The breakup of East Gondwana: Assimilating constraints from Cretaceous ocean basins around India into a best-fit tectonic model

• Published in: Journal of Geophysical Research: Solid Earth
• Main Authors: Gibbons, AD, Whittaker, JM, Muller, RD
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-Blackwell Publishing Inc. 2013
• Subjects: Earth Sciences; Geology; Marine Geoscience; Conrad Rise; East Antarctica; East Ridge; Elan Bank; Kerguelen; Wharton; Antarc*; Antarctica
• Online Access: https://doi.org/10.1002/jgrb.50079; http://ecite.utas.edu.au/84430

Published models for the Cretaceous sea!oor-spreading history of East Gondwanaresult in unlikely tectonic scenarios for at least one of the plate boundaries involved and/orviolate particular constraints from at least one of the associated ocean basins. We link EastGondwana spreading corridors by integrating magnetic and gravity anomaly data from theEnderby Basin off East Antarctica within a regional plate kinematic framework to identify aconjugate series of east-west-trending magnetic anomalies, M4 to M0 (~126.7120.4 Ma).The mid-ocean ridge that separated Greater India from Australia-Antarctica propagatedfrom north to south, starting at ~136Ma northwest of Australia, and reached the southern tipof India at ~126 Ma. Sea!oor spreading in the Enderby Basin was abandoned at ~115 Ma,when a ridge jump transferred the Elan Bank and South Kerguelen Plateau to the Antarcticplate. Our revised plate kinematic model helps resolve the problem of successive two-waystrike-slip motion between Madagascar and India seen in many previously publishedreconstructions and also suggests that sea!oor spreading between them progressed fromsouth to north from 94 to 84 Ma. This timing is essential for tectonic !ow lines to match thecurved fracture zones of the Wharton and Enderby basins, as Greater India gradually beganto unzip from Madagascar from ~100 Ma. In our model, the 85-East Ridge and KerguelenFracture Zone formed as conjugate !anks of a leaky transform fault following the~100Ma spreading reorganization. Our model also identi"es the Afanasy NikitinSeamounts as products of the Conrad Rise hotspot.