DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY TO ACCOMPANY MAP MF-1411-C MINERAL RESOURCE POTENTIAL OF THE LAUREL-MCGEE ROADLESS AREA, MONO COUNTY, CALIFORNIA SUMMARY REPORT

SUMMARY Geologic and geochemical investigations and a survey of mines and prospects, conducted to evaluate the mineral resource potential of the Laurel-McGee Roadless Area, Mono County, Calif, ( Identified mineral resources in or near the Laurel-McGee Roadless Area occur at the Lucky Strike prospect where there are small resources (table 1, map sheet) of zinc, silver, copper, and lead. The Hard Point mine about 0.5 mi outside the roadless area, contains some tungsten resources and tungsten production has been recorded there and from the nearby Morhardt mine. On the basis of these occurrences, an area around and including these mines and prospects has a moderate potential for tungsten resource with low potential for silver, copper, zinc, and lead resources. The north edge of the roadless area lies within the Long Valley caldera. Parts of this volcanic structure have geothermal resource potential. Present and past exploration for geothermal resources indicate that areas with enough heat to be a possible geothermal resource are far removed from the roadless area

Dispersion patterns as a possible guide to ore deposits in the Cerro Colorado district, Pima County, Arizona

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A study of the geology and hydrothermal alteration north of the Creede mining district, Mineral, Minsdale, and Saguache Counties, Colorado

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Environmental Geochemistry in Yellowstone National Park—Natural and Anthropogenic Anomalies and Their Potential Impact on the Environment

In cooperation with the National Park Service, the U.S. Geological Survey conducted a stream-sediment-based environmental geochemical study in and near Yellowstone National Park (the Park). The main goals of the study were to (1) determine background concentrations for as many as 49 elements in samples of rock and stream sediment, (2) establish a geochemical baseline during the 1990s for future reference, (3) identify the source(s) of anomalies for selected elements, and (4) identify potential chemical impacts on the Park environment, especially on wildlife. Two areas of the Park containing identified environmental geochemical problems were selected for detailed study: (1) an area in the western part of the Park that includes the Gibbon, Firehole, and Madison River basins, and (2) an area in the northeastern part that includes the Soda Butte Creek and Lamar River basins and part of the Yellowstone River basin. The geology of the first area is characterized mainly by Quaternary felsic volcanic rocks. Localities with major geothermal activity are present in this area. The second area has more complex geology that consists primarily of Tertiary volcanic rocks of intermediate composition and Precambrian schists and gneisses. Also present are scattered exposures of Paleozoic clastic and carbonate rocks and Quaternary felsic volcanic rocks. Geothermal activity is very limited in this area. Both study areas contain extensive deposits of glacial, fluvial, or lacustrine origin. Analyses for as many as 49 elements in 393 samples of stream sediment collected from throughout the Park were evaluated statistically, including factor analysis. A five-factor model classified the elements on the basis of two lithologic factors, one mineral-deposit-related factor, one geothermal-process-associated factor, and one “miscellaneous” factor. Data from the factor analysis, when combined with the distributions of anomalies for the elements determined in this study, show that most (34) of the elements are best correlated with rock chemistry. Many of these elements can be used to discriminate between major lithologic units and can therefore be used to assist geologic mapping studies in the Park area. Anomalies of As, Cs, F, Hg, Mo, S, Sb, Tl, and W were determined to be associated with areas of geothermal activity. Of these nine elements, cesium is the best discriminator between anomalies related to geothermal activity and those related to outcrops of mineralized rock and to past mining activity near the Park. The effects of mineralization and past mining activity in the Cooke City, Mont., area, outside but near the northeastern boundary of the Park, are defined by anomalies of Ag, As, Au, Cu, Fe, Hg, Mo, Pb, S, Sb, Se, Te, Tl, W, and Zn, and possibly F. The effects are delineated best by anomalies of Au, Cu, and Te. Relatively weak anomalies of some of these elements extend as far as 18 km inside the Park. In the area of Slough Creek, in the northeastern area of the Park, the source for a high concentration of lead was determined to be anthropogenic because of the sample location and a lack of anomalies of other elements that commonly are associated with natural lead anomalies. This anomaly probably is related to past fishing activity. In high concentrations, a number of the elements associated with geothermal activity in the Park are potentially toxic to animals. Currently, only one of the 49 elements determined (fluorine) is known to affect the health and longevity of wildlife in the Park. Additional studies are needed to determine whether other elements are impacting the Park environment, including wildlife

