Nature and timing of extinctions in Cretaceous-Tertiary planktic foraminifera preserved in Deccan intertrappean sediments of the Krishna–Godavari Basin, India

Triggering of the largest Deccan eruptions by the Chicxulub impact

“…In wells penetrating the subsurface part of the Rajahmundry Traps of southeastern India, now recognized as isolated, preserved distal Deccan fl ows (Self et al, 2008b), Keller et al (2012) found Danian zone P1a planktic foraminifera in an intertrappean layer between the two exposed basalt units of the Rajahmundry Traps, which have been identifi ed chemically as Ambenali below and upper Mahabaleshwar Formation above. This at fi rst looks like the same situation as at Jhimili, but Keller et al (2012) also reported Upper Maastrichtian foraminifera from sedimentary layers intercalated in the lower basalt fl ows.…”

“…In any case, it seems reasonable to assume that if the Deccan Traps eruptions contributed to the main Cretaceous-Paleogene extinctions, then the Wai Subgroup pulse of eruptions was the likely culprit. Although the timing and duration of the Kalsubai, Lonavala, and Wai Subgroup formations are not well constrained, it also appears likely that the Cretaceous-Paleogene boundary and the Chicxulub impact may have occurred at or just before the onset of the huge Wai Subgroup eruptions (e.g., Keller et al, 2012).…”

Emplacement characteristics, time scales, and volcanic gas release rates of continental flood basalt eruptions on Earth

“…One of the most famous examples is the mass extinction event at the end-Cretaceous (ca. 66 Ma) and its coincidence with the emplacement of the Deccan Traps continental fl ood basalt province in India (e.g., Vogt, 1972;Courtillot, 1999;Keller et al, 2008Keller et al, , 2012. Moreover, this is the only well-substantiated case of an asteroid impact coinciding with a continental fl ood basalt event and a mass extinction event (e.g., Keller, 2014, this volume).…”

“…The proxy record, including the mass extinction events themselves, clearly suggests signifi cant environmental perturbation around the time of continental fl ood basalt volcanism (e.g., Li and Keller, 1998;Courtillot and Renne, 2003;Wilf et al, 2003;Visscher et al, 2004;Wignall, 2005;Thibault and Gardin, 2006;Wignall et al, 2009;Keller et al, 2012;Sun et al, 2012;Joachimski et al, 2012;Bryan and Ferrari, 2013). However, one of the challenges that remains is to fi nd a primary marker for the volcanism within these same archives, allowing a clear causal relationship to the environmental perturbation to be developed, rather than purely markers indicating environmental change.…”

“…The entire duration of Deccan volcanism may have been ~3 m.y., although this still remains to be thoroughly documented. Some continental fl ood basalt provinces may show evidence of two or more peaks in magma output; it has been suggested that the Deccan had three pulses, with the main pulse emplacing a considerable portion of the total volume in as little as 500,000 yr or less (Chenet et al, 2009;Keller et al, 2008Keller et al, , 2012.…”