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Paleoenvironmental recovery from the Chesapeake Bay bolide impact; the benthic foraminiferal record

C. Wylie Poag
Paleoenvironmental recovery from the Chesapeake Bay bolide impact; the benthic foraminiferal record (in The ICDP-USGS deep drilling project in the Chesapeake Bay impact structure; results from the Eyreville core holes, Gregory S. Gohn (editor), Christian Koeberl (editor), Kenneth G. Miller (editor) and Wolf Uwe Reimold (editor))
Special Paper - Geological Society of America (2009) 458: 747-773

Abstract

The late Eocene Chesapeake Bay bolide impact transformed its offshore target site from an outer neritic, midshelf seafloor into a bathyal crater basin. To obtain a depositional record from one of the deepest parts of this basin, the U.S. Geological Survey (USGS) and the International Continental Scientific Drilling Program (ICDP) drilled a 1.76-km-deep core hole near Eyreville, Virginia. The Eyreville core and eight previously cored boreholes contain a rarely obtainable record of marine deposition and microfossil assemblages that characterize the transition from synimpact to postimpact paleoenvironments inside and near a submarine impact crater. I used depositional style and benthic foraminiferal assemblages to recognize a four-step transitional succession, with emphasis on the Eyreville core. Step 1 is represented by small-scale, silt-rich turbidites, devoid of indigenous microfossils, which lie directly above the crater-filling Exmore breccia. Step 2 is represented by very thin, parallel, silt and clay laminae, which accumulated on a relatively tranquil and stagnant seafloor. This stagnation created a dead zone, which excluded seafloor biota, and it lasted approximately 3-5 ka. Step 3 is an interval of marine clay deposition, accompanied by a burst of microfaunal activity, as a species-rich pioneer community of benthic foraminifera repopulated the impact site. The presence of a diagnostic suite of agglutinated foraminifera during step 3 indicates that paleoenvironmental stress related to the impact lasted from approximately 9 ka to 400 ka at different locations inside the crater. During step 4, the agglutinated assemblage disappeared, and an equilibrium foraminiferal community developed that contained nearly 100% calcareous species. In contrast to intracrater localities, core sites outside and near the crater rim show neither evidence of the agglutinated assemblage, nor other indications of long-term biotic disruption from the bolide impact.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 458
Title: Paleoenvironmental recovery from the Chesapeake Bay bolide impact; the benthic foraminiferal record
Title: The ICDP-USGS deep drilling project in the Chesapeake Bay impact structure; results from the Eyreville core holes
Author(s): Poag, C. Wylie
Author(s): Gohn, Gregory S.editor
Author(s): Koeberl, Christianeditor
Author(s): Miller, Kenneth G.editor
Author(s): Reimold, Wolf Uweeditor
Affiliation: U. S. Geological Survey, Woods Hole, MA, United States
Affiliation: U. S. Geological Survey, Reston, VA, United States
Pages: 747-773
Published: 2009
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
ISBN: 978-0-8137-2458-4
References: 70
Accession Number: 2010-012520
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sect., 1 plate, 4 tables, geol. sketch map
N37°19'00" - N37°19'00", W75°58'60" - W75°58'60"
Secondary Affiliation: University of Vienna, AUT, AustriaRutgers State University of New Jersey, USA, United StatesHumboldt University Berlin, DEU, Federal Republic of Germany
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201008
Program Name: USGSOPNon-USGS publications with USGS authors
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