Age of the Deccan traps using 187Re–187Os systematics

A suite of basaltic rocks sampled over a vast exposure and stratigraphic thickness in the Deccan traps has been investigated for Os isotopic systematics. The results plot on a very well defined Re–Os isochron corresponding to an age of 65.6±0.3 Ma (2σ uncertainty). This age is in excellent agreement with previous K–Ar and Ar–Ar data. Os data also imply a short duration of volcanism, which should have important implications on mantle geodynamics. The 187Os/188Os initial ratio is typically chondritic: 0.12843±0.00047 (2σ) and indicates that metasomatism and crustal contamination played only a very minor role in the Re–Os budget during formation of the Deccan traps.