Cassidy, KF, Czarnota, K, Huston, D, Maidment, D, McIntyre, A, Meixner, T, Neumann, NL, Potter, A and Bagas, L 2006, New data and new concepts for the Paterson Orogen: Geological Survey of Western Australia, Record 2006/3, p. 8–10. Cawood, PA and Korsch, RJ 2008, Assembling Australia: Proterozoic building of a continent: Precambrian Research, v. 166, p. 1–35.

The broad similarity of crustal residence ages for all terranes in the Rudall Province indicates that they share a common heritage, although Mesoproterozoic reworking (infra-crustal magmatism) apparently occurred only in the Tabletop Terrane. These data indicate that the Rudall Province formed in an autochthonous setting and thus all components are endemic to the West Australian Craton. There is no necessity to invoke transfer of North Australian Craton terranes to the West Australian Craton margin or an accretionary style of orogenesis for the Rudall Province. The major suture between the North and West Australian Cratons must lie to the present-day east of the Rudall Province.

Cawood, PA and Tyler, IM 2004, Assembling and reactivating the Proterozoic Capricorn Orogen: lithotectonic elements, orogenies, and significance: Precambrian Research, v. 128, p. 201–218.

A younger phase of crust formation at 1.96 Ga is indicated by Hf isotopes of a c. 1450 Ma monzogranite in the Talbot Terrane. This isotope signature appears to be similar to a dominant basement component in the Musgrave Province.

Collins, WJ, Gray, CM and Goode, ADT 1988, The Parnell Quartz monzonite: a Proterozoic zoned pluton in the Archaean Pilbara Block, Western Australia: Australian Journal of Earth Sciences, v. 35, p. 535–547.

Claoue-Long, J, Maidment, D, Hussey, K and Huston, D 2008, The duration of the Strangways Event in central Australia: Evidence for prolonged deep crust processes: Precambrian Research, v. 166, p. 246–266. Claoue-Long, JC and Hoatson, DM 2005, Proterozoic mafic-ultramafic intrusions in the Arunta Region, central Australia: Part 2: Event chronology and regional correlations: Precambrian Research, v. 142, p. 134–158. Clarke, GL 1991, Proterozoic tectonic reworking in the Rudall Complex, Western Australia: Australian Journal of Earth Sciences, v. 38, p. 31–44.

Collins, WJ and Shaw, RD 1995, Geochronological constraints on orogenic events in the Arunta Inlier: a review: Precambrian Research, v. 71, p. 315–346.

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Kirkland CL, Wingate MTD, Tyler IM and Spaggiari CV 2009, 184367: metagranodiorite, Dwarf Well: Geochronology Record 846: Geological Survey of Western Australia, 4p.

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Howard HM, Werner M, Smithies RH, Kirkland CL, Kelsey DL, Hand M, Collins A, Pirajno F, Wingate MTD, Maier WD and Raimondo T 2011b, The geology of the west Musgrave Province and the Bentley Supergroup — a field guide: Geological Survey of Western Australia, Record 2011/4, 119p.

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Nelson, D 2004a, 148922: crystal-vitric tuff, Koonong Pool; Geochronology Record 249: Geological Survey of Western Australia, 4p.

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Nelson, D 2004b, 148925: coarse lithic sandstone, Koonong Pool; Geochronology Record 250: Geological Survey of Western Australia, 6p.

Reading, AM, Tkalcic, H, Kennett, BLN, Johnson, SP and Sheppard, S 2012, Seismic structure of the crust and uppermost mantle of the Capricorn and Paterson Orogens and adjacent cratons, Western Australia, from passive seismic transects: Precambrian Research, v. 196–197, p. 295–308.

Nelson, DR 1995a, 104932: garnet-biotite-muscovite syenogranite gneiss, Sundowner drillhole; Geochronology Record 31: Geological Survey of Western Australia, 4p.

