Analysis of diverse geologic, geophysical, and geochemical data shows that six of eight extensive lineament systems delineated in Landsat images of Nevada are morphologic and tonal expressions of three broad structural zones. The lineament systems defined in this report are the Walker Lane, Rye Patch, Midas, Pancake Range, Warm Springs, Timpahute, Pahranagat, and Northern Nevada Rift. The three structural zones are the Walker Lane structural zone, the Humboldt structural zone, and the Southern Nevada structural zone.

The northwest-trending Walker Lane structural zone, which includes the Walker Lane lineament system, is 150 to 200 km wide and is marked by northwest-oriented faults, a broad belt of high-frequency aeromagnetic anomalies, and concentrations of volcanic rocks 34 to 6 m.y. old. The northwest-trending Rye Patch lineament system may mark the northeast boundary of this structural zone, and is characterized by stratigraphic discontinuities, alignment of aeromagnetic anomalies, and contrasting aeromagnetic anomaly patterns on opposing sides.

Northern Nevada is dominated by the northeast-trending, 150 to 200-km wide Humboldt structural zone which is marked by the Midas lineament system, northeast-oriented faults, broad gravity anomalies, and the Battle Mountain heat-flow high; this zone appears to extend into central Montana. The Humboldt structural zone is transected by the Northern Nevada Rift lineament system, which is partly defined by a relatively narrow belt of north-northwest-trending basaltic dikes that produce a series of pronounced aeromagnetic highs.

The east-trending, 150 to 175-km wide Southern Nevada structural zone includes the Pancake Range, Warm Springs, and Timpahute lineament systems; this zone is marked by disruption and termination of ranges, stratigraphic discontinuities, east- to east-northeast-trending faults, and an easterly grain in the aeromagnetic and gravity patterns. The other lineament system in southern Nevada, the northeast-trending Pahranagat, may lie within a poorly defined southward extension of a broad structural zone defined in Utah by a belt of volcanic rocks 34 to 0 m.y. old, stratigraphic discontinuities, coincidence with three extensive gravity lineaments, and a belt of aeromagnetic anomalies.

This paper proposes that the lineament systems, except for the Northern Nevada Rift lineament system, are conjugate shears formed during and after middle Miocene extension of the Great Basin; these lineament systems probably reflect only the most recent movement along broad crustal zones, which may be of pre-Miocene age. The three documented structural zones and possibly one including the Pahranagat lineament system may reflect transition zones between the central Great Basin, where 30% extension has been documented, and the adjacent regions that responded differently to spreading since middle Miocene time. The Humboldt structural zone appears to be especially important for geothermal and mineral exploration in Nevada because of the presence of the Battle Mountain heat-flow high and a high concentration of metal districts within this zone in Nevada.