--> Abstract: Prodelta Turbiditic Channels and Lobes, Upper Aberdeen Member to Lower Kenilworth Member, Green River Embayment, Book Cliffs, Utah: Integral Components of River-Dominated Deltas, by Simon A.J. Pattison, Trevor A. Hoffman, and R. Bruce Ainsworth; #90039 (2005)

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Prodelta Turbiditic Channels and Lobes, Upper Aberdeen Member to Lower Kenilworth Member, Green River Embayment, Book Cliffs, Utah: Integral Components of River-Dominated Deltas

Simon A.J. Pattison1, Trevor A. Hoffman2, and R. Bruce Ainsworth3
1 Brandon University, Brandon, MB
2 University of Alberta, Edmonton, AB
3 Shell Todd Oil Services Ltd, New Plymouth, New Zealand

Marine mudstone-encased, turbiditic channels and lobes are concentrated in a 50 to 90 m thick zone, within the upper Aberdeen Member to lower Kenilworth Member stratigraphic interval (Blackhawk Formation, Campanian), Green River embayment, Book Cliffs, Utah. The upper Aberdeen Member is marked by turbiditic channels at two distinct levels. The channels are 1 to 9 m thick and are exposed in patchy outcrops on the desert floor. Each channel consists of a stack of sharp-based, concave-up, gently-dipping packages of inclined heterolithic stratification (IHS), that vary from mudstone- to sandstone-rich. Onlap, low angle truncation surfaces, and pinch and swell geometries are common within individual IHS packages. Channel facies are dominated by sharp-based Tc and Tbc Bouma beds. Carbonaceous matter, convolute bedding, climbing ripples, hyperpycnites and mildly bioturbated intervals are locally abundant. The lower Kenilworth Member is characterized by turbiditic lobes along two horizons. The KPS1 (Kenilworth parasequence 1) lobe is at least 1 km long, 500 m wide and 5 m thick, while the KPS2 lobe is 5 km long, greater than 2 km wide and is 8 m thick. These turbiditic lobes have a maximum sandstone content of approximately 40 % and consist of Tc and Tbc Bouma beds. Load casts, flame structures and weakly hummocky cross-stratified sandstones are locally abundant. The turbiditic channels and lobes were deposited below fair weather wave base, in an inner shelf environment, and appear detached from their time equivalent delta front deposits. River-dominated deltaic facies models require revision to include prodelta turbiditic channels and lobes.

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