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Magnetic fabric and tectonic setting of the Early to Middle Jurassic felsic dykes at Pitt Point and Mount Reece, eastern Graham Land, Antarctica

Published online by Cambridge University Press:  23 September 2011

Jiří Žák ,
Igor Soejono ,
Vojtěch Janoušek  and
Zdeněk Venera
Jiří Žák*
Affiliation:
Institute of Geology and Palaeontology, Faculty of Science, Charles University, Albertov 6, Prague 12843, Czech Republic Czech Geological Survey, Klárov 3, Prague 11821, Czech Republic
Igor Soejono
Affiliation:
Czech Geological Survey, Klárov 3, Prague 11821, Czech Republic
Vojtěch Janoušek
Affiliation:
Czech Geological Survey, Klárov 3, Prague 11821, Czech Republic Institute of Petrology and Structural Geology, Charles University, Faculty of Science, Albertov 6, Prague 12843, Czech Republic
Zdeněk Venera
Affiliation:
Czech Geological Survey, Klárov 3, Prague 11821, Czech Republic
*
jirizak@natur.cuni.cz
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Abstract

At Pitt Point, the east coast of Graham Land (Antarctic Peninsula), the Early to Middle Jurassic (Toarcian–Aalenian) rhyolite dykes form two coevally emplaced NNE–SSW and E–W trending sets. The nearly perpendicular dyke sets define a large-scale chocolate-tablet structure, implying biaxial principal extension in the WNW–ESE and N–S directions. Along the nearby north-eastern slope of Mount Reece, the WNW–ESE set locally dominates suggesting variations in the direction and amount of extension. Magnetic fabric in the dykes, revealed using the anisotropy of magnetic susceptibility (AMS) method, indicates dip-parallel to dip-oblique (?upward) magma flow. The dykes are interpreted as representing sub-volcanic feeder zones above a felsic magma source. The dyke emplacement was synchronous with the initial stages of the Weddell Sea opening during Gondwana break-up, but it remains unclear whether it was driven by regional stress field, local stress field above a larger plutonic body, or by an interaction of both.

Keywords

Anisotropy of magnetic susceptibility (AMS)Antarctic peninsulaChon Aike silicic large igneous provinceGondwana break-upregional extensionTrinity Peninsula Group
Type
Earth Sciences
Information
Antarctic Science , Volume 24 , Issue 1 , 06 February 2012 , pp. 45 - 58
Copyright
Copyright © Antarctic Science Ltd 2011

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Supplementary material: File

Zak Supplementary Table

List of the AMS parameters for the analyzed specimens. Coordinates are WGS84.

Download Zak Supplementary Table(File)
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