Late Paleozoic-Early Triassic Mega Sequences of Southern Pangea Supercontinent: Their Climate and Tectonic Regime between Panthalassa and Tethys: an overview
The contiguous assembly of continental plates in southern Pangea, comprising South America, Afro-Arabia, India, Antarctica and Australia constituted original “Gondwana”, bounded by Panthalassa in the south and Tethys to the north. The sedimentary sequences overlying the super continental crust at Pangean stage have been referred to as Pangea Mega Sequence (PMS), the term is synonymous with the term “Lower Gondwana” of Indian stratigraphy ranging in age from Permo-Carboniferous to Early Triassic, exhibiting similar characters across the whole of Gondwana . During the Permo-Triassic extreme climatic variations across Gondwana were experienced beginning with Gondwana glaciation in the Late Carboniferous to Early Permian, followed by warm to semi-humid, and arid to hot conditions by the Late Permian-Early Triassic. The depositional period of PMS was equally governed by three contrasting tectonic regimes: i) compressive conditions on the Panthalassan edge of Gondwana plates along the southern margin; ii) corresponding trans-pressional sags forming interior cratonic basins of southern Africa, and iii) transtension and rifting experienced in the north along the Tethys margin and adjoining intracratonic basins. The resultant glacial and non-glacial facies developed are exemplified in the corresponding Gondwana sediment assemblage of peri/intracratonic tectonic basins of southern Pangean supercontinent. Stratigraphic setting, lithofacies, depositional environments and climatic history of the aforesaid sequences are reviewed in selective basins of Afro-Arabia, India, Antarctica, Australia, and detached blocks of East and Southeast Asia. The striking similarities between the lithofacies indicate matching climate/depositional conditions and similar timing of tectonic pulses. A synthesis of records on the direction of Permian glacial transport and paleocurrents of succeeding fluvial system in different basins of southern Pangea reveals a radial paleodrainage pattern in central-eastern Gondwanaland as in Antarctic highland, directed towards SW in South Africa, N in India, NW in West Australia, and SE in Eastern Australia. The paper explains the causes of climatic changes, the influence of pole drifting and arrangement of seas and continent.