Winding down the Chicxulub impact: The transition between impact and normal marine sedimentation near ground zero

Abstract

The upper suevite, Transitional Unit, and overlying green marlstone on the peak ring of the Chicxulub impact structure at Site M0077 appear to record a complete transition from resurge deposits into post-impact sediments. Several marine-target impact craters record similar successions but the Transitional Unit in Chicxulub appears most similar to the record in the Chesapeake Bay impact structure. This is likely because they are relatively large craters with target materials consisting of water saturated sedimentary rocks overlying crystalline basement. Other craters such as Lockne record a more gradual transition over tens of meters of deposits with tremendous variation depending on location within the crater. Thus, we find that the Transitional Unit at Site M0077 records the waning energy related to post-impact seismic and mass-wasting events and the tsunami and seiches these induced eventually giving way to normal marine Paleogene sedimentation. Such a sequence may be indicative of marine impacts.