Publications

The Cactus Queen Mine is located in the western Mojave Desert in Kern County, California. The Cactus Queen gold-silver (Au-Ag) deposit is similar to other Au-Ag deposits hosted in Miocene volcanic rocks that consist of silicic domes and associated flows, pyroclastic rocks, and subvolcanic intrusions. The volcanic rocks were emplaced onto a basement of Mesozoic silicic intrusive rocks. A...

This isostatic residual gravity map is part of a regional effort to investigate the tectonics and water resources of the central Coast Range. This map serves as a basis for modeling the shape of basins and for determining the location and geometry of faults in the area. Local spatial variations in the Earth's gravity field (after removing variations caused by instrument drift, earth...

No abstract available.

Ground magnetic data contain information, not pre-sent in aeromagnetic data, which may be useful for precisely mapping near-surface faults and contacts, as well as constraining or aiding interpretation of other geophysical methods. However, collecting ground magnetic data on foot is labor-intensive and is therefore limited to small surveys. In this article, we present two newly developed...

This multimedia model and report show and describe digital three-dimensional faulted surfaces and volumes of lithologic units that confine and constrain the basin-fill aquifers within the Espanola Basin of north-central New Mexico. These aquifers are the primary groundwater resource for the cities of Santa Fe and Espanola, six Pueblo nations, and the surrounding areas. The model...

In Yucca Flat, on the Nevada National Security Site in southern Nevada, the migration of radionuclides from tests located in the alluvial deposits into the Paleozoic carbonate aquifer involves passage through a thick, heterogeneous section of late Tertiary and Quaternary alluvial sediments. An understanding of the lateral and vertical changes in