1993/08/13 by Asish R. Basu, Paul R. Renne, Deb K. DasGupta +2 · 314 citations
Chemistry · Earth and Planetary Sciences · #Alkali metal #Basalt #Chemistry #Deccan Traps #Flood basalt #Geochemistry #Geological and Geochemical Analysis #Geology #High-pressure geophysics and materials #Igneous rock #Large igneous province #Magmatism #Mineralogy #Paleontology #Physics #Plume #Volcanism #earthquake and tectonic studies
paper · doi:10.1126/science.261.5123.902
published in Science 261(5123), 902-906 (American Association for the Advancement of Science)
openalex publication_date 1993/08/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/23
Several alkalic igneous complexes of nephelinite-carbonatite affinities occur in extensional zones around a region of high heat flow and positive gravity anomaly within the continental flood basalt (CFB) province of Deccan, India. Biotites from two of the complexes yield (40)Ar/(39)Ar dates of 68.53 +/- 0.16 and 68.57 +/- 0.08 million years. Biotite from a third complex, which intrudes the flood basalts, yields an (40)Ar/(39)Ar date of 64.96 +/- 0.1 1 million years. The complexes thus represent early and late magmatism with respect to the main pulse of CFB volcanism 65 million years ago. Rocks from the older complexes show a (3)He/(4)He ratio of 14.0 times the air ratio, an initial (87)Sr/(86)Sr ratio of 0.70483, and other geochemical characteristics similar to ocean island basalts; the later alkalic pulse shows isotopic evidence of crustal contamination. The data document 3.5 million years of incubation of a primitive, high-(3)He mantle plume before the rapid eruption of the Deccan CFB.