Collaborative Research: Reconstructing the Origins of the Colorado River: An Integrative Study of the Miocene-Pliocene Bouse Formation

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Despite nearly a century of study, the conditions that controlled initiation of the mighty Colorado River remain poorly understood and vigorously debated. This project seeks to reconstruct the origins of the Colorado River through multidisciplinary study of the Bouse Formation, a complex sedimentary deposit that accumulated in the lower reaches of the valley during river initiation between ~ 6.0 and 4.5 million years ago. The study benefits from collaborations among university professors and students, state and federal agency scientists, a county museum paleontologist, and a local high school teacher. The PI's will use integrated datasets to determine if the Bouse Formation formed in a brackish marine estuary or a large inland lake isolated from the ocean, a key distinction for understanding the origins of the river. This study also explores when and how waters of the Colorado River first reached the sea. Hypotheses will be tested through study of stratigraphic architecture, sedimentology, carbonate geochemistry (including C, O, Sr, and S isotopes), and geochronology. Hypothesis tests emphasize cross-correlation of radiogenic and stable isotope data with major and trace-element chemistry in a precise stratigraphic and structural framework. The PI's will run two workshops: one to engage a broad community of geoscientists, and one to plan a future scientific drilling proposal.