Sedimentary-rock hosted gold deposits in Nevada

The Carlin Unconformity or Carlin Trend is a geologic feature in northeastern

Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...

which represents a period of erosion or non-deposition likely associated with a collision between a

tectonic Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents ...

crustal block called a

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust (geology), crust fragment formed on a tectonic plate (or broken off from it) and Accretion (geology), accreted or "Suture (geology), sutured" to crust lying on another pla ...

and the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacif ...

. The collision occurred during the Mississippian Period, about 350 million years before present. The collision is associated with the

Antler Orogeny The Antler orogeny was a tectonic event that began in the early Late Devonian with widespread effects continuing into the Mississippian and early Pennsylvanian. Most of the evidence for this event is in Nevada but the limits of its reach are un ...

. The collision induced higher crustal temperatures and pressures which produced numerous hot springs along the suture zone. Several episodes of subsurface magmatism are known to have occurred subsequent to the collision, associated with tectonic forces affecting the entire

Basin and Range Province The Basin and Range Province is a vast physiographic region covering much of the inland Western United States and northwestern Mexico. It is defined by unique basin and range topography, characterized by abrupt changes in elevation, alternating ...

. During each of these episodes, and particularly during the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

epoch, hot springs brought dissolved minerals toward the surface, precipitating them out along fissures. Among these minerals were

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile me ...

and silver. The Carlin Gold trend is one of the world's richest gold mining districts. It is a belt of gold deposits, primarily in

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

limy

sediments Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity In physics, gravity () is a fundame ...

, that is about wide and long, extending in a north-northwest direction through the town of

Carlin, Nevada Carlin is a small city located near the western border of Elko County in northeast Nevada, west of the city of Elko. It is part of the Elko Micropolitan Statistical Area. Carlin sits along Interstate 80 at an elevation of approximately . As of ...

. Gold was first discovered in the area in the 1870s, but there was little production until 1909, and only about 22,000 ounces was produced through 1964. By 2008, mines in the Carlin Trend had produced over 70 million ounces of gold, worth around $85 billion at 2010 prices.

See also

References

Further reading