Publications

A geophysical survey was conducted to determine the depth of the base of the water-table aquifer in the southern part of Jackson Hole, Wyoming, USA. Audio-magnetotellurics (AMT) measurements at 77 sites in the study area yielded electrical-resistivity logs of the subsurface, and these were used to infer lithologic changes with depth. A 100–600 ohm-m geoelectric layer, designated the Jackson aquife

The Thermal Emission Spectrometer spectra of low albedo surface materials suggests that a four to one mixture of pyroxene to plagioclase, together with about a 35 percent dust component provides the best fit to the spectrum. Qualitative upper limits can be placed on the concentration of carbonates (

The U.S. Geological Survey is conducting research on the impacts of produced waters on petroleum resource development and the environment. Ongoing multidisciplinary investigations are focused on the 1) quantity and quality of current water production, 2) geologic and geochemical parameters that influence the viability of injection wells, and 3) processes that affect the dispersion of inorganic and

Calcite is ubiquitous at Yucca Mountain, occurring in the soils and as fracture and cavity coatings within the volcanic tuff section. Strontium is a trace element in calcite, generally at the tens to hundreds of ppm level. Because calcite contains very little rubidium and the half-life of the 87Rb parent is billions of years, the 87Sr/86Sr ratios of the calcite record the ratio in the water from w

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No abstract available.

No abstract available.

Molybdenum (Mo) is an essential element for many plants and animals (Newton and Otsuka, 1980). Because of its chemical properties, Mo readily provides sites for reactions and catalysis in biochemical systems (Haight and Boston, 1973). It is therefore important to understand the processes that control the distribution, speciation, and behavior of Mo in the surficial environment. These processes wil

Since the first studies of sulfur isotope variations in natural materials (Thode, 1949), it has been apparent that there are large and dramatic variations of 34S/32S ratios and that sulfur isotope studies are a powerful tool for interpreting the origins of sulfur-bearing minerals. However, sulfur is such a common element in the Earth's crust (sixteenth most abundant, averaging 0.03 wt %; Mason, 19

The genesis of gold deposits along the Carlin trend is not fully understood. Many of the significant mineral deposits in the Carlin trend were formed during the Tertiary as a result of interrelated high-angle basin-and-range faulting, intrusive igneous activity, and hydrothermal processes (Radtke, 1985). According to Shawe (1991), the linearity of the gold deposits along the Carlin trend and the s

Comprehensive models of ore genesis incorporate metal sources, transport and concentration mechanisms, and preservation mechanisms. Analogous concepts apply to the problem of metal migration from mines, mine wastes, and mine tailings, including: the concentrations, mineralogical occurrence, and availability of metals in mineral deposits, host rocks, mine wastes, and tailings (the source); the mech

Mining of mineral deposits in the Rocky Mountains has left a legacy of acidic inflows to otherwise pristine upland watersheds. Since 1986, the U.S. Geological Survey has studied physical, chemical, and biological processes that affect the transport and transformation of metals in St. Kevin Gulch, an acidic, metal-rich stream near Leadville, Colorado. Well-known chemical processes have been quantif