Reconnaissance Stream-Sediment Geochemistry of Death Valley National Monument, California

Hofstra, A.; Fey, D.; Motooka, J.; Roushey, B.; Bradley, L.

To meet the goals of the National Mineral Resource Assessment Program (NAMRAP) of the U.S. Geological Survey (USGS), a geochemical survey of southern California was begun in 1991 to document the geochemical landscape of this region. The southern California area under study (Figure 1) includes desert lands (Basin and Range, Mojave Desert, Sonoran Desert, and Salton Trough physiographic provinces) and southern coastal mountain ranges (Transverse and Peninsular Ranges). This area is endowed with a wide variety of mineral wealth (Albers, 1981) including active mines producing gold, rare-earth elements, zeolites, borates, and a variety of other industrial minerals and construction material and has had significant past production of base-metals, iron, silver, tungsten, and mercury. Geochemical data for much of this region is inadequate or out of date. It is thus critical for the long-term mineral supply of the nation, for informed land-use planning decisions, and for environmental concerns that we increase our understanding of the geochemical variability of this region. Geochemical data from a variety of sources exists for much of southern California and in 1992 these data were compiled, evaluated, and an eight element (Pb, Zn, Cu, Au, Ag, As, Sb, and Mo) geochemical anomaly map was produced for the area south of latitude 37°N (Folger et al, 1994). This work showed that there were several large areas, mostly national monuments and military reservations, that had not been sampled previously. The areas lacking geochemical data are so numerous and so large in southern California desert lands (Figure 1) that mineral belts and geochemical trends in this region could be overlooked using existing data. To adequately assess the geochemical variation of southern California it is necessary to obtain data in the poorly characterized areas. As part of this effort a geochemical survey of Death Valley National Monument, excluding the part in Nevada, was conducted in September of 1992. The major features of Death Valley are shown on a shaded relief map (Figure 2) from Chalfant (1936). The Monument covers a large part of the Death Valley I°x2° quadrangle and part of the Goldfield quadrangle to the north and Trona quadrangle to the south. Descriptions of the geology and mineral resources of Death Valley are in Albers (1981), Hunt (1975), Hunt and Mabey (1966), Streitz and Stinson (1974). The rocks in the Monument range from Precambrian to Tertiary in age and contain a wide variety of metallic minerals and nonmetallic industrial minerals. Metals that have been of most economic significance, in approximate order of value, are lead, gold, silver, tungsten, zinc, antimony, and iron.

Reconnaissance Stream-Sediment Geochemistry of Death Valley National Monument, California

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