Geochemistry of soil contamination from lead smelters near Eureka Nevada

<p>Eureka, Nevada, was once a boom-mining town with peak production of Pb, Ag, and Au between the 1870s and 1890s. Most of the ores from the area were processed in two smelters located at the north and south edges of the town. Smelter effluent was exhausted in the vicinity of the smelter furnaces with little regard to potential health concerns. </p> <p>For this study, 186 soil samples from sites in the area surrounding Eureka were analysed for 43 elements. Factor analysis and element plots identified 16 smelter-related elements: Ag, As, Bi, Cd, Cu, Hg, In, Mo, Pb, S, Sb, Sn, Te, Tl, W, and Zn. Eight other elements (Ba, Be, Co, Cr, Mn, Ni, U, and V), whose distributions are controlled by the chemical composition of the underlying substrate material, were also evaluated. </p> <p>Of these 24 elements, only six (As, Cd, Pb, Tl, Sb, and Mn) had concentrations that exceeded U.S. Environmental Protection Agency (EPA) estimated residential soil screening levels considered to represent possible health risks. For some analysed elements (In, S, Te, and W) no screening levels have been established. Whether these elements, or any of the others determined, constitute a health risk in the local population is not known. </p

Applications of Trace-Element and Stable-Isotope Geochemistry to Wildlife Issues, Yellowstone National Park and Vicinity

