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DYNAMIC STRATIGRAPHY WORKGROUP |
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Genetic connection between anomalously-extending sandstone tongues and thrust-belt transverse zone conglomerate complexes in the Cordilleran Foreland Basin
People: Jennifer Aschoff, Ron Steel
Research question(s): Current foreland basin models do not adequately explain basin evolution in the context of complete “foreland basin systems” (sensu DeCelles and Giles, 1996), and do not integrate proximal (<100 km) and distal depositional zones (>100 km) in any detailed way. However, hinterland-derived sediment, and the record of tectonics it supplies, is stored not just in heavily-studied proximal zones, but throughout the basin.
Summary of work: Detailed consideration of sediment deposited within all depozones of foreland basin systems supplies more information than traditional approaches. Enigmatic marine sandstone tongues (traversing >700km) locally occupy distal (eastern) zones of the North American Cordilleran foreland basin. The process by which these tongues crossed astonishingly long distances and how they relate to stages of basin development are unresolved problems in sedimentary geology. The Upper Cretaceous (Campanian) Cozzette Member and eastern equivalents comprise one such tongue, stretching from Utah to Central Colorado. The Cozzette Member. broadly correlates spatially and temporally with syntectonic, transverse-zone conglomerate complexes (sensu Lawton et al., 1994). This conglomerate complex is partly represented by quartzite conglomerates of the Price River Fm within the Cordilleran thrust belt. Given appropriate sea-level conditions, conglomerate complexes may have provided critical sediment point sources and the driving force required to feed rapidly-prograding deltas and basinward-extending sandstones. Establishing the precise connectivity of proximal and distal deposits within a chronostratigraphic and sequence-stratigraphic framework will elucidate the genesis of basinward-extending sandstone tongues. Furthermore, establishing such a detailed up- to down-dip connection provides a more detailed view of foreland basin development and the record of tectonics in the context of a complete foreland basin system (sensu DeCelles and Giles, 1999). This project exploited the incredible exposures, subsurface and stratigraphic/biostratigraphic database available for Campanian strata exposed in Central Utah. I extended existing stratigraphic correlations (Hettinger and Kirschbaum, 2002; Horton et al., 2004) further up-dip into the Wasatch Plateau area and further down-dip into Central Colorado.
Publications and presentations: See Dr. Jennifer Aschoff's website for a current list of publications, students and on-going research projects http://geology.mines.edu/faculty/jaschoff.html
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