Mass extinction and Pangea integration during the Paleozoic-Mesozoic transition

Abstract

The greatest Phanerozoic mass extinction happened at the end-Permian to earliest Triassic. About 95% species, 82% genera, and more than half families became extinct, constituting the sole macro-mass extinction in geological history. This event not only caused the great extinction but also destroyed the 200 Myr-long Paleozoic marine ecosystem, prompted its transition to Mesozoic ecosystem, and induced coal gap on land as well as reef gap and chert gap in ocean. The biotic crisis during the Paleozoic-Mesozoic transition was a long process of co-evolution between geospheres and biosphere. The event sequence at the Permian-Triassic boundary (PTB) reveals two-episodic pattern of rapidly deteriorating global changes and biotic mass extinction and the intimate relationship between them. The severe global changes coupling multiple geospheres may have affected the Pangea integration on the Earth’s surface spheres, which include: the Pangea integration→enhanced mountain height and basin depth, changes of wind and ocean current systems; enhanced ocean basin depth→the greatest Phanerozoic regression at PTB, disappearance of epeiric seas and subsequent rapid transgression; the Pangea integration→thermal isolation effect of continental lithosphere and decrease of mid-ocean ridges→development of continental volcanism; two-episode volcanism causing LIPs of the Emeishan Basalt and the Siberian Trap (259–251 Ma)→global warming and mass extinction; continental aridification and replacement of monsoon system by latitudinal wind system→destruction of vegetation; enhanced weathering and CH4 emission→negative excursion of δ 13 C; mantle plume→crust doming→regression; possible relation between the Illawarra magnetic reversal and the PTB extinction, and so on. Mantle plume produced the Late Permian LIPs and mantle convection may have caused the process of the Pangea integration. Subduction, delamination, and accumulation of the earth’s cool lithospheric material at the “D” layer of CMB started mantle plume by heat compensation and disturbed the outer core thermo-convection, and the latter in turn would generate the mid-Permian geomagnetic reversal. These core and mantle perturbations may have caused the Pangea integration and two successive LIPs in the Permian, and probably finally the mass extinction at the PTB. Permian-Triassic boundary, mass extinction, Pangea integration, multi-sphere coupling mantle plume