ABSTRACT The Bingham District is a large polymetallic mining district centered on an Eocene porphyry copper deposit 20 miles southwest of Salt Lake City, Utah. Since its discovery in 1863 the district has at various times been a silver-lead, gold, lead-zinc-silver, and copper-gold-molybdenum district. The Bingham District is located in a zone of overlap between the Basin and Range extensional terrain and the Cordilleran fold and thrust belt. Permian quartzites and limestones were folded and thrust-faulted during several Mesozoic orogenies and then intruded by 39.8 to 37.5 Ma calcalkaline monzonite, quartz monzonite, and quartz latite. Volcanic breccias and flows petrochemically similar to the intrusions were erupted from centers close to the deposit from 39 to 33 Ma. The Bingham Porphyry Copper Deposit exhibits the concentric alteration and mineralization zoning characteristic of many porphyry deposits. However, the deposit is notable for the magnitude and intensity of the various kinds of mineralization present: It is one of the largest copper deposits in the world with pre-mining reserves of almost 3 billion tons of 0.67 percent copper ore. Nested within the copper orebody are overlapping zones of molybdenum, gold, and silver mineralization that mimic the shape of the copper deposit and contain greater than 0.1 percent MoS 2 , 0.01 ounces per ton gold, and 0.5 ounces per ton silver respectively. Major copper-gold skarn deposits flank the copper orebody on two sides. They include the Carr Fork Deposit (61 million tons of 1.90 percent copper, 0.01 ounces per ton gold, and 0.31 ounces per ton silver) and the North Ore Shoot Deposit (82 million tons of 2.81 percent copper, 0.05 ounces per ton gold, and 1.57 ounces per ton silver). Vein and replacement lead-zinc-silver deposits located in a halo around the porphyry and skarn deposits have produced 28 million tons at an average grade of 8.6 percent lead, 6.6 percent zinc, 5.0 ounces per ton silver, and 0.039 ounces per ton gold. The Barneys Canyon and Melco Deposits located five miles north of the porphyry copper deposit have combined pre-mining reserves of 19 million tons at a grade of 0.05 ounces per ton gold. They are sediment-hosted gold deposits characterized by sub-micron sized disseminated gold mineralization, an arsenic-antimony-barium-mercury-thallium geochemical signature, low silver and base metal contents, and an almost complete absence of quartz veining. The deposits lie at the outer edge of an extensive arsenic-gold geochemical halo about the Bingham Porphyry Copper Deposit, but chronological and genetic relationships to the porphyry deposit have not been clearly established.

Abstract Copper-gold skarns peripheral to the porphyry copper deposit in the Bingham mining district, Utah, contain a geologic resource of over 7 million tons of copper and 9 million ounces of gold. The skarn deposits, hosted by Pennsylvanian limestone beds within the contact metamorphic aureole of the Tertiary Bingham stock, have been mined intermittently since 1896. In the late 1960s, two large deposits were discovered at depth on the north side of the district by The Anaconda Company and Kennecott Copper Corporation: the Carr Fork mine, operated by Anaconda from 1979 to 1981, and the North Ore Shoot deposit, which has not entered production. Recent drilling by Kennecott on the eastern flank of the North Ore Shoot has resulted in discovery of the Fortuna deposit. These three areas are all part of the same, continuous skarn system. A remarkable horizontal and vertical extent of skarn is displayed within the Bingham district. Mineralized skarn occurs in a zone roughly 2,000 feet wide around the quartz monzonite porphyry phase of the Bingham stock and extends over a mile vertically from surface exposures to the deepest drill-hole intersection. Skarn ore, delineated by the +1 percent copper grade contour, lies outside the porphyry copper ore shell and extends to a lower elevation. The Carr Fork orebodies consist predominantly of chalcopyrite in retrograde-altered garnetite skarn. In the North Ore Shoot and Fortuna deposits, massive sulfide replacement bodies are the principal ore type, although mineralized garnetite is also present. Pyrite-gold mineralization that crosscuts copper-gold skarn has been found in the Bingham skarn deposits, but its relationship to other gold mineralization in the district is unclear. Beyond the zone of copper-iron-gold mineralization, lead-zinc-silver deposits occur in limestone and other host rocks within a broad halo nearly one mile wide.

