GEOCHEMICAL-SEDIMENTARY-PALEONTOLOGICAL CONSTRAINTS FOR PERMIAN-TRIASSIC TRANSITION IN THE NEO-TETHYS SEA: EVIDENCE FROM SPITI VALLEY, INDIA
Unlike other global P-T sections, marine anoxia seems to have been restricted to the deeper waters of the Neo-Tethys and did not significantly affect the productivity of shallow waters in the Late Permian. Extinction occurred rapidly under oxic conditions in a regressing sea. Sharp fluctuations and highly depleted values in δ13Ccarb and δ18Ocarb in the Early Triassic Mikin Formation suggest a warmer arid climate with strong weathering fronts and rapid sea-level changes. We propose that the synchronicity of the Siberian Trap volcanism and the Araguainha impact in Brazil was the chief trigger for this catastrophe. Isotopically-depleted CO2 dominated the atmosphere-marine exchange, impacting the geochemical composition of the Neo-Tethys Sea. This study adds new perspectives to the possible mechanism of rapid environmental change at the P-T transition, especially in the Peri-Gondwanan realm. While the discovery of fossils in the ferruginous layer suggests the need for more biostratigraphic and chronological control, we believe a combination of factors including volcanism, meteorite impact, marine regression and anoxia were the drivers to this ecological bottleneck.