Introduction Evaluation Prospects










Northern Nevada Rift Domain

The Northern Nevada Rift Domain is characterized by major sub-parallel, northeast-striking, high-angle normal faults which both bound and segment the ranges and basins contained within the domain. Middle Miocene (13.8-16.3 Ma) basalt, basaltic andesite, and rhyolite flows and dikes are abundant within the northern portion of the domain which is contained between two major northwest-trending lateral faults.

The western fault boundary of this domain extends from the northwest-trending faults forming the western margin of the Red Hills-Roberts Mountains and northern Simpson Park Mountains, through the major change in structural style and range orientations near Cortez and between the northern Shoshone Range and Argenta Rim, and along the northwestern flank of the Sheep Creek Range. The eastern fault boundary is less well defined than the western boundary. This boundary separates the Sulphur Spring and Pinon Ranges along Union Pass, crosses the Humboldt River near Palisade where the river shows a major bend in course, and extends along the northeastern portion of the Sheep Creek Range to north of Midas where it disappears under the Owyhee Plain Domain.

The Northern Nevada Rift domain is about 30 miles wide and 110 miles long and is well developed from the northern portion of the Roberts Mountains through the northern Simpson Park and Cortez Mountains, Dry Hills, northern Shoshone and Sheep Creek Ranges, to north of the Midas area. Well developed northeast-striking faults that characterize this domain are down to the north from the northern Roberts Mountains to the Argenta Rim, and are dominantly down to the south from the Sheep Creek Range north to Midas. This suggests an extensional axis of the rift within Boulder Valley. The intensity of high-angle faulting also increases northward form the Argenta Rim with abundant northwest-trending high-angle faults also well displayed in the northern portion of the rift domain.

The Northern Nevada Rift Domain structurally overprints the older and more extensive Antler Thrust Domain which is locally exposed beneath the thick volcanic cover. Internal structure within the large fault block basins and ranges of the Northern Nevada Rift domain is characterized by this domain which is described above.

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Last modified: 09/12/06