Letters Nature and timing of extinctions in Cretaceous-Tertiary planktic foraminifera preserved in Deccan intertrappean sediments of the Krishna–Godavari Basin, India G. Keller a,n , T. Adatte b , P.K Bhowmick c , H. Upadhyay c , A. Dave c , A.N. Reddy d , B.C. Jaiprakash d a Geosciences Department, Princeton University, Princeton, NJ 08544, USA b Geological and Paleontological Institute, Anthropole, CH-1015 Lausanne, Switzerland c KDMIPE, ONGC, Dehradun, India d ONGC, Regional Geoscience Laboratory, Chennai, India article info Article history: Accepted 11 June 2012 Communicated by P. DeMenocal Available online 13 July 2012 Keywords: Deccan volcanism KTB mass extinction environmental changes Krishna–Godavari Basin India abstract In C29r below the Cretaceous-Tertiary boundary (KTB) massive Deccan Trap eruptions in India covered an area the size of France or Texas and produced the world’s largest and longest lava megaflows 1500 km across India through the Krishna–Godavari (K–G) Basin into the Bay of Bengal. Investigation of ten deep wells from the K–G Basin revealed four lava megaflows separated by sand, silt and shale with the last megaflow ending at or near the KTB. The biologic response in India was swift and devastating. During Deccan eruptions prior to the first megaflow, planktic foraminifera suffered 50% species extinctions. Survivors suffered another 50% extinctions after the first megaflow leaving just 7–8 species. No recovery occurred between the next three megaflows and the mass extinction was complete with the last mega-flow at or near the KTB. The last phase of Deccan volcanism occurred in the early Danian C29n with deposition of another four megaflows accompanied by delayed biotic recovery of marine plankton. Correlative with these intense volcanic phases, climate changed from humid/tropical to arid conditions and returned to normal tropical humidity after the last phase of volcanism. The global climatic and biotic effects attributable to Deccan volcanism have yet to be fully investigated. However, preliminary studies from India to Texas reveal extreme climate changes associated with high- stress environmental conditions among planktic foraminifera leading to blooms of the disaster opportunist Guembelitria cretacea during the late Maastrichtian. & 2012 Elsevier B.V. All rights reserved. 1. Introduction The biologic and environmental effects of Deccan volcanism and its potential cause-and-effect relationship with the demise of the dinosaurs and the Cretaceous-Tertiary boundary (KTB) mass extinction are the major unsolved problems in KTB studies today. The Deccan volcanic province is one of the largest volcanic eruptions in Earth’s history and today covers an area of 512,000 km 2 (Fig. 1A), or about the size of France or Texas. The original size prior to erosion is estimated to have been 1.5 mil- lion km 2 and the volume of lava extruded about 1.2 million km 3 , which today can be seen as layers of lava flows with an estimated total thickness of 3500 m (Fig. 1B; Chenet et al., 2007). Deccan volcanism has been advocated as the potential cause for the KTB catastrophe for over thirty years (e.g., McLean, 1978, 1985; Courtillot et al., 1986, 1988; Venkatesan et al., 1993; Raju et al., 1995). However, this hypothesis was considered unlikely because a direct link to the mass extinction remained elusive in the absence of Deccan lava flows interbedded with marine sediments rich in microfossils to assess the nature of the mass extinction. Moreover, volcanism was generally believed to have occurred over at least one million years and possibly several million years, leaving sufficient time for recovery between eruptions. Over the past several years a number of multi-disciplinary studies have changed this perception and directly linked Deccan volcanism to the KTB mass extinction: (1) Improved dating of the 3500 m thick Deccan lava pile revealed that the major eruptions occurred in three phases with variable intensity: phase-1 (6% of total lava pile) in the late Maastrichtian (base C30n, 67.4 Ma), the main phase-2 (80%) in C29r below the KTB and phase-3 (14%) in the early Danian base C29n (Fig. 2; Chenet et al., 2007, 2008; Jay and Widdowson, 2008). (2) Massive eruptions in phase-2 and phase-3 created Earth’s largest and longest lava flows (Self et al., 2008). (3) Phase-2 was directly linked to the KTB mass extinction based on planktic foraminifera, which suffered the most devastat- ing mass extinction globally (Keller et al., 2008, 2009b, 2011a). Still missing from these early results is critical information concerning the onset and age of the main Deccan phase, the Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/epsl Earth and Planetary Science Letters 0012-821X/$ - see front matter & 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.epsl.2012.06.021 n Corresponding author. Tel.: þ1 609 258 4117; fax: þ1 609 258 2593. E-mail address: gkeller@princeton.edu (G. Keller). Earth and Planetary Science Letters 341-344 (2012) 211–221