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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 68 (1984)

Issue: 7. (July)

First Page: 934

Last Page: 934

Title: Economic Potential for Upper Cretaceous and Lower Tertiary Rocks Near Helper, Carbon County, Utah: ABSTRACT

Author(s): Richard E. Carroll

Abstract:

Exceptionally good exposures of Late Cretaceous and early Tertiary rocks in the western Book Cliffs area near Helper, Utah, allow detailed study of nearshore clastic sediments. The Mancos Shale is an organic-rich, silty shale, interrupted regularly by tongues of fine to medium-grained sandstone that thin to the east. The Garley Canyon and Emery Sandstones, which are the two main sandstone members in this area, exhibit a prograding clastic shoreline sequence from open-marine and lower shoreface to upper shoreface environments. Thinner sandstones also crop out in the area that indicate minor pulses of deltaic progradation and exhibit one or more of these facies. These sandstones pinch out eastward, and are offset by normal faults to the west; therefore, hydrocarbon accumula ion is likely to occur in areas to the west.

The coal-bearing Blackhawk Formation is also well exposed within the study area, and is interpreted as a wave-dominated delta complex. Coal-forming swamps were situated directly on beach ridges. Several of these economically important coal seams pinch out westward (landward) within the study area. This stratigraphic interplay between terrestrial sedimentation and the coal-forming swamp environment provides details for refining coal exploration models.

Upon completion of regional stratigraphic analyses, thickness variations in Upper Cretaceous and lower Tertiary formations may provide a more precise indication for the time of crustal uplift associated with the San Rafael swell.

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