Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published May 22, 1998 | public
Journal Article

Geochemical Evidence for a Comet Shower in the Late Eocene

Abstract

Analyses of pelagic limestones indicate that the flux of extraterrestrial helium-3 to Earth was increased for a 2.5-million year (My) period in the late Eocene. The enhancement began ∼1 My before and ended ∼1.5 My after the major impact events that produced the large Popigai and Chesapeake Bay craters ∼36 million years ago. The correlation between increased concentrations of helium-3, a tracer of fine-grained interplanetary dust, and large impacts indicates that the abundance of Earth-crossing objects and dustiness in the inner solar system were simultaneously but only briefly enhanced. These observations provide evidence for a comet shower triggered by an impulsive perturbation of the Oort cloud.

Additional Information

© 1998 American Association for the Advancement of Science. Received 13 January 1998; accepted 27 March 1998. We thank P. Weissman for a constructive and thoughtful review and D. Patterson and K. Robinson for assistance with sample preparation. Supported by NASA and by the David and Lucille Packard Foundation through a fellowship award to K.A.F.

Additional details

Created:
August 22, 2023
Modified:
October 20, 2023