This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Continent collisions can form large plateaus, like Tibet, producing thick crust and high topography that affects climate change. How plateaus grow to become so large is unresolved: either the lower parts of Earths crust flow at depths where the temperatures are high (>30 km), or the crust thickens in a more brittle fashion along faults that transect the entire crust. This research focuses on this question using exposures of the lower crust in the Pamir Mountains of Tajikistan. The impact of this research should be considerable and broad because of the archetypal nature of the Tibetan and Pamir plateaus.
The PIs test models for crustal thickening within the framework of three hypotheses: the Pamir lower crust was thickened and exhumed by local intracontinental shortening during the Cenozoic, thickened by Cenozoic long-distance flow and exhumed by local intracontinental shortening during the Cenozoic, or thickened and exhumed mostly before the collision between India and Asia. These hypotheses will be evaluated by U/Pb dating of zircon to determine crystallization ages of plutons, Lu-Hf and Sm-Nd dating to measure crustal thickening ages, thermobarometry to determine exhumation depths, 40Ar/39Ar, fission-track, and (U+Th)/He dating to constrain thermal histories, and structural analysis to determine deformation histories.
