Crustal architecture of the oblique-slip conjugate margins of George V Land and southeast Australia

• Main Authors: Stagg, HMJ, Reading, AM
• Format: Conference Object
• Language: English
• Published: US Geological Survey and The National Academies Press 2007
• Subjects: Earth Sciences; Geophysics; Seismology and seismic exploration; Antarctic; East Antarctica; George V Land; The Antarctic; Antarc*; Antarctica
• Online Access: http://pubs.usgs.gov/of/2007/1047/srp/srp109/of2007-1047srp109.pdf; https://doi.org/10.3133/of2007-1047.srp109; http://ecite.utas.edu.au/78384

A conceptual, lithospheric-scale cross-section of the conjugate, oblique-slip margins of George V Land, East Antarctica, and southeast Australia (Otway Basin) has been constructed based on the integration of seismic and sample data. This cross-section is characterised by asymmetry in width and thickness, and depth-dependent crustal extension at breakup in the latest Maastrichtian. The broad Antarctic margin (~360 km apparent rift width) developed on thickcrust (~42 km) of the Antarctic craton, whereas the narrow Otway margin (~220 km) developed on the thinner crust (~31 km) of the RossDelamerian Orogen. The shallow basement (velocities ~5.5 km.s -1 ) and the deep continentalcrust (velocities >6.4 km.s -1 ) appear to be largely absent across the central rift, while the mid-crustal, probably granitic layer (velocities ~6 km.s -1 ) is preserved. Comparison with published numerical models suggests that the shallow basement and deep crust may have been removed by simple shear, whereas the mid-crust has been ductilely deformed.