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Paleontological interpretations of crater processes and infilling of synimpact sediments from the Chesapeake Bay impact structure

Jean M. Self-Trail, Lucy E. Edwards and Ronald J. Litwin
Paleontological interpretations of crater processes and infilling of synimpact sediments from the Chesapeake Bay impact structure (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: 633-654

Abstract

Biostratigraphic analysis of sedimentary breccias and diamictons in the Chesapeake Bay impact structure provides information regarding the timing and processes of late-stage gravitational crater collapse and ocean resurge. Studies of calcareous nannofossil and palynomorph assemblages in the International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) Eyreville A and B cores show the mixed-age, mixed-preservation microfossil assemblages that are typical of deposits from the upper part of the Chesapeake Bay impact structure. Sparse, poorly preserved, possibly thermally altered pollen is present within a gravelly sand interval below the granite slab at 1392 m in Eyreville core B, an interval that is otherwise barren of calcareous nannofossils and dinocysts. Gravitational collapse of water-saturated sediments from the transient crater wall resulted in the deposition of sediment clasts primarily derived from the nonmarine Cretaceous Potomac Formation. Collapse occurred before the arrival of resurge. Low pollen Thermal Alteration Index (TAI) values suggest that these sediments were not thermally altered by contact with the melt sheet. The arrival of resurge sedimentation is identified based on the presence of diamicton zones and stringers rich in glauconite and marine microfossils at 866.7 m. This horizon can be traced across the crater and can be used to identify gravitational collapse versus ocean-resurge sedimentation. Glauconitic quartz sand diamicton dominates the sediments above 618.2 m. Calcareous nannofossil and dinoflagellate data from this interval suggest that the earliest arriving resurge from the west contained little or no Cretaceous marine input, but later resurge pulses mined Cretaceous sediments east of the Watkins core in the annular trough. Additionally, the increased distance traveled by resurge to the central crater in turbulent flow conditions resulted in the disaggregation of Paleogene unconsolidated sediments. As a result, intact Paleogene clasts in Eyreville cores are rare, but clasts of semilithified Potomac Formation silts and clays are common.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 458
Title: Paleontological interpretations of crater processes and infilling of synimpact sediments from the Chesapeake Bay impact structure
Title: The ICDP-USGS deep drilling project in the Chesapeake Bay impact structure; results from the Eyreville core holes
Author(s): Self-Trail, Jean M.Edwards, Lucy E.Litwin, Ronald J.
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, Reston, VA, United States
Affiliation: U. S. Geological Survey, Reston, VA, United States
Pages: 633-654
Published: 2009
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
ISBN: 978-0-8137-2458-4
References: 55
Accession Number: 2010-012516
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. cols., 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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