Origins and Tectonics of the Greater Himalayan Sequence

Understanding the processes that shape the rocks we observe today relies on the ability to unravel past events. The Himalayas have been shaped by active mountain-building processes over millions of years, yet the original rocks that make up these mountains remain poorly understood. The purpose of this study is to investigate the sedimentary and igneous rock types of the Greater Himalayan Sequence. Researchers will assess the original geologic settings to reconstruct the early tectonics of the region. New models will help explain processes associated with tectonic collisions and mountain building. Researchers will collaborate in the field and lab to train graduate and undergraduate students. This project also supports an early-career researcher. This project will examine the Greater Himalayan Sequence (GHS) to determine its geologic and tectonic origins, including the sedimentary provenance, overall depositional setting, petrogenesis of its igneous components, and its original tectonic setting. Field work includes measuring ‘pseudo-stratigraphic’ sections and structural transects, collecting (meta)sedimentary samples for provenance analysis by detailed detrital zircon uranium-lead (U-Pb) geochronology and hafnium (Hf) isotope composition. Detailed bulk-rock geochemistry combined with in-situ zircon U-Pb geochronology, Hf- and oxygen-isotope signatures, and trace elemental analyses will be conducted on the complete range of igneous rocks in the GHS to constrain the petrogenesis and magmatic sources (i.e., mantle versus crust) through time and space. Regional rock section thicknesses, textural, and compositional trends as well as detrital zircons will aid in determining first-order depositional setting and provenance of the sedimentary rocks. The geochemical and isotopic data from the granitoids will be used to discriminate compositional signatures relating to the tectonic environment(s) from which the magmas were generated and the overall orogenic configuration of North-East Gondwana during the early Paleozoic (approximately 540 -440 million years ago). Their findings will improve understanding of the tectonic evolution of the ancient supercontinents Gondwana and Laurasia, the breakup of these landmasses, and the links between mountain building, changes in ocean chemistry, and the diversification of marine life during the Cambrian Period. 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.