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Dissertation/Thesis Abstract

Sedimentology and stratigraphy of the Miocene-Pliocene Bouse Formation near Cibola, Arizona and Milpitas Wash, California: Implications for the early evolution of the Colorado River
by Homan, Mindy Beth, M.S., University of Oregon, 2014, 128; 1573466
Abstract (Summary)

The ~5.6-4.8 Ma Bouse Formation, exposed along the lower Colorado River, contains a well exposed but debated record of river integration. Sedimentologic and stratigraphic analysis aid interpretation of depositional processes, relative water depth, depositional environments, stratal architecture, and basin-filling history. Data collected include detailed measured sections, facies descriptions, and fault measurements. Seven lithologically distinct units have been identified along with numerous marine sedimentary structures and fossils. The Bouse Formation preserves a systematic sequence-stratigraphic architecture that records two cycles of base level rise and fall. Lacustrine versus estuarine interpretation remains elusive, though new isotope and micropaleontology data suggest a shift from marine to lacustrine. Constructed stratigraphic facies panels reveal a wedging geometry indicative of syn- to post-depostional tilting, leading us to propose a "sag basin" model during deposition of the Bouse. Finally, the newly described Bouse upper limestone unit resolves a long-standing debate over the age of the first through-going river.

Indexing (document details)
Advisor: Dorsey, Rebecca J.
Commitee: Miller, Marli B., Retallack, Gregory J.
School: University of Oregon
Department: Geological Sciences
School Location: United States -- Oregon
Source: MAI 54/03M(E), Masters Abstracts International
Subjects: Geology
Keywords: Bouse formation, Colorado plateau, Colorado river, Mixed carbonate and siliciclastic, Sag basin, Sedimentology and stratigraphy
Publication Number: 1573466
ISBN: 978-1-321-50742-3
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