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Gondwana (/ ɡ ɒ n d ˈ w ɑː n ə /) [1] was a large landmass, sometimes referred to as a supercontinent.The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia, Zealandia, Arabia, and the Indian subcontinent.
Wegener's continental drift hypotheses is a logical consequence of: the theory of thrusting (alpine geology), the isostasy, the continents forms resulting from the supercontinent Gondwana break up, the past and present-day life forms on both sides of the Gondwana continent margins, and the Permo-Carboniferous moraine deposits in South Gondwana.
During the early breakup of Gondwana and associated continental rifting, the Patagonian landmass underwent large-scale rotations. Paleomagnetic data from late Jurassic-early Cretaceous rocks in the southern portion of the North Patagonian Massif indicate that clockwise rotation of up to 30 degrees occurred in that area during the Early ...
Karoo-Ferrar formed just prior to the breakup of Gondwana in the Lower Jurassic epoch, about 183 million years ago; [4] this timing corresponds to the early Toarcian anoxic event and the Pliensbachian-Toarcian extinction. [5] It covered about 3 x 10 6 km 2. [6]
The initiation of Gondwana breakup, and transform faulting along the Davie Fracture Zone, occurred in the Toarcian (about 182 million years ago) following the eruption of the Bouvet (Karoo) mantle plume. At this time East Gondwana, comprising the Antarctic, Madagascar, Indian, and Australian plates, began to separate from the African plate.
The Gondwana supercontinent began to break up in the Middle Jurassic, about 167 million years ago. At that time, East Gondwana, comprising Antarctica, Madagascar, India, and Australia, began to separate from Africa. East Gondwana then began to separate about 115–120 million years ago when India began to move northward. [5]
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[1] [3] These sediments deposited as result of a regional marine transgression swept over the Horn of Africa during the initial break-up of Gondwana. Resultant rocks include sandstone, limestone, shale, marls and evaporites (Adigrat Sandstone, Antalo Limestone, Amba Aradam Formation). [1]