Targeting Geothermal Resources in the Lahontan Valley, Nevada;Analysis of Neogene Faulting Through 2D Seismic,Topographic, and Satellite Imagery Analysis

摘要

We analyze and interpret seven depth-migrated 2D seismic reflection profiles at Naval Air Station Fallon (NASF), in conjunction with topographic and air photo analysis, to better understand the location, geometry, and sense of slip of Neogene faults within and adjacent to the Lahontan Valley near Fallon, Nevada. Our analysis reveals a zone of northeast-striking normal faults in eastern Lahontan Valley, informally referred to as the Lahontan fault zone (LFZ), beneath the NASF Mainside facilities. The LFZ structures consistently displace Tertiary basalts and an overlying section of Neogene (?) to Quaternary lacustrine and fluvial deposits down to the west. North of NASF Mainside we identify several northwest-striking faults intersecting LFZ faults at near right angles. These northwest-trending structures comprise the southern margin of the Sagouse fault zone, which has Quaternary geomorphic expression within the Lahontan Valley. East of NASF Mainside, northeast-dipping traces of the Rainbow Mountain fault zone are imaged in the 2D seismic reflection data and exhibit Quaternary geomorphic expression at the surface. Relatively high temperatures encountered in exploratory boreholes southeast of the Mainside airfield are spatially associated with the LFZ, and specifically may be localized along a change in structural trend from NNW-striking faults south of NASF to the NNE-strike of the LFZ. At least some of the LFZ faults appear to intersect and/or terminate against strands of the NNW-striking Sagouse fault zone in the northern part of the seismic array. The structural complexity associated with slip transfer from the LFZ to the Sagouse fault zone may be associated with locally increased fracture density and permeability, and thus be prospective for further geothermal exploration.