Lithological, Structural, Chemical and Mineralogical Patterns in a Precambrian Stratiform Gold Occurrence Yavapai County, Arizona
Published:January 01, 1987
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M. M. Swan, D. M. Hausen, R. A. Newell, 1987. "Lithological, Structural, Chemical and Mineralogical Patterns in a Precambrian Stratiform Gold Occurrence Yavapai County, Arizona", Proterozoic Ore Deposits of the Southwestern U.S., Ed DeWitt
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Coincident with and largely confined to the sulfide-bearing strata are anomalous amounts of Au, As, Sb, Cu, Pb, Zn and Ag with associated silicification, sericitization and carbonatization. Geochemical and alteration changes are complex normal to bedding planes, probably reflecting continual and abrupt changes in exhalite precipitation. In the plane of bedding, they show a more general systematic pattern indicating relatively stable sea floor topography. Facies changes of mineralization observed along strike are believed to reflect varying Eh and pH conditions during exhalite deposition (6, 7). A crude generalization of the pattern, starting from the rhyolite dome and proceeding south, can be summarized as:
Carbonate facies (strike length = 0.8 km),
Sulfide facies and carbonate facies (strike length = 4 km),
Carbonate facies (strike length = 1.6 km) (Fig. 4).
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Proterozoic Ore Deposits of the Southwestern U.S.
This field conference of the Society of Economic Geologists, held in conjunction with the 1987 Annual Meeting of the Geological Society of America in Phoenix, Arizona, investigates various Proterozoic ore deposits in southeastern California and western and central Arizona. The trip starts in Las Vegas, Nevada, and ends in Phoenix, Arizona. Although Proterozoic ore deposits and geology are emphasized, the field trip traverses a variety of tectonic provinces, each containing ore deposits of various ages. Many geologic features and ore deposits that are not Proterozoic in age will be discussed during the course of the trip, but no stops will be made to investigate any of these, features.
The morning part of the trip starts in the Mesozoic foreland fold and thrust belt of Nevada and southeastern California, goes just east of the Mesozoic batholith belt of California, and ends in crystalline basement containing Early and Middle Proterozoic metamorphic and plutonic rocks. Within this basement is exposed the Middle Proterozoic Mountain Pass Carbonatite deposit, the largest source of rare-earth elements in the world. The Mountain Pass Carbonatite will be the focus of our morning stops.
The afternoon part of the trip crosses Early Proterozoic high-grade metamorphic rocks and plutonic rocks east of Mountain Pass. Ore deposits noted along the afternoon portion of the trip include middle Tertiary epithermal, gold-rich veins at Searchlight, Nevada, and disseminated gold deposits in Tertiary volcanic rocks near Hart Peak in the New York Mountains. The trip continues across the Colorado River trough along the border of California and Arizona, where crystalline basement and its cover of Tertiary volcanic rocks and plutons have been greatly extended along listric normal faults and low-angle detachment faults. The afternoon part of the trip ends in Oatman, Arizona, a district famous for its middle Tertiary epithermal, gold-rich deposits. The ore deposits at Oatman will be the subject of a slide show and talk after supper on the first night of the trip.
The first day ends with an evening drive across a middle Tertiary volcanic pile near Oatman. The first night will be spent in Kingman, Arizona.
Assemble at the Las Vegas Convention Center, south of the Hilton Hotel. Take any main street south to Tropicana Avenue. Turn west on Tropicana, past the Las Vegas Strip, and continue to Interstate Highway 15. Turn south on Interstate 15 toward Mountain Pass, California. Mileage starts at 0.0.