Published:January 01, 1987
The morning part of the trip starts in Kingman, near the western edge of the Colorado Plateau, and traverses the Transition Zone of Arizona. Proterozoic rocks are abundant along this section of the trip and consist mainly of foliated to undeformed Early Proterozoic granite to granodiorite (~ 1700 Ma) cut by undeformed Middle Proterozoic leucocratic and potassic granite (~1400 Ma). Relatively small belts of Early Proterozoic meta-sedimentary and metavolcanic rocks are preserved within the terrane dominated by Proterozoic intrusive rocks. Much of the Early Proterozoic geologic history in this part of Arizona is unknown.
Ore deposits characteristic of this part of the Proterozoic are: 1) 1700 Ma volcanogenic massive sulfide deposits in metasedimentary and metavolcanic rocks (Hualapai metallic mineral district, northern Hualapai Mountains); 2) 1700 Ma gold-rich quartz veins related to Early Proterozoic granodiorite and diorite (Cottonwood district in the Cottonwood Cliffs); 3) 1700 Ma pegmatite deposits related to evolved granites (Aquarius Mountains district in the Aquarius Mountains and the Kingman Feldspar mine north of Kingman); and 4) 1400 Ma tungsten-rich quartz veins related to potassic granites (Ophir, Fluorescent, and Three-In-One districts in the Hualapai Mountains.
Phanerozoic deposits include base-metal-rich veins and copper-rich disseminated and stockwork systems related to Laramide intrusives in the central Cerbat Mountains and Hualapai Mountains, and middle Tertiary vein systems on the west side of the Hualapai Mountains.
Our arrival in Bagdad in the late morning will bring us to the first major 1700 Ma volcanogenic massive sulfide ore deposits in Arizona, those in the Old
Figures & Tables
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.