--> Abstract: Outcrop Characterization of Along-Strike Variability in Shallow and Marginal-Marine Strata, by Gary J. Hampson, M. Royhan Gani, Nawazish Irfan, and Kathryn E. Sharman; #90078 (2008)

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Outcrop Characterization of Along-Strike Variability in Shallow and Marginal-Marine Strata

Gary J. Hampson1, M. Royhan Gani2, Nawazish Irfan1, and Kathryn E. Sharman1
1Department of Earth Science and Engineering, Imperial College London, London, United Kingdom
2Energy and Geoscience Institute, University of Utah, Salt Lake City, United Kingdom

Current sequence stratigraphic models emphasise changes in architecture down depositional dip, but considerable variability in sandbody geometry, distribution, connectivity, and quality can occur along depositional strike at play-to-reservoir scales. This variability reflects differences in local process regime, in addition to lateral variations in sediment supply and tectonic subsidence. Here we present preliminary results that describe along-strike variability in stratigraphic architecture in a high-quality outcrop dataset that exemplifies a number of shallow- and marginal-marine environments.

The Star Point and Blackhawk Formations crop out in the eastern Wasatch Plateau of central Utah, where they form a continuous, 100-km long escarpment oriented sub-parallel to regional depositional strike that exposes c. 120 m of shallow-marine strata and c. 300 m of overlying marginal-marine strata. The escarpment is contiguous with the extensively documented, dip-oriented exposures of the Book Cliffs. The strata constitute an overall wave-dominated deltaic succession, which contains a number of smaller depositional systems including: (1) regressive wave-dominated shoreface, (2) regressive fluvial-dominated delta front, (3) transgressive barrier islands and lagoons, (4) coal-bearing lower delta plain, (5) fluvial and/or estuarine channel belts (valley fills?). Logged sections illustrate subtle variations in fluvial influence within the wave-dominated delta front, and systematic changes in fluvial style and channel stacking on the delta plain. Facies-architecture panels constructed from cliff-face photomontages illustrate stratigraphic and palaeogeographic controls on sandbody type and connectivity. In combination, these data enable the construction of a regional sequence stratigraphic framework that illustrates architectural variability along depositional strike.

 

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas