Cordilleran tectonics have created the Basin and Range landscape and interior drainage of the Great Basin, provided a rain shadow to make Nevada the nation’s driest state, and generated frequent earthquakes along normal and strike-slip faults.

Nevada’s geologic fortunes make it the leading state in the production of gold, barite, diatomite, and mercury and currently the only state that produces magnesite, lithium, and the specialty clays, sepiolite and saponite. Nevada is also a major producer of geothermal power and gypsum.  The metals are primarily related to igneous activity, with major pluses of magma during the Jurassic, Cretaceous, and Tertiary.  Barite is mined from Paleozoic sedimentary rocks, and gypsum occurs in sedimentary beds of Permian, Triassic, Jurassic, and Tertiary age.  Lithium is extracted from brine beneath an unusual playa. Geothermal power production primarily occurs along Quaternary faults.  Other significant metals include silver, copper, lead, zinc and molybdenum.

Mountain ranges in Nevada, commonly about 10 miles wide and rarely longer than 80 miles, are separated by valleys.  The geologic structure that controls this basin-and-range topography is dominated by faults.  Nearly every mountain range is bounded on at least one side by a fault that has been active, with large earthquakes, during the last 1.6 million years.  For the last several million years, these faults have raised and occasionally tilted the mountains and lowered the basins.  Over the years, these basins have filled with sediments that are derived from erosion of the mountains and that are locally tens of thousands of feet thick.

Many of the range-bounding faults are still active.  Nevada is the third most seismically active state in the nation (behind California and Alaska), over the last 150 years, a magnitude 7 or greater earthquake has occurred somewhere in Nevada about once every 30 years.  Most faults are normal, although some are strike-slip faults.  The most apparent zone of strike-slip faults in Nevada is in a 50-mile wide swath along the northwest-trending border with California, the Walker Lane.  These northwest-trending faults are accommodating part of the motion between the Pacific Plate, which is moving relatively northwest, and the North American plate, which is moving relatively southeast.  The San Andreas Fault takes up most of the motion between these two plates. The generally north-south trend of mountain ranges in most of Nevada transforms into northwest-trending ranges within the Walker Lane.

A western continental margin, similar to the Atlantic coast of today, persisted for hundreds of millions of years before the more active Pacific coast margin of today began to take shape about 360 million years ago.  Repeated and prolonged periods of interactions between the North American Plate and oceanic plates, expressed in folds, thrust fault, strike-slip faults, normal faults, igneous intrusions, volcanism, metamorphism, and sedimentary basins, are recorded in the rocks.  Some of the oldest rocks in Nevada occur near Las Vegas and the same great unconformity that separates the Paleozoic from the Precambrian at the base of the Grand Canyon is exposed at the foot of Frenchman Mountain, just east of Las Vegas.  Evidence for major Mesozoic thrusting is easily seen in the Spring Mountains west of Las Vegas.

Nevada rocks document volcanic and intrusive igneous activity intermittently and repeatedly from earliest geologic history to within the last few thousand years.  Nevada’s igneous rocks are connected to seafloor spreading about 450 million years ago (much like the Mid-Atlantic Ridge or the East Pacific Rise today), collisions of ancient and modern plates, and hot spots in the Earth’s mantle and perhaps outer core (some Nevada volcanic rocks can be correlated with the Yellowstone hot spot, which, as a result of plate tectonics, was once underneath and produced volcanoes in southern Idaho and northern Nevada).

Some of the volcanic rocks in western Nevada represent the precursor of the Cascade Range, and significant intrusions about 40, 100, and 160 million years ago are probably linked to similar plate tectonic settings, whereby oceanic plates were subducted beneath western North America.

Most, but not all, ore deposits in Nevada are associated with igneous activity.  In some cases, metals came from the magmas themselves, and in other cases, the magmas provided heat for circulation of hot water that deposited metals in veins and fractured sedimentary rocks.  Some spectacular mineral specimens occur in ore deposits that formed when magmas intruded and metamorphosed sedimentary rocks.

Much of the gold comes from a northwest-trending belt of gold deposits in northeastern Nevada known as the Carlin trend.  One of the interesting features of the Carlin trend is that nearly all of the gold is contained in microscopic particles with Paleozoic sedimentary rocks.  Although the sedimentary hosts for the gold are more than 250 million years old, the actual mineralization may have occurred much later (approximately 40 million ears ago) in association with igneous activity.

Adapted from:
Geology of Nevada
Jonathan G. Price
State Geologist ad Director Nevada Bureau of Mines and Geology
Mail Stop 178
University o0f Nevada, Reno
Reno, Nevada 89557-0088