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The AAPG/Datapages Combined Publications Database

Houston Geological Society Bulletin


Houston Geological Society Bulletin, Volume 36, No. 5, January 1994. Pages 9-9.

Abstract: The Open-Coast Clastic Depositional Model, Theme and Variations


H. Edward Clifton

Studies of modern coastal systems indicate that the upward depositional facies sequence- -bioturbated inner shelf -crossbedded upper shoreface - planar-laminated foreshore - nonmarine deposits- characterizes most open-coast clastic successions. This generalized model has been applied successfully to a variety of ancient coastal deposits, owning largely to consistency of both processes and preservation through gee logic time. Any such model, however, must accommodate significant internal variability, imposed by differences in sediment texture, nearshore bathymetric profile, ambient energy, storm events, and relative sea-level change. The resulting variations about the basic theme are reasonably predictable and provide a basis for enhanced paleo-environmental understanding. Ignoring them, however, can lead to misinterpretation of ancient coastal deposits.

As one example, the fine-grained, low-energy, microtidal Texas Gulf shorefaces have a distinctive vertical sequence that contrasts sharply, as one might expect, with that of the more energetic Pacific coast. The Gulf of Mexico sequence also differs, however, to nearly the same degree from that generated in a similar low-energy, microtidal setting on coarse-grained Mediterranean coasts.

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