Part 1. Regional Studies and Epithermal Deposits

Northern Nevada is one of the Earth’s premier gold- and silver-producing regions, and gold and silver are mined from a wide range of deposit types (Table 1). Current production largely comes from Carlin-type sedimentary rock-hosted disseminated gold deposits (Christensen, 1995; Teal and Jackson, 1997; Bettles, 2002), many of which lie along linear trends (Fig. 1; Roberts, 1960, 1966; Berger and Bagby, 1991). The small area of the Carlin trend (approximately 8 x 65 km) is North America’s most prolific gold mining district, producing nearly 125 t (4 Moz) of gold annually. Since large-scale mining began in 1965 with the opening of the Carlin mine, the Carlin trend has produced more than 1555 t (50 Moz) of gold. During 2001, gold production from the entire state of Nevada was nearly 253 t (8.13 Moz), which accounted for approximately 76 percent of the United States and 10 percent of the world production (Price and Meeuwig, 2002). In 2001, only the countries of South Africa and Australia produced more gold than the state of Nevada. In addition, Nevada produced 543 t (17.4 Moz) of silver in 2001—about 31 percent of the United States production and 3 percent of the world production. In 1996, the Mineral Resources Program of the U.S. Geological Survey began a multidisciplinary project to investigate the origin of gold deposits in northern Nevada. This project was undertaken in collaboration with the Nevada Bureau of Mines and Geology, the Ralph J. Roberts Center for Research in Economic Geology at the University of Nevada, Reno, several other universities, and numerous mining companies active in the region. In addition, several universities and mining companies were conducting research on the origin of gold deposits in northern Nevada. This research built on more than a century of studies by the …