The discovery in 1976 of Trap Spring oil field in Railroad Valley, Nevada, and the 1979 discovery of West Rozel oil field in the Great Salt Lake, Utah, have focused attention on the Great Basin. To date, five fields have been discovered which include, in addition to the mentioned fields, the Rozel Point (circa 1904), Eagle Springs (1954), and Currant oil fields (1978). All fields produce from either Tertiary lake sediments or fractured volcanic rocks. Accumulations occur in truncation-fault traps or in drape-over faulted structure.

Exploration for Tertiary hydrocarbon accumulations consists of (1) mapping basin source rocks with proper depth for maturity, (2) presence of good reservoir rocks, and (3) delineation of traps by photogeologic-geomorphic techniques, gravity surveys, and seismic shooting.

Wells drilled in many basins have recorded good shows of oil and gas both in Tertiary and Paleozoic rocks. Other oil and gas indications include the Bruffey oil and gas seeps (Pine Valley, Nevada), the Wells oil seep (west of Wells, Nevada), an asphaltite dike in Mississippian rock in the Pinon Range east of Pine Valley, and the West Brigham City and Farmington gas area (Carson Sink, Nevada). Oil source units include the various Cretaceous to Tertiary lake deposits (Sheep Pass Formation, Elko shale, Kinsey Canyon formation, Newark Canyon Formation, and King Lear Formation), Mississippian Chainman Shale, Devonian Pilot Shale, and Ordovician Vinnini shale.

In addition to Tertiary prospects, some Paleozoic plays exist, which include the Mississippian Diamond Peak (Illipah, Scotty Wash) sandstone facies change to the east into the Chainman Shale, occurring in central Nevada east of the Antler orogeny. Structural prospects exist in the Basin and Range province, with potential Paleozoic reservoirs. In addition, reef prospects may be present in the Silurian and Devonian of Nevada. Continued exploration for both Tertiary and Paleozoic prospects should result in significant discoveries of oil and gas.

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