PROVENANCE ANALYSIS OF PROPOSED MIOCENE RIVER GRAVELS, NORTHERN ARIZONA

This project addresses provenance of Miocene river gravels in northern Arizona. One published model proposes a major Miocene River system, predating the Colorado River system, that flowed southwest from the Rocky Mountains through northern Arizona, turned north through eastern Nevada, Idaho, and Montana, entered Canada’s eastward flowing drainage system, and flowed into the Labrador Sea’s Saglek Basin. The Saglek Basin is a massively bedded deltaic system that experienced millions of years of significant sedimentation until approximately 5 Ma, concurrent with the opening of the Gulf of California. The convergence of the Miocene and Saglek River Systems would have created a drainage basin for nearly half the North American continent. The first step in my analysis was a literature review of the history of the patterns of uplift and erosion in eastern Nevada, southern Utah, northern Arizona, and the four corners region to gain an understanding of Miocene paleogeography. I then completed a provenance analysis of Miocene gravel samples using vein quartz as the principle source indicator. The provenance analysis involved the identification, collection, counting, sorting, percentage breakdown, and source identification of samples from northern Arizona and eastern Nevada. I created ternary diagrams to analyze the maturity of the sediment. My results support the proposed Miocene River path through northern Arizona. A better understanding of the drainage pattern during the Miocene will help scientists better understand the evolution of the Colorado River system and the Colorado Plateau paleoenvironment.