2015 Geodynamics Program:
Geologic Study Tour To The Greater Yellowstone Geoecosystem
June 25 - July 3, 2015
This year’s study tour highlighted various stages in the evolution of the Snake River Plain–Yellowstone Plateau bimodal volcanic province, and associated faulting and uplift, also known as the track of the Yellowstone hotspot. The 17-Ma Yellowstone hotspot track is one of the few places on Earth where time-transgressive processes on continental crust can be observed in the volcanic and tectonic (faulting and uplift) record at the rate and direction predicted by plate motion. Recent interest in young and possible renewed volcanism at Yellowstone along with new discoveries and synthesis of previous studies, i.e., tomographic, deformation, bathymetric, and seismic surveys, provide a framework of evidence of plate motion over a mantle plume.
The trip was organized to present an overview into volcanism and tectonism in this dynamically active region. Visits included a tour of the Cretaceous copper and Mo porphyry mines at Butte, MT, the young (2000-15,000-year old) basaltic Craters of the Moon volcanic field, exposures of 12–4 Ma rhyolites and edges of their associated collapsed calderas on the Snake River Plain, and exposures of faults which show an age progression similar to the volcanic fields. The geology of both Grand Teton and Yellowstone National Parks is profoundly affected by processes associated with the Yellowstone hot spot track. The Parks are located in the youngest parts of the Snake River Plain-Yellowstone Plateau, a time- and spatial-transgressive volcanic-tectonic province which has developed over the last 17 Ma in response to the southwest movement of the North American plate over a fixed melting anomaly. The track of the Yellowstone hot spot is represented by a systematic northeast-trending linear belt of silicic, caldera-forming volcanism that arrived at Yellowstone around 2 Ma, was near American Falls, Idaho about 10 Ma, and started about 17 Ma near the Oregon-Nevada-Idaho border. Uplift and faulting have migrated to the northeast in advance of volcanism; this pattern of volcanism, faulting, and uplift along the Snake River Plain-Yellowstone Plateau province now defines the 750-km-long Yellowstone hotspot track (Pierce and Morgan, 1992, 2009).