Aouelloul - Hypervelocity Impact Crater

Alternate Names
Local Language
Coordinates 20° 14' 28" N; 12° 40' 29" W
Notes
  1. On a plateau of gently dipping sandstones in the Adrar region of the Western Sahara Desert, Mauritania.
Country Mauritania
Region Adrar
Date Confirmed 1966
Notes
  1. Analysis of Ni-rich Fe spherules (1.7 to 9 wt% Ni) within Si-rich glass interpreted as projectile component (Chao et al., 1966) (Koeberl et al., 1998). Quartz grains show abundant planar and subplanar fractures; many are healed with fluid inclusion trails, however these are not unambiguous indicators of shock (Koeberl et al., 1998).
Buried? No
Drilled? No
Target Type Sedimentary
Notes
  1. Ordovician Zli and Oujeft sandstones (Monod, 1952) (Fudali and Cassidy, 1972). As well, the gravity anomaly corresponds to a maximum sedimentary fill thickness of 70 to 100 ft (Fudali and Cassidy, 1972).
Sub-Type Sandstone
Apparent Crater Diameter (km) 390 m
Age (Ma) 3.1 ± 0.3
Notes :
  1. 3.1 ± 0.3 Ma determined by K-Ar of impact glass (Fudali and Cressy, 1976) Previous age constraints: 3.3 ± 0.5 Ma determined by fission track analysis of impact glass (Storzer, 1971)

Method :
  1. K-Ar
Impactor Type IIIB, IIID, or pallasites or an impactor of tektite-like glass sourced from the Lunar mantle
Notes
  1. Based on anomalous Ni, Ir, and Ge content in glasses (Morgan et al., 1975). or \"\"It thus appears that the projectile was composed of tektite glass in both cases; no ordinary meteorite can supply the observed siderophile abundances and also the observed amount of chromium\"\" (O\'Keefe, 1987). Note: A LL6 ordinary chondrite Zerga meteoritite was found in close proximity to Aouelloul, however the meterorite is entirely coincidental and not related to the genesis of the Aouelloul crater (Fudali and Cressy, 1976).

Advanced Data Fields

Notes

Erosion
3
  1. The well-developed rim rises 15-25 m above the surroundings (Koeberl et al., 1998); crater-fill products are preserved (Monod, 1952).
Final Rim Diameter
Unknown
Apparent Rim Diameter
390 m
Rim Reliability Index
2
  1. Consists of a pentagonal-shaped depression with a flat floor and a raised rim (Monod, 1952).
Crater Morphology
Simple
Central Uplift Diameter
km
Central Uplift Height
Unknown
Uplift Reliability Index
Structural Uplift
Unknown
Thickness of Seds
Target Age
Palaeozoic
Marine
No
Impactor Type
IIIB, IIID, or pallasites or an impactor of tektite-like glass sourced from the Lunar mantle
  1. Based on anomalous Ni, Ir, and Ge content in glasses (Morgan et al., 1975). or \"\"It thus appears that the projectile was composed of tektite glass in both cases; no ordinary meteorite can supply the observed siderophile abundances and also the observed amount of chromium\"\" (O\'Keefe, 1987). Note: A LL6 ordinary chondrite Zerga meteoritite was found in close proximity to Aouelloul, however the meterorite is entirely coincidental and not related to the genesis of the Aouelloul crater (Fudali and Cressy, 1976).
Other Shock Metamorphism
Lechatelierite Baddeleyite
  1. Baddeleyite in glass (El Goresy et al., 1965) and lechatelierite (El Goresy et al., 1968).
Shatter Cones
No
  1. Not in literature.
Planar Fractures
No
  1. \"A large fraction of the quartz grains show abundant subplanar and planar fractures...Many of the fractures are healed and are evident only as fluid inclusion trails\" (Koeberl et al., 1998).
Planar Deformation Features
Yes
  1. \"A few grains showed sets of narrow and densely spaced fluid inclusions trails in one (rarely two) orientations per grain, which could be possible remnants of planar deformation features (PDFs), although such an interpretation is not unambiguous\" (Koeberl et al., 1998).
Diaplectic Glass
No
Coesite
No
Stisovite
No
Crater Fill
  1. No brecciation. Impact glass from crater, with resemblances to the target sandstone but also with possible meteorite origins; these impactites are similar to tektites but not tektites themselves (Chao et al., 1966) (Gucsik et al., 2004). S: Ni-Fe spherules 0.2 - 50 microns in diameter occur in siliceous glass bands. The glass samples (2 - 5 cm long) analyzed by (Chao et al., 1966) were found as isolated glass fargments (melt beads) around the crater, i.e., in its immediate vicinity. T: Tektite-like glass is found at the site, but the tektite is possibly the impactor, not an impactite via (O\'Keefe, 1987). The stratigraphic position at which the glass (Koeberl et al., 1998) found is not clear. They analyzed ~200 glass and target rock samples, and the glasses were \"\"found predominantly on the south, southeast, and north outer flank of the crater rim, with less than 10 pieces recovered from inside the rim on the southeast side\".
Proximal Ejecta
G, S
Distal Ejecta
Dykes
Volume of Melt
Depth of Melting

