Coastal ecosystem responses to late stage Deccan Trap volcanism: the post K-T boundary (Danian) palynofacies of Mumbai (Bombay), west India

Mumbai Island Formation intertrappean faunal and floral communities are conspicuously distinct from those common to many pre K-T boundary, late Maastrichtian intertrappeans across the Deccan province. The latter sedimentary intercalations mostly developed in cognate semiarid, palustrine ecosystems; by contrast, those around Mumbai evolved in sheltered, peripheral marine settings, within subsiding continental margin basins unique to this late Deccan stage, and under an increasingly humid Danian climate. Geochemical analyses reveal that Mumbai sedimentation and diagenesis were intimately related to local explosive volcanic and regional intrusive activity at c. 65-63 Ma. Although tectonic and igneous events imprinted their signatures throughout these sedimentary formations, organisms usually sensitive to environmental perturbations, including frogs and turtles, thrived. Critically, palynofacies data demonstrate that, whilst plant material deposition was responsive to environmental shifts, there were no palpable declines in floral productivity following Mumbai pyroclastic discharges. Therefore, it is implausible that this late stage explosive volcanism influenced major ecosystem collapses globally.