High-precision U-Pb Zircon Age Calibration of Mid-Miocene Flora Northern Idaho

The Mid-Miocene Climatic Optimum (MMCO) marks a warming excursion lasting from ~17-14 Ma. Although the cause and consequences of this excursion are not well understood, the eruptions of the Columbia River Basalt Group (CRBG) are hypothesized to be one potential forcing. Kasbohm et al. (2018) refined the timeline of the CRBG eruptions however a framework that integrates the CRBG flows, Miocene vegetation, and Milankovitch orbital parameters over the geologic timescale is still needed to understand the interplay of global and regional systems before, during, and after the MMCO. Exposures of the Clarkia Formation contain mid-Miocene flora and climate proxy records that are stratigraphically constrained by volcanic tuffs. We will date two tuff samples from the Clarkia flora using high-precision U-Pb dating. From our analyses we expect to temporally constrain the associated flora, and correlate the results with the broader climatic, geologic, and biotic systems changes.