Multiproxy evidence of main Deccan Traps pulse near the Cretaceous-Tertiary boundary

TitleMultiproxy evidence of main Deccan Traps pulse near the Cretaceous-Tertiary boundary
Publication TypeBook Chapter
Year of Publication2013
AuthorsAdatte, T, Keller, G
Book TitleProceedings of XXIII Indian Colloquium on Micropaloentology and Stratigraphy and International Symposium on Global Bioevents in Earth's History
ChapterPart III, Pp. 243
EditionSpecial Publication
PublisherGeological Society of India
KeywordsGlobal Bioevents, KTB, PE

Recent studies indicate that the bulk (80%) of Deccan trap eruptions occurred over a relatively short time interval in magnetic polarity C29r, whereas multiproxy studies from central and southeastern India place the Cretaceous-Tertiary (KT) mass extinction near the end of this main phase of Deccan volcanism suggesting a cause-and-effect relationship. Beyond India multiproxy studies also place the main Deccan phase in the uppermost Maastrichtian C29r below the KTB (planktic foraminiferal zones CF2-CF1), as indicated by a rapid shift in 187Os/188Os ratios in deep-sea sections from the Atlantic, Pacific and Indian Oceans, coincident with rapid climate warming, coeval increase in weathering, a significant decrease in bulk carbonate indicative of acidification due to volcanic SO2, and major biotic stress conditions expressed in species dwarfing and decreased abundance in calcareous microfossils (planktic foraminifera and nannofossils). These observations indicate that Deccan volcanism played a key role in increasing atmospheric CO2 and SO2 levels that resulted in global warming and acidified oceans, respectively, increasing biotic stress that predisposed faunas to eventual extinction at the KTB.