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The marine-target Wetumpka impact structure examined in the field and by shallow core-hole drilling

By
David T. King, Jr.
David T. King, Jr.
1 Geology Office, Auburn University, Auburn, Alabama 36849, USA
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Jens Ormö
Jens Ormö
2 Centro de Astrobiología (CSIC-INTA), Instituto Nacional de Técnica Aeroespacial, 28850 Torrejon de Ardoz, Madrid, Spain
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Published:
December 01, 2011

The Wetumpka impact structure (near the town of Wetumpka, Alabama) has a semicircular crystalline rim that is ~5 km in diameter. This marine-target impact structure developed in both poorly consolidated, water-saturated sediments and underlying crystalline basement. Previous studies have described a semicircular, crystalline rim, an interior structure-filling unit, and an exterior disturbed terrain developed within the sedimentary target sequence outside the southwestern part of the central basement crater. Based on new field and drill-core observations, we recognize the following specific structural and lithological features: overturned crystalline rim flap; slumped interior megablock terrain; central polymict breccia (originating as near-field ejecta); interior marine chalk deposits and reworked glauconitic sands (formed by resurge and postimpact deposition); and a collapsed southern part of the rim with overturned flap (mainly developed within the sedimentary target rocks). In this paper, we describe the origin of these features and present a new reconstructed sequence of events.

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GSA Special Papers

Analogs for Planetary Exploration

W. Brent Garry
W. Brent Garry
Planetary Science Institute, Tucson, Arizona, USA
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Jacob E. Bleacher
Jacob E. Bleacher
NASA Goddard Space Flight Center, Planetary Geodynamics Lab, Greenbelt, Maryland, USA
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Geological Society of America
Volume
483
ISBN print:
9780813724836
Publication date:
December 01, 2011

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