Paper No. 38-8
Presentation Time: 3:30 PM
CONSTRAINING TIMESCALES OF MAGMATIC PROCESSES IN THE COLUMBIA RIVER FLOOD BASALT PROVINCE
HLINKA, Lisa, Earth and Atmospheric Science, City College of New York, New York, NY 10031; School of Earth and Environmental Sciences, Queens College, City University of New York, Flushing, NY 11367; Earth and Environmental Sciences, The Graduate Center, City University of New York, New York, NY 10016, BLACK, Benjamin A., Earth and Atmospheric Science, City College of New York, New York, NY 10031; Earth and Environmental Sciences, The Graduate Center, City University of New York, New York, NY 10016, LONGPRÉ, Marc-Antoine, School of Earth and Environmental Sciences, Queens College, City University of New York, Flushing, NY 11367; Earth and Environmental Sciences, The Graduate Center, City University of New York, New York, NY 10016 and SCHOENE, Blair, Department of Geosciences, Princeton University, Princeton, NJ 08544
Flood basalt volcanism represents the largest scale endmember of volcanism on Earth. Constraining the tempo of magmatism and lava emplacement is critical to understanding the climatic and environmental consequences of flood basalt volcanism. The Miocene age ~210,000 km3 Columbia River Flood Basalt (CRB) province in the Northwestern United States is the youngest, and best-preserved example of flood volcanism on Earth [1]. While geochronology increasingly constrains the formation-level tempo of CRB emplacement [1], the timescales of magmatic processes during emplacement of individual units remains an open question. Prior work has developed timescale estimates of CRB dike emplacement via thermochronology modeling [2, 3]. The Maxwell Lake dike, a feeder dike to the Wapshilla Ridge Member, the most voluminous identified unit in the CRB at ~50,000 km3, is predicted to have generated steady heating from a sustained magma flow over 1–6 years [2]. Maximum eruption rates for Wapshilla Ridge flows are estimated at 3 to 5 km3d-1 [3].
In this work, we present textural and compositional data for crystals from Wapshilla Ridge Member pyroclastic deposits. We examine the tempo of CRB volcanism through the lens of chemical zoning patterns in olivine phenocrysts and microphenocrysts and diffusion chronometry modeling. Crystals may hold clues to quantify transit times of magma in the plumbing system as well as inform lava emplacement timescales, contributing to a more robust understanding of magmatic processes during CRB flood volcanism and their potential climatic impacts.
[1] Kasbohm, J. and Schoene, B., 2018. Rapid eruption of the Columbia River flood basalt and correlation with the mid-Miocene climate optimum. Science Advances. 4, 1–9
[2] Karlstrom, L. et al., 2019. Bayesian Markov-Chain Monte Carlo Inversion of Low-Temperature Thermochronology Around Two 8−10 m Wide Columbia River Flood Basalt Dikes. Frontiers in Earth Science 7, 90
[3] Petcovic, H.L. and Dufek, J.D., 2005. Modeling magma flow and cooling in dikes: Implications for emplacement of Columbia River flood basalts. Journal of Geophysical Research: Solid Earth 110, 1–15.
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