Continental flood basalt (CFB) volcanism is hypothesized to have played a causative role in global climate change and mass extinctions. Uncertainties associated with radiometric dating preclude a clear chronological assessment of the environmental consequences of CFB volcanism. Our results document a 25% decline in the marine 187Os/188Os record that predates the Cretaceous-Tertiary boundary (KTB) and coincides with late Maastrichtian warming. We argue that this decline provides a chemostratigraphic marker of Deccan volcanism and thus constitutes compelling evidence that the main environmental consequence of Deccan volcanism was a transient global warming event of 3° to 5°C that is fully resolved from the KTB mass extinction.

Sediment depth is given in mbsf. For Atlantic and Pacific sites age models are based on linear interpolation between magnetic reversal boundaries and the KTB. For the Indian Ocean the age model is based solely on biostratigraphy and is less well constrained.

Supplement to: Ravizza, Gregory E; Peucker-Ehrenbrink, Bernhard (2003): Chemostratigraphic Evidence of Deccan Volcanism from the Marine Osmium Isotope Record. Science, 302(5629), 1392-1395