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TitleCloud Creek structure, central Wyoming, USA: impact origin confirmed
AuthorStone, D S; Therriault, A M
SourceMeteoritics and Planetary Science 38, 3, 2003 p. 445-455,
Alt SeriesGeological Survey of Canada, Contribution Series 2002105
Mediapaper; on-line; digital
File formatpdf
AreaWyoming; Casper; United States of America
Lat/Long WENS-106.7167 -106.7000 43.1833 43.1667
Subjectsextraterrestrial geology; structural geology; craters; meteorite craters; structural features; morphology; faults; sedimentary rocks; carbonates; metamorphism, shock; Cloud Creek Structure; Paleozoic; Triassic; Jurassic; Mesozoic
Illustrationssketch maps; stratigraphic sections; graphs; tables; seismic profiles; cross-sections
Released2003 03 01
AbstractThe circular Cloud Creek structure in central Wyoming, USA is buried beneath approximately 1200 m of Mesozoic sedimentary rocks and has a current diameter of approximately ?7 km. The morphology/morphometry of the structure, as defined by borehole, seismic, and gravity data, is similar to that of other buried terrestrial complex impact structures in sedimentary target rocks, e.g., Red Wing Creek in North Dakota, USA. The structure has a fault-bordered central peak with minimum diameter of approximately 1.4 km, composed predominantly of Paleozoic carbonates thickened by thrust faulting and brecciation, and is elevated some 520 m above equivalent strata beyond the outer rim of the structure. There is a approximately 1.6 km wide annular trough sloping away from the central peak (maximum structural relief, 300 m) and terminated by a detached, fault-bounded, rim anticline. The youngest rocks within the structure are Late Triassic (Norian?) clastics and these are overlain unconformably by post-impact Middle Jurassic (Bathonian?) sandstones and shales. Thus, the formation of the Cloud Creek structure is dated chronostratigraphically as approximately 190+ or -20 Ma.
Reported here for the first time are measurements of planar deformation features (PDFs) in shocked quartz grains in thin sections made from drill cuttings recovered in a borehole drilled at the southern perimeter of the central peak. Other, less definitive microstructures consistent with impact occur in samples collected from boreholes drilled into the central peak and rim anticline. The shock-metamorphic evidence confirms an impact origin for the Cloud Creek structure.

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