Rapid eruption of the Deccan flood basalts at the Cretaceous/Tertiary boundary

Abstract

The accumulation of flood basalts of the Deccan Traps, western India, is one of the most remarkable volcanic provinces on Earth in sheer extent and volume. These rocks are akin in composition and occurrence to other extensive continental basalt provinces, usually located near plate margins, but distributed worldwide and of various ages¹. Recent interest in the Deccan flood basalts has increased with the suggestion that this volcanic activity may have coincided with mass faunal extinctions and/or meteorite impact at the Cretaceous/Tertiary boundary^2–5; critical to these correlations are the age and age range of the volcanic rocks. Here we report ⁴⁰Ar–³⁹Ar geochronological results from stratigraphically controlled, geochemically well characterized tholeiitic basalts from the thickest sequence of the Deccan flood basalts, Western Ghats⁶. The samples dated span a section ∼2,000m thick, and range in age from 66.6 to 68.5 Myr. There is no significant difference in age from the stratigraphically oldest to the youngest rocks. It appears, then, that this sequence of lavas was erupted rapidly and can be correlated in time with events at the Cretaceous/Tertiary boundary.