GEOGRAPHICAL EVOLUTION FROM LAURASIA TO PANGAEA

Abstract

SUMMARY Three major continents, Angaraland, Laurasia and Gondwanaland, and a number of microcontinents straddled almost all the climatic zones of the world during the Upper Palaeozoic. The positions of these continents is broadly known from palaeomagnetic, stratigraphical, palaeoclimate, faunal and floral evidence. Using this evidence it is possible to establish the chronological sequence of continental collisions against Laurasia leading up to the assembly of the Pangaea supercontinent in the Permian. Laurasia was the dominant equatorial landmass made up of the existing continents of Europe with Greenland and North America. Continental collisions involving Nova Scotia, Spain, The Mauritanides and south Europe can be recognised during the Devonian and Carboniferous. Collisions between the major continents of Angaraland, Laurasia and Gondwanaland took place in the Permian and forms the final phase of Pangaea accretion. The Pangaea linked assembly of continents is the culmination of Palaeozoic accretion and the essential starting point of the more precisely known Mesozoic continental movements. Throughout the period of Upper Palaeozoic continental convergence the history of migration of the tetrapods, first amphibians and the later reptiles, provides a record of continental connections. The early amphibians in particular were restricted to the vicinity of continental wetlands, but they were able to migrate to new territory during successive continental collisions with Laurasia. During the Permian, at the time of the Pangaea fit, land routes were established between all the continents and the tetrapods quickly dispersed through the vast single landmass. Land connection between