Nikhil Sharma , Thierry Adatte, Torsten Vennemann, Blair Schoene, Gerta Keller, Syed F. R. Khadri

Large Igneous Provinces (LIPs) have been widely studied over the past decades due to their likely link to mass extinction events. Previous work involving U-Pb zircon dating of the Deccan lava flows indicates that the main phase-2 began 250 Ka before the Cretaceous-Paleogene (K-Pg) mass extinction boundary and continued into the early Danian, suggesting a cause-and-effect relationship. Closer to the eruption centre, intra-volcanic red weathered horizons known as red boles mark quiescent periods between basalt flows. Red boles have increasingly attracted the attention of researchers to understand the prevailing climatic conditions during the Deccan volcanic activity for their ability to yield crucial evidence of environmental changes triggered by volcanic activity using different geochemical proxies such as major elemental composition, bulk rock and clay mineralogy, weathering indices, paleo-precipitation estimates and stable isotope analysis. Our results indicate that red boles are characterized by concentrations of immobile elements such as Al and Fe3+ ions that are typical of paleo-laterites, which develop over short periods of weathering. Identified clay minerals consist mostly of smectite indicative of semi-arid monsoonal conditions. Weathering indices suggest intense weathering most likely linked to increasing acid rains while stable H- and O-isotope compositions suggest increasing paleoclimate instability in parallel to increased eruption rates just before the K-Pg boundary. The multi proxy approach is compatible with a cause-and-effect relationship between the Deccan Trap eruptions and the K-Pg mass extinction.