[N] 2012 Chicxulub meteorite was just too small to cause the K/T extinction
Chicxulub impact as the sole or even major contributor to the KT mass extinction is not supported by evidence
Keller, G., (2012) The Cretaceous-Tertiary Mass Extinction, Chicxulub Impact, and Deccan Volcanism. Earth and Life, International Year of Planet Earth, 759-793
Abstract
After three decades of nearly unchallenged wisdom that a large impact (Chicxulub) on Yucatan caused the end-Cretaceous mass extinction, this theory is facing its most serious challenge from the Chicxulub impact itself, as based on evidence in Texas and Mexico and from Deccan volcanism in India. Data generated from over 150 Cretaceous–Tertiary (KT) boundary [Cretaceous–Paleogene] sequences to date make it clear that the long-held belief in the Chicxulub impact as the sole or even major contributor to the KT mass extinction is not supported by evidence.
The stratigraphic position of the Chicxulub impact ejecta spherules in NE Mexico and Texas and the impact breccia within the crater on Yucatan demonstrate that this impact predates the KTB by about 300,000 years. Planktic foraminiferal and stable isotope analyses across the primary impact ejecta layer reveal that not a single species went extinct as a result of this impact and no significant environmental changes could be determined.
The catastrophic effects of this impact have been vastly overestimated. In contrast, recent advances in Deccan volcanic studies indicate three volcanic phases with the smallest at 67.5 Ma, the main phase at the end of the Maastrichtian (C29r), and the third phase in the early Danian C29r/C29n transition (Chenet et al. 2007). The main phase of eruptions occurred rapidly, was marked by the longest lava flows spanning 1500 km across India, and ended coincident with the KT boundary. The KT mass extinction may have been caused by these rapid and massive Deccan lava and gas eruptions that account for ∼80% of the entire 3500 m thick Deccan lava pile.
In 2001 Keller wrote about the Chicxulub meteorite: This theory unquestionably has great sex appeal. The largest and most fascinating creatures that ever roamed the Earth were wiped out in a single day in a ball of fire caused by a meteorite impact that leaves behind the crater of doom.
No wonder the hypothesis captured the minds and hearts of the public. But apart from the appeal to the imagination, the theory is also supported by undeniable geochemical and geophysical evidence of a bolide impact on the Yucatan Peninsula about 65 million years ago.
The existence of an impact crater alone, however, neither proves nor explains the demise of the dinosaurs, or the mass extinction of any other groups. . . .Ultimately, the validity of any mass extinction hypothesis depends on how well it explains the paleontological record.