Chemical stratigraphy of subsurface lava flows from the Koyna (KBH1) core and correlation with the southwestern stratigraphy of the Deccan Traps

Posted on 06.10.2021 - 11:04
Earlier studies resolve well-constrained stratigraphy of southwestern Deccan Traps, although lack in adequate subsurface data. To establish stratigraphy and its correlation with the main Deccan Formations, we report flow-wise physical and chemical data of a c. 932 m thick core. We document 37 lava flow-units and 4 lava-flow groups having similar major-oxides. These groups fit into two of the recognized chemostratitigraphic Formations, and transitional Poladpur–Ambenali lavas. Also, data plots confine to Poladpur and Ambenali Formation on Ba vs. Sr, Ba vs. Zr/Nb; Ba/Y vs. Zr/Nb; and Ba, Sr, Ba/Y, Zr/Nb vs. height bivariate diagrams. Lava flows match with Khumbarli and Mahabaleshwar Ghat sections and Killari core. The granitoid basement vs. GPB; and Poladpur vs. Ambenali Formation contacts lie at -332.5 and c. 482 m a. s. l., respectively. Moreover, southern overstepping of chemostratigraphic units endorses asymmetry of Deccan edifice due to northward motion of the Indian plate over nascent Reunion Plume (c. 67–64 Ma). Oldest 66.4 Ma lava flow predates KPB (66.052 Ma) by <0.35 Ma, with much of the Wai Subgroup erupted syn or >0.55 Ma post KPB, but restricted lava thickness at the contact between Poladpur–Ambenali Formations provides a reference point in the Deccan stratigraphy.

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., Sonu; Kumar, Amit; Satyanarayanan, M.; Pathak, Vamdev; Vedanti, Nimisha (2021): Chemical stratigraphy of subsurface lava flows from the Koyna (KBH1) core and correlation with the southwestern stratigraphy of the Deccan Traps. Geological Society of London. Collection. https://doi.org/10.6084/m9.figshare.c.5490944.v2
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