Abstract The Bingham mining district is located in the northeastern Basin and Range province of west-central Utah, immediately southwest of Salt Lake City. Mineralization in the district was first recognized in 1850, placer gold production began in 1864, and successful lead-silver production followed a few years later with the arrival of the railroad. The production of high-grade copper-gold ore started in 1897. Utah Copper became the first flourishing low-grade porphyry copper operation in 1904, using block caving, but switched to large-scale open pit methods a couple years later. Bingham is one of the most productive mining districts the world. The district is zoned outward from porphyry Cu-Mo-Au through Cu-Au skarn, pyrite halo, Pb-Zn-Ag vein and replacement deposits to distal sedimentary rock-hosted Au ores. District metal production includes over 2.8 billion tons of porphyry ore, averaging approximately 0.7% Cu, 0.05% Mo, 0.4 ppm Au, and 3 ppm Ag; 32.8 million tons of lead-zinc-silver ores with recovered grades of 7% Pb, 3% Zn, 125 ppm Ag, and 1 ppm Au; and an additional 30.6 million tons of 2.1 ppm Au in sedimentary rock-hosted gold ores. The remaining porphyry resources total an additional 1.4 billion tons of 0.5% Cu, 0.07% Mo, 0.2 ppm Au, and 2 ppm Ag.

Abstract Latitic volcanic rocks about 39 to 38 Ma and 33 to 31 Ma occur along the eastern flank of the Oquirrh Mountains in the vicinity of the Bingham Canyon porphyry Cu-Au-Mo deposit. Extrapolation of the basal contact of the 39 Ma volcanic rocks shows that they likely covered parts of the Bingham intrusions less than 500 m above the pre-mining surface. Some Bingham intrusions may have vented to the surface to help form the volcanic sequence. Minette and shoshonite lavas occur in subordinate amounts within the volcanic sequence. Minette dikes (37.74 ±0.11 Ma) in the Bingham Canyon ore body are the same age as late mineralized porphyry dikes (37.72 ± 0.09 Ma) and unaltered minette flows (37.82 ± 0.14 Ma). These ages confirm that minette magma may have played a role in the petrogenesis of ore-related intrusions in the Bingham mining district.

Abstract Erastus Bingham and his two sons, Thomas and Sanford, began ranching in a wooded canyon in the Oquirrh Mountains in 1848. This was a year after the Latter-day Saint (LDS) pioneers entered the Great Salt Lake Valley, then a part of Mexico (Arrington and Hansen, 1963). They were probably the first Caucasians to recognize mineralized rock in the Oquirrh Mountains and brought their discovery to LDS President Brigham Young. 1 Young, however, wisely counseled the Saints to settle and farm Utah to provide the necessities of life and avoid the pursuit of precious metals: Instead of hunting gold let every man go to work at raising wheat, oats, barley, corn, and vegetables and fruit in abundance that there may be plenty in the land (Robertson and Harris, 1962). Young did, however, encourage the utilitarian production of coal and iron from the Iron Springs area in southwestern Utah, near Cedar City, in 1851. The Mormon (LDS) pioneers also began a lead mine, discovered by Henry Rollins, and furnace for bullets near Minersville in 1858 (Salt Lake Mining Review, 9/15/1902). They also began producing salt from the Great Salt Lake as early as 1847 (Arrington, 1963). In 1864, Young persuaded a wagon train of pioneers headed for Idaho to set up their saw mill in Bingham Canyon (Boutwell, 1905). Logging flourished in the canyon for the next several years (Spendlove, 1937). In 1848, gold was discovered at Sutter's Mill in California. The eager Forty-Niners rushed through Utah en route to California, but were

Abstract The Bingham Canyon porphyry Cu-Mo-Au deposit is located in the central part of the Oquirrh Mountains, 30 km southwest of Salt Lake City, Utah. The Cu-Au-Mo deposit lies at the center of a large polymetallic district, which includes proximal Pb-Zn-Ag replacement and distal sediment-hosted gold mineralization. Open-pit copper mining commenced in 1906 and through 2011 has produced 2.666 billion tonnes of ore averaging 0.74% Cu, 0.035% Mo, 0.448 g/t Au, and 3.29 g/t Ag. Bingham lies near the west end of an 80-km-long belt of petrochemically similar Eocene to Oligocene intrusions and coeval volcanic rocks, which host base and precious mining districts. The Bingham district is centered on the Bingham stock, a multiphase mid-Eocene intrusion emplaced into a thick succession of folded mid- to upper Paleozoic siliciclastic and carbonate rocks. The 2 × 2 km Bingham stock consists mainly of premineral equigranular monzonite that was intruded successively by a 2-km-long dike-like body of quartz monzonite porphyry (QMP), long narrow dikes and sills of intramineral latite porphyry (LP), and narrower dikes of late-mineral quartz latite porphyry (QLP). The intrusions and associated porphyry-style mineralization dip steeply to the northwest and persist from the pre-mine surface at 2,390 m to below sea level. U-Pb zircon dating indicates a 38.6 Ma age for the equigranular monzonite and suggests that the subsequent porphyry intrusions were emplaced at ∼ 38 Ma. Porphyry intrusion and mineralization were approximately synchronous. Early actinolite-stable alteration in igneous and sedimentary rocks is flanked by distal chlorite-epidote alteration. Magnetite-destructive secondary biotite alteration is pervasive in intrusive rocks that contain > 0.7% copper but typically is fracture-controlled and overprints earlier actinolite alteration in lower grade intrusive rocks and quartzites. K-feldspar alteration accompanies the highest grade copper and gold mineralization. Sericitic alteration is locally pervasive but, more typically, it is restricted to the margins of late quartz-pyrite veins. Late, low-temperature montmorillonite ± kaolinite alteration is ubiquitous in the intramineral porphyries and adjacent equigranular monzonite. An outer zone of 0.35 to > 0.70% Cu mineralization surrounds and overlaps an inner zone of 0.05 to > 0.15% Mo mineralization, which in turn forms a cupola around a barren core. Intense bornite-chalcopyrite-chalcocite-gold mineralization (> 0.7% Cu and > 1 g/t Au) occurred directly above the barren core but has largely been removed by mining. The copper mineralization in the flanks of the deposit is dominated by chalcopyrite. Copper and gold grades decrease downward but quartz-molybdenite stockwork mineralization grading > 0.05% Mo extends to the lower limit of drilling. Equigranular monzonite is the predominant ore host, containing 53% of the ore mined to date. Vein types proceed in a sequence from early biotite through quartz-sulfide to late anhydrite and zeolite. Early copper-bearing quartz veins are truncated by the LP and QLP dikes, but later copper-bearing veins cut the dikes. Cathode luminescence studies indicate that copper-bearing sulfides were deposited within micro-fractures and vugs created by dissolution of earlier quartz. Quartz-molybdenite veins postdate the copper-bearing veins and cut all of the porphyries. Vein densities reach > 10 vol % in the barren core and decrease to ∼ 1 vol % at the outer boundary of the > 0.35% Cu zone. Published fluid inclusion and vein density studies, together with modeled grade distributions, show that mineralization was precipitated by a plume of metal-bearing fluid approximately 2 km in diameter, centered near the southeastern edge of the QMP. The barren core apparently represents an upflow zone near the top of which supercritical fluids separated into vapor and brine. Copper-bearing sulfides and gold precipitated as vapor-dominant fluids cooled from 430° to 350°C. Inclusions in quartz from the deep flanks of the copper deposit indicate similar fluid compositions, but less separation into vapor and brine.

Abstract Sediment-hosted, disseminated gold deposits in the Mercur district and Bameys Canyon in the Bingham district are infolded and thrust-faulted Paleozoic sediments of the Oquirrh Mountains, Utah. Folding and thrust faulting occurred in a Jurassic event and the Cretaceous Sevier Orogeny (Armstrong, 1968; Almendinger and Jordan, 1981; Almendinger et al.,1984; Snoke and Miller, 1988). The Oquirrh Mountain range is allocthonous and is underlain by the east-vergent Oquirrh thrust (Presnell, 1992; Presnell and Parry, 1995) not te Charleston thrust. Mercur is located . in the southern Oquirrh Mountains dominated by a series of northwest trending anticline-syncline pairs. Barneys Canyon and Bingham are in the central Oquirrh mountains where structural complexity results from the east -vergent thrust belt interacting with the Uinta arch.