Reconnaissance investigations have been conducted to identify how geochemical techniques can be applied to biological studies to assist wildlife management in and near Yellowstone National Park (the Park). Many elements (for example, As, B, Be, Ce, Cl, Cs, F, Hg, K, Li, Mo, Rb, S, Sb, Si, and W) are commonly enriched in (1) thermal waters in the Yellowstone area, (2) rocks altered by these waters, (3) sinter and travertine deposits, and (4) soils and stream sediments derived from these rocks. Some of these elements, such as As, F, Hg, and Mo, may be toxic to wildlife and could be passed up the food chain to many species of animals. Three investigations are described here. The first discusses the abundance and distribution of selected elements in the scat (feces) of bison (Bison bison), elk (Cervus elaphus), and moose (Alces alces) collected in and near the Park from areas underlain by both unaltered and hydrothermally altered rock. As compared to mean values for stream-sediment analyses, those of scat analyses collected in the Yellowstone area show relatively high concentrations for 12 elements. This suite of elements comprises (1) hydrothermally related elements (As, Br, Cs, Mo, Sb, and W), (2) essential major elements for plants (Ca and K) and some trace elements (Ba, Rb, and Sr) that commonly proxy (substitute) for Ca or K, and (3) zinc. The behavior of zinc is not understood. It is an essential element for plants and animals but does not normally proxy for either Ca or K. Zinc is also not related to hydrothermal activity. This unique behavior of zinc is discussed in other parts of this investigation. Six elements (Cr, Hg, Ni, Pb, Se, and U) that can be toxic to wildlife are present in low concentrations in scat, reflecting their generally low concentrations in rock and stream-sediment samples collected throughout the Park. The chemistry of large-animal scat provides information on the feeding habits of large animals in the Park. Scat chemistry shows a high spatial correlation with fossil or active thermal areas or with areas immediately downstream from thermal areas. The longer that animals forage in these localities, the more likely it is that they may ingest significant amounts of potentially toxic elements such as arsenic. A second investigation describes the concentration levels of hydrothermal mercury and other elements in cutthroat trout (Oncorhynchus clarki bouvieri) and lake trout (Salvelinus namaycush). These elements are derived from sublacustrine hot springs and their habitats in Yellowstone Lake, and this study demonstrates that mercury can be used as a tracer in animal ecology studies. Mercury concentrations are significant in the muscle (average 0.9 ppm, dry weight for both) and liver (average cutthroat = 1.6 ppm, dry weight; average lake trout = 2.1 ppm) of cutthroat and lake trout populations. The mercury levels in fish are believed to be related to mercury introduced to the lake by sublacustrine hot springs, which have dissolved mercury concentrations of as much as 0.170 ppb. Methylation of mercury in thermal waters is probably carried out by methanogenic or sulfate-reducing bacteria that live around sublacustrine hot springs and are consumed by crustaceans such as amphipods, which are a major food source for the cutthroat trout. The mercury levels in the cutthroat trout are transferred to lake trout and to land animals that eat trout. For example, hair of grizzly bears that have been collected near Yellowstone Lake have high mercury levels (0.6–1.7 ppm, dry weight), whereas hair of bears sampled at more remote areas in the greater Yellowstone ecosystem have low mercury contents (0.006–0.09 ppm, dry weight). This observation provides strong evidence that mercury in grizzly bears is derived from feeding on spawning cutthroat trout in the spring and early summer. Studies of mercury and metal contents in other grizzly bear food sources (plants and animals) show that only cutthroat trout are strongly enriched in mercury. These data can potentially be used to quantify the percentage of the bear population that eats cutthroat trout and to determine how far individual bears travel to Yellowstone Lake to eat them. A third investigation describes carbon-, nitrogen-, and sulfur-isotope compositions in grizzly bears and in some of their foods and describes how these data can be applied to studies of grizzly bear demographics. δ13C values in the Yellowstone ecosystem range from –21.7 ‰ to –30.4 ‰, a range that reflects the influence of C3 plants on the carbon reservoir and probably the effect of elevation on physiological processes. δ15N values range from –2.3 ‰ to 11.0 ‰ and show classical trophic enrichments with respect to most grizzly bear food sources. Cutthroat trout δ15N values (8.3±1.0 ‰) may reflect the importance of sublacustrine hydrothermal springs to the food chain in Yellowstone Lake. Lake trout have even larger δ15N values (11.0±0.4 ‰) that are consistent with their feeding on cutthroat trout. Grizzly bear δ15N values range from 7.0 ‰ to 8.8 ‰. Although grizzly bears are known to eat cutthroat trout, trophic enrichment in δ15N above values found in trout is not apparent in analyses of bear hair. This discrepancy occurs because δ15N values are averaged over one year and include the significantly lower δ15N values of vegetable food sources consumed by bears while their hair is growing. δ34S values in the ecosystem range from –3.1 ‰ to 11.1 ‰. δ34S values of fish (1.2±0.5 ‰) are nearly the same as those in sulfate from thermal springs. Vegetation (clover, cow parsnip, and spring beauty), ungulates (deer, elk, and bison), and moths show a greater range of δ34S values (–3.3 ‰ to 3.2 ‰). However, bears show higher δ34S values (3.2 ‰ to 5.4 ‰ in muscle and 6.1 ‰ to 8.7 ‰ in hair) that are consistent with the consumption of whitebark pine nuts (δ34S = 8.3 ‰ to 11.4 ‰). δ34S values in bears and their food sources seem to be constrained by the major sources of sulfate and sulfide sulfur in the igneous and sedimentary rocks that underlie much of the Park. The large δ34S values found in bear tissues are consistent with the documented fact that most grizzly bears eat substantial amounts of whitebark pine nuts when available. This consumption occurs during hair growth in the fall, thus providing an isotopic marker that may be useful in quantifying nut consumption in individual bears. These three studies show some different ways that geochemical techniques can be applied to biologic issues. The results suggest that integration of geochemistry into specific biologic studies may help address issues of interest to wildlife managers in Yellowstone National Park and the greater Yellowstone ecosystem