Road log from Mountain Pass, California, to Oatman, Arizona: 96.5 miles
Published:January 01, 1987
0.0 Bailey Road interchange at Interstate Highway 15. Go south over the Interstate and take the northbound entrance ramp toward Las Vegas.
1.4 Large roadcuts on the right in 1700 Ma foliated granite and high-grade metamorphic rocks.
1.6 Outcrops to the left contain low-angle faults cutting high-angle foliated metaplutonic rocks. At 12:00 are Castle Peaks on the far horizon in the northern New York Mountains (Miller and others, 1986). These sculptured peaks are Tertiary volcanic rocks which rest depositionally on 1660 Ma (Wooden and others, 1986) Ieucocratic granite (unit Xg1, fig. 3).
2.4 Roadcuts in Tertiary fanglomerate. Past roadcuts, views to both left and right show pronounced foliation and layering of light-colored Early Proterozoic granitic rocks that intruded darker ampibolite and mixed gneiss. Mineral Hill on the right; 1400 Ma syenite and granite crop out on the ridge at 3:00. Farther south along Mineral Hill are numerous prospect pits containing thorium-rich, rare-earth-element-rich veins. The extent of mineralization related to the Mountain Pass Carbonatite south, past Mineral Hill, is unknown.
3.7 View into Ivanpah Valley and across Ivanpah Lake. Mountains in the distance are the McCullough Range, which contain granulite-facies gneissic rocks (Clarke, 1985; Anderson and others, 1985) and 1700 Ma plutonic rocks. Rectangular ponds at the southern end of Ivanpah Lake are waste water storage for the Mountain Pass mine.
4.6 Nipton Road exit. Take the exit to the right.
4.9 Stop sign. Turn right onto highway leading to Nipton, California, and on to Searchlight, Nevada. Entering East Mohave National
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.