| Basis for focus area |
This focus area covers the Park City-Gold Hill belt, coincident with the most well defined sections of the Uinta-Cortez axis and the Bingham–Gold Hill mineral trend (other terms for the area covered include Bingham–Park City uplift, Uinta axis, Cortez–Uinta axis, Uinta–Gold Hill trend, Uinta arch, Uinta–Cottonwood arch, Oquirrh–Uinta mineral belt, and Oquirrh–Uinta transverse zone) and is based on mining districts from Krahulec (2018b), the Uinta-Cortez axis (Vogel and others, 2001), the Oquirrh-Uinta transverse zone (Rowley, 1998), and the Uinta Tooele structural trend (Clark, 2020). It includes the major mining districts Park City, Bingham, and Mercur, as well as the following moderate to minor districts: Alpine-Silver Lake, American Fork, Big and Little Cottonwood, Elkhorn, Gold City, Gold Hill, Granite Peak, Lehi, Ophir, Settlement Canyon, Stockton, Sunshine, Third Term, West Dip, and White Pine. There are multiple mineral systems in the mineral belt, but the majority of major mineralization falls under the porphyry Cu-Mo-Au system. |
| Identified resources |
Historical production of arsenic, bismuth, fluorite, lead, manganese, tungsten, uranium, and zinc; current production of copper, gold, PGE, molybdenum, rhenium, silver, and tellurium. |
| Production |
Park City district: (1875-1978): 16,721,723 tons, 1,453,867 oz Au 253,344,128 oz Ag, 2,708,146,385 lbs Pb, 1,487,843,818 lbs Zn, 128,967,698 lbs Cu (John, 2006); Cottonwood districts: (1867-1976): ~830,023 tons containing 30,609 oz Au, 17,476,243 oz Ag, 18,110,308 lbs Cu, 251,811,521 lbs Pb, 24,487,428 lbs Zn (James, 1979); American Fork district: ~175,000 tons ore at >500 ppm Ag, 9 ppm Au, 11% Pb, 2.6% Zn, 1% Cu (Krahulec, 2018b); Bingham district: There has been major mining since 1903. Mining through 2017 totaled more than 3.2 Gt of porphyry ore averaging 0.72% Cu 0.057% MoS2, 0.012 oz/t Au, 0.09 oz/t Ag from the Bingham Canyon mine; 8.9 Mt of skarn ore averaging 2.20% Cu, 0.077 oz/t Au, 1.32 oz/t Ag; 32.8 Mt replacement ore averaging 6.8% Pb, 2.8% Zn, 0.38% Cu, 3.65 oz/t Ag, 0.041 oz/t Au; 5.9 Mt of Cu-rich lodes averaging 2.05% Cu, 0.073 oz/t Au, 1.98 oz/t Ag, 0.2% Pb; 30.6 Mt of ore from distal disseminated deposits averaging 0.060 oz/t Au (Krahulec, 2018a); Stockton district; In the Stockton district, total production from polymetallic replacement deposits was about 2 Mt that averaged 7.7% Pb, 2.7% Zn, 0.3% Cu, 157 ppm Ag, and 1.27 ppm Au (Krahulec, 2018b). Ophir district: Mines in the Ophir district produced 2.8 Mt of ore that averaged 6.2% Pb, 1.5% Zn, 0.8% Cu, 237 ppm Ag, and 0.21 ppm Au (Krahulec, 2018b). Mercur: 2,605,037 ounces Au along with 1,183,724 ounces Ag and 3469 flasks of Hg (Krahulec, 2018b). Moderate production from other mining districts like Gold Hill and American Fork. |
| Status |
Past and current mining at Bingham (Au, Cu, Ag, Mo) and Kiewit (Au); Active exploration at Mercur, Gold Hill, Ophir, and Stockton. |
| Estimated resources |
Bingham Canyon mine: 2020 end-of-year: 552 Mt of porphyry reserves at 0.44% Cu, 0.031% Mo, 0.16 ppm Au, and 2.11 ppm Ag; 285 Mt porphyry resources at 0.38% Cu, 0.017% Mo, 0.20 ppm Au, and 1.79 ppm Ag; 20 Mt skarn resources at 3.65% Cu, 1.62 ppm Au, and 20.95 ppm Ag in the North Rim skarn (Rio Tinto, 2021a). Stockton porphyry copper deposit: estimated resources 170 Mt at 0.41% Cu, 0.14 ppm Au (Krahulec, 2015). Ontario mine: 1980 reserves: 1,328,000 tons @ 4.5 opt Ag, 5.9% Pb, 9.2% Zn; White Pine Fork molybdenum deposit: 16 Mt @ 0.1% MoS2 resources. |
| Geologic maps |
Majority of the belt is covered by 1:24,000 mapping, with the exception of Mercur district. |
| Geophysical data |
Inadequate Rank 4 aeromagnetic coverage. |
| Favorable rocks and structures |
