Deccan Volcanism Linked to the Cretaceous-Tertiary Boundary Mass Extinction: New Evidence from ONGC Wells in the Krishna-Godavari Basin

Abstract

A scientific challenge is to assess the role of Deccan volcanism in the Cretaceous-Tertiary boundary (KTB) mass extinction. Here we report on the stratigraphy and biologic effects of Deccan volcanism in eleven deep wells from the Krishna-Godavari (K-G) Basin, Andhra Pradesh, India. In these wells, two phases of Deccan volcanism record the world's largest and longest lava mega-flows interbedded in marine sediments in the K-G Basin about 1500 km from the main Deccan volcanic province. The main phase-2 eruptions (~80% of total Deccan Traps) began in C29r and ended at or near the KTB, an interval that spans planktic foraminiferal zones CF1-CF2 and most of the nannofossil Micula prinsii zone, and is correlative with the rapid global warming and subsequent cooling near the end of the Maastrichtian. The mass extinction began in phase-2 preceding the first of four mega-flows. Planktic foraminifera suffered a 50% drop in species richness. Survivors suffered another 50% drop after the first mega-flow, leaving just 7 to 8 survivor species. No recovery occurred between the next three mega-flows and the mass extinction was complete with the last phase-2 megaflow at the KTB. The mass extinction was likely the consequence of rapid and massive volcanic CO 2 and SO 2 gas emissions, leading to high continental weathering rates, global warming, cooling, acid rains, ocean acidification and a carbon crisis in the marine environment.Deccan volcanism phase-3 began in the early Danian near the C29R/C29n boundary correlative with the planktic foraminiferal zone P1a/P1b boundary and accounts for ~14% of the total volume of Deccan eruptions, including four of Earth's longest and largest mega-flows. No major faunal changes are observed in the intertrappeans of zone P1b, which suggests that environmental conditions remained tolerable, volcanic eruptions were less intense and/or separated by longer time intervals thus preventing runaway effects. Alternatively, early Danian assemblages evolved in adaptation to high-stress conditions in the aftermath of the mass extinction and therefore survived phase-3 volcanism. Full marine biotic recovery did not occur until after Deccan phase-3. These data suggest that the catastrophic effects of phase-2 Deccan volcanism upon the Cretaceous planktic foraminifera were a function of both the rapid and massive volcanic eruptions and the highly specialized faunal assemblages prone to extinction in a changing environment. Data from the K-G Basin indicates that Deccan phase-2 alone could have caused the KTB mass extinction and that impacts may have had secondary effects.

Triggers of Permo-Triassic boundary mass extinction in South China: The Siberian Traps or Paleo-Tethys ignimbrite flare-up?

“…1) as documented by the oxygen isotopes of the conodonts in South China . The rise of temperature in sea water is similar to the global warming due to the Deccan Trap eruption (Keller et al, 2011;Li and Keller, 1998;) and the Emeishan LIP eruption . However, the global warming began after the MEH (Fig.…”

Atmospheric halogen and acid rains during the main phase of Deccan eruptions: Magnetic and mineral evidence

“…Most of the lava pile (80%) erupted during phase 2 in the latest Maastrichtian paleomagnetic chron C29r. The fi nal phase 3 erupted in the early Danian base of C29n and accounts for ~14% of total Deccan eruptions (Chenet et al, 2007(Chenet et al, , 2008Keller et al, 2011Keller et al, , 2012. The original size prior to erosion is estimated to have been 1.5 × 10 6 km 2 , and the volume of lava extruded is estimated at ~1 × 10 6 km 3 (Self et al, 2006;Chenet et al, 2007).…”

A preliminary test of the press-pulse extinction hypothesis: Palynological indicators of vegetation change preceding the Cretaceous-Paleogene boundary, McCone County, Montana, USA

“…The last 450,000 yr of the Cretaceous were warm (Li and Keller, 1999), with cooling beginning ~100,000 yr before the Cretaceous-Paleogene boundary (Wilf et al, 2003). Warming during the last half million years of the Cretaceous may have been associated with CO 2 emissions from the fi rst Deccan Trap "megapulse" that began near the C30r-C30n transition, while subsequent latest Cretaceous cooling may have been linked to SO 4 and particulate emissions associated with initiation of the second and largest pulse that began during the C29r magnetochron (Self et al, 2006;Chenet et al, 2007Chenet et al, , 2008Chenet et al, , 2009Keller et al, 2009Keller et al, , 2011. Although the temporal precision of our study and the others discussed herein does not allow for defi nitive correlation of these climate events with the Russell Basin palynospecies richness decline, it does suggest volcanically mediated climatic coolinga press disturbance-as a hypothesized driver of changes in plant community structure observed between −1.4 m and −1.0 m.…”