--> ABSTRACT: New Play Concepts in Wyoming's Green River Basin: Integrated Sequence Stratigraphic and Synsedimentary Tectonic Analysis Pays!, by R. H. Mead and L. F. Krystinik; #91021 (2010)

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New Play Concepts in Wyoming's Green River Basin: Integrated Sequence Stratigraphic and Synsedimentary Tectonic Analysis Pays!

MEAD, RICHARD H. and LEE F. KRYSTINIK

The Upper Cretaceous Almond Formation of southwestern Wyoming is a transgressive sequence set composed of approximately 15 backstepping barrier and shoreline complexes. Synsedimentary tectonic warping, faulting, and uplift has profoundly altered the stratigraphic character of the Almond. Recurrent structural movement along a series of faults created a north-south trending antiform with an area of approximately 200 square miles (560 square Km), which caused marine barriers to stack along its eastern flank, and exaggerated erosion along subregional sequence boundaries.

Based on outcrop studies, the Almond has generally been assumed to pinch in the vicinity of the Rock Springs Uplift. An additional 8 shoreline complexes and the progradational turnaround above the maximum flooding surface at the top of the Almond have been identified in the subsurface. Outcrop evidence of the Almond west of the Rock Springs Uplift is masked by the structurally induced unconformity at the base of the Lance Formation.

By integrating sequence stratigraphic and synsedimentary tectonic analysis, play concepts have been recognized in both stratigraphic and paleostructural traps. Stratigraphic traps include updip pinchouts against paleostructures, preservation of sand below ravinement surfaces on subsiding fault blocks, distal sand bodies associated with lowstand shorelines, and subcrop targets related to truncation surfaces. Paleostructural movement also created fault traps and diagenetic traps which have been largely ignored in the past.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.