Possible Triggering of the Largest Deccan Traps Eruptions By the Chicxulub Impact

Mark A Richards1, Walter Alvarez2, Stephen Self2, Leif Karlstrom3, Paul R Renne4, Michael Manga5, Courtney Jean Sprain6, Jan Smit7, Loÿc Vanderkluysen8 and Sally A Gibson9, (1)University of California Berkeley, Department of Earth and Planetary Science, Berkeley, United States, (2)University of California Berkeley, Berkeley, CA, United States, (3)University of Oregon, Department of Earth Sciences, Eugene, United States, (4)Berkeley Geochronology Center, Berkeley, United States, (5)University of California Berkeley, Earth and Planetary Science, Berkeley, United States, (6)University of Florida, Department of Geological Sciences, Gainesville, United States, (7)VU University Amsterdam, Amsterdam, Netherlands, (8)Drexel University, Biodiversity, Earth & Environmental Science, Philadelphia, PA, United States, (9)University of Cambridge, Earth Sciences, Cambridge, United Kingdom
Abstract:
New constraints on the timing of the Cretaceous-Paleogene (K-Pg) mass extinction and the Chicxulub impact, together with a particularly voluminous and apparently brief eruptive pulse toward the end of the “main-stage” eruptions of the Deccan continental flood basalt province, suggest that these three events may have occurred within less than about a hundred thousand years of each other. Partial melting induced by the Chicxulub event does not provide an energetically-plausible explanation for this coincidence, and both geochronologic and magnetic-polarity data show that Deccan volcanism was underway well before Chicxulub/K-Pg time. However, historical data document that eruptions from existing volcanic systems can be triggered by earthquakes. Seismic modeling of the ground motion due to the Chicxulub impact suggests that the impact could have generated seismic energy densities of order 0.1-1.0 J/m3 throughout the upper ~200 km of the Earth’s mantle, sufficient to trigger volcanic eruptions worldwide based upon comparison with historical examples. Triggering may have been caused by a transient increase in the effective permeability of the existing deep magmatic system beneath the Deccan province, or mantle plume “head.” It is therefore reasonable to hypothesize that the Chicxulub impact might have triggered the enormous Poladpur, Ambenali, and Mahabaleshwar (Wai sub-group) lava flows that account for >70% of the Deccan Traps main-stage eruptions. This hypothesis is consistent with independent stratigraphic, geochronologic, geochemical, and tectonic constraints, which combine to indicate that at approximately Chicxulub/K-Pg time a huge pulse of mantle plume-derived magma passed through the crust with little interaction, and erupted to form the most extensive and voluminous lava flows known on Earth. High-precision radioisotopic dating of the main-phase Deccan flood basalt formations may be able either to confirm or reject this hypothesis, which in turn might help determine whether this singular outburst within the Deccan Traps (and possibly volcanic eruptions worldwide) contributed significantly to the K-Pg extinction.
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