The ongoing tectonic collision between India and Asia began about 59 million years ago, creating the highest mountains on Earth. While the tectonic history of the last 28 million years is well documented in the Himalayan Mountains, the earlier phase of the collision remains poorly understood. During this earlier phase of collision sedimentary rocks were intensely folded and buckled in the region north of Nepal in southern Tibet. This project will use new field and laboratory analytical techniques to determine how the rocks in this region were deformed during the early phase of the collision. Results from this work will help discriminate between models for the India - Asia collision and evaluate whether the southern Tibet region contains ~2,000 km of shortening. In addition, this project will: 1. enhance multi-disciplinary training of graduate and undergraduate students from historically underrepresented groups; 2. strengthen international scientific collaborations; and 3. develop new, and augment existing, science-focused outreach opportunities for K-12 students from historically underrepresented groups.
This project focuses on the Tethyan fold-thrust belt on the southern margin of the Himalayan-Tibetan orogen in order to determine the style, magnitude, and timing of shortening. Little is known about the evolution of the fold-thrust belt from collision at ~59 million years ago until the oldest dated Himalayan thrust at ~28 million years ago. A complete study from the Indus-Yarlung suture zone in the north to the South Tibetan detachment system in the south will establish a minimum shortening estimate that incorporates all scales of deformation, and determine what happened during Paleocene-Eocene time (60 to 30 million years ago). Research will focus on four transects that combine structural field studies with laboratory analyses of apatite fission track, (U-Th)/He in zircon, and U-Pb detrital zircon geochronology. These data will inform new balanced cross sections and four thermokinematic models. Results will be used in new models for the evolution of the Tethyan fold-thrust belt, which will be combined with existing cross sections in Nepal and Bhutan to provide a lithospheric evolution of the entire system.
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.
