⁴⁰Ar‐³⁹Ar ages of Bombay trachytes: Evidence for a Palaeocene phase of Deccan volcanism

Abstract

We present 40 Ar‐ 39 Ar ages of 60.4±0.6 Ma and 61.8±0.6 Ma (2σ) for Deccan Trap trachytes from Manori and Saki Naka, Bombay, situated in the tectonized Panvel flexure zone along the western Indian rifted continental margin. These ages provide clear evidence that (i) these trachytes are of Palaeocene age and therefore substantially younger than the lower part of the main flood basalt sequence exposed in the Western Ghats, which precedes the K‐T Boundary in age and (ii) the formation of the Panvel flexure along the west coast must have been subsequent to ∼60 Ma. Considering early alkaline Deccan rocks previously dated at ∼68.5 Ma, the total duration of Deccan volcanism was at least ∼8 MY.