Scherer, E, Munker, C and Mezger, K 2001, Calibration of the lutetiumhafnium clock: Science, v. 293, p. 683–687.

Nelson, DR 1995b, 104938: pegmatite, Coondegoon; Geochronology Record 35: Geological Survey of Western Australia, 4p.

Scrimgeour, I 2003, Developing a revised framework for the Arunta Region, Annual Geoscience Exploration Seminar (AGES) 2003: Record of Abstracts, Northern Territory Geological Survey Record 2003-001.

Nelson, DR 1995c, 104980: monzogranite gneiss, Graphite Valley; Geochronology Record 3: Geological Survey of Western Australia, 4p.

Scrimgeour, IR, Kinny, PD, Close, DF and Edgoose, CJ 2005, High-T granulites and polymetamorphism in the southern Arunta Region, central Australia: evidence for a 1.64 Ga accretional event: Precambrian Research, v. 142, p. 1–27.

Nelson, DR 1995d, 104981: biotite-muscovite monzogranite gneiss, southern part of Graphite Valley; Geochronology Record 4: Geological Survey of Western Australia, 4 p. Nelson, DR 1995e, 104989: muscovite quartzite, Fingoon Quartzite; Geochronology Record 5: Geological Survey of Western Australia, 4p.

Sheppard, S, Bodorkos, S, Johnson, SP, Wingate, MTD and Kirkland, CL 2010a, The Paleoproterozoic Capricorn Orogeny: intracontinental reworking not continent-continent collision: Geological Survey of Western Australia, Report, 33p.

Nelson, DR 1995f, 110056: biotite-hornblende granodiorite gneiss, Rooney Creek; Geochronology Record 518: Geological Survey of Western Australia, 4p.

Sheppard, S, Johnson, SP, Wingate, MTD, Kirkland, CL and Pirajno, F 2010b, Explanatory notes for the Gascoyne Province: Geological Survey of Western Australia, 336p.

Nelson, DR 1995g, 111843: biotite-muscovite monzogranite gneiss, Poynton Creek; Geochronology Record 520: Geological Survey of Western Australia, 5p. Nelson, DR 1995h, 111854: biotite-muscovite granodiorite gneiss, Poonemerlarra Creek west; Geochronology Record 521: Geological Survey of Western Australia, 5p.

Sircombe, KN 2002, Reconnaissance detrital zircon geochronology provenance of the Palaeoproterozoic Ashburton Formation: implications for Pilbara and Yilgarn amalgamation: Geological Society of Australia; 16th Australian Geological Convention, Adelaide, South Australia, Abstracts v. 67, p. 147.

Nelson, DR 1995i, 112310: granodiorite gneiss, Dunn Creek west; Geochronology Record 471: Geological Survey of Western Australia, 4p.

Sircombe, KN 2003, Age of the Mt Boggola volcanic succession and further geochronological constraint on the Ashburton Basin, Western Australia: Australian Journal of Earth Sciences, v. 50, p. 967–974. Smith, SG 1996, Geology and geochemistry of the Warrabarty carbonatehosted Zn–PB prospect, Paterson Orogen, Western Australia. PhD thesis, University of Tasmania.

Nelson, DR 1995j, 112341: micromonzogranite (meta-aplite) dyke, Rudall airstrip; Geochronology Record 472: Geological Survey of Western Australia, 4p.

Smithies, RH and Bagas, L 1997, High pressure amphibolite-granulite facies metamorphism in the Paleoproterozoic Rudall Complex, central Western Australia: Precambrian Research, v. 83, p. 243–265.

Nelson, DR 1995k, 112379: biotite monzogranite (augen) gneiss, Split Rock; Geochronology Record 473: Geological Survey of Western Australia, 4p.

Smithies, RH, Hickman, AH and Nelson, DR 1999, New constraints on the evolution of the Mallina Basin, and their bearing on relationships between the contrasting eastern and western granite–greenstone terranes of the Archaean Pilbara Craton, Western Australia: Precambrian Research, v. 94, p. 11–28.

