RII Track-4: Using Zircon (U-Th)/He Thermochronology to Explore a Link Between Mesozoic Tectonism and Nonmarine Sedimentation in the Eastern Tibetan Plateau

University Of South Alabama, Mobile AL

Investigators

Abstract

The Tibetan Plateau, the largest and highest plateau on Earth, is a product of the India-Asia continent-continent collision. Because collision is ongoing, geologic processes can be observed and measured, making the Tibetan Plateau an ideal natural laboratory for tectonic investigations. While modern observations and measurements provide details pertaining to active tectonics of the plateau, studies show that ancient, inherited crustal features are a primary control for how the plateau is currently developing. In the eastern Tibetan Plateau, sedimentary and igneous rocks are exposed at the surface that provide a record of these ancient, pre-India-Asia tectonic events; however, these rocks remain largely unstudied. Therefore, the goal of this proposal is to investigate the age and geologic relationships of sedimentary and igneous rocks in the eastern Tibetan Plateau. This study will utilize field and laboratory methods to determine the timing and rates of pre-India-Asia geologic processes. By integrating field data with modern age dating techniques, the ability to quantify when and how these rocks were exhumed to the Earth’s surface will be possible. Advancing our knowledge in this region will allow us to better understand the Tibetan Plateau, as well as older mountain belts and large plateaus on Earth. Modern observations and measurements of Tibetan Plateau provide insights into active tectonic processes during plateau development. However, to fully incorporate these data a better understanding of inherited, Mesozoic tectonic fabrics must be established. In the eastern Tibetan Plateau, the northern Yidun terrane contains Mesozoic sedimentary and igneous rocks that record contractional deformation and exhumation; thereby, providing an opportunity to understand the spatial and temporal development of deformation in the Tibetan Plateau prior to the Cenozoic India-Asia collision. The goal of this proposal is to investigate a link between the exhumation of the Late Triassic Ganzi Pluton and development of two nonmarine sedimentary basins that are in stratigraphic and structural contact with the pluton. To approach this goal, the Principal Investigator (PI) proposes to use bedrock and detrital zircon (U-Th)/He thermochronology, working in collaboration with the Basin Analysis and Helium Thermochronology Laboratory (BAHTL) at the University of Connecticut, directed by Dr. Julie C. Fosdick. The proposed work is designed to address two main objectives, train the PI in zircon (U-Th)/He techniques and interpretations, and collect thermochronology data to explore a link between Mesozoic tectonism and nonmarine sedimentation. Results from this project will advance our understanding of Mesozoic tectonics in the eastern Tibetan Plateau, providing initial crustal input parameters for mechanical models. Advancing our knowledge of geologic processes that develop high-elevation (> 4 km) mountains and plateaus will help us better integrate large data sets that seek to understand global-scale natural processes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.