--> The Effects of Contemporaneous Tectonism on Sediment Distribution: Frontier Formation, Green River Basin, Wyoming, by J. C. Horne, A. J. Scott, J. R. Foster, and E. Gomez; #90986 (1994).

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Abstract: The Effects of Contemporaneous Tectonism on Sediment Distribution: Frontier Formation, Green River Basin, Wyoming

John C. Horne, Alan J. Scott, John R. Foster, Ernest Gomez

The Frontier Formation of the Green River basin, Wyoming provides an excellent example of the interplay among sedimentation, contemporaneous tectonics, and eustatic fluctuations of sea level. During the interval of time when the Frontier sediments were deposited in the Green River basin, thrust uplift was occurring in the Sevier Orogenic Belt to the west of the basin. The thrust sheets provided ample sediment to the western margin of the Western Interior Seaway. These Frontier sediments accumulated in wave-dominated deltaic, strandplain, coastalplain, and fluvial depositional environments.

Crustal loading by the thrust sheets initiated rapid subsidence in the foreland basin in the western part of the Green River basin. It also caused a peripheral bulge (paleo-Moxa Arch) to develop along the eastern margin of the area of rapid subsidence. Frontier sediments form a depositional thin over this bulge. Along the northwest margin of the paleo-Moxa Arch, a southwest to northeast trending linear feature (the Opal Hinge) separates nonmarine sediments to the northwest from dominantly marine sediments to the southeast.

Complicating this interplay of tectonics and sedimentation during Frontier accumulation was a major fall of eustatic sea level in the middle Turonian. This lowstand interrupted marine sedimentation and exposed most of the western part of the Green River basin. Valleys incised into the underlying marine sediments, and only the southeastern part of the basin remained submerged during this time. Lowstand shoreface sediments were deposited along the shoreline. With the subsequent transgression and rise in base level, the incised valleys filled with coarse sediments, and marine sedimentation returned with the deposition of a series of retrogradational shoreface parasequences.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994