Authors : Magloire Francois Fabien

Volume/Issue : Volume 8 - 2023, Issue 10 - October

Google Scholar : https://tinyurl.com/4w9nzjwh

Scribd : https://tinyurl.com/2csjjz35

DOI : https://doi.org/10.5281/zenodo.10029241

Abstract : The fragmentation history of East-Gondwana is divided in five periods, each period being preceded by mid-oceanic ridge closings and jumps. These plate movements were controlled by three branches of convection currents (CC): the western, the central and the eastern ones. Period 1 began with the rise of compressional constraints in the Neo-Tethys region caused by the anticlockwise rotation of East- Antarctica/Australia as the interaction effect with the newly formed off-South African E-W CC at M10. This led to the northward detachment of continental fragments from Northwest Australia and northeast India, the creation of an oceanic basin north of India and the spreading cessation of the Somali Basin at M0. Period 2 was marked by southward ridge jumps from the Somali Basin and the north of India. The influence of the E-W CC ended after the Lower Aptian fan-like rifting between India and Sri Lanka. From then on, plate movements occurred in N-S direction and the rotation of East-Antarctica/Australia got reversed. This period ended with the fan-like spreading of the Western Enderby Basin, during which the two arms of the central CC reunited and East-Antarctica/Australia was “trapped” within the South Pole Region and rotated anticlockwise. During Period 3, simultaneous ridge jumps in Middle Cenomanian conducted to the fan-like eastward opening of the Eastern Enderby Basin, whereas rifting activities occurred between Madagascar and India and between East-Antarctica and Australia. In Lower Campanian, the oceanic opening between East- Antarctica and Australia provoked the dispersal of the Eastern Enderby CC allowing the creation of new oceanic basins from C33 to C31 and a backward ridge propagation at C32. Starting from C31, the northwestward propagating CC underwent sidelong collisions with the Great Mascarene Basin before setting between the Seychelles and India where they merged with the “jumped” Mascarene CC at C29. After the collision of India against Eurasia in Middle Eocene (C21), Period 4 was marked by the creation of SEIR, the connection of CIR with SEIR and the separation of SWIR from CIR. Northward ridge jumps from SWIR at C5 generated the East-African Rift system. A pre- breakup rifting phase started since the Pleistocene in N-S direction.

Keywords : East-Gondwana; Plate Tectonics; Up-Welling Mantle Convection Currents; Mid-Oceanic Ridges; Oceanic Opening.