TY - JOUR

T1 - The spatial and temporal evolution of strain during the separation of Australia and Antarctica

AU - Ball, Phillip

AU - Eagles, Graeme

AU - Ebinger, Cindy

AU - McClay, Kenneth

AU - Totterdell, J.M.

PY - 2013

Y1 - 2013

N2 - [1] A re-evaluation of existing onshore and offshore gravity, magnetic, seismic reflection, and well datafrom the Australo-Antarctic margins suggests that magmatism and along-strike lithospheric heterogeneitieshave influenced the localization of initial rifting. The 3-D crustal architecture of the Australian andAntarctic margins, which formed during multiple rifting episodes spanning 80 Myr, reveal localasymmetries along strike. Rift structures from the broad, late Jurassic (165–145 Ma) rift zone are partiallyoverprinted by a narrower, mid-to-late Cretaceous rift zone (100 Ma), which evolved in highly extendedcrust. This late-stage rift zone is located within a region of heterogeneous crust with faults that cut late synriftstrata, interpreted as a continent ocean transition zone. This late stage transitional rift is populated byseismically identified rift-parallel basement highs and intracrustal bodies with corresponding positiveBouguer gravity and magnetic anomalies. These undrilled features can be interpreted as exposures ofexhumed mantle rocks, lower crustal rocks and/or as discrete magmatic bodies. Our results suggest thatstrain across an initially broad Australo-Antarctic rift system (165–145 Ma) migrated to a narrow rift zonewith some magmatism at 100–83 Ma. Breakup did not occur until 53 Ma within the eastern Bight-Wilkesand Otway-Adelie margin sectors, suggesting a west to east propagation of seafloor spreading. Theprolonged eastward propagation of seafloor spreading processes and the increased asymmetry of theAustralian-Antarctic margins coincides with a change from rift-perpendicular to oblique rifting processes,which in turn coincide with along-strike variations in cratonic to Palaeozoic lithosphere

AB - [1] A re-evaluation of existing onshore and offshore gravity, magnetic, seismic reflection, and well datafrom the Australo-Antarctic margins suggests that magmatism and along-strike lithospheric heterogeneitieshave influenced the localization of initial rifting. The 3-D crustal architecture of the Australian andAntarctic margins, which formed during multiple rifting episodes spanning 80 Myr, reveal localasymmetries along strike. Rift structures from the broad, late Jurassic (165–145 Ma) rift zone are partiallyoverprinted by a narrower, mid-to-late Cretaceous rift zone (100 Ma), which evolved in highly extendedcrust. This late-stage rift zone is located within a region of heterogeneous crust with faults that cut late synriftstrata, interpreted as a continent ocean transition zone. This late stage transitional rift is populated byseismically identified rift-parallel basement highs and intracrustal bodies with corresponding positiveBouguer gravity and magnetic anomalies. These undrilled features can be interpreted as exposures ofexhumed mantle rocks, lower crustal rocks and/or as discrete magmatic bodies. Our results suggest thatstrain across an initially broad Australo-Antarctic rift system (165–145 Ma) migrated to a narrow rift zonewith some magmatism at 100–83 Ma. Breakup did not occur until 53 Ma within the eastern Bight-Wilkesand Otway-Adelie margin sectors, suggesting a west to east propagation of seafloor spreading. Theprolonged eastward propagation of seafloor spreading processes and the increased asymmetry of theAustralian-Antarctic margins coincides with a change from rift-perpendicular to oblique rifting processes,which in turn coincide with along-strike variations in cratonic to Palaeozoic lithosphere

M3 - Article

JO - Geochemistry, Geophysics, Geosystems

JF - Geochemistry, Geophysics, Geosystems

SN - 1525-2027

ER -