Skip to Main Content
Book Chapter

Rock-avalanche and ocean-resurge deposits in the late Eocene Chesapeake Bay impact structure: Evidence from the ICDP-USGS Eyreville cores, Virginia, USA

By
Gregory S. Gohn
Gregory S. Gohn
U.S. Geological Survey, 926A National Center, Reston, Virginia 20192, USA
Search for other works by this author on:
David S. Powars
David S. Powars
U.S. Geological Survey, 926A National Center, Reston, Virginia 20192, USA
Search for other works by this author on:
Henning Dypvik
Henning Dypvik
University of Oslo, P.O. Box 1047, Blindern, N-0316 Oslo, Norway
Search for other works by this author on:
Lucy E. Edwards
Lucy E. Edwards
U.S. Geological Survey, 926A National Center, Reston, Virginia 20192, USA
Search for other works by this author on:
Published:
January 01, 2009

An unusually thick section of sedimentary breccias dominated by target-sediment clasts is a distinctive feature of the late Eocene Chesapeake Bay impact structure. A cored 1766-m-deep section recovered from the central part of this marine-target structure by the International Continental Scientific Drilling Program (ICDP)–U.S. Geological Survey (USGS) drilling project contains 678 m of these breccias and associated sediments and an intervening 275-m-thick granite slab. Two sedimentary breccia units consist almost entirely of Cretaceous nonmarine sediments derived from the lower part of the target sediment layer. These sediments are present as coherent clasts and as autoclastic matrix between the clasts. Primary (Cretaceous) sedimentary structures are well preserved in some clasts, and liquefaction and fluidization structures produced at the site of deposition occur in the clasts and matrix. These sedimentary breccias are interpreted as one or more rock avalanches from the upper part of the transient-cavity wall. The little-deformed, unshocked granite slab probably was transported as part of an extremely large slide or avalanche. Water-saturated Cretaceous quartz sand below the slab was transported into the seafloor crater prior to, or concurrently with, the granite slab. Two sedimentary breccia units consist of polymict diamictons that contain cobbles, boulders, and blocks of Cretaceous nonmarine target sediments and less common shocked-rock and melt ejecta in an unsorted, unstratified, muddy, fossiliferous, glauconitic quartz matrix. Much of the matrix material was derived from Upper Cretaceous and Paleogene marine target sediments. These units are interpreted as the deposits of debris flows initiated by the resurge of ocean water into the seafloor crater. Interlayering of avalanche and debris-flow units indicates a partial temporal overlap of the earlier avalanche and later resurge processes. A thin unit of stratified turbidite deposits and overlying laminated fine-grained deposits at the top of the section represents the transition to normal shelf sedimentation.

You do not currently have access to this article.

Figures & Tables

Contents

GSA Special Papers

The ICDP-USGS Deep Drilling Project in the Chesapeake Bay impact structure: Results from the Eyreville Core Holes

Gregory S. Gohn
Gregory S. Gohn
U.S. Geological Survey, Reston, Virginia, USA
Search for other works by this author on:
Christian Koeberl
Christian Koeberl
Department of Earth & Planetary Sciences, Rutgers University, USA
Search for other works by this author on:
Kenneth G. Miller
Kenneth G. Miller
Museum für Naturkunde–Leibniz Institute at Humboldt University Berlin, Germany
Search for other works by this author on:
Wolf Uwe Reimold
Wolf Uwe Reimold
Museum für Naturkunde–Leibniz Institute at Humboldt University Berlin, Germany
Search for other works by this author on:
Geological Society of America
Volume
458
ISBN print:
9780813724584
Publication date:
January 01, 2009

References

Related

Citing Books via

A comprehensive resource of eBooks for researchers in the Earth Sciences

Related Book Content
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal