EAGER: Application of 26Al-10Be Dating to Alluvial-Lacustrine Successions of Unaweep Canyon: Implications for Geomorphic and Climatic Evolution in the Colorado Plateau

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

EAGER: Application of 26Al-10Be Dating to Alluvial-Lacustrine Successions of Unaweep Canyon: Implications for Geomorphic and Climatic Evolution in the Colorado Plateau Gerilynn Soreghan, University of Oklahoma EAR-0934259 Abstract Unaweep Canyon of western Colorado is a geomorphic enigma whose age and origin has considerable bearing on our understanding of landform and climate evolution of the greater Colorado Plateau for both the late Paleozoic and late Cenozoic. This proposal seeks funding for measurement of the cosmogenic radionuclides 26Al and 10Be in quartz from core and outcrop of Plio-Pleistocene sediment within and near Unaweep Canyon. The Plio-Pleistocene sediments were newly mapped in 2003-2006, and the core was collected in 2004. Our preliminary data indicate that Unaweep Canyon is a Paleozoic landform buried by later Paleozoic and Mesozoic sediments and then re-exhumed during the Cenozoic, a controversial claim. Despite considerable age-dating efforts in our previous research, we have found no material in this sedimentary succession that can be dated using conventional methods. Thus, the purpose of this proposal is to apply newly developed methods of ?burial dating? based on the production and decay of cosmic-ray-produced radionuclides to determine the age of the sediments from the newly acquired core and the newly mapped outcrops. Successful dating of the target sediments will yield three tangible benefits. First, it will solve a significant regional geologic problem by establishing the timeline of geomorphic events and will yield insight into the rate and nature of Cenozoic fluvial incision of the Colorado Plateau?a long-standing problem. Second, it will help to move a newly developed dating method from the developmental stage into practical applications. Third, the borehole penetrates ~ 150 meters of lacustrine sediments believed to be of middle Pleistocene age, thus offering the potential to access an extremely valuable record of Pleistocene paleoclimate and paleoenvironment. This work will also result in significant broader impacts, including strengthening interdisciplinary collaborations, exposing students to cutting-edge techniques, and disseminating the research via publication and classroom use. This project is ?high risk-high payoff? because it involves application of new expertise, but offers potential for great dividends in terms of research advances in geomorphology and paleoclimate.