Carbonatite alkaline magmatism associated with continental flood basalts at stratigraphic boundaries: Cause for mass extinctions

Abstract

The debate between the impact scenario and the hypothesis of the Deccan volcanism leading to Cretaceous/Tertiary (K/T) extinctions is far from settled. We add a new dimension to this debate by introducing an overlooked aspect of the Deccan volcanism, the emplacement and eruption of associated carbonatite‐alkaline complexes, which are capable of rapidly injecting catastrophic amounts of CO 2 and SO 2 into the atmosphere. 40 Ar‐ 39 Ar dating of one of the several coeval late‐Deccan alkaline pulses has revealed that this alkaline volcanism took place at the K/T boundary. A conservative estimate shows that these activities can indeed emit a substantial amount of CO 2 and SO 2 , comparable to that of an impact scenario, which could have enhanced the catastrophic effects of the ongoing basaltic eruptions. Other major Phanerozoic extinctions also show contemporaneity with the late carbonatite‐alkaline pulses of associated flood basalt provinces, suggesting a causal relationship between such carbonatite‐alkaline magmatisms and the mass extinctions.