Breakup of Pangea and Gondwana

The breakup of Pangea and Gondwana is of considerable interest among geologists studying the origin and development of the continents. It all began in the middle of the Paleozoic era, when two continental conglomerates were formed: one - Laurasian, the other - Gondwana. Each of them consisted of several ancient continental blocks, welded together by mountain-fold belts. The Gondwana conglomerate was located mainly in the southern hemisphere and became the arena of a powerful Late Paleozoic glaciation. The Laurasian block stretched across the tropics and subtropics. By the middle of the Carboniferous period, these supercontinents first approached, and then closed in the belt of the modern Western Mediterranean and the Gulf of Mexico. A new formation arose, which geologists called Pangea. A vast ocean stretched around Pangea. This ocean was named Tethys.

The breakup of Pangea and Gondwana is of considerable interest among geologists studying the origin and development of the continents

In the southern part of Pangea, glaciers were still sliding down from the heights, when the first signs of an unstable state appeared, in which the tectonosphere found itself at the boundary of the Paleozoic and Mesozoic. Splits of the earth's crust took place. Giant faults cut through the earth's crust mainly at the junction of the Laurasian and Gondwana megablocks. Basalt lavas poured out along these gaps, which were soon filled with water, and in some places volcanic eruptions occurred. Over time, the relief of the land became more and more indented and contrasting. Finally, individual cracks began to merge together, forming a single branched system of deflections, which were framed by blocky ridges. The landscape of a number of the interior regions of Pangea, apparently, began to resemble modern East Africa.

One system of continental rifts, skirting the Bahamian ledge, from the area of present-day Gulf of Mexico extended along the Appalachian Mountains, by then already largely cut by erosion. The rifts developed towards Tethys, deeply wedged into Pangea in the east. Another chain of rifts formed in the southern, Gondwana part of the supercontinent. Rifts, like cracks on a shattered plate, ripped through it from edge to edge. Thus, the directions of the main splits were outlined, which soon led to the division of Pangea into the Laurasian and Gondwana continental blocks, and then into smaller fragments.

Now it is still difficult to determine when the complete splitting of the continental crust took place and the first areas with oceanic crust appeared on the site of land rifts. Indirect data indicate that the age of the most ancient parts of the crust with a typical oceanic structure does not exceed 180-160 million years, it is Middle Late Jurassic. Thus, the process of splitting the continental substrate of Pangea took an extremely long time, approximately 80-100 million years. However, this was only the first act of the drama. It ended with the emergence of the protooceanic depression of the Central Atlantic, which separated the African-South American ledge of Gondwana from the North American block, which in the strip from Greenland to the British Isles was still connected with Eurasia.

Thus, already at the turn of the Jurassic and Cretaceous periods, the Laurasian and Gondwana blocks parted and Pangea ceased to exist. The Gondwana block, which remained relatively intact, disintegrated into several large fragments during the Cretaceous. Already in the Neocomian time, a complex system of continental rifts was formed between Africa and South America, which had previously formed a single whole, with individual segments stretching far away from the main direction of splits. In the Early Cretaceous, the Hindustan, Madagascar, and Australo-Antarctic blocks broke away from Africa. The disintegration of Gondwana ended in the Cenozoic separation of Antarctica from Australia.