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Chapter 5
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Sequence Stratigraphy
of Turonian-Santonian Strata, Kaiparowits Plateau, Southern Utah, U.S.A.:
Implications for Regional Correlation and Foreland Basin Evolution
Keith W. Shanley
Shell Development Company
Houston, Texas, U.S.A.
Peter J. McCabe
U.S. Geological Survey
Denver, Colorado, U.S.A.
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ABSTRACT
Outcrops of Turonian through Campanian
strata in the Kaiparowits Plateau of southern Utah provide a unique opportunity
to examine both shallow-marine and continental strata within the context
of unconformity-bounded depositional sequences. This approach provides
insights to the evolution of the strata within the plateau as well as regional
chrono- and lithostratigraphic relationships within the southwestern Colorado
Plateau.
We recognize five unconformity-bounded
depositional sequences. These sequences are defined by regional surfaces
of erosion that juxtapose amalgamated fluvial deposits over shoreface,
alluvial plain, or coal-bearing strata and reflect an abrupt basinward
shift in facies tracts . Between these sequence boundaries transgressive
and highstand systems tracts are recognized. Transgressive systems tracts
are characterized by a progression from amalgamated channel deposits to
isolated meanderbelts that have evidence of tidal influence within what
is otherwise a wholly alluvial succession. These tidally-influenced fluvial
deposits are temporally equivalent to marine maximum flooding surfaces.
Early-highstand systems tract deposits are characterized by thick, aggradational
shoreface parasequences, thick coal beds, and isolated meanderbelt sandstones
encased in thick, fine-grained flood plain strata. Late-highstand systems
tract deposits are relatively thin and are characterized by progradational
shoreface parasequences, thin, discontinuous coal seams, and fine-grained
channel deposits. We interpret these changes in stratigraphic architecture
to reflect significant changes in stratigraphic base level that we have
correlated to adjacent outcrop belts in the Wasatch
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