Stratigraphic evolution of an estuarine fill succession, and reservoir characterization of inclined heterolithic strata, cretaceous of Southern Utah, USA

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Title Stratigraphic evolution of an estuarine fill succession, and reservoir characterization of inclined heterolithic strata, cretaceous of Southern Utah, USA
Publication Type thesis
School or College College of Mines & Earth Sciences
Department Geology & Geophysics
Author Purcell, Ryan Michael
Date 2015
Description A complex mixture of wave, tide, and fluvial energies form paralic strata, and although these units are important hydrocarbon reservoirs, they are complex and poorly understood. This study documents the architecture of an estuarine succession using outcrops of the Upper Cretaceous John Henry Member of the Straight Cliffs Formation, southern Utah (USA). Terrestrial LiDAR, photomosaics, 18 detailed measured sections, and 652 paleocurrent indicator measurements inform this stratigraphic analysis. The ~65-m-thick interval of interest records evolution of a mixed-energy to wave-dominated estuary, with basal elongate tidal bars overlain by carbonaceous bay fill, tidal flat deposits, a bayhead delta, and ultimately a coastal plain succession. A detailed interpretation of the ~8.5-m-thick by 550-m-wide bayhead delta outcrop highlights internal architecture as well as the relationship between the bayhead delta, the underlying tidal bar units, and the overlying coastal plain strata. Within the bayhead delta, beds are composed of very fine- to medium-grained trough cross-stratified, rippled (some climbing), planar laminated, planar cross-stratified sandstones, and interbedded mudstone/siltstone. These units thicken and coarsen vertically. Statistical analysis of the bayhead delta indicates that average bedding thickness, net to gross, amalgamation ratio and grain size increase down-dip, and vertically up-section. This study compares grain size analysis results to a published study of a heterolithic fluvial point bar to provide guidelines for subsurface differentiation of inclined heterolithic strata, and to better predict the impact on reservoir distribution and probable fluid flow pathways. Understanding the variety of expressions and reservoir behavior of IHS intervals will guide future studies of heterogeneous paralic reservoirs.
Type Text
Publisher University of Utah
Subject Cretaceous; Estuary; Inclined heterolithic strata; Southern Utah; Stratigraphy
Dissertation Name Master of Science in Geology
Language eng
Rights Management ©Ryan Michael Purcell
Format application/pdf
Format Medium application/pdf
Format Extent 27,563 bytes
Identifier etd3/id/4048
ARK ark:/87278/s62g0wtg
Setname ir_etd
ID 197598
Reference URL https://collections.lib.utah.edu/ark:/87278/s62g0wtg
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