WHAT CAN MAGNETOTELLURICS TELL US ABOUT THE YELLOWSTONE-SNAKE RIVER HOTSPOT?

In the summer of 2003, we collected magnetotelluric (MT) data at sites along a transect across the Snake River Plain (SRP) to map the conductivity structure of this region. Our objective is to detect conductive anomalies associated with the Yellowstone hotspot, and ultimately, to place limits on the temperature and melt fraction of these features. To this end, we collected long period electrical and magnetic data at 19 sites using the NIMS equipment from the EMSOC instrument pool, and broadband field data at 2 sites using SIO’s MT equipment. The sites were located along a northwest-southeast line stretching from near Challis to the southeast corner of Idaho, at an average spacing of 20 km.

Initial results of inversions of these data suggest that the mantle in this region is unusually conductive, suggesting that it is anomalously warm in this region. Detailed mantle structure in this region is, however, partially masked by the presence of highly conductive features at depths from approximately 5-30km. Further work is proceeding on imaging the mantle conductivity structure in greater detail.