References

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T Monod, A Pourquié (1951) Le cratère d'Aouelloul (Adrar, Sahara occidental), Bulletin de l’Institut fondamental d’Afrique noire

F C Leonard (1955) Mineral formulas, the classificational sequence, and the Aouelloul crater, Meteoritics 1(3), p. 324-327, Wiley-Blackwell, url, doi:10.1111/j.1945-5100.1955.tb01357.x

A E Goresy (1965) Baddeleyite and Its Significance in Impact Glasses, Journal of Geophysical Research 70(14)

R L Fleischer, P B Price (1967) Ages of impact glasses from the Ashanti and Aouelloul craters: A correction, Geochimica et Cosmochimica Acta 31, p. 2451-2452, url, doi:https://doi.org/10.1016/0016-7037(67)90017-8

E C T Chao (1967) Shock Effects in Certain Rock-Forming Minerals, Science 156

J Gilchrist, A N Thorpe, F E Senftle (1969) Infrared analysis of water in tektites and other glasses, Journal of Geophysical Research 74(6), p. 1475-1483, url, doi:10.1029/JB074i006p01475

John A O'Keefe (1971) Physical chemistry of the Aouelloul glass, Journal of Geophysical Research 76(26), p. 6428-6439, American Geophysical Union (AGU), url, doi:10.1029/jb076i026p06428

D Storzer (1971) Fission track dating of some impact craters in the age range between 6,000y and 300 m.y., Meteoritical Society

R F Fudali, W A Cassidy (1972) Gravity reconnaissance at three Mauritanian craters of explosive origin, Meteoritics 7(1), p. 51-70, Wiley, url, doi:10.1111/j.1945-5100.1972.tb00424.x

P J Cressy, C C Schnetzler, B M French (1972) Aouelloul glass: Aluminum 26 limit and some geochemical comparisons with Zli sandstone, Journal of Geophysical Research 77(17), p. 3043-3051, American Geophysical Union (AGU), url, doi:10.1029/jb077i017p03043

J W Morgan, H Higuchi, R Ganapathy, E Anders (1975) Meteoritic material in four terrestrial meteorite craters, Proc. Lunar Sci. Conf. 6th, R B Merrill, N J Hubbard, W W Mendell, R J Williams (ed.), url

R F Fudali, P J Cressy (1976) Investigation of a new stony meteorite from Mauritania with some additional data on its find site: Aouelloul crater, Earth and Planetary Science Letters 30(2), p. 262-268, url, doi:10.1016/0012-821X(76)90253-3

C Koeberl (1983) Zhamanshinites and Aoelloul-Glass Main Element Analyses and Correlations, Lunar and Planetary Science XIV, url

J A O'Keefe (1985) Aouelloul and Zhamanshin: Tektite Impact Craters?, Bulletin of the American Astronomical Society 17, p. 713, url

J A O'Keefe (1985) Aouelloul and Zhamanshin: Tektite Impact Craters?, 17th Annual DPS Meeting

J A O'Keefe (1987) Zhamanshin and Aouelloul: Craters produced by impact of tektite-like glasses?, Meteoritics 22(3), url

