¹S.James et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70081]
¹Department of Geology, University of Kerala, Thiruvananthapuram, India
²Department of Earth and Planetary Science, University of Tokyo, Tokyo, Japan
Published by arrangement with John Wiley & Sons

At ~66 Ma, the Cretaceous–Paleogene Boundary (KPB) sections at Anjar and Um Sohryngkew (India) were 14,333 and 16,549 km, respectively, from Chicxulub, making them the farthest distal KPBs. The spatial and temporal proximity of the sites to Deccan volcanism makes them important locations to better understand the impact-volcanism debate. This study integrates petrological, mineralogical, and geochemical techniques to distinguish signatures of the instantaneous Chicxulub impact from those of the prolonged Deccan volcanism (lasting ~10 my). The sites contained two ejecta components: a potential spherule (Um Sohryngkew) and Ir-anomalies. The poorly preserved spherule (~240 μm diameter) exhibited mineral dendrites. At Anjar, two Ir-anomalies are noted: 8.50 ppb (SGA-2; ~3.19 m below Flow IV) and 1.16 ppb (SGA-12). Four Ir-anomalies are noted at Um Sohryngkew: 1.36 ppb (SMU-19; 28.44 m from the oldest layer), 3.17 (SMU-14), 7.00 (SMU-7), and 1.19 ppb (SMU-6). Multiple Ir-anomalies, elevated background-Ir, and glass shards at both sites highlight a greater influence of Deccan volcanism than previously recognized. Deccan magma-based Ir-enrichment is unlikely as such values were not reported in Deccan basalts, but higher Ir-concentrations in sedimentary layers point to indirect contributions from Deccan outgassing. Thus, the findings of the study underscore the complex interplay of Deccan volcanism and Chicxulub impact across the Indian Subcontinent.