Integrated Research Studies - Metal Cycling in Arid Environments
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Playa deposits in the Great Basin, southern California, and Arizona, contain significant quantities of trace metals and metalloids that accumulated from groundwater, geothermal water, and eolian dusts. These metals are reworked from mineralized bed rock, ore deposits, alluvium, and volcanic ash to form unusually large concentrations of environmental concern and possible economic potential. The playa deposits can, in turn, serve as a source of metals-laden eolian dust to downwind deposition areas. It is critically important for the USGS to be able to identify and characterize metals from this source to a) understand the stability and content of metals stored in the playa b) be able to determine the amount and pathway of metals transported from the playas and their impact on "background" metal concentrations in mineralized areas, both mined and unmined; c) understand the impact of climate, hydrologic and land-use changes on metal dispersion; and d) understand whether metals associated with dust could adversely impact the health of humans, domestic stock, and wildlife.
Currently there is no systematic, integrated approach to describing metal-rich playas. This subtask will support development of methods of solid earth geophysics, geochemistry and remote, spectral imaging to more thoroughly describe the metal-rich playas. Improved geophysical methods are needed to describe the extent of metaliferous solutions in the subsurface and evaluate probable flow paths. Geochemical understanding is lacking for the distribution of metals among precipitated salts and residual brines. Development of spectral methods would facilitate quick and broad-scale assessment of metals in these deposits, and they would allow for an assessment of changes in metals content, concentration, and distribution over time. The purpose of this subtask activity is to combine spectral, geophysical, and geochemical investigations to facilitate the development of remote, spectral identification of metals in playa deposits.
Our objectives are to:
- Assess the current "state-of-the-art" in the remote sensing community regarding the identification of metals content and mineralogy in playa deposits.
- Conduct geochemical investigations on the playa deposits, in regards to the suite of metals present, their concentrations, mineralogic associations, and variability among playas.
- Use the geochemical information to develop and refine spectral identification methods.
- Constrain the source and transport pathways of metals to the playa surface using geophysical methods.
In Review or In Press
Cutler, N.K., Stillings, L.L., McCormack, J.K., 2010, Sediment phase associations of tungsten in the alluvial aquifers, Fallon, Nevada: U.S. Geological Survey Open-File Report 2010-1175, in press.
Cutler, Nicole K., Stillings, Lisa L., and McCormack John K., Geochemistry and mineralogy of sediments, and solid phase partitioning of tungsten and other metals in the alluvial aquifers, Fallon, Nevada, in USGS review, to be submitted for external publication (Chemical Geology).
Cutler, Nicole K., Stillings, Lisa L., and Seiler, Ralph L., Geochemical controls on Tungsten concentration in groundwater aquifers, Fallon Nevada: in preparation.
Breit, G.N., Goldstein, H.L., Reynolds, R.L., and Yount, J.C., 2009, Distribution of major anions and trace elements in the unsaturated zone at Franklin Lake Playa, California, USA, in, Oren, A., Naftz, D., Palacios, P., and Wurtsbaugh, W.A.(eds.), Saline lakes around the world: Unique systems with unique values, Natural Resources and Environmental Issues, volume XV, S.J. and Jesse E. Quinney Natural Resources Research Library, Logan Utah, USA, p. 93-103.
Cutler, Nicole K., 2011,. The geochemistry of groundwater and sediments governing tungsten concentration in the basin-fill aquifers Fallon, Nevada: M.S. Thesis, University of Nevada Reno.
Fosbury, D., Walker, M., and Stillings, L.L., 2008, Chemical Analyses of Ground Water in the Carson Desert near Stillwater, Churchill County, Nevada, 2005: U.S. Geological Survey Open-File Report 2008-1201, 17 p.
Presentations, Posters, Abstracts
Cutler, N.K., Stillings, L.L., and McCormack, J.K., 2009, Sediment phase associations of tungsten in the alluvial aquifers, Fallon, Nevada: Geological Society of America Abstracts with Programs, v. 41, no. 7, p. 328. View Cutler GSA abstract.
Mackay School of Earth Sciences Mail Stop 176
Reno, NV 89557-0047
Subtask Contact: Lisa Stillings