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The Breakup of Antarctica, India and Australia

The breakup of Antarctica, India and Australia can be traced accurately, and here we look a bit further into the process. India ‘left’ Madagascar behind on its way towards Eurasia, and the responsible forces down below can be analyzed as shown here:

The breakup of Antarctica, India and Australia

The convection roll forcing India to cross equator is marked specially with wide red and blue lines. After entering the area above the adjacent large scale convection roll, India turns anti-clockwise.

Australia, on the other hand, follows a northern trend within a single convection roll. The eastern edge is confined with a downwelling division line, shaping the mountain range on that side.

For animation, see here: https://www.earthbyte.org/gondwana-breakup-and-the-plate-tectonic-evolution-of-the-tethyan-oceans/

The Indo-Australian Plate does therefore move in the same direction. Note that upwelling and downwelling of large-scale convection rolls does not govern tectonic drift directions. The direction is determined much more randomly, and once on the move, the opposing small-scale convection rolls get decoupled and the pro-active convection rolls rend to get coupled to the tectonic plate bottom. Yet, it is easy to see that the alignment of convection rolls is a ruling factor for the drift direction of India and Australia for the last 50 Ma.

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