Bolide impact effects on the West Florida Platform, Gulf of Mexico: End Cretaceous and late Eocene

Geosphere
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Abstract

This study documents seismic reflection evidence that two different bolide impacts significantly disrupted stratigraphic and depositional processes on the West Florida Platform. The first impact terminated the Late Cretaceous Epoch (Chicxulub; ~66 Ma; end Maastrichtian age). The second took place in the late Eocene (Chesapeake Bay; ~35 Ma; Priabonian age). Both impacts produced far-reaching seismic shaking and ground roll, followed by an impact-generated tsunami, the effects of which are evident in the seismostratigraphic record. The Chicxulub seismic shaking caused collapse and shoreward retreat of the Florida Escarpment, and widely disrupted (faulting, folding, slumping) normal flat-lying shelf beds. The associated tsunami currents redistributed these shelf deposits, and mixed them together with collapse debris from the escarpment, to form a thick wedge of sediments along the base of the escarpment. The Chesapeake Bay impact created a mounded sedimentary deposit near the outer edge of the late Eocene ramp slope. This deposit also has a bipartite origin. A lower layer is marked by en echelon faulting created in situ by seismic shaking, whereas an upper layer represents sediments redistributed from the late Eocene shelf and upper ramp slope by tsunami-driven bottom currents (debris flows, contour currents, slumps). This is the first report of seismic effects from the Chesapeake Bay impact in the Gulf of Mexico. These results further demonstrate that large-scale marine bolide impacts have widespread effects on the stratigraphic and depositional record of Earth.

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Publication type Article
Publication Subtype Journal Article
Title Bolide impact effects on the West Florida Platform, Gulf of Mexico: End Cretaceous and late Eocene
Series title Geosphere
DOI 10.1130/GES02472.1
Volume 18
Issue 3
Year Published 2022
Language English
Publisher Geological Society of America
Contributing office(s) Woods Hole Coastal and Marine Science Center
Description 27 p.
First page 1077
Last page 1103
Country Unted States
State Florida
Other Geospatial Gulf of Mexico
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