Temporal Pulses of Volcanism Within the Track of the Yellowstone Hotspot

Quaternary basalt lava flows of the eastern Snake River Plain (ESRP) show a spatially diachronous age distribution in contrast to the systematic 17 to 0.6 Ma age progression of silicic volcanic deposits from SW to NE (respectively) along the track of the Yellowstone Hotspot. Generally, basalt lava flows erupted coincidently with large volume rhyolitic flows of major caldera eruptions associated with the position of the Yellowstone Hotspot. However, basalt eruptions have continued within the ESRP as recently as 2 ka including the location that experienced caldera-forming eruptions at 10 Ma. We compiled available ages of basalt lava flows in the ESRP over a distance of 450 km from Yellowstone National Park, Wyoming to Twin Falls, Idaho. We compared the ages of basalt flows with the ages of recent Yellowstone Plateau caldera eruptive activity at 2.0, 1.2, 0.6, and post 0.6 Ma. We find temporal correlations between basalt eruptive activity within the ESRP and Yellowstone Plateau silicic and mafic caldera eruptive activity. The Yellowstone Plateau and regions of the ESRP at distances of 120, 180, 210, and 360 km southwest of the Yellowstone Plateau experienced eruptive activity at the same times. We suggest synchronized temporal pulses of volcanic activity occur along the track of the Yellowstone Hotspot. This contention is supported by active extension occurring within the ESRP and the presence of low velocity bodies within upper mantle beneath the track of the Yellowstone Hotspot, which extends from the Yellowstone Plateau to Twin Falls.