The crustal thickness and structure onshore varies between tectonic domains, thinning from 35-40 km onshore to approximately 10 km beneath the magnetic quiet zone offshore.  Euler deconvolution solutions calibrated with seismic reflection data reveal two discrete sub-parallel rift systems.  Rift Structures of the western rift system overlap that of the eastern rift system, but they are separated by approximately 200 km.  Each system terminates at or near to the boundary of the Gawler craton, suggesting that the craton served as an obstacle to rift propagation. 

The Ceduna sub-basin, which contains up to 15 km of primarily post-rift strata, lies between the two rift zones.  During Syn-rift II, a new rift zone developed oceanward of the Syn-Rift I along the western rift zone.  Minor magmatism and possible mantle exhumation is observed during the second rifting stage and within ~10 My prior to the first well-defined seafloor spreading anomaly. The asymmetry of the conjugate Australian and Antarctic margins may be explained by the along-axis propagation of two spatially separated rifts that eventually linked via a NW-striking system of faults, or through discrete rift jumps to the NE within the rift-overlap zone.  Using observations of the location and distribution of basement related structures, a revised model for breakup between Australia and Antarctica is proposed.

 

HESS Club

5:30 - 6:30 Social Hour

6:30 Dinner

Talk After dinner