(Metzger) from the Upper Cambrian of Baltoscandia

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The acrotretacean brachiopod Ceratreta tanneri (Metzger) from the Upper Cambrian of Baltoscandia Lars E. Holmer ;Leonid E. Popov

Online publication date: 06 January 2010

To cite this Article Holmer, Lars E. andPopov, Leonid E.(1990) 'The acrotretacean brachiopod Ceratreta tanneri (Metzger)

from the Upper Cambrian of Baltoscandia', GFF, 112: 3, 249 — 263 To link to this Article: DOI: 10.1080/11035899009454772 URL: http://dx.doi.org/10.1080/11035899009454772

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The acrot ret acean b rach iopo d Cerat reta ta12 neri (Metzger) from the Upper Cambrian of Baltoscandia

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LARS E. IiOLhIER and LEONlD E. POPOV

Holmer. L. E. & Popov, L. E., I990 09 15: The acrotretacean brachiopod Crratrcta latirirri (hletzger) from the Upper Cambrian of Baltoscandia. GlJologiska Formitigetis i Stockholtti For/iatidli/igar, Vol. I 12, Pt. 3, pp- 249-263. Stockholm. ISSN 0016-786X. Ccratrcta tatitii,ri is a widespread and biostratigraphically significant species within Baltoscandia. In northern Estoni? and the Leningrad district (USSR) i t is restricted lo the Upper Cambrian quartzose Lhgase and Ladoga formations (louer ll'esterga~~doditia Biozone). In S w d c n it has been found in the Upper Cambrian alum shales in Ostergotland, where it is associated with trilobites of the Liytoplastirs to lower Peltirra biozones; in the Siljan district (Dalarna) the species has been isolated from the secalled 'Obolus' beds, situatcd directly above the Precambrian basement. Previously, Cambrian rocks w r c thought to be missing from this area, and the occurrence of C. tatitieri (associated with Utigirla itiortiata) is of palaeogcographical importance as it implies a late Cambrian, rather than an early Ordovician dating for the transgression of the early Palaeozoic sca into the Siljan district. C. latrricvi is redescribed mainly on the basis of new material from Sweden and USSR. 0 Bracliiopoda, Lirigirlata. Acrotretacea, Ceratreta tanneri (A1etzgi;r). Biostratigraplry,palaeogeograpliy, Upper Cariibriari, riorthrrti Estonia. Letiitigrad district. USSR. Ostergotland, Dalarna. Swden. . of Pa/aeotitolog,: n0.v SSS. S-7S1 22 Uppsa!a. Swedeti. atid Lars E. l ~ o h e r Itistiliire Lcotiid E. Popo,; K V X X I , Srvdtiij pr. 74, Letiitigrad, 199 026. USSR. Alatiiiscript receiwd 7 Jatiirary 1990. revisid rtiariiiscript received I Jirtir 1.990.

Investigations of Cambrian-Ordovician boundary beds in Raltoscandia have increased recently due largely to !he activities of the IUGS Working Group, while trying to define a globally acceptable stratotype section. This work has concentrated to a great extent on the south-eastern part of the region; in northern Estonia and the Leningrad district, a biostratigraphical zonation has been developed, which is based partly on phosphatic inarticulate brachiopods (Kaljo et al. 1986, 1988; Heinsalu et al. 1987; Popov et al. 1989; Mens et al. 1989). The recent investigations have shown that the Middle and Upper Cambrian sequence of northern Estonia and the Leningrad district (Fig. I) is fairly complete; it consists mainly 'of quartzose,. fine-grained sands and silts, which have yielded conodonts but lack trilobites (e.g., Mens ct al. 1987; Popov et al. 1989). In contrast, the correlative succession in Scandinavia is dominated by alum shales (Fig. 2), where the biostratigraphical zonation is based almost entircly on'trilobites (e.g., Martinsson 1974); the conodont zonation through this interval has not yet been worked out in detail (Muller 1959, 1971). As noted by Popov et al. (1989), the endemic, mostly obolid faunas of the south-eastern Raltic d o not provide very good opportunitie's

for exact correlations with the standard Cambrian succession of the rest of Raltoscandia, but at the beginni'ng of the Late Cambrian some widespread acrotretacean brachiopod genera occur (e.g., Attgidolre/o and Ceralreta). The acrotrctacean Ceratrcta tariricri (Metzger) was until recently known only from basement fissure fillings of unknown age on the island of &and (Metzger 1922; Martinsson 1968); however, it has now been recorded also from the Upper Cambrian Ulgase and Ladoga formations in the Leningrad district and northern Estonia (Kaljo ct al. 1986; Mens et al. 1989; I'opov et al. 1989; Fig. 1). The main object of this paper is to review the stratigraphical and geographical distribution of C. fatitieri, as well as to describe well-preserved, new material from Sweden; for comparative purposes, specimens from Estonia and Finland are also illustrated.

i\li~fhotls.- The'matcrial was prepared from the quartzose rocks either mechanically with a needle, or by means of dilute (30%) HF (see, e.g., Schallreuter 1982 for details on this method); specimens from calcareous beds (USUally stinkstone concretions) within the alum shales were isolated by etching with weak (10%)

Lars E. Ilolrric~rarid Lcoriid E. Popor

CFF 112(1990)


250

Fig. I. 0 A. Map of Baltoscandia showing localities: Syas' (X), Langbcrgsoda-6jcn (9), Siljan district (10). 0 B. Simplificd geological map of bstergotland (after Dahlman in D r u m 61 Dahlman 1980. PI. I ) showing localities: Uorghamn quarry ( I I), Mrstad quarry (12). VSstanA quarry (13), Ljung quarry (14). SkAningstorp boring core ( I 5). 0 C. Sketch map of northern Estonia showing distribution of the Ulgase Formation and localities: Hundikuristik, hiiiekalda (I), Iru (2). Kallavere (3). Valkla (4), Turjekeldcr ( 5 ) , boring core no. hi-77 (6), boring core no. K-,1653. Lcgcnd: clay (I), silt (11). isopach (Ill). Cliff ('Baltic-Ladoga Clint' scnsu I'opov et al. 1989) (IV), arca of non-dcposition (V). localitics (VI).

acetic acid, using standard techniques. Measurements (in niillimetres if not stated othcnvisc) have bccn madc on thc matcria1,as follows (Fig. 3): W, L, H = width, Icngth, height

ofvalve; WI, LI =width, length ofdorsal pscudointerarca; W G = width of median groove; WMB, LMB = width, lcngth of median buttress; W M I , LM 1 = width, lcngth of cardinal musclc scars;

Ceratreta tannerijrom fhc Upper Curribriati 251

GFF I I2 (I 990)

Conodont biozones

Lingulate biozones

Trilobite biozones

ostergotland

Estonia

Leningrad district

I

'Diclyonema' Shale


proavus

I

I

I

I

Maardu Lornashka

Tsitre

Ladoga ijtgase

Tg. 2. Stratigraphical subdivision of the Upper Cambrian and lower Tremadoc (Pakerortian Stage) in Ostergotland, northern Estonia, and Leningrad district (after Popov et al. 1989, table 5).

WM2, LM2 = width, length of antero-central niuscle scars; LS, BS, HS, = length, beginning, height of dorsal median septum; PHS = position of maximum height of dorsal median septum; WPF, LPF = width, length of exterior pedicle foramen; WPT = width of interior pedicle tube; LAP, HAP = length, height of apical process. Repository. - The studied material is housed in the Department of Palaeozoology, Swedish Museum of Natural History, Stockholm (KM Br); Geological Survey of Sweden, Uppsala (SGU Type); Institute of Palaeontology, Uppsala (PMU), Sweden.

Systematic palaeontology Ccratrcta tariricri (Mctzgcr, 1922) Figs. 3-6, Tables 1-4 Syriorijwiy. - 0 I9 I I Brachyopode - Wiman (iri Tanner), p. 10, PI. 21-5. 0 *I922 Acrotreta Taririeri n.sp. - Metzger, p. 4, fig. I A-I. 0 v I929 /1crotr'eta - ijpik, p. I 3. v I 910 ricrotrcjta sp. \\'estergArd, p. 29. 1960 Acrotreta - Muiir-

isepp, p. 39. 0 v1968 Ceratreta taririeri (Metzger) - Martinsson, p. 139, figs. 2-7. 0 1982 Ceratwta taritmi (Metzger) - Tynni, p. 49, PI. 1:l-2. 0 v1986 Ccraircta iatitieri (Metzger) Popov (it1 Kaljo et al.), p. 102, fig. 3. 0 v1989 Ceratreta taririeri (Metzger) - I'opov (iri Popov et al.), p. 130, figs. 4-16.0 v1989Ceratreta talirieri - Puura (in Mens et al.), p. 109. Systeriiatic positioti. - Class Lingulata Goryansky & Popov, 1985; Order Acrotretida Kuhn, 1949; Superfaniily Acrotretacea Schuchert, 1893; Family Ceratrctidae Rowell, 1965. Lc>ctotjppe- Selected Martinsson (1968, p. 143). Dorsal valve (coll. V. Korvenkontio) figured by Metzger (1922, fig. IC), from fissure filling nr 3 (Tanner I9 1 1, PI. 1) at Lhgbergsoda-Ojen, parish of Saltvik, h a n d . [According to Martinsson (1968) the lectotype was discovered by him in the Geological Museum, University of HeIsingfors, Finland. However, the present whereabouts of this specimen can unfortunately not be determined (M. Fortelius, Helsingfors, pers. comm. 1988).]

Arailablc. rnatcrial. - Several hundred isolated

252 Lars E. Iloltrirrarirl Lcoriid E. Popor

GFF I I2 (1990)


W M l -W

Fig. 3. Dravings of Civam l a rarrrreri (hletzger, 1922). showing location of nieasurements (Tables 1-4). 0 A. Dorsal interior, based on SGU Typc 8 0 3 3 . 0 B. Posterior vicw of ventral exterior, based on SGU Type 8 0 3 4 . 0 C. Oblique anterior view of ventral interior, based on SGU Type 8027. All from Upper Cambrian alum shales, Peltura Biozonc, Farstad quarry, Ostcrgotland, Sweden; all x24.

complete dorsal and ventral valves in addition to numerous smaller fragments. Dimensions of figured valves; SGU Type 8020 (W 2.00, L 1.74), SGU Type 8021 (W 2.16, L 1.96), SGU Type 8022 (W 2.08, L 1.48), SGU Type 8023 (W 2.52, L 1.96), SGU Type 8024 (W 2.20, L 1.88), SGU Type 8025 (W 2.24, L 1.92), SGU Type 8026 (W 2.17, L I .6 I , H I .24), SGU Type 8027 (W 2.69, I, 1.96), SGU Type 8028 (W 2.28, L 1.72, H 1.86), SGU Type 8029 (W 2.20, L 1.64, H 1.24), SGU Type 8030 (W 1.68, L 1.20, H 0.74), SGU Type 8031 (damaged), SGU Type 8032 (W 2.23, L 1.77, H I .6 I), SGU Type 8033 (W 2.28, L 1.76), SGU Type 8034 (W 2.40, L 1.76, H 1.64); SGU Type 8035 (W 1.76, L 1.32); PMU F24 (W 1.68, L 1.32), PMU F34 (W 1.16, H 0.72), PMU F35 (W 2.40, H 1.40), PMU F36 (damaged), PMU.Ogl34(W 1.52, L l.l6), PMU Og135 (W. 1.36, L 1.04). PMU Og136 (W 2.92, L 2.24, H 1.60), PMU &I37 (W 1.76, L 1.32); RM Br133875 (W 3.80, L 3.24); KM Br133876 (W 4.16, L 4.00); RM Br133877 (W 3.44); KM Br133878 (W 4.40).

Diugriosis. - Ventral valve generally more than half as high as wide, with lenticular pcdicle foramen half as wide as long; interior pedicle tube and apical process occupying more than half the height and length of valve. Dorsal pseudointerarea occupying more than half the valve width; median buttress usually well-developed; dorsal median septum usually occupying three quarters of the valve length. Dcwripfioii. - The measurements and ratios given below refer to average values (if not stated othenvise) in asseniblages from Ostergotland (Sweden;Tables I-2)and core R-1653 (northern Estonia; Tables 3-4). Shells ventribiconvex; usually transversely oval, but very irregular in outline, 80-91% as long as wide, maximum width usually somewhat posterior to midlength of shell. ornamentation of low, irregular, discontinuous growth lines, with rounded cross-section, generally densely spaced, but \vavelength varying from less than 10 pni to 70 pm.

Fi.q 4. Ci>rarrcmlariticri (hletzger, 1922); Sneden, Ostcrgotland, Upper Cambrian alum shales, Peltura Biozone. VZstanA quarry (A-C. F-H, J, N, P), Barstad quarry (K-hl, 0); Finland, Ahnd, fissure filling at U n g bergsoda-Ojen (D-E): Estonia, Boring core no. K-1653 (88.40-89.65 m; Fig. 8B), Ulgase Formation (I). 0 A. Exterior ofdorsal valve, SGU Typc 8020, x19. 0 B. Interior of dorsal valve, SGU Typc 8021, x19. 0 C . Detail of pscudointcrarca of B, x 4 0 . 0 D. Interior of dorsal valve, PhlU F24 (previously figured by hlartinsson 1968, Fig. 48). x19. 0 E. Detail of pscudointcrarca of D, ~ 4 2 0 . F. Lateral view of exterior ofjuvenile dorsal valve, SGU Typc 8022, x19. 0 G. Detail of ornamentation of F. x85. 0 H. Posterior view of F, showing larval shell.

Ceratreta tannerifion1 the Upper Cambrian 253


GFF112(1990)

x61. 0 1. Detail of pseudointerarea of dorsal valve, R M Br133875, x42. 0 J. Lateral view of interior ofjuvenile dorsal valve, PhlU bgl34, x50. 0 I(. Interior of gerontic dorsal valve, SGU Type 8023, x19. 0 L. Lateral view of K, x!9. 0 hl. Lateral view of dorsal interior SGU Type 8024, x19. 0 N. Interior ofjuvenile dorsal valve, PMU Og135, x19. 0 0.Oblique anterior viewbf dorsal median septum with spines, SGU Type 8025, x50. 0 P. Interior ofjuvenile dorsal valve, lacking median septum, SGU Type 8035, x19.


254

Lars E. llolinrr aiid Leoriid E. Popov

GFF 1 I 2 ( I 990)

Fix. 5. Ccrarrrra Iartitcvi (hletzger, 1922); Sweden, 6stergotland, Upper Cambrian alum shales, Peltura Bio?me. Barstad quarry (A, C. E. G ) , Vastana quarry (D, F, J); Finland, Aland, fissure filling at LangbergsodaOjen (€ H-I, I,K). 0 A. Exterior of ventral valve, SGU Type 8026, x19. 0 B. Posterior view of ventral exterior. PhlU F35 (previously figured by hlartinsson 1968, fig. 7F), x19. 0 C. Interior of ventral valve, SGU Type 8027, x19. 0 D. Lateral profile of ventral exterior, SGU Type 8028, x19. 0 E. Exterior of ventral valve, SGU Type 8029, x19. 0 F. Lateral profile of ventral exterior. PMU Og136, x19. 0 G. Lateral profile ofjuvenile ventral valve, SGU Type 8030, x19. 0 H. Exterior of ventral valve, PhlU F34 (previously figured by hiartinsson 1968, fig. 7E), x19. 0 1. Detail of pedicle foramen of 11, x69. 0 J. Lateral view of interior of broken ventral valve, showing median septum, apical process, and pedicle tube, SGU Type 8031, x19. 0 K. Lateral view of ventral interior, showing median septum and pedicle tube, PhlU F36, x42.

Ventral valve strongly convex to subconical, 6 5 4 7 % as high as wide; maxi'nium height usually somewhat posterior to midlength of valve; lateral profile, inclination, and shape of posterior slope extrcmcly variable, from strongly recurved, with concave and apsacline posterior slope to catacline, or procline with straight posterior slope; ventral pseudointerarea poorly defined, but usually with intertrough up to 0.45

mm wide tapering towards pedicle foramen. Lenticular pedicle foramen, about 0.10 mm wide and 0.20 mm long, situated posterior of apex. Ventral interior dominated by high apical process and interior pedicle tube, 0.30 mm wide, occupying 62% of valve height; internal pedicle opening elongated and rounded posteriorly, lapering anteriorly; apical process sometimes forming a median septum, extending for 55%


GFF 112 (1990)

Ceratreta tannerifiont thc Upper Curribriait 255

Fis. 6. Cipratrctu tumcri (hletzger, 1932). Estonia, Boring core no. R-1653 (88.40-89.65 m; Fig. 8B), Upper Cambrian Ulgase Formation. 0 A. Dorsal exterior, KlLl Br133876, X I I . 0 B. Interior ofdorsal valve (etched with HF), Khl Br133875, x13. 0 C. Lateral profile of B, x13. D. Detail of pseudointerarea of B, x38. 0 E. Lateral profile of dorsal exterior, R M Br133877, X II . 0 F. Detail of ornamentation of E, x76. 0 G . hteral profile of ventral exterior. Rhl Br133878, X II . 0 H. Detail of pedicle foramen of G, x30.

of the valve length from the posterior margin. Distinctly thickened growth tracks of ventral cardinal and antero-central muscle scars along posterior surface, the former starting at 75-94% of the valve height, and extending to about 0.20-0.40 mm from posterior margin; muscle scars widely spaced and slightly divergent, occupying 73%. of valve width; antero-central muscle growth track originating at 55-57% of the valve height, and extending to about 0.60 rnm from posterior margin; muscle scars situated directly postero-lateral to pedicle tube, closely spaced, occupying 29Yo'of valve width. Ventral visceral area distinctly pitted, with polygonal pits. Lateral profile of dorsal valve usually low to almost flat, with slightly recurved umbo; maximum height situated posterior to midlength of valve. Dorsal pseudointerarea wide, occupyingt 57-59% of valve width; propareas anacline and

narrow; median groove triangular and wide, generally occupying 62%of the width of the pseudointerarca. Triangular median buttress usually developed, situated directly anterior to the median groove. Dorsal cardinal muscle scars usually raised and platform-like, 49-57% as long as wide, extending t o 41% of the valve length from the posterior margin; muscle sears widely spaced, occupying 54-67% of valve width; antero-central muscle scars usually raised, knoblike, situated at 62%of the valve length from the posterior margin. Dorsal median septum low but long, extending to 75-88% of the valve length from the posterior margin; triangular in lateral profile, with maximum height at about midlength of valve; sometimes with one to three septa1 spines at anterior end. Well-defined dorsal limbus, about 0.12-0.20 mm from valve margin.

256

GFF 112(1990)

Lars E, IlolIncJratid Lconid E. Popov

Table 1. Crralrern Iati~~eri, averge dimensions and ratios of dorsal valves from the Upper Cambrian of 6slergotland, Sweden. W L UW WI LI LIAVI WhlI LhlI LhlllWh1l Wh12 Lh12 LS BS HS 23 45 44 44 21 21 44 45 49 49 49 50 50 11 51 ~~

mean 1.98 1.59 0.298 0.268 s min 1.30 1.00 max 2.64 2.28

80% 1.14 4.982 0.271 65% 0.60 9O'lb 1.84

PHS

WhIB LhlB

II

mean s min max


~

WG

45 0.714 0.157 0.186 0.84 0.24 1.44 1.20 22 1.09

28 0.41 0.109 0.24 0.68

0.21 0.078 0.08 0.48

18% 4.197 10% 29%

1.37 0.211 0.74 1.83

0.67 0.113 0.36 0.96

49% 5.194 37% 61%

0.60 0.128 0.44 0.93

1.03 1.22 0.136 0.213 0.88 0.74 1.30 1.80

0.36 0.096 0.10 0.60

0.53 0.123 0.37 0.76

28 0.17 0.061 0.08 0.32

Tubkc 2. Cimrrcla tajincri, avcmgc dimensions and ratios of ventral valves from thc Upper Cambrian of &tergotland, Sweden. W 21 mean 2.19 s 0.302 min 1.64 max 2.92 I1

L 21 1.75 0.261 1.21 2.32

UW 21 80% 4.980 71 Yo 90%

H 20 1.50 0.407 0.74 2.56

WPF I1 0.10 0.025 0.08 0.16

LPF I1 0.21 0.057 0.08 0.30

WhlI Lhll 15 6 1.58 1.16 0.216 0.129 1.04 1.00 1.83 1.32

Lhl1IWhll 8 47To 15.650 34% 75%

Wh12 6 0.64 0.091 0.56 0.80

Lh12 3 0.76 0.60 0.88

LAP 17 0.93 0.236 0.52 1.36

IIAP

WPT 14 0.99 0.30 0.222 0.052 0.64 0.23 1.20 0.36 5

7 b b k 3. Cr.ra/rcra raltncri, average dimensions and ratios of dorsal valves from the Upper Cambrian Ulgase Formation (Uoring core R-1653). Estonia. W

L

9 mean 3.50 3.15 s 0.594 0.621 min 2.30 2.00 max 4.40 3.90 II

14

UW

WI

LI

LI/WI

WhlI Lh1I

LMlAVhlI

LS

DS

11s

8 87% 3.091 83"/0 93%

9 2.00 0.325 1.60 2.45

10 0.19 0.058 0.15 0.35

9 10% 3.371 7% 18%

7 1.86 0.253 1.50 2.25

7 57% 6.500 49% 68%

4 2.18 0.312 1.75 2.50

7 0.77 0.360 0.30 1.20

6 9 1.64 1.19 0.180 0.255 1.40 0.85 1.85 1.55

Table 4. Cera/rc,ra/annc,ri, average dimensions and ratios ofvcntral valves from the Uppcr Cambrian UlgaseFormation (Boring core R-1653). Estonia.

w 1 1 9 mean 3.32 s 0.331 min 2.75 max 3.60

L'

uw

tI

9 3.04 0.430 2.05 3.40

9 91% 7.294 75% 97%

9 2.14 0.309 1.50 2.60

Disczission. - The above description gives only a very generalized picture of this very variable species. There are some differences between the assemblages of C. tarirreri from Sweden, Finland, and the, East Baltic, in (1) the size range (Tables 1-4), (2) the dominant outline of the valves, and (3) the ornamentation. The specimens in the rather small assemblages from the Leningrad region and northern Estonia are (1) considerably larger, ranging from 2.3 mm to 4\40 mm wide (Tables 3-4), and generally have (2) a

7 1.06 0.190 0.80 1.30

WG

less asymmetrical shape, as well as (3) a more subdued ornamentation, as compared with the Swedish and Finnish material. However, considering the variation illustrated by the much larger assemblages from Sweden, there seems little reason to doubt that the described material, from all three areas, belonged to a single species with a highly variable morphology. As noted by Martinsson ( I 968) and Popov et al. (1989), C. fariireri is closely similar to the type species, C. /rrbi>sBell, I94 I from the Upper Cambrian of USA; a comparative discussion of the two taxa is given by these authors. The shell structure of C. tatitteriwas not investigated in detail, but some broken shells show a 'columnar' structure (in the sense of Holmer 1989), which appears to be identical to that of other acrotretacean brachiopods. Contrasting views as to the origin of this type of shell structure have been published recently by Ushatinskaya & Zezina (1988), Ushatinskaya et al. (1988), and Holmer (1989).

GFF I I2 (1990)

Review ofstratigraphiFa1 and geographical distribution


Alatid, Fiiilattd On the island of Aland (as well as in some areas of Sweden and mainland Finland), the Precambrian basement contains a system of deep fissures that are filled with sandstones, conglomerates, or other clastic rocks. The sediments in these fissures were evidently deposited during early Palaeozoic transgressions. Most of the fillings have been assumed to be of Early Cambrian age, but the exact dating remains uncertain in many instances, largely due to that biostratigraphical diagnostic fossils are scarce (see Martinsson 1968, 1974; Tynni 1978, 1982, for summaries).

Ldrigbergsiida-tjjetz.- At this beach locality (no. 9, Fig. IA; no. 53, Bergman 1982, fig. I), in the

Ceratreta tannerifrotn the Upper Combriati 257

present at the Cambrian-Ordovician boundary level, which in Scandinavia has been placed traditionally at the upper boundary oftherlcerocare Biozone (Fig. 2; see also Martinsson 1974). The alum shalesrange in age from late Middle Cambrian to Late Cambrian, and consist mainly of black shales with lenses of bituminous limestone (usually termed stinkstone or anthraconite; see Berg-Madsen 1989 for a discussion of these terms), but in addition, in the Middle Cambrian, there are locally also some fine interbeds of sandstone (e.g., Westergard 1940, Bruun & Dahlman 1980, Andersson et al. 1985). The Lower Ordovician. (Tremadoc) ‘Dictyonenia’ Shale is adirect lithologicalcontinuation of the Cambrian alum shales; it was referred to as the Upper Member of the Alum Shale Formation by Andersson et al. (1985). According to Westergard (1922, 1940, 1944) and Tjernvik (1 956, 1958)Rliab~litioporajlabclR. socialis, and R. desntograptoideshas l~orr~zis, been found in the ‘Dictyonema’ Shale (representing zones B and C of Erdtmann 1982, fig.

northern part of the island of h a n d , the sandstones of a basement fissure filling contain numerous shells of Cerafrefafanneri. The occurrence was first noted by Tanner (1911), and 1). Wiman (iri Tanner 191 1, p. 10) suggested that the occurrence of the brachiopod, as well as the Rorgharwi quarry. -The Borghamn boring, situgeneral lithology of the deposit indicated an ated in Borghamn quarry, 500 m north of Omearly Cambrian age. This view was also sup- berg (locality I I , Fig. IB), penetrated some 30 ported by Metzger ( 1 922), who described Acro- m of the Middle Cambrian to Lower Ordovician trefatanneri. Martinsson ( 1968), while referring sequence (Westergi3rd 1940). From this boring the species to Ceratreta, discussed in more de- Westergard (1940, p. 29) reported the occurtail the age of the fissure filling and suggested rence of an unnamed species of Acrolrefa, here referred to Cerafreta tarineri. The brachiopod that the occurrence of a ceratretine brachiopod could point to a Late Cambrian, or possibly was encountered in beds at 12.64-13.85 m (Fig. Early Ordovician age for the deposit (cf. Rowell 7A) that were assigned tentatively to the Lower Ordovician ‘Dictyonema’ Shale; n o specimens 1965, p. H278). An Early Ordovician dating was preferred by Tynni (1 982), based on acritarchs of ‘Dicfyonenta’ (= Rhabdinopora) have been isolated from the sandstones with C. faririeri; found from these beds, and part of the same however, his acritarch assemblage could equally interval in the core (13.17-14.25 m; Fig. 7A) well be taken as indicating a Late Cambrian age yielded the trilobite Lepfoplastrrsosfrogotliicirs. (S. Hagenfeldt, Stockholm, pers. comm. 1988). Henningsmoen (1957, p. 173) noted that all Other samples (from sandstones that lack C. other species of Leptoplasftrsarerestricted to the tatirzeri) from the same fissure filling have Upper Cambrian (Leproplasttrs Biozone), and yielded Lower Cambrian acritarchs, and, as sug- suggested that the specimens might have been gested by Tynni (1 982, p. 5 I), it is likely that the redeposi ted. As proposed by Bruun & Dahlman ( I 980). it arenites at Langbergsoda-Ojen were deposited is more likely that the interval (12.60-14.25m; during at least two separate phases. Fig. 7A) with Leptoplastiu and C. tartrieri actually belongs to the Upper Cambrian Lepfoplastta Ostergotland, Swederr Biozone. The overlying bed of stinkstone ( I I . 10-12.60 m; Fig. 7A) is assigned tentatively to In this province the sedimentary rocks (Lower Cambrian to lower Silurian) are preserved in an the PelfirmBiozone. The Cambrian-Ordovician asymmetrical tectonic basin, which dips gently boundary in the Borghamn core is probably situto the NW (Fig. 1R). A considerable hiatus of ated some four metres (at the level 11.10 m; varying magnitude (but at least comprising thE Fig. 7A) above that proposed by WestergArd entire Upper Cambrian Acerocare Biozone) is (1940). The only other fossils found in this part

258

Lars E. Ilolmer and Leonid E. Popov


A

CFF I I2 (1990)

B

Fig. 7. 0 A. Faunal log from the Borgharnn boring core (locality I I , Fig. IB; after Westergird 1940, p. 20 and Bruun 61 Dahlman 1980, fig. 31). 0 B. Faunal log from Vastani quarry (locality 13, Fig. IB; after Westergard 1922. fig. 17). Legend: glauconitic limestone (I), sandstone (2), alum shale (3). lenses of stinkstone (4).

of the sequence is Hyolithes sp. and ‘ArclraeortIris’? sp. (Fig. 7A). The overlying beds (10.25- I I. 10 m; Fig. 7A) are referred tentatively to the ‘Dictyonema’ Shale, but since the index fossil is lacking it is possible that also this interval belongs to the Upper Cambrian. In this case the Tremadoc is not represented in the core; the glauconitic sandstone, following directly above the alum shales, has yielded ‘an Arenig age fauna of conodonts (kindly identified by A. Lofgren, Lund) and phosphatic inarticulate brachiopods.

Udrsfad qirarry. - This quarry is situated less than one kilornetre northeast of Borghamn quarry (locality 12; Fig. IB). The lowermost Ordovician sequence in the quarry (temporarily exposed in a trench) was describcd by Rosen (1916), and more recently Bruun & Dahlman (1980) briefly summarised the logs of three borings penetrating the Cambrian-Ordovician se: quence; the acritrachs from the Lower Cambrian

sequence in one of these drillings (BSrstad 2) was investigated by Eklund (1990). The Upper Cambrian succession appears to be similar to that at Borghamn, and the alum shales and stinkstones of the Leptoplastus and Peltura biozones are about 2-3 m thick (the thickness varies soniewhat in different parts of the quarry); the Lower Ordovician ‘Dictyonema’ Shale (which has yielded Rhabditropora) is much thicker than at Borghamn, consisting of more than 6 m ofalum shales includinga unit (0.5-1.2 m thick) of grey, calcareous sandstone close to the base (Bruun & Dahlman 1980). A small (c. 500 g) boulder (no. 2, coll. A.H. WestergSrd 1939; deposited at SGU, Uppsala) of stinkstone has yielded several hundred specimens of Ceratreta tanneri. By lithology, the boulder probably comes from the uppermost bed of stinkstone (Pelttira Biozone) in the quarry, but there are no associated fossils, other than ‘Archueorthis’? SP.

CFF I I2 (1990)


Viisfatid qirarry. - This locality (no. 13, Fig. 1 B), which is sometimes referred to as Borens-

berg or Husbyfjol, is situated in the southeastern part of the district; the Cambrian-Ordovician sequence was described in detail by Westergard (1922, 1940, 1944) and the Lower Ordovician by Tjernvik (1956). Two borehole logs were published by Bruun & Dahlman (1980). The Upper Cambrian is more complete than at the two previous localities, up to 9 m thick; six of the eight Upper Cambrian trilobite biozones are represented in the quarry, with only the P. rriirior and Acerocare biozones lacking (Bruun & Dalilman 1980). Ceratrefa faritieri has been isolated from.small stinkstone concretions (5.6-6.5 ni, Fig. 4B), belonging to the Profopelfirra praecirrsor Biozone; the concretions also yielded Upper Cambrian conodonts. Two samples (probably collected by S. R o s h , Uppsala) stated as coming from ‘the second highest bcd of stinkstone’ in the quarry also contain a similar fauna (6.5-6.9 m, Fig. 4B). The uppermost stinkstone bed (5.1-5.6 m, Fig. 4B) belongs to the Pelfirra scarabaeoides Biozone. Ljuii.yqirarrjp.- I n addition to the localiticslisted above C. tanneri has been found in an erratic bouldcr (no. 33, coll. G. Holm 1875; deposited at SGU, Uppsala) of Upper Cambrian stinkstone (?f’C.ltlrra Biozone) at Ljung quarry (locality 14, Fig. IB). The boulder also yielded Upper Cambrian conodonts.

Dalartia, Swedeti In the Siljan district the Loner I’alaeozoic is preserved within a tectonically complex ringstructure, which probably represents a hypervelocity impact crater (see Jaanusson 1982 for a recent summary). The presence of the so-called ‘Obolus’ beds (conglomerates and sandstones), which rest directly on top of the I’recanibrian basement at the base of tlie I’alaeozoic rocks, is well-kno\y (see, e.g., Moberg 8:Segerberg 1906; Tjernvik 1956; Jaanusson 1982; Wickman & Nystrijm 1985, for a revicw). The ‘Obolus’ beds are absent locally (e.g., at Talubacken; Uergstroni 1988) and their thickness varies considerably; in the Djupgrav section the conglomerate is about 3 m thick, and a shaly layer close to the top has yielded Rliabdiriopora socia1i.s (Thorslund 6:Jaanusson 1960; Jaanusson 1982), whilst at Sjurberg, the thickness is only 0.15-0.80 m (Tjernvik 1956). As noted by Jaanusson (1982) it is evident that the rapid 131era1 variations in the thickness and lithology of

Ceratreta tanneriJroni rlie Upper Curribriati 259 these beds reflect the uneven topography of the pre-Ordovician land surface. The ‘Obolus’ bcds have previously yielded only mostly worn specimens and fragments of ‘Obolirs apollinis’ Eichwald [= UIigirla itigrica (Eichwald)] and ‘Oboltn triarigirlaris’ Mickwitz [= Urigirla iriorriata (Mickwitz); see also Mickwitz 1896, p. 301, which have been taken generally as indicators of an Early Ordovician age. Gardsjo. - At this locality (no. 10, Fig. IA), erratic boulders (coll. G . Holm 1890, deposited at SGU, Uppsala) of a soft sandstone contain numerous valves of UiigirIa iriorriafa(Thorslund & Jaanusson 1960; Jaanusson 1982). Thorslund & Jaanusson (1960, p. 24) suggested that the exceptionally well-preserved, thin valves of this brachiopod indicate that they had not been redeposited, in contrast to the othenvise mostly fragmentary obolid fauna present in the ‘Obolus’ beds at other localities. During the present study, numerous fragments of Ccrafreta faririeri were extracted from the silica-cemented sandstone by means of HF; the boulders have not yielded any other determinable fossils. Some poorly preserved, extremely worn fragments of ventral valves, questionably referrable to C. fanricri, were isolated from the ‘Obolus’ bcds at Silverberg and Vikarby (see Thorslund & Jaanusson 1960; Wickman 6:Nystrom 1985, for a brief description of these localities) where they are associated with similarly worn fragments of Urigirla irigrica and U. iriornafa. As suggested by Hadding (1927, p. 90) it is clear that several phases have been involved in the formation of the ‘Obolus’ beds in Dalarna.

Est 011 ia In northern Estonia the Ulgase and Tsitre formations represent the basal two units of the Upper Cambrian succession; according to Popov et al. (1989, fig. 2 ) , the tentative level of the Cambrian-Ordovician boundary (which these authors place at tlie base ofthe Corrlylochs proarirs Biozone) falls within the overlying Manrdu Meniber(the lower part ofthe Kallavere Formation in the sense of Kaljo et al. 1986). The entire Upper .Cambrian-Treniadoc (Pakerortian) succession is dominated by quartzose rocks. The exposures of the Ulgase Formation are known along thc cliff between Tallinn and the Turjekelder rivulet (Fig. IC), and from this area C. fantiivi has been found in the olgase Formation at eight localities, which are briefly described and discussed below. The lithology

260 Lars E. Ilolturr aiidLeotiidE. Popor

of the Ulgase Formation is dominated by light


coloured, yellow o r grey, quartzose, silty sands and silt (up to 14 m thick), underlain by the Lower Cambrian Tiskre Formation (see Popov et al. 1989 for a recent detailed description of the litho- and biostratigraphy).

liiiridikiirisfik.- This locality (no. I , Fig. IC) is a natural outcrop along the Hundikuristik rivulet at the Kadriorg Park, Tallinn (see also Miiiirisepp 1958, p. 60; Popov et al. 1989, p. 6 I , figs. 1 , l O ) ; the iflgase Formation is about 3.6 m thick and a sample (no. E-2013, Popov et al. 1989, fig. 10) from the uppermost 40 cni has yielded two valves of C. f a r y r i .The associated lingulate fauna includes Oepikifes fiagilis Popov & Khazanovitch (10 valves), Ungula inornata (9 valves), and Atigiilotrefa yostapicalis Palmer (70 valves). The upper boundary to the Maardu Member coincides with a discontinuity surface. ~lluekalda. - This section, which is situated very close to Hundikuristik (no. I , Fig. lC), in the eastern margin of the Kadriorg Park, Tallinn, was recently described in detail by Mens et al. (1989). The ulgase Formation (3.20 m thick) has yielded one valve of C. faririeri in sample no. 86-6 of Mens et al. ( I 989, fig. 1 A); the associated fauna includes U.iriorrinta, Oepikifes sp., and the conodont Pliakclorlris fetiiiis. Irii. - T h e iflgase Formation at this locality (no. 2, Fig. IC) is exposed along the right side of the Pirita river, Tallinn (see also M risepp 1958, p. 60; Popov et al. 1989, p. 61, figs. 1 , 10). Only the upper 4.4 m of the unit are accessible; a single valve of C. tatrtieri has been found in a sample (no. E-42/a8, Popov et al. 1989, fig. 10) from the lower 1.6 m of the formation, together with (1. itiortiafa (9 valves); another specimen of C. faririeri was found in a sample (no. E42/a7, Popov et al. 1989, fig. 10) 1.4 m from the top, associated only with two valves of 0. fiagilis.

Kallawre - The locality (no. 3, Fig. IC) is a natural outcrop (see also Popov et al. 1989, p. 58, fig. lo). The Ulgase Formation is subdivided into two memb$rs; fossils are most frequent in the uppermost part ofthe upper member, which has yielded a single valve o f C. tarttieri in a sample (no. E-60/3, Popov et a\. 1989, fig. lo), 1.5 m below the top. The associated brachiopod fauna consists of 0, fiagilis (7 valves) and U.t iriortiafa ( I 4 valves).

GFF 112 ( I 990)

I'aalkla river. - Only the upper part of the Ulgase Formation is exposed at this locality (no. 4, Fig. IC), where two valves of C. faririeri were found in the uppermost sample (no. E-4/6, Popov et al. 1989, fig. lo), together with 0. fiagilis (57 valves) and U. inornata (6 valves). The upper boundary with the basal detritic bed of the Maardu Formation is defined by a discontinuity surface. Tirrjckelder rivulet. - The locality (no. 5, Fig. IC) is a natural outcrop at the waterfall on the Turjekelder rivulet (see also Kaljo et al. 1986, fig. 3; Popov et al. 1989,.p,95, figs. I , 8, 14). The upper 5.4 m of the Lhgase Formation is exposed, and within this interval eight valves of C. taritreri have been isolated from two samples (nos. E-23/10-1 I , Popov et al. 1989, fig. 8) in the lowermost 1.6 m, together with 0.fiagilis (65 valves) and A . poslapicalis (29 valves); a single valve of C. /arirreri occurs also in a sample (no. E-23/13, Popov et al. 1989, fig. 8) from the interval 2.3-0.8 m below the top of the formation, alsoin associationwith 0. fragilis (61 valves) and A. yosfapicalis (3 valves). Kaljo et nl. ( I 986, fig. 3) recorded the conodonts Pliakdohrs tnriiis, Frrrrrishitra cf. frrrtiishi, and Prootic~oto~lirs terasliirnai from the interval 2.3-3.0 m below the upper boundary of the Tsitre Formation. The acritarch assemblage from the lowermost part of the Turjekelder section is typical for the Oleriris Biozone (Volkova 1982). Boririg core r i a Al-77. -This core was drilled at a site (no. 6, Fig. 2C) 12 km to the south-west of the Turjekelder section. It was referred to briefly by Popov et al. (1989, figs. 1 , 14), but the succession in the core has never been described in detail (the following description was kindly made available by K. Khazanovitch, Lcningrad). Greyish-green clays of the Lower Cambrian Tiskre Formation (unit A, Fig. 8A) underlie the Ulgase Formation, which is 9.5 m. thick; it can be divided into five units (B-F, Fig. 8A). The lowermost unit (B, 36.6-38.8 m, Fig. 8A) consists ofbrownish-grey, quartzose silts and weakly cemented siltstones with a 10 cm thick layer of green clay close'to the bottom; from this interval 0. fiagilis (31 valves), A . posfapicalis (3 valves), C. tur~ri(vi(1 valve), and fragments of Tor~~lldla sulcata was isolated. The overlying unit (C, 34.3-36.6 m, Fig. 8A) is made up entirely of light-grey, quartzose, sandy silts with somedetritusofobolid shells. Unit D(3 1.9-34.3 m, Fig. 8A) consists of light-grey silt and poorly

Ceratreta tannerifioni the Upper Cambrian 261

GFF I I2 ( 1 990)

m

B

.-

w


!.-.d-;

.!]

1_1 7

3

4

8

9

0

&& !J a E a

Fig. 8. A. Faunal log from boring core no. hl-77 (locality 6, Fig. IC). 0 B. Faunal log from boringcore no. K-1653 (locality 7, Fig. IC). Lithologiessimplified after K. Khazanovitch, p e n comm. Legend: clay ( I ) , silt (2), fine-grained sand (3). pyrite (4), detritus of obolids ( 5 ) , disarticulated valves o f obolids (6), kerogcnous clay (7). discontinuity surface (8), glauconite (9).

cemented, quartzose siltstone with thin layers of pyrite; a total of 41 valves of C. faririeri has of a brownish-grey kerogenous clay, as well as been isolated from the lowerrnost and uppersome black obolid detritus; it yielded 0.fragilis most beds of this unit. The middle, thin unit (C, (62 valves) and fragments of T. sitleafa. The 88.70-88.80 m, Fig. 8B) is made up of dark, uppermost two units comprise light-grey, brownish-grey, kerogenous clays and light-grey quartzose, sandy silts (E, 29.8-31.9 m, Fig. 8A), silts, whereas the upper unit (D, 88.40-88.70 and weakly cemented, quartzose siltstone (F, m, Fig. 8B) has greyish-green silts in the lower 29.3-29.8 m, Fig. 8A), with black-coloured de- part, and light-grey silts, with thin layers of tritus of obolid shells. kerogenous clay towards the top; the uppermost The Ulgase Formation is overlain by the fine- unit yielded 50 valves of C. fantreri, as well as grained sands of the Tsitre Formation (unit G, some well-preserved tubes of Torellellasiilcara. Fig. 8A); in the lower part Oepikifes friquefrirs According to V. Volkova (Novosibirsk; pers. Popov 6r Khazanovitch (4 valves), U. irigrica (9 cpmrn. 1989) the acritarch assemblage from the valves), Oepikifcsobfirsirs(Mickwitz)(4 valves), Ulgase Formation in the core includes CriSclirnidlifes celafirs (Volborth)(S valves) has sfalliriiirrii raridoriierisc, Cytnalogalea spp., Dasydiacrodiirm caiidatirrii, Itnpliivicirliu spp., been found. Leiojrsa sfoiiriioiietisis, Leiosphaeridia spp., Boririg core 110. R-1653. - The drill site (no. 7, Sfelldiiriafiirii sp., Titnofeeria laticarae, T. Fig. IC) is about 12 km south-east of the town phospliorifica, Veryhacliiiiiii dirtnoti f ii, and Virlof Rakvere; like the previous core, it has been cariisphacra firrbafa,which are all present also referred to only very briefly by Popov et al. in the upper part of Zone A3 (microflora assemb(1989, fig. I). According to personal communi- lage A3b) in the Upper Cambrian of eastern cation from K. Khazanovitch (Leningrad), the Newfoundland (Martin & Dean 1981); the range iflgase Formation (overlying the Lower of this zone corresponds to the lower part of the Cambrian Tiskre Formation, unit A, Fig. 8B) is Paraboliria spiriirlosa Biozone. only 1.25 m thick; it can be divided into three The overlying Maardu Member (unit E, units (B-D, Fig. 8B). The lowermost part (unit 88.15-88.40 ni, Fig. 8B) consists of light-grey, B, 88.80-89.65 m, Fig. 8B) consists of greyish- detritic and shelly sands, which contain fraggreen, silty clays and silt with scattered grains ments of U. itigrica; the sands with obolid de-

262 Lars E. Iloltner atid Leotiid 6 Popov

tritus continue up into the upper Suurj6gi Member (unit F, 88.40-85.85 m, Fig. 8B), which has some poorly preserved valves of S. celatirs encrusted by the problematic fossil Marctisodictyon priscrrm.


Len ingrad district, USSR In the Leningrad district, the fairly complete Upper Cambrian sequence, represented by the mainly quartzose Ladoga Formation (correlative of the Ulgase and Tsitre formations in Estonia; fig. 2), is exposed mainly along the Volkhov and Syas’ rivers (see Popov et al. 1989 for details). From the latter locality (no. 8, Fig. 2A) one sample (no. L-l7/33V, Popov et al. 1989, fig. 2) collected from the lowermost bed of the Ladoga Formation has yielded a single ventral valve of C. fatrtieri, associated with 0. fiagilis ( I 9 valves), Rebroyia cliertierskae Popov & Khazanovitch (23 valves), A. postapicalis (4 valves), and numerous juveniles of Utigirla sp. The sample also contained the conodonts Firrtiishiria fiiriiislii and Phakelodits fetiiris.

Discussion and conclusions In the Leningrad district and northern Estonia, Popov et al. (1 989, tables 5,8) recently proposed a lingulate (=phosphatic inarticulate brachiopods) and conodont zonation through the Middle-Upper Cambrian and Pakerortian sequence (see also Kaljo ct al. 1986); in this scheme C. tatitieri occurs in the lowermost Upper Cambrian Utigirla itiortta fa/Atigirlofrefaposfapicalis Biozone, corresponding to the lower part of the Westergaardodina Biozone (If’. bicrrspidata Subzone; Fig. 2), within the lower part of the iflgase and Ladoga formations. Because the conodont biozonation has not yet been worked out through these beds in Scandinavia, it is not entirely clear how the zonation in eastern Baltoscandia correlates with the standard Scandinavian trilobite biozones. However, according to Popov et al. (1989, table 8; Fig. 2) the Olcnus Biozone appears to be roughly equivalent to the zone of U. itiortiata. the occurrence Of .’ itiorriataand .‘ fatirieriin the ‘Obolus’ beds in Dalarna (Gardsjo) indicate that they’ at least appears correspond to the u. itiortiafa Biozone (and 11’. bicirspidata Subzone) as developed in eastern Baltoscandia. This is of Some palaeogeographical importance as it implies a late Cambriap dating for the transgression of early Palaeozoic sea into the Siljan district; the trans-

GFF I12 (1990)

gression seems to have begun some time during the early Late Cambrian (Oletiirs Biozone), but the occurrence of worn specimens of C. farztteri together with Utrgirla itigrica and U. itiortiata at other localities (Vikarby, Silverberg) in the same district shows that the formation of the ‘Obolus’ beds continued up into the later parts of the Late Cambrian. The ‘Obolus’ beds at yet other localities (e.g., Sjurberg) also include a lower Arenig fauna of phosphatic inarticulates (Holmer, unpublished). Previously the basal ‘Obolus’ beds were considered to be entirely of early Tremadoc age (e.g., Jaanusson 1982). The beds with C. taritieri in the upper Alum Shale Formation in Ostergotland appear to be slightly younger than those in other parts of Baltoscandia; they contain the zonal trilobites Leptoplast 11s and Peltirra (Profopelt iira praecirrsor Subzone), which can be correlated tentatively with the Utigula cotiresa Biozone (and the upper part of the Westergaardodina Biozone; Fig. 2) in eastern Baltoscandia. The distribution of C. tatitieri referred to above indicates that the species is restricted to the Upper Cambrian, ranging in Baltoscandia from the Oletiirs to lower Peltirra biozones. Although some authors (Westergird 1940; Tynni 1982) tentatively have referred the sequences with C. taritieri on h a n d (LSngbergsoda-Ojen) and in Ostergotland (Borghamn) to the Lower Ordovician, it is not associated with an undoubted lower Tremadoc (I’akerortian) fauna or flora. Acknoi~ledgcr~ic~nis. - This study was carried out at the VSEGEI, Leningrad (L. E. Popov), the Section of Palaeozoology. Swedish hluseum o f Natural History, Stockholm, and the Institute o f Palaeontology, Uppsala (L. E. Holmer), and the assistance o f all the staff at these institutions i s gratefully acknouledged. In particular. the assistance of hleit Lindell (Uppsala) in the picking o f etched residues is greatly appreciated, as \re11 as that of Lennart Andenson (Stockholm) and Dagmar Engstrom (Uppwla) in completing the figures. We are grateful to Valdar Jaanusson (Stockholm) and hfichael G . Bassctt (Cardim for comments o n both the language and scientific content. The manuscript also benefitted from comments by Jan Bergstrom (Stockholm). The work has bcen s u p ported by grants (to L. Holmer) from the Swedish Natural Science Rescarch Council and the Section o f Palacoroology, Swedish hluseum o f Natural History.

References Andcrsson. A., Dahlman, B., Gee. D.G. 6: SnSII, S., 1985: The Scandinavian alum shales. Sreriges Gi,ologiska Utiders6kriitig Ca 56, I-SO. Berg-hfadscn. V., 1989: Origin and usage o f the geological terms orsten, stinkstone, and anthraconite. Archive3 of h’afItrallI;Jlov16. 191-208. Bergman. L., 1 9 8 2 Clastic dykes in the h a n d islands, SW Finland and their origin. Geological Sitney of Finland. h l h i n 317. 7-33. nergstrorn. S. hi., 1 9 8 8 O n Pander‘s Ordovician conodonts: distribution and significance of the Priniodits elqans fauna in Baltoscandia. Senckenbergiana lerliaea 69, 217-251.


GFF112(1990) Uruun, A. & Dahlman, B., 1980: Den paleozoiska berggrunden. In H. Wikman. A. Uruun & B. Dahlman: Beskrirning [ill bcrggrimdskartarr Linlitpin