Collaborative Research: Evaluating Ancestry of the Tibet Plateau: Did a Mesozoic Proto-plateau Exist?

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Despite much investigation, when and how the Tibet plateau attained its elevation is a major unresolved problem in Earth science. This is partly due to the fact that early history of plateau growth is unknown. In recent years, many researchers have emphasized the effects of early Cenozoic India-Asia collision on the timing of increased elevation of the Tibet plateau; however, mechanical modeling of this increase in elevation requires improved constraints on the initial boundary conditions that existed prior to the impingement of India with Asia. This project employs a multi-disciplinary test of the hypothesis that a proto-plateau resulted from crustal thickening due to Mesozoic continent-continent collisional systems along the Qiangtang terrane borderlands prior to the collision of India with Asia. Reconstructing the upper crustal configuration of eastern Tibet prior to the Indian collision is performed using methods in sedimentology, stratigraphy, structure, stable isotope paleoaltimetry, geochemistry, geochronology, and basin modeling of the Mesozoic Qamdo basin in southeastern Tibet. Investigations of paleoenvironmental data from study of sedimentary deposits reveal patterns of aridification to compare with those indicative of plateau development. Comparison of sedimentary provenance of Qamdo basin deposits with lithologies of surrounding structural highlands and the structural kinematic history of adjacent deformation belts is used to model tectonic evolution and surface configuration of the region. Oxygen isotopic composition of paleosol carbonates is employed to assess paleoelevation history of the area and detect possible episodes of plateau rise. Documenting this early history of Tibet plateau evolution is required to address several outstanding issues of scientific and societal importance. First, research results provide constraints on initial input parameters that will improve the calibration of mechanical models of plateau development, as well as the threshold conditions under which extrusion tectonism was later initiated in the region. Also, the geological history of the Tibet plateau is thought to be tightly linked to major changes in climate patterns and wholesale secular changes in ocean chemistry due to chemical influx from the rivers that drain the Tibet plateau. Because chemical erosion of rocks consumes carbon dioxide from the atmosphere, erosion of the widespread uplifted region of the Tibet plateau, enhanced by a monsoonal climate, is a potential driver of global cooling episodes. Finally, the plate tectonic processes that formed the Tibet region bear the most relevance to the plate tectonic processes operating today that control the distribution of major seismic, volcanic, and mass wasting (e.g., landslide) hazards around the globe, as highlighted by the 2008 Wenchuan earthquake centered on the eastern Tibet plateau margin. In addition to the scientific objectives of this project, it is supporting the training of two Ph.D. students and three undergraduate students in a STEM discipline. Scientific collaboration between students and faculty at West Virginia University (U.S.), the University of Alabama (U.S.), and Nanjing University (China), is an important component of this project.