--> Abstract: Tectonic Significance of Shelf Turbidite Bodies in the Upper Aberdeen Member to Lower Kenilworth Member Stratigraphic Interval, Cordilleran Foreland Basin, Book Cliffs, Eastern Utah, by Simon A. J. Pattison; #90039 (2005)
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Tectonic Significance of Shelf Turbidite Bodies in the Upper Aberdeen Member to Lower Kenilworth Member Previous HitStratigraphicNext Hit Interval, Cordilleran Foreland Basin, Previous HitBookNext Hit Cliffs, Eastern Utah

Simon A. J. Pattison
Brandon University, Brandon, MB

Shelf turbidite bodies (channels and lobes) are concentrated in a 50 to 90 m thick Previous HitstratigraphicNext Hit interval in the upper Aberdeen and lower Kenilworth members (Blackhawk Formation, Upper Cretaceous), Previous HitBookNext Hit Cliffs, eastern Utah. Within the study area, turbiditic channels are more common in the upper Aberdeen Member, while turbiditic lobes are more common in the lower Kenilworth Member. Paleoshoreline trends were oriented N14°E in the upper Aberdeen versus N18°W in the lower Kenilworth. A sequence boundary (SB) occurs at the contact between the Aberdeen and Kenilworth members, and is demarcated by marine mudstone-encased, iron-rich siltstones, sandstones and coarse-grained lag deposits (i.e. pebbles, shark's teeth, shell fragments). Paleocurrent data indicates a N42°E paleoshoreline trend and, therefore, the “lowest” lowstand shoreline was southeast of the study area. A short-term pulse of tectonic uplift and subsidence, northwest of the Previous HitBookNext Hit Cliffs, is inferred from these observations. This would explain the (i) generation of shelf turbidites because of the increase in slope, (ii) concentration of turbiditic channels and lobes in a narrow Previous HitstratigraphicNext Hit interval, (iii) introduction of coarse-grained sediments into the basin during maximum uplift, (iv) transgressive modification of the coarse-grained lowstand deposits during early subsidence, (v) clockwise (N14°E to N42°E: uplift) to counter-clockwise (N42°E to N18°W: subsidence) rotation of the paleoshoreline trends through time, and (vi) progradational (upper Aberdeen to SB) to retrogradational (SB to lower Kenilworth) stacking pattern of the shelf deposits. Early results demonstrate that many isolated sandstone bodies of the Prairie Canyon Member in eastern Utah and western Colorado occur within the upper Aberdeen to lower Kenilworth Previous HitstratigraphicTop interval.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005