Stratigraphy, structure and volcanology of the SE Deccan continental flood basalt province: implications for eruptive extent and volumes

Abstract

The Deccan Volcanic Province is one of the world's largest continental flood basalt provinces, and derives additional importance because its eruptions (64–67 Ma) straddle the Cretaceous–Tertiary boundary. To better assess the environmental impact of Deccan volcanism, and its possible effect upon Cretaceous–Tertiary boundary biota, it is necessary to document the stratigraphy, chronology and volume of the eruptions. New chemostratigraphical data permit mapping of the SE Deccan. These data strengthen the likelihood that the Rajahmundry Traps of eastern India were originally fed by long-distance flows, and are an extension of the Main Deccan Volcanic Province. An east–west cross-section reveals a depression or ‘moat’ around the SE periphery of the Deccan Volcanic Province. This provided a site in which shallow lakes initially formed, and along which later lava eruptions became channelled and confined. Published palaeomagnetic data indicate that the lavas of the SE Deccan were erupted during Chron 29R, coeval with the Cretaceous–Tertiary boundary, and the chemostratigraphic data place the associated lake sediments (i.e. Lameta Group) beneath and within lavas of the Wai Subgroup. Finally, these new map data are combined with previous work to provide a quantitative estimate for the original Deccan Volcanic Province eruptive volume of c . 1.3 × 10 6 km 3 .

A combined Y/Ho, high field strength element (HFSE) and Nd isotope perspective on basalt weathering, Deccan Traps, India

“…between eruptions, consistent with the compositional uniformity exhibited by the thick (c. 500 m), uncontaminated MORB-like Ambenali Formation, which is widespread across the Main Deccan Province (MDP; Jay and Widdowson, 2008). By contrast, the Chhindwara area was peripheral to the MDP, possibly more distal from the eruptive source, and accordingly received flows only from the largest, most voluminous outpourings; this episodic arrival of lavas would allow for a greater degree of magmatic evolution and contamination between successive eruptions.…”

The Siberian Traps and the End-Permian mass extinction: a critical review

“…To put this into perspective, 3 million km 3 would bury an area equivalent to the entire UK beneath a layer of basalt some 12 km thick, or an area the size of China beneath a layer about 300 m thick. However, even the minimum estimate is significantly larger than recent estimates for the Deccan Traps (~1.3×10 6 km 3 ) [21] .…”

Deccan volcanism, the KT mass extinction and dinosaurs

“…This has been confi rmed by magnetostratigraphy and geochemical similarities with the main Deccan volcanic province to the west (Lightfoot et al 1990;Subbarao and Pathak 1993;Banerjee et al 1996;Baksi 2001;Jay and Widdowson 2008;Jay et al 2009). The Rajahmundry traps, which reach 1000 km across India, are thus the longest lava fl ows known in Earth history (Self et al 2008a) and may represent the volcanic acme of phase 2 ending at or near the KT mass extinction (Keller et al 2008a).…”

“…In the past few years, signifi cant advancements have been made with respect to the age of volcanic eruptions based on 40 K/ 40 Ar and 40 Ar/ 39 Ar dating (e.g. Knight et al 2003Knight et al , 2005Pande et al 2004;Baksi 2005;Chenet et al 2007Chenet et al , 2008 and geochemical characterization of different eruptions (Jerram and Widdowson 2005;Jay and Widdowson 2008;Jay et al 2009). …”