SPATIAL AND TEMPORAL CONSTRAINTS ON THE END-MAASTRICHTIAN OCEAN ACIDIFICATION RELATED TO DECCAN VOLCANISM (Invited Presentation)

End-Maastrichtian pulsed Deccan volcanic eruptions of main phase-2 resulted in a cumulative loading of the atmosphere with tens of thousands gigatons of CO₂ and SO₂; persistently high atmospheric pCO₂ resulted in surface ocean acidification. Assessing the geographic extent of acidification, and the temporal associations with faunal and climate changes are critical to understand the link between Deccan volcanism and the end-Cretaceous mass extinction. Evidence of Deccan volcanic effects was recently recorded [1,2] in sediments of zone CF1 (last ~110 ky of the Maastrichtian) in France (Bidart), Austria (Gamsbach) and now in Spain (Agost) by mercury enrichment, magnetic susceptibility and dissolution effects in foraminifera. In this study, we explore the onset, duration and nature of these Deccan volcanism related effects in the Western Tethys and correlate these with similar events recorded in the Eastern Tethys and India.

Preliminary results show poor planktic foraminifer test preservation in the top ~1 m (zone CF1) at Agost, correlative with high-stress conditions preceding the mass extinction horizon at Bidart, Gamsbach and Elles (Tunisia). Correlative zone CF1 sediments in the eastern Tethys (Egypt, Israel) show inverse correlation between carbonate preservation and blooms of the disaster opportunist Guembelitria that links ocean acidification with high-stress conditions in planktic foraminifera. Close to the volcanic source in India significantly stronger carbonate dissolution effects are recorded in Meghalaya [3] to the northeast and in intertrappean sediments between the longest lava flows of the Deccan volcanic province that ended with the mass extinction [4]. Global documentation of Deccan volcanism-related proxies and environmental effects preceding the KTB mass extinction is now possible and brings much needed clarity and improved understanding of the catastrophic effects of Large Igneous Province (LIP) volcanic eruptions during four of the five big mass extinctions in Earth’s history.

References:

¹ Punekar et al., 2016, Paleogeography Paleoclimatology, Paleoecology, 441 (2016), 116-136.

² Font et al., 2016, Geology, 44(2), 171-174.

³ Gertsch et al., 2011, EPSL 310, 272-285.

⁴ Keller et al., 2014, GSA Special Paper 505; doi:10.1130/2014.2505(03)