High precision U-Pb dating of seminal earth events

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The overarching goal of my research program is to investigate the feedbacks between Earth's sedimentary record and its climate by determining what drives climatic variability and how it results in changes in the sedimentary record. Climatic variability is directly implicated in mass extinctions recorded in the sedimentary record, and also controls the deposition of sediments through changes in the Earth's orbital parameters (Milankovitch cycles). Unfortunately, the drivers of climate variations, for example large igneous provinces, which are thought to cause the climate change that drives mass extinctions, are typically found in other parts of the world than the sediments containing the mass extinction event. Therefore proving causation between the events is problematic. Also, regular alternations in sediments may have a hierarchical structure and dominant periodicities of cyclicity as expected from orbital forcing, however without an independent check on the deposition rate the proof of climate driven forcing is not possible. My long term objective is to tackle these problems using a combination of high precision U-Pb geochronology and isotope stratigraphy to determine tempo of changes in the stratigraphic record. This proposal focus on two main themes to address this objective:*******1. Determining the relationship between the Wrangellia flood basalts (WFB) and the Carnian Pluvial Event (CPE), where climatic perturbations caused rapid extinction rates, and set the stage for the expansion of the dinosaurs. By dating the CPE in the stratigraphic sections in Italy, and dating the WFB on Vancouver Island at high precision, we will determine if there is a causal relationship between the two events. We will augment the study using isotope proxies (Os and Mo) in our newly temporally calibrated sedimentary sections to precisely determine the effects of the WFB in the sedimentary record. Our results will have implications for the cause of mass extinctions and we anticipate that this integrated stratigraphic and geochronologic approach will become the baseline for future studies. ******2. Determine whether the cyclic deposition banded iron formation (BIF) sediments in Australia was forced by the climate. The cyclic nature of these sediments and the apparent consistency of the cyclicity over large areas suggests a climatic control, but current depositional rate estimates based on imprecise and inaccurate U-Pb zircon ages are not suitable to confirm this. We will apply state of the art U-Pb dating techniques to accurately reconstruct depositional rates to determine whether the cyclicty in BIF is orbitally forced. We will combine our age models with isotopic tracers (Mo isotopes) to help elucidate the origin of BIF and potentially determine if climate played a role in the oxygenation of the Earth's atmosphere. This innovative study has potentially ground breaking implications for not only BIF formation, but also the parameters of the solar system.******