3D High-resolution geophysical characterization of the Borax Lake Hydrothermal System in the Alvord Basin, southeastern Oregon

The Borax Lake Hydrothermal System is an active group of hot springs located in the Alvord Basin, Oregon. There are over 100 hot springs aligned linearly in the north-south direction (Fairley et al., 2003) suggesting active north-south faulting. A left lateral offset in the surface trend of the hot springs indicates the presence of fault strands perhaps due to rotation and transfer of strain. Previous studies have shown relationships between faults and various groundwater properties such as groundwater flow fields, spring discharge, water table elevations (Rojstaczer et al., 1995; Melchiorre and Criss, 1999), and occurrence of geothermal springs (Curewitz and Karson, 1997). Results from a nearby 2D seismic profile indicate a shallow (< 100 m depth) mid-basin basement high that is approximately aligned with the springs at the surface (Bradford et al., 2004). We collected high-resolution 3D seismic reflection and magnetic data around the step-over in the trend of the hot springs. The results from the 3D seismic reflection survey indicate faults connect to the hot springs at the surface and may act as the conduits for upflowing water. A 3D inversion of total field magnetic data reveals conduit-like structures of low magnetic susceptibility that may represent channels of preferential fluid flow.