Magnetotelluric data collected along five profiles show deep resistivity 
structures beneath the Battle Mountain-Eureka and Carlin gold trends in 
north-central Nevada, which appear consistent with tectonic breaks in 
the crust that possibly served as channels for hydrothermal fluids.  It 
seems likely that gold deposits along these linear trends were, 
therefore, controlled by deep regional crustal fault systems.  Two-
dimensional resistivity modeling of the magnetotelluric data generally 
show resistive (30 to 1,000 ohm-m) crustal blocks broken by sub-
vertical, two-dimensional, conductive (1 to 10 ohm-m) zones that are 
indicative of large-scale crustal fault zones.  These inferred fault 
zones are regional in scale, trend northeast-southwest, north-south, and 
northwest-southeast, and extend to mid-crustal (20 km) depths.  The 
conductors are about 2- to 15-km wide, extend from about 1 to 4 km below 
the surface to about 20 km depth, and show two-dimensional electrical 
structure.  By connecting the locations of similar trending conductors 
together, individual regional crustal fault zones within the upper crust 
can be inferred that range from about 4- to 10-km wide and about 30- to 
150-km long.  One of these crustal fault zones coincides with the Battle 
Mountain-Eureka mineral trend. The interpreted electrical property 
sections also show regional changes in the resistive crust from south to 
north.  Most of the subsurface in the upper 20 km beneath Reese River 
Valley and southern Boulder Valley are underlain by rock that is 
generally more conductive than the subsurface beneath Kelly Creek Basin 
and northern Boulder Valley.  This suggests that either elevated-
temperature or high-salinity fluids, alteration, or carbonaceous rocks 
are more pervasive in the more conductive area (Battle Mountain Heat-
Flow High), which implies that the crust beneath these valleys is either 
more fractured or has more carbonaceous rocks than in the area surveyed 
along the 41st parallel.