Giant comets and mass extinctions of life

Abstract

I find evidence for clustering in age of well-dated impact craters over the last 500 Myr. At least nine impact episodes are identified, with durations whose upper limits are set by the dating accuracy of the craters. Their amplitudes and frequency are inconsistent with an origin in asteroid breakups or Oort cloud disturbances, but are consistent with the arrival and disintegration in near-Earth orbits of rare, giant comets, mainly in transit from the Centaur population into the Jupiter family and Encke regions. About 1 in 10 Centaurs in Chiron-like orbits enter Earth-crossing epochs, usually repeatedly, each such epoch being generally of a few thousand years duration. On time-scales of geological interest, debris from their breakup may increase the mass of the near-Earth interplanetary environment by two or three orders of magnitude, yielding repeated episodes of bombardment and stratospheric dusting. I find a strong correlation between these bombardment episodes and major biostratigraphic and geological boundaries, and propose that episodes of extinction are most effectively driven by prolonged encounters with meteoroid streams during bombardment episodes. Possible mechanisms are discussed.

arXiv comment10 pages, 11 figures

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Cited by in corpus (10)

• Solar System Physics for Exoplanet Research
• Dynamical evolution and end states of active and inactive Centaurs
• The hazard from fragmenting comets
• The threat of Centaurs for terrestrial planets and their orbital evolution as impactors
• Influence of the Centaurs and TNOs on the main belt and its families
• Rings under close encounters with the giant planets: Chariklo vs Chiron
• The journey of Typhon-Echidna as a binary system through the planetary region
• Searching for Biosignatures in Exoplanetary Impact Ejecta
• "Isocrater" impacts: Conditions and mantle dynamical responses for different impactor types
• Beyond the New Horizon: The Future of Pluto