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Flood basalts represent major events in Earth History, in part because they are linked to large climate perturbations and mass extinctions. However, the durations of individual flood basalt eruptions, which directly impact potential environmental crises, are poorly constrained. Here we use a combination of paleomagnetic data and thermal modeling to create a magnetic geothermometer (MGT) that can constrain the active transport lifetime of magmatic conduits and intrusions. We apply the MGT technique to eight feeder dike segments of the Columbia River basalts (CRB), demonstrating that some dike segments were actively heating host rocks for less than one month, while other segments may have been active for several years. Results suggest that eruption rates, localized spatially along-strike of dike segments, were as high as 1–8 km3 day−1. These results help contextualize field evidence for contrasting CRB eruption durations and suggest a pathway for constraining the tempo of global flood basalt magmatism that is beyond the resolution of geochronology.

Original Citation

Biasi, J., Karlstrom, L. (2021). Timescales of magma transport in the Columbia River flood basalts, determined by paleomagnetic data. Earth and Planetary Science Letters, 576, 117169,