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Main Andean sinistral shear along the Cooper Bay Dislocation Zone, South Georgia?

Open-File Report 2007-1047-SRP-034

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DOI: 10.3133/ofr20071047SRP

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Abstract

The Cooper Bay Dislocation Zone (CBDZ) represents a major NW-SE trending tectonic boundary within the island of South Georgia that juxtaposes components of a Middle Jurassic to mid-Cretaceous island-arc and back-arc- basin system. New detailed structural data from the southern end of the dislocation zone reveal that earliest displacement along the boundary appears to have been associated with dip-slip reverse shear, characterised by widespread proto- to meso-mylonitic granitic rocks within the basement assemblage exposed to the southwest of the shear zone. Along the northeast margin, highly sheared and mylonitised metasedimentary and metabasic rocks reveal sinistral strike-slip kinematics and a sub-horizontal mineral lineation. Narrow zones of sinistral shear are locally superimposed within the basement rocks along the SW margin, that together with the presence of brittle sinistral faults suggest that the strike-slip component of deformation postdates the dip-slip. Comparison with the tectonic history of the Rocas Verdas Marginal Basin, Fuegian Andes, suggests that the sinistral shear event preserved along the CBDZ maybe be related to Late Cretaceous, main Andean orogenic transpression, although a Cenozoic event cannot to ruled out.

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Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Main Andean sinistral shear along the Cooper Bay Dislocation Zone, South Georgia?
Series title:
Open-File Report
Series number:
2007-1047-SRP-034
DOI:
10.3133/ofr20071047SRP
Year Published:
2007
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Description:
4 p.
Larger Work Type:
Report
Larger Work Subtype:
USGS Numbered Series
Larger Work Title:
Antarctica: A Keystone in a Changing World--Online Proceedings for the Tenth International Symposium on Antarctic Earth Sciences. Santa Barbara, California, U.S.A.--August 26 to September 1, 2007
Other Geospatial:
Antarctica
Additional Online Files(Y/N):
N