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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 69 (1985)

Issue: 2. (February)

First Page: 294

Last Page: 294

Title: Exhumed Shoreface and Tidal-Delta Complexes in Lower Cretaceous Ferron Delta (Central Utah): ABSTRACT

Author(s): C. R. Ossian

Article Type: Meeting abstract


Numerous studies of modern shoreface and tidal-delta complexes have appeared in the literature, but few well-documented ancient examples are known. In the Lower Cretaceous (Turonian) Ferron delta complex of the Mancos Shale in central Utah, such a system has been recognized in outcrop. This complex is part of the transgressive destructional phase of the Ferron delta and represents a shoreface setting overstepped by rapid transgression, buried and preserved within fine-grained, shallow shelf sediments. The facies tract is now exposed by erosion and the exhumed surface has been examined in detail.

The exposed parts of the shoreface complex consist of 9 km of upper-shoreface and foreshore settings, tidal inlets with recurved accretionary spits, ebb-tidal delta bodies, and extensive washover fans. Within the outcrop belt, two inlet complexes have been positively recognized and parts of a third complex may be present. Behind the shoreface complex are shallow and restricted lagoons with locally extensive tidal channels.

Geometry of the ebb-tidal delta bodies and their suites of preserved sedimentary features support a model of strong longshore current systems from south to north along the edge of a large embayment. Studies of basin geometry, shelf width, probable nature of the adjacent land surface, and paleocirculation patterns have all combined to provide data for this model of a mesotidal setting with associated shoreface, lagoonal, and tidal-facies tracts.

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