Nelson, DR 1995l, 112397: coarse-grained porphyritic biotite monzogranite (augen) gneiss, Watrara Inlier; Geochronology Record 474: Geological Survey of Western Australia, 4p. Nelson, DR 1995m, 113002: granodiorite gneiss, Cotton Creek; Geochronology Record 475: Geological Survey of Western Australia, 4p.

Smithies, RH, Howard, HM, Evins, PM, Kirkland, CL, Kelsey DE, Hand M, Wingate, MTD, Collins, AS and Belousova, E 2011, Hightemperature granite magmatism, crust-mantle interaction and the Mesoproterozoic intracontinental evolution of the Musgrave Province, central Australia: Journal of Petrology, v. 52, p. 931–958.

Nelson, DR 1996a, 112101: biotite-epidote monzogranite gneiss, Larry Creek; Geochronology Record 522: Geological Survey of Western Australia, 4p. Nelson, DR 1996b, 112102: seriate biotite metamonzogranite, southern part of the Watrara Inlier; Geochronology Record 523: Geological Survey of Western Australia, 4p.

Smithies, RH, Howard, HM, Evins, PM, Kirkland, CL, Kelsey, DE, Hand M, Wingate, MTD, Collins, AS, Belousova, E and Allchurch S 2010, Geochemistry, geochronology and petrogenesis of Mesoproterozoic felsic rocks in the western Musgrave Province of central Australia and implication for the Mesoproterozoic tectonic evolution of the region: Geological Survey of Western Australia, Report, 73p.

Nelson, DR 1996c, 112160: garnet microgneiss, Harbutt Range; Geochronology Record 489: Geological Survey of Western Australia, 4p.

Spaggiari, CV, Kirkland, CL, Pawley, M, Smithies, RH, Wingate, MTD, Doyle, M, Blenkinsop, T, Clarke, C, Oorschot, C, Fox, L and Savage, J 2012, The geology of the east Albany–Fraser Orogen — a field guide: Geological Survey of Western Australia, Record 2011/23, p. 97.

Nelson, DR 1996d, 113035: orthogneiss, east of South Rudall Dome; Geochronology Record 476: Geological Survey of Western Australia, 5p. Nelson, DR 1996e, 118914: foliated granite, north of Harbutt Range; Geochronology Record 485: Geological Survey of Western Australia, 4p.

Sun, S-s, Warren, RG and Shaw, RD 1995, Nd isotope study of granites from the Arunta Inlier, central Australia: constraints on geological models and limitation of the method: Precambrian Research, v. 71, p. 301–314.

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Kirkland et al. Thorne, AM and Seymour, DD 1991, Geology of the Ashburton Basin: Geological Survey of Western Australia, Report 139, 141p. Tyler, IM 2000, Paleoproterozoic orogeny in Western Australia: GSWA 2000 extended abstracts: geological data for WA explorers in the new millennium: Geological Survey of Western Australia, Record 8, p. 7–8. Tyler, IM, 2005, AUSTRALIA; Proterozoic, in Encyclopedia of Geology edited by RC Selley, LRM Cocks and IR Plimer, Oxford, Elsevier, p. 208. Tyler, IM and Thorne, AM 1990, The northern margin of the Capricorn Orogen, Western Australia; an example of an Early Proterozoic collision zone: Journal of Structural Geology, v. 12, p. 685–701. Valley, JW 2003, Oxygen isotopes in zircon, in Zircon edited by J Hanchar and P Hoskins: Reviews in Mineralogy and Geochemistry, v. 53, p. 343–385. Van Kranendonk, MJ, Collins, WJ, Hickman, A and Pawley, MJ 2004, Critical tests of vertical vs. horizontal tectonic models for the Archaean East Pilbara Granite-Greenstone Terrane, Pilbara Craton, Western Australia: Precambrian Research, v. 131, p. 173–211. Van Kranendonk, MJ, Smithies, RH, Hickman, AH and Champion, DC 2007, Chapter 4.1 Paleoarchean development of a continental nucleus: the East Pilbara Terrane of the Pilbara Craton, Western Australia: Developments in Precambrian Geology, v. 15, Elsevier, p. 307. Wade, B, Barovich, K, Hand, M, Scrimgeour, I and Close, D 2006, Evidence for early Mesoproterozoic arc magmatism in the Musgrave Block, central Australia; implications for Proterozoic crustal growth and tectonic reconstructions of Australia: Journal of Geology, v. 114, p. 43–63. Wade, BP, Kelsey, DE, Hand, M and Barovich, KM 2008, The Musgrave Province: stitching north, west and south Australia: Precambrian Research, v. 166, p. 370–386. Williams, SJ 1986, Geology of the Gascoyne Province, Western Australia: Geological Survey of Western Australia, Report 15, 85p. Williams, IR and Myers, JS 1990, Paterson Orogen, in Geology and Mineral Resources of Western Australia: Western Australia Geological Survey, Memoir 3, p. 274–275. Woodhead, JD and Hergt, JM 2005, A preliminary appraisal of seven natural zircon reference materials for in situ Hf isotope determination: Geostandards and Geoanalytical Research, v. 29, p. 183–195. Wyatt, B, Mitchell, M, White, B, Shee, S, Griffin, W and Tomlinson, N 2002, The Brockman Creek kimberlite, east Pilbara, Australia: Extended Abstracts of the 4th International Archean Symposium, AGSO, Geoscience Australia Record 2001/37, p. 208–211. Wyborn, LAI 2001, Paterson Orogen synthesis: Geoscience Australia report, 24 p. Zhao, J-x and Bennett, VC, 1995, SHRIMP U–Pb zircon geochronology of granites in the Arunta Inlier, central Australia: implications for Proterozoic crustal evolution: Precambrian Research, v. 71, p. 17–43. Zhao, J-x and McCulloch, MT 1995, Geochemical and Nd isotopic systematics of granites from the Arunta Inlier, central Australia: implications for Proterozoic crustal evolution: Precambrian Research, v. 71, p. 265–299.

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REPORT 122

Information Centre Department of Mines and Petroleum 100 Plain Street EAST PERTH WA 6004 Phone: (08) 9222 3459 Fax: (08) 9222 3444

THE CRUSTAL EVOLUTION OF THE RUDALL PROVINCE FROM AN ISOTOPIC PERSPECTIVE

Further details of geological products and maps produced by the Geological Survey of Western Australia are available from:

Kirkland et al.

This Report outlines the crustal evolution of the Rudall Province, with particular emphasis on the development of the Talbot and Connaughton Terranes. Components within the Rudall Province have been linked to the Arunta Orogen of the North Australian Craton and hence regarded as exotic terranes on the margin of the West Australian Craton. This work presents time constrained Hf isotopes to elucidate the affinity of the Rudall Province and refine models for its genesis. The Rudall Province is divided into three lithotectonic elements known as the Talbot, Connaughton, and Tabletop Terranes. The Talbot and Connaughton Terranes were affected by magmatism produced during the collision between the West and North Australian Cratons at 1800–1765 Ma. Zircons within granitic rocks related to this event indicate crustal residence ages of 3.4 – 2.4 Ga, which have similarity to crustal sources with the basement of the Capricorn Orogen. Additionally, the Hf isotopic signature of the Rudall Province has similarity to components of the c. 1800 Ma Bridget Suite, which has a clear association to the Pilbara Craton. Hence, sources for most isotopic compositions preserved within the Rudall Province are present within the proximal West Australian Craton and an exotic origin for the Rudall Province is unlikely. A distinctive phase of crust formation at 1.9 Ga in the Talbot Terrane implies an affinity to a major deep lithospheric source of similar age in the Musgrave Province and could indicate a regional underplate of this age.