Middlesboro - Hypervelocity Impact Crater

Alternate Names
Local Language
Coordinates 36° 37' 35" N; 83° 43' 35" W
Notes
  1. The city of Middlesboro, in SE Kentucky.
Country United States of America
Region Kentucky
Date Confirmed 1966
Notes
  1. Confirmed by shatter cones in boulders near the central uplift (Dietz, 1966).
Buried? No
Notes
  1. Approximately half of the distributed area is covered in Quaternary alluvium (Englund and Roen, 1963).
Drilled? Yes
Notes
  1. Shallow water wells have been drilled into the structure (Steinemann, 1980)
Target Type Sedimentary
Notes
  1. Sandstones, conglomerates, siltstones, coal and shales of Pennsylvanian age (Englund and Roen, 1963).
Sub-Type Coal, Conglomerate, Sandstone, Shale, Siltstone
Apparent Crater Diameter (km) 5.5 km
Age (Ma) <299
Notes :
  1. The youngest deformed rocks are Pennsylvanian in age; the formation is post Pennsylvanian (Englund and Roen, 1963). *Minimum age is poorly constrained and is estimated based on erosion.

Method :
  1. Stratigraphy
Impactor Type Unknown

Advanced Data Fields

Notes

Erosion
7
  1. Extensive erosion occurred in this area; the crater floor has been removed and the substructure is now exposed (Grieve, 1982).
Final Rim Diameter
Unknown
Apparent Rim Diameter
5.5 km
  1. The diameter of 5.5 km is based on the distance between the average outer boundaries between deformed and non-deformed strata (Milam et al., 2004). Diameter first reported as 4 miles (~6 km) but all recent publications cite a ~5.5 km diameter with most recent being (Hower et al., 2009). (Englund and Reon, 1963) (Dietz, 1966) (Steinemann, 1980).
Rim Reliability Index
1
  1. Structural uplift was initially estimated at ~244 m. Based on well logs, SU is estiamted at a minimum of 132 m and maximum of 543 m (Milam et al., 2004). Used the median of this range, 337.5 m
Crater Morphology
Complex
Central Uplift Diameter
0.5km
Central Uplift Height
Unknown
Uplift Reliability Index
3
Structural Uplift
340 m
Thickness of Seds
Target Age
Palaeozoic
Marine
No
Impactor Type
Other Shock Metamorphism
No
Shatter Cones
Yes
  1. Shatter cones were observed in two residual boulders (of presumed Breathitt Siltstone) from the central uplift (Dietz, 1966). "Patterns of concave striations suggestive of shatter coning" were also observed in Lee Sandstone (Dietz, 1966).
Planar Fractures
No
Planar Deformation Features
Yes
  1. PDF (c, omega and pi) in quartz grains (Bunch, 1968) (French, 1970).
Diaplectic Glass
No
Coesite
No
Stisovite
No
Crater Fill
  1. Crater deeply eroded. No evidence of melt (Milam et al., 2004).
Proximal Ejecta
Distal Ejecta
Dykes
Volume of Melt
Depth of Melting

References

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K J Englund, J B Roen (1963) Origin of the Middlesboro Basin, Kentucky, U. S. Geological Survey Professional Paper, p. E20-E22, U. S. Geological Survey, Reston, VA, url

Robert S Dietz (1966) Shatter cones at the Middlesboro structure, Kentucky, Meteoritics 3(1), p. 27-29

C F Steinemann (1980) A gravity study of the Middlesboro cryptoexplosive structure, M.S, Univeristy of Kentucky, p. 58, url

W S Hale-Erlich, J L Coleman, C D Faris (1988) Hydrocarbon potential of Middlesboro Crater, Bell County, Kentucky, Annual Meeting of the American Association of Petroleum Geologyists, url

K A Milam (1998) Mapping, modeling and geomorphology of the Middlesboro impact structure; Middlesboro, Kentucky, Abstracts with Programs - Geological Society of America 30(4), p. 51, Geological Society of America (GSA), Boulder, CO, url

S F Greb, D R Chesnut Jr (1998) Impact of an astrobleme on coal mining in part of the Eastern Kentucky coal field, AAPG Bulletin 82(9), p. 1767, American Association of Petroleum Geologists, Tulsa, OK, url

K A Milam, K W Kuehn (1999) Middlesboro, KY; further evidence for an impact origin, Abstracts with Programs - Geological Society of America 31(7), p. 124, Geological Society of America (GSA), Boulder, CO, url

K A Milam, K W Kuehn (2002) Shocked conglomerates from the Middlesboro impact structure, Abstracts with Programs - Geological Society of America 34(2), p. 9, Geological Society of America (GSA), Boulder, CO, url

K W Kuehn, K A Milam, W M Andrews Jr (2003) Role of geology in economic development at Middlesboro; geologic overview of Middlesboro and Cumberland Gap, Annual Field Conference of the Kentucky Society of Professional Geologists 2003, Kenneth W Kuehn, Keith A Milam, Margaret Luther Smath (ed.), p. 10-15, Kentucky Society of Professional Geologists, Lexington, KY, url

K A Milam, K W Kuehn (2003) Field guide to the Middleboro impact structure and beyond, Annual Field Conference of the Kentucky Society of Professional Geologists 2003, Kenneth W Kuehn, Keith A Milam, Margaret Luther Smath (ed.), p. 30-44, Kentucky Society of Professional Geologists, Lexington, KY, url

S F Greb (2003) Mining and construction obstacles in the Middlesboro Basin, Kentucky, Annual Field Conference of the Kentucky Society of Professional Geologists 2003, Kenneth W Kuehn, Keith A Milam, Margaret Luther Smath (ed.), p. 17-22, Kentucky Society of Professional Geologists, Lexington, KY, url

K A Milam, K Kuehn, B Deane (2004) Central uplift formation at the Middlesboro impact structure, Kentucky, USA, Abstracts of Papers Submitted to the Lunar and Planetary Science Conference 35, p. unpaginated, Lunar and Planetary Science Conference, Houston, TX, url

K A Milam, B Deane (2005) Petrogenesis of central uplifts in complex terrestrial impact craters, Abstracts of Papers Submitted to the Lunar and Planetary Science Conference 36, p. unpaginated, Lunar and Planetary Science Conference, Houston, TX, pdf

J C Hower, S F Greb, K W Kuehn, C F Eble (2009) Did the Middlesboro, Kentucky, bolide impact event influence coal rank?, International Journal of Coal Geology 79(3), p. 92-96, Elsevier B.V., url, doi:10.1016/j.coal.2009.05.003

Enrico Flamini, A Coletta, M L Battagliere, M Virelli (2019) Middlesboro, USA, Encyclopedic Atlas of Terrestrial Impact Craters, p. 557-559, Springer, Cham, url

Lars Wihanto, Thomas Kenkmann (2023) Geophysical and structural analyses of the Middlesboro impact structure, Kentucky, USA: Reactivation of a thrust detachment of the Appalachian foreland fold-and-thrust belt, Meteoritics and Planetary Science, University of Arkansa, doi:10.1111/maps.14107