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Thrust-generated fan-delta deposition; Little Muddy Creek Conglomerate, SW Wyoming

David A. Pivnik
Thrust-generated fan-delta deposition; Little Muddy Creek Conglomerate, SW Wyoming
Journal of Sedimentary Petrology (July 1990) 60 (4): 489-503


The upper Cretaceous Little Muddy Creek conglomerate in southwestern Wyoming is an often-cited example of a thin-skinned, thrust-derived conglomerate that has been used to date absolute and relative timing of thrust sheet motion in the Idaho-Wyoming-Utah fold and thrust belt. Despite the regional tectonic significance of the Little Muddy Creek conglomerate, no quantitative sedimentological or compositional analyses are available in the literature. Sedimentological analysis indicates that the Little Muddy Creek conglomerate was produced by forelandward (eastward) progradation of a marine fan-delta that emanated from the thrust ridge above the old Absaroka thrust. Fan-delta deposits are overlain by nearshore, inner-shelf, outer-shelf and slope deposits which record sedimentation as motion on the old Absaroka thrust began to wane. A two-dimensional provenance modeling technique described herein compares hypothetical, synorogenic-sediment compositions with actual compositional data from the Little Muddy Creek conglomerate. The two-dimensional modeling is a refinement of previous, one-dimensional models in that it is based upon the reconstruction of syn-thrusting hanging wall and footwall geometries. The provenance modeling shows that compositional data from the Little Muddy Creek conglomerate record uplift followed by gradual cessation thereof on the old Absaroka thrust. Sedimentological and compositional interpretations are integrated, allowing for an evaluation of the tectonic controls on deposition of this thin-skinned, thrust-derived conglomerate.

ISSN: 0022-4472
Serial Title: Journal of Sedimentary Petrology
Serial Volume: 60
Serial Issue: 4
Title: Thrust-generated fan-delta deposition; Little Muddy Creek Conglomerate, SW Wyoming
Author(s): Pivnik, David A.
Affiliation: Univ. Rochester, Dep. Geol. Sci., Rochester, NY, United States
Pages: 489-503
Published: 199007
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 42
Accession Number: 1990-046089
Categories: Sedimentary petrologyStructural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sect., geol. sketch maps
N41°00'00" - N45°00'00", W111°04'60" - W104°04'60"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1990
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