The Park City-Gold Hill belt is the Utah portion of a major lineament of geophysical anomalies, faults of the same strike, plutons, and major mining districts and marks the boundary between the Archean Wyoming province to the north and Paleoproterozoic Yavapai province to the south. The zone of crustal weakness has had periods of activity from the Paleoproterozoic through Cenozoic time, with the igneous intrusions and extrusions of the central Wasatch Mountains the most recent evidence of this activity (Vogel and others, 2001). Eocene intrusions have the most significant mineral association, though Jurassic intrusions also have small, high grade critical mineral enriched deposits, for example, Gold Hill. Intrusions emplaced mainly into folded and faulted carbonate Paleozoic basement. The Park City porphyries, Park Premier porphyry, and Indian Hollow plug are in the Park City area. Farther west, the Alta, Clayton Peak, and Little Cottonwood stocks are in the Wasatch Range. The Bingham and Last Chance stocks are in the Oquirrh Mountains. Stockton has the Spring Gulch and Soldier Canyon stocks. South Mountain contains a few small basaltic dikes. The Stansbury Mountains have small rhyolitic intrusions and rhyolitic to intermediate extrusive rocks. The Cedar Mountains have rhyolitic to intermediate extrusive rocks and a small rhyolitic plug. An Eocene intrusion occurs at Gold Hill, along with an older Jurassic-age stock. These igneous rocks are associated with the wave of volcanism that swept north to south through Utah in Eocene to Oligocene time (about 40 to 23 Ma). Associated with the intrusives are the major mining districts of Park City (metal resources of Ag, Pb, Au and Zn) and Bingham (Cu, Au, and Mo), as well as the smaller districts of Big and Little Cottonwood (Ag, Pb), American Fork (Au, Pb, Ag), Stockton (Pb, Ag, Au, Zn), Gold Hill (As, Au, Ag), and several others (Clark, 2020). |
| Deposits |
Bingham Canyon (MRDS dep_id: 10129805), Lark, Barneys Canyon, Melco, Ophir Hill, Hidden Treasure, Mercur, Gold Hill, Ontario, Silver King, Park City Consolidated, Mayflower, Emma, Flagstaff. |
| Evidence from mineral occurrences |
MRDS; UMOS (Utah Geological Survey, 2021). |
| Geochemical evidence |
Bingham hosts Bi, In, PGE, Re, Te, Sn, and W in porphyry ore (Kocher, 2017; Brodbeck and others, 2020; Tomlinson and others, 2021). Rubright (1978) noted that polymetallic replacement deposits in the Ophir district contained minor W in wolframite and scheelite and anomalous Bi. Ore samples from Big Cottonwood district locally have high As contents (James, 1979), and Big Cottonwood was the leading Bi producer nationally in the early 1900s (Mills and Rupke, 2020). |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
See Hilpert and Roberts (1964), Rowley (1998), Erickson (1976), and Krahulec (2018b). |
| Comments |
This focus area is a large regional area that covers other focus areas that are smaller and more specific to local geology and mineralization. The intention of this focus area is to show regional potential related to a well known and documented structural, igneous, geophysical, and mineral province, whereas the more specific focus areas provide vectoring for known mineralization. This district includes the world-class Bingham porphyry Cu-Au-Mo system, the Ophir district, and the Park City district. The Little Cottonwood district was the largest Bi producer in the United States in the first part of the 1900s. Gold Hill is the largest As and W producer in Utah. |
| Cover thickness and description |
Variable. |
| Authors |
Stephanie Mills. |
| New data needs |
Regional aeromagnetics survey to create a regional interpretation of major structural, igneous, geophysical, and mineral trend; modern geochronology to better identify magmatic evolution and overprinting mineral potential. |
| Geologic mapping and modeling needs |
Digitization and synthesis of existing maps to identify gaps; 1:24,000 scale mapping over Mercur. |
| Geophysical survey and modeling needs |
High-resolution, Rank 1 aeromagnetic and radiometric surveys. |
| Digital elevation data needs |
Lidar variable. High-resolution lidar needed to define mine waste and tailings under reclamation for examination of mining waste potential. |
