PALEOGEOGRAPHY AND SEDIMENTATION SETTINGS DURING PERMIAN-TRIASSIC REORGANIZATIONS IN BIOSPHERE

Abstract

Origination and growing aridity of Pangea and transition from glacial to ice-free climate led in the Permian-Early Triassic to substantial reorganization in all biosphere subsystems. Lithological-paleogeo- graphic maps drawn for the late Sakmarian-early Artinskian and late Kazanian-early Toarcian periods of the Permian and for the Induan Age of the Early Triassic illustrate main paleogeographic changes that were related to the Pangea uplift, successive regression of epicontinental seas, disappearance of glacial sedimentation areas, progradation of arid and semiarid sedimentation, expansion and multiplication of closed basins, and reduced surficial but enhanced groundwater discharge into shelf seas surrounding Pangea. This distorted the global bal- ance of mineral exchange between land and ocean and reduced the terrigenous influx of nutrients and primary productivity in ocean that could destruct the former feeding chains and represent one of possible factors respon- sible for mass extinction at the end of the Permian.