LAUSR

Abstract In this study, we reconstruct water-column oxygen availability during the deposition of Late Permian shales (Wuchiapingian to approximately early Changhsingian) using the geochemistry and morphology of sedimentary pyrite (FeS2). Deposition of the shales occurred prior to the end-Permian mass extinction within the southern Neo-Tethys Ocean (Spiti region, Himachal Pradesh, India). We found that the variability of pyritic sulfur to organic carbon (Spyr/Corg) and the pyritic sulfur isotopic composition (δ34Spyr) did not record changes in oxygen availability at Spiti sections. This was due to the removal of original pyritic sulfur by modern oxidative weathering and diagenetic pyrite formation which overwhelmed the original δ34Spyr values. However, pyrite framboid size distributions was a reliable recorder of paleoredox conditions. The degree of oxygen limitation varied with multiple transient euxinic events interrupting a predominantly oxic-dysoxic trend near the top of the Gungri Formation upper member (approximately late Wuchiapingian to early Changhsingian). These transient euxinic intervals provide important insight and regional evidence of environmental stress and instability in the southern Neo-Tethys well prior to the end-Permian mass extinction.