USING PALEOSECULAR VARIATION AND VOLCANOLOGY TO CONSTRAIN ERUPTIVE RATES OF CONTINENTAL FLOOD BASALTS (Invited Presentation)

Large Igneous Provinces (LIPs) represent the largest volcanic events in Earth's history, with eruptions of millions of cubic km of lava flows typically in less than a million years. These events frequently coincide with significant climatic and environmental perturbations, including mass extinctions. Although we have conceptual models of LIP-climate interaction, a quantitative model of the Earth system responses requires a high resolution (100s of year) constraint of the eruptive tempo. Despite significant improvements in the precision of geochronological results, these methods can only determine the time between individual lava flows if they are separated by 10s-100s of ka. A chronometer with the requisite (relative) time resolution is the analysis of paleomagnetic directions recorded in successive lava flows in the context of paleo-secular variation of the magnetic field. Although this approach has been used for several LIPs, previous work has yet to consider how the quasi-cyclic nature of paleo-secular variation can introduce spurious correlations. We have addressed these challenges by developing a forward modeling approach to compare synthetic eruptive histories with the paleomagnetic datasets in a Bayesian inversion framework. In contrast to previous work, we utilize the complete statistical properties of the flow-by-blow records (e.g., a fraction of lava flows in directional groups and a mean number of lava flows with similar directions) along with the existing geochronological and volcanological constraints to determine the permissible eruptive histories. We will present the results of this methodology to the pre-existing paleo-magnetic datasets for multiple continental flood basalt provinces - Deccan Traps, Central Atlantic Magmatic Province, North Atlantic Magmatic Province, and Siberian Traps. We find significant differences in the time interval between individual eruptions for different CFBs that have significant implications for the environmental impacts of these different CFBs. As an independent validation of our results, we also discuss constraints of eruption rates from 3D LIP flow architecture, individual lava flow morphology, and the micro-physical flow texture of LIP flows. Overall, our results provide a new framework for constraining the eruptive tempo of LIPs and understanding their environmental impact.