R A F Grieve, James B Garvin, J M Coderre, J Rupert (1989) Test of a geometric model for the modification stage of simple impact crater development, Meteoritics 24(2), p. 83-88, Wiley, url, doi:10.1111/j.1945-5100.1989.tb00948.x

K Matsubara, J Matsuda, C Koeberl (1991) Noble gases in impact glasses., Antarctic Meteorites XVI 16, M Zbik (ed.), p. 140-142, url

D Matthies, C Koeberl (1991) Fluorine and boron geochemistry of tektites, impact glasses, and target rocks, Meteoritics 26, p. 41-45, url

K Matsubara, J-I Matsuda, C Koeberl (1991) Noble gases and K-Ar ages in Aouelloul, Zhamanshin, and Libyan Desert impact glasses, Geochimica et Cosmochimica Acta 55, p. 2951-2955, url, doi:10.1016/0016-7037(91)90460-M

C Koeberl, P Auer (1992) Geochemistry of Impact Glass from the Aouelloul Crater, Mauritania, Abstracts of the Lunar and Planetary Science Conference 22, p. 731, url

K Matsubara, J Matsuda, C Koeberl (1993) Noble gas compositions in Muong Nong-type tektites, Meteoritics 28(3), p. 392-393, url

C Koeberl (1994) African meteorite impact craters: characteristics and geological importance, Journal of African Earth Sciences 18(4), p. 263-295, doi:https://doi.org/10.1016/0899-5362(94)90068-X

C Koeberl (1994) Tenoumer (Mauritania), Journal of African Earth Sciences 18(4), p. 263-295

M Chaussidon, C Koeberl (1995) Boron content and isotopic composition of tektites and impact glasses: Constraints on source regions, Geochimica et Cosmochimica Acta 59(3), p. 613-624, url, doi:10.1016/0016-7037(94)00368-V

A Beran, C Koeberl (1997) Water in tektites and impact glasses by fourier-transformed infrared spectrometry, Meteoritics & Planetary Science 32, p. 1-216, Meteoritical Society, url, doi:10.1111/j.1945-5100.1997.tb01260.x

C Koeberl, W U Reimold, S B Shirey (1998) The Aouelloul crater, Mauritania On the problem of confirming the impact origin of a small crater, Meteoritics & Planetary Science 33, url, doi:10.1111/j.1945-5100.1998.tb01655.x

A Gucsik, C Koeberl, Franz Brandstätter, E Libowitzky, M Zhang (2004) Infrared, Raman, and cathodoluminescence studies of impact glasses, Meteoritics & Planetary Science 39(8), p. 1273-1285, url

H E Newsom, M B E Boslough (2008) Impact melt formation by low-altitude airburst processes, evidence from small terrestrial craters and numerical modeling, Lunar and Planetary Science XXXIX 39, p. 1460, url

J M Frías, F G Talavera, F Rull, F López-Vera, R Capote del Villar, J M N Latorre, L Sánchez-Pinto, J R Rondón, Ja R Losada, M T F Sampedro, M P M Redondo, C Menor-Salvan (2008) Impactos en Mauritania: nuevos datos mineralógicos, texturales y geoquímicos de las megabrechas de Richat y del cráter meteorítico de Aouelloul, Geo-Temas 10, url

P Rochette, J Gattacceca, B Devouard, F Moustard, N S Bezaeva, C Cournède, B Scaillet (2015) Magnetic properties of tektites and other related impact glasses, Earth and Planetary Science Letters 432, p. 381-390, Elsevier, url, doi:10.1016/j.epsl.2015.10.030

E C Ould, Mohamed Navee, H C Aoudjehane, David Baratoux, Ludovic Ferrière, M S Ould Sabar (2019) Aouelloul impact crater, Mauritania: New structural and lithological data, Large Meteorite Impacts VI, url

M D Martino, A Coletta, M L Battagliere, M Virelli (2019) Aouelloul, Mauritania, Encyclopedic Atlas of Terrestrial Impact Craters, p. 69-71, Springer International Publishing, doi:10.1007/978-3-030-05451-9_9