Seminar

Cratonic interiors exhibit long-term isolation from active plate margins, and are thus traditionally viewed as tectonically stable features with long term erosional stability. Despite minimal tectonic disruption over 100–1000 Ma time scales, low–temperature apatite (U-Th)/He and apatite fission track thermochronometric studies provide evidence that cratonic cores can exhibit complex thermal evolutions that can involve multiple phases of heating and cooling associated with burial and exhumation, respectively. With recent advancements in the zircon (U-Th)/He system, including the development of the zircon damage and annealing model (ZRDAAM), it is now possible to capture complex low-temperature thermal evolutions that extend over a billion years. Tracking the ancient low–temperature thermal evolution of cratons is essential to understand the mechanisms that control the elevations of quiescent continental interiors. It has been proposed that, due to the observed cooling of the mantle from ~2 Ga to the present, large-scale emergence of stable continents, from a dominantly water world to a terrestrial world, occurred during the Neoproterozoic, irreversibly altering Earth’s weathering regime, climate, and biogeochemical cycling. If a large–scale continental emergence event occurred, shallowly buried rocks within continental interiors would be expected to gradually cool as these rocks are gradually denuded with the rising elevations above sea level. Cratonic interiors that have not experienced peak temperature exceeding ~220° C for over a billion years have the potential to record this large-scale cooling event using ZRDAAM, and compilations of regional and global thermochronometric data from these settings are necessary to test this hypothesis. This study intends to produce robust low–temperature thermal models from cratonic interiors, and primarily focuses on the ancient low–temperature thermal evolution of the Bundelkhand craton and surrounding Vindhyan basin of central India. Preliminary zircon (U-Th)/He results from the Sons Valley Vindhyan basin indicate that the eastern Bundelkhand craton has remained relatively passive for over a billion years, and hence this region provides an ideal setting to test the potential for a major Neoproterozoic cooling event due to denudation consequent of continental emergence. Additionally, this study will test the utility of ZRDAAM in constraining thermal evolutions of ancient basins, test various models for Vindhyan basin development, track ancient first-cycle (volcanic) zircons, and provide a broad spatial understanding of the ancient low¬¬–temperature thermal evolution of central India.