| Abstract: | The late Eocene Chesapeake Bay bolide impact transformed its offshore target site from an outer neritic, midshelf seafl oor 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 Scientifi c 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-fi lling Exmore breccia. Step 2 is represented by very thin, parallel, silt and clay laminae, which accumulated on a relatively tranquil and stagnant seafl oor. This stagnation created a dead zone, which excluded seafl oor biota, and it lasted ~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 ~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. ?? 2009 The Geological Society of America. |
| Genre: | Article |
| ProdID: | 70034005 |
| Citation Author: | Poag, C. W. |
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| Citation End Page: | 773 |
| Citation Issue: | 458 |
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| Citation Language: | English |
| Citation Larger Work Title: | Special Paper of the Geological Society of America |
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| Citation Number Of Pages: | 27 |
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| Citation Search Results Text: | Paleoenvironmental recovery from the Chesapeake Bay bolide impact: The benthic foraminiferal record; 2009; Article; Journal; Special Paper of the Geological Society of America; Poag, C. W. |
| Citation Start Page: | 747 |
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| Citation Year: | 2009 |
| Type: | citation/reference |
| Text: | Paleoenvironmental recovery from the Chesapeake Bay bolide impact: The benthic foraminiferal record; 2009; Article; Journal; Special Paper of the Geological Society of America; Poag, C. W. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1130/2009.2458(32) |
| Date Other: | Thu, 1 Jan 2009 00:00 -0600 |
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