Road Log from Bell Ranch Prospect to Phoenix, Arizona: 80.5 miles
Published:January 01, 1987
0.0 Bell Ranch northeast of Mayer, Arizona. Proceed on dirt road down the Agua Fria River.
0.9 Road leaves valley bottom and climbs to the south through metasedimentary rocks.
1.3 Road from the Binghampton and Copper Queen mines joins this road on the left.
2.7 Crossing small cattleguard.
3.1 View in the distance at 9:00 to 10:00 shows drill pad used by Billiton to explore the Copper Mountain area. Drill pad is now used as a quarry for mining of hematite-stained metarhyolite.
3.7 Road makes sharp turns around small hills. Visible in the distance at 12:00 are high peaks in the southern Bradshaw Mountains near Horsethief Basin.
4.0 Road crests small ridge. High peak in the far distance at 12:00 to 12:15 is Brady Butte, elev. 6,400 ft (fig. 53). The peak and the ridge extending to the south are composed of the 1750±10 Ma Brady Butte Granodiorite, the oldest dated rock in Arizona (Anderson and others, 1971). The pluton intrudes metavolcanic rocks similar to those seen between Prescott and Mayer, and has been deformed and recrystallized during regional metamorphism (Blacet, 1966; DeWitt, in press; Blacet, 1985). Unconformably overlying the pluton is the Texas Gulch Formation (fig. 43), a sequence of metamorphosed volcaniclastic and sedimentary material that has been multiple deformed (O'Hara and others, 1978; Karlstrom and O'Hara, 1984; Karlstrom and Conway, 1986) at the northern margin of the pluton.
Also visible from this location at about 12:00, directly over the town of Mayer and the smelter stack, are the
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.