SEISMIC CONSTRAINTS ON GEOTHERMAL RESOURCES BENEATH THE WESTERN AND CENTRAL SNAKE RIVER PLAIN

Using seismic data, we identify crustal sills and shallow permeable pathways that presumably produce the high heat flow expression within the central and western Snake River Plain (SRP) region of southern Idaho. While the topographic, volcanic and thermal signature of the eastern and central SRP directly maps to the track of the Yellowstone hotspot, this expression beneath the western SRP remains enigmatic. We forward model receiver function waveforms from the Earthscope Automated Receiver Survey (EARS) data and analyze seismic velocity datasets from IRIS to identify anomalous velocity layers in the lower to middle crust that may relate to either partial melt or cooled sills. We find the majority of identified sills to be located along the southern portions of the western SRP. To tie these 15-30 km deep sills to geothermal exploration depths of the upper few km, we utilize high-resolution seismic reflection imaging to locate faults that can act as a conduit for hot water upwelling. We identify and characterize a series of faults along the southern margin of the western SRP that correspond with high heat flow areas. These faults have a history of late Quaternary motion that may promote the interplay with heat sources at depth. We find that faults and identified heat sources along the southern margin are pronounced and contrast with the region along the northern margin of the western SRP where our seismic analysis suggests little evidence for buried sill layers with few large displacement faults.