Negative δ¹³C excursion and anoxia at the Permo-Triassic boundary in the Tethys Sea

Abstract

The Permian-Triassic (P-T) sections in Spiti valley, Himalaya represent sedimentary deposits of a shallow sea and show a sharp negative transition of δ ¹³C in total organic matter, kerogen fraction and carbonate phase. This excursion occurs across the upper part of the Permian shale culminating in a ferruginous band, which marks the peak of anoxicity after a period of generally low-oxygenated condition in the basin, as inferred on the basis of trace element analysis. Presence of carbon isotopic shift along with anoxia is similar to that observed in many P-T sections over the globe and suggests that Permo-Triassic transitional records of the Neo-Tethys are preserved in the ferruginous band of the Spiti valley sections.