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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 53 (1969)

Issue: 3. (March)

First Page: 712

Last Page: 712

Title: Previous HitDeltaicNext Hit Previous HitEnvironmentsNext Hit: ABSTRACT

Author(s): James M. Coleman, Sherwood M. Gagliano, John C. Ferm

Article Type: Meeting abstract


Deltas are zones of interaction between fluvial and marine processes, and their deposits are transitional between terrestrial-alluvial and open-marine sediments. Initial inspection of a Previous HitdeltaicNext Hit sedimentary wedge suggests the presence of a hopelessly complex interfingering sequence of beds; however, closer examination reveals an orderly arrangement of environmentally determined facies. In vertical sequence predictable progradational and transgressive sequences can be recognized and related to cyclic growth and deterioration of the delta system. Areal distribution of facies can be related best to three major components of the delta: the upper Previous HitdeltaicNext Hit plain, lower Previous HitdeltaicNext Hit plain, and subaqueous delta. Marginal Previous HitdeltaicNext Hit basins and marginal Previous HitdeltaicNext Hit plains also may be developed a "appendices" to the delta. Within this gross framework distinctive facies assemblages are recognizable, reflecting different environmental conditions in both modern and ancient deltas; i.e., the assemblage of Previous HitenvironmentsNext Hit and resulting lithofacies and biofacies within any major component is different in each delta and depends on such factors as climate, tectonic activity, nature and quantity of transported load, tidal influence, sea-state conditions, etc. With this working concept it is no longer essential to search for modern analogs to each Previous HitdeltaicTop sequence found in ancient rocks, but rather a flexible delta model may be developed which will accommodate all variations in nature and intensity of processes acting on the delta. Utilizing such a process-form model, examples of modern delt ic facies and ancient rock counterparts can be analyzed.

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Copyright 1997 American Association of Petroleum Geologists