This project will test the hypotheses that (1) the Paleoproterozoic, Mesoproterozoic, Neoproterozoic, and Cambrian of all parts of the Himalaya are part of a continuous passive margin succession and not part of an accreted terrane; (2) that neodymium isotopic values (Ã¥Nd) of Himalayan rocks are primarily controlled by depositional age, rather than by geographical source; and (3) that the erosion of Neoproterozoic and Cambrian material from the northern or ?inner? part of the Lesser Himalaya (LH) requires that uplift in that region took place several million years before currently accepted. Confirmation of these hypotheses, which preliminary data suggests is likely, will be achieved by detailed stratigraphic correlation between strata of the Himalayan region and the Indian craton. If confirmed, our results will require that progressive unroofing of a continuous margin succession took place, initially with erosion of a thick succession of ?outer? LH-age strata with a geochemical signature identical to that of the Greater and Tethyan Himalaya. As a consequence, the initiation of uplift of the LH took place significantly earlier in the Miocene than currently invoked, thus significantly revising the Cenozoic uplift history of the Himalayan region. Hence in addition to clarifying the pre-deformational history of the northern Indian margin, this proposal will impact understanding of Himalayan tectonics, uplift, and erosion. Furthermore, the fossils present in these deposits are poorly known and detailed analysis may also provide novel insights into early eukaryotic evolution. As the world?s greatest mountain chain the Himalaya has significant impact on a wide range of environmental issues, ranging from the chemistry of ocean waters to the nature of global climate. Accurate understanding of this influence requires knowledge how global systems changed during the growth of these mighty mountains. This, in turn, requires knowledge of conditions prior to the event that initiated Himalayan uplift ? the collision of the Indian subcontinent with Asia. This project brings together scientists with a wide range of experience who will jointly investigate the geological relationship between rocks that make up the much of the Himalayan bedrock and those that occur within the heart of India itself. This comparison will test the currently popular idea that much of the Himalaya is ?exotic?, meaning that it was not originally attached to the core landmass of India. This idea is important because, if correct, it means that PIs can ?fingerprint? the uplift and erosional history of the Himalaya based on when ?exotic? and, when truly Indian materials, first appeared in the record of Himalayan uplift and erosion recorded in the rocks of the Bay of Bengal and other areas. PIs initial studies suggest that the ?exotic? idea is incorrect, and rests on a misunderstanding of the ages of formation of the original Himalaya rocks. If PIs are right, it will suggest that the southern Himalaya began uplift 5 million years before currently accepted, and will reconcile an important global geochemical shift with the timing of Himalayan uplift. In addition to training undergraduate and graduate students, this award also will facilitate publication of children?s book on global environmental change in a major Indian regional language, and its dissemination to village schools in rural Bengal.
The PIs and their students carried out an interdisciplinary investigation of the Proterozoic-Cambrian strata deposited in northern India, in order to better constrain their age and their correlation with Proterozoic-Cambrian successions elsewhere in the world, particularly in the nearby Chinese blocks. The integrate biostratigraphic, chemostratigraphic, sedimentological, and detrital zircon data to resolve the stratigraphic correlation and sedimentary provenance of the northern India Proterozoic-Cambrian successions. Their data reveal that Proterozoic successions in in the Lesser Himalaya can be correlated with those in Indian Craton, suggesting that parts of the Lesser Himalaya may have been marginal extension of the Indian Craton during the Proterozoic. In addition, new paleontological data from the Birmania Basin in Rajasthan suggest that the phosphatic Birmania Formation can be correlated with the Ediacaran Doushantuo Formation in South China, consistent with paleogeographic reconstructions in which both were part of the Gondwana during the Ediacaran Period. Further, new biostratigraphic data from the lower Madhubani Group in the Indo-Gangetic Basement suggest an early Neoproterozoic age of this stratigraphic unit, which can be correlated with the Bhander Group in the Vindhyan Basin on the India Craton. Stratigraphic data provide fundamental constraints on the tectonic and erosional history of the Himalaya because it is necessary to understand what the Indian margin was like prior to the collision of India with Asia and the subsequent associated orogenic activity. Our work has had long term and on-going impact in this area. Because of its significant contribution to global erosional budgets, understanding the basic geological history of the Himalaya has important implications for understanding secular changes in oceanic seawater chemistry. Similarly, as Himalayan uplift history is inferred from the geological record and uplift has a significant on global climatic change, understanding Himalayan geology has important implications for global climatic history. The project provided research opportunities for three PhD graduate students at Virginia Tech. One of them defended his dissertation recently and is currently a visiting faculty at a university. The two other graduate students are in progress and both have promise to have a successful career in geoescience education and research. The research project also created synergies among four American universities (Virginia Tech, University of Nevada Las Vegas, University of California at Riverside, and Colorado College) and an Indian institution (Birbal Sahni Institute of Palaeobotany, Lucknow). All PIs are involved in undergraduate education, and scientific data from this project enables them to bring the most up-to-date scientific knowledge directly to the classroom. The PIs have also contributed to K-12 and public education, through the publication of a children's book on the Earth history, public lectures at the Virginia Tech Museum of Geosciences and Virginia Association of Science Teachers, and the organization of Earth Science workshops for K-12 science teachers in Virginia.
