EurekaMag
+ Translate
+ Most Popular
Gaucher's disease;thirty-two years experience at Siriraj Hospital
A study of Macrobathra Meyrick from China (Lepidoptera, Cosmopterigidae)
First occurrence in ores of tetragonal chalcocite
Effects of trace element nutrition on sleep patterns in adult women
N.Z. range management guidelines. 2. Design of grazing management systems for tussock country
A case of lipoma of the esophagus
A revision of world Acanthosomatidae (Heteroptera: Pentatomidae): keys to and descriptions of subfamilies, tribes and genera, with designation of types
Life history of the coronate scyphozoan Linuche unguiculata (Swartz, 1788)
Perceptual restoration of obliterated sounds
Mutagenicity studies on two chromium(III) coordination compounds
The formation of the skeleton. I. Growth of a long bone. 1st appearance of a center of calcification
Leucopenia and abnormal liver function in travellers on malaria chemoprophylaxis
The joint commission: four key root causes loom large in sentinel event data
Treatment of vitiligo with topical 15% lactic acid solution in combination with ultra violet-A
Behaviour of dairy cows within three hours after feed supply: I. Influence of housing type and time elapsing after feed supply
Observations of the propagation velocity and formation mechanism of burst fractures caused by gunshot
Management and control of patients with type 2 diabetes mellitus in Lebanon: results from the International Diabetes Management Practices Study (IDMPS)
The diet composition and nutritional knowledge of patients with anorexia nervosa
Physoporella croatica Herak, 1958 of the Slovak karst Anisian (Slovakia, the West Carpathians Mts.)
Bright lights, big noise. How effective are vehicle warning systems?
Ein Plesiosaurier-Rest mit Magensteinen aus mittlerem Lias von Quedlinburg
Incidence of Chlamydia trachomatis in patients with sterility
Monster soup: the microscope and Victorian fantasy
Preliminary tests with residual sprays against poultry lice
Duration of the life of plants in phylogeny

Evidence of meteoritic impact, crater-filling stratigraphy, and collateral effects of impact at Wetumpka Crater, Alabama, USA


Evidence of meteoritic impact, crater-filling stratigraphy, and collateral effects of impact at Wetumpka Crater, Alabama, USA



Abstracts with Programs - Geological Society of America 31(7): 124



Wetumpka impact crater (Elmore County, Alabama) is an exposed, semi-circular structure, at least 6.5 km in diameter, which is located today at the juncture between Alabama's Coastal Plain and Appalachian piedmont regions. Wetumpka crater was formed on Alabama's Late Cretaceous continental shelf where target stratigraphy included 120 m of unconsolidated sediment and underlying crystalline piedmont basement rock. Asymmetry suggests that the impacting bolide had a low angle of incidence. Evidence of meteoritic impact at Wetumpka comes from multiple sources. Most importantly, impact-breccia matrix contains moderately abundant, fine-sand sized shocked-quartz grains which display two intersecting sets of PDFs. Also, plagioclase and mica show impact-related microstructures. Gamma-gamma coincidence spectrometry of breccia matrix shows iridium content as high as 0.21 ppb, suggesting a meteoritic component of approximately 0.04%. A high-resolution gravity profile across Wetumpka impact crater reveals a 10 mGal total anomaly (+2 mGal at rim; -8 mGal at center) consistent with impact cratering. Surficial investigations and core data from two centrally located drill holes indicate that Wetumpka's crater-filling unit is apparently composed of two stratigraphic zones: (1) a well-exposed upper veneer of disturbed (i.e., folded, faulted, overturned, and clastic-dike injected) target strata up to approximately 65 m thick and (2) an underlying impactoclastic unit over 135 m thick. Wetumpka's impactoclastic unit consists of intercalated impactite sands and monomict and polymict impact breccias with an admixture of 1 to 5-m blocks of crystalline rock and semi-consolidated target strata. Except for a small area of a few thousand square meters at crater center, the impactoclastic unit is not exposed on the crater floor. Collateral effects of Wetumpka impact include development of an adjacent, graben-bearing terrain, approximately equal in size to the crater itself (located aside the southwestern quadrant of the crater), and possible seismically disturbed coeval strata in eastern Alabama.

Accession: 018428730

Download citation: RISBibTeXText

Related references

Mathematical model and impact conditions for Wetumpka impact crater, Alabama, USA. Meteoritics and Planetary Science 41, Supplement: A49, 2006

Marine impact craters on Earth; field investigation of the Wetumpka impact structure, a well-preserved marine impact crater, and the K-T boundary in the Alabama Gulf Coastal Plain. GSA Today 17(9): 57-58, 2007

Geophysical investigation of a suspect impact crater in Wetumpka, Alabama. Pages 57-68 1997, 1997

Wetumpka impact structure (Alabama), a Late Cretaceous marine-target crater. Abstracts with Programs - Geological Society of America 32(7): 161, 2000

Tabular comparisons of the Flynn Creek impact crater, United States, Steinheim impact crater, Germany and Snowball explosion crater, Canada. Pages 125-162 1977, 1977

The horseshoe-shaped rim of Wetumpka marine impact crater; from oblique impact or heterogeneity in the rim?. Abstracts with Programs - Geological Society of America 36(5): 266-267, 2004

The Wetumpka impact crater and the Late Cretaceous impact record. Pages 25-56 1997, 1997

Wetumpka impact crater. Pages 1-23 1997, 1997

Wet-target effects on the syn-impact partial filling and post-impact burial of the Chesapeake Bay impact crater, southeastern Virginia. Abstracts with Programs - Geological Society of America 34(6): 544, 2002

Structure-filling stratigraphy of the marine-target Wetumpka impact structure, Alabama, USA. Open-File Report - U S, 2004

Structure-filling stratigraphy of the Late Cretaceous Wetumpka marine-target impact structure, Alabama. Abstracts with Programs - Geological Society of America 38(3): 82, 2006

Distribution of crater ejecta of the Bosumtwi impact-crater lake, Ghana; comparison with the crater ejecta of the Ries Crater, Germany. Pages 41-43 1998, 1998

Structural comparison between the Chesapeake Bay impact crater, USA, and the Ries Crater, Germany; how did the central crater basin form?. Open-File Report - U S, 2004

Wetumpka crater tours; impact geology and educational outreach in the field. Abstracts with Programs - Geological Society of America 38(3): 82, 2006

Crater modification and geologic activity in Enceladus heavily cratered plains; evidence from the impact crater distribution. Icarus 202.2, 2009