Crustal structure in southern Tyrrhenian sea from ...

Crustal structure in southern Tyrrhenian sea from seismic processing of HG-MEDOC WARR line.

R. de Franco, G. Caielli, G. Biella, G. Boniolo, A. Corsi, A. Morrone, A. Tento, G. Tango C. Ranero, V. Sallares, M. Prada I. Grevemeyer N. Zitellini

Istituto per la Dinamica dei Processi Ambientali, IDPA-CNR, Milan, Italy Barcelona Center for Subsurface Imaging, ICM-CSIC, Barcelona, Spain GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany Istituto Scienze Marine, ISMAR-CNR, Bologna, Italy

32 GNGTS TRIESTE 18-20 nov 2013

AIMS of the Presentation •Framework: MEDOC project (MEDiterràneo OCcidental) is a Spain-Germany-Italy cooperation project for the exploration of the crustal structures of the Balearic, Ligurian and Tyrrhenian basins.

•A new procedure of static corrections for Wide-Angle Reflection/Refraction (WARR) Data •Data Processing of HG-WARR MEDOC Line

•New results on the crustal structure in southern Tyrrhenian sea a contribution to the study of the processes of formation of rifted continental margins.


THE MEDOC PROJECT

A

B

M

Magnaghi Vavilov Smt Smt

F

Campanian Margin

H H

Flavio Gioia Smt

Campanian Terrace

E

Cornaglia Terrace

C Sardinia Margin

D

G G

Marsili Smt

N

MEDOC project acquired a total of 17 (2800 km) MCS (Multi-Channel Seismic Reflection) lines and 5 WARR (Wide-Angle-Reflection/Refraction) profiles using OBS, OBH and land-stations installed in Corsica and Sardinia. 32 GNGTS TRIESTE 18-20 nov 2013

WIDE ANGLE REFLECTION\REFRACTION SEISMIC DATA MEDOC HG LINE: EXPERIMENTAL LAYOUT

H

5 LAND STATIONS (IDPA-CNR) SARDINIA-CORSICA MARGIN

Vessel Sarmiento de Gamboa (CSIC) MCS data & WARR Shooting

G

5 OBS (UTM-CSIC) AND 25 OBH (Geomar) TYRRHENIAN SEA FLOOR Vessel Urania (ISMAR-CNR) OBSOBH deployment WARR-Data


DATA ACQUISITION & PROCESSING WARR DATA Common receiver gather data construction (navigation, shoting files) MCS Data WARR Data

MOHO

PmP Phases Refracted wave

Spectral Analysis Data Filtering Butterworth Band Pass hz (signal signature 7-8 hz)

4-15

First arrivals Picking

Pn Phases

MCS and WARR seismic data were acquired shooting twice the same lines using different devices, geometry and acquisition parameters

MCS data were acquired in common shot gather from 3450 m streamer (276 ch), shot spacing 50 m, fold 35, source 9 G-II airguns 3040 inch3 WARR data were acquired in common receiver gather from OBH, OBS, in-land Stations; 90 s shoting interval, ~220 m shot spacing, source two arrays of 6 G-II airguns, 4600 inch3.

WARR Static correction

Panel LMO Pn Imaging depth conversion

Panel NMO

PmP picking & depth conversion

Refraction Velocity analysis 32 GNGTS TRIESTE 18-20 nov 2013

WARR STATIC CORRECTIONS MOTIVATIONS TO DEVELOP A PROCEDURE FOR WARR STATIC CORRECTIONS

•In the standard WARR interpretation procedures (Trial&error method or traveltime inversion&Tomography) it is difficult to assign the correct seismic phases to the observed arrivals on profiles. •In the signal processing procedures detection and stacking routines are applied to the traces in order to enhance and focusing Pg, Pn and PmP phases and to obtain simplified transforms of the wave field and then to construct crustal (with different scales) images. 32 GNGTS TRIESTE 18-20 nov 2013

PROCESSING PROPOSED GLOBAL WARR STATIC CORRECTION RESIDUAL CORRECTION SHOT/RECEIVER CORRECTION (short wavelength effect of (long wavelength effect of the top of crustal basement) bathymetry)

+

i i i DTRE S T S m oot h TO bs

i DTRE S ( 0) Sea Bottom Morphology i DTRE S ( 0) Basin Morphology

DTLi j

DTLj

DTL

H Bj a t sm t ; DTLi VCb a s

j

DTLi H Bi a t sm t

1 1 VS VCb a s

Shot-ith VS

HiBatsmt

HjBatsmt

DTiRES(>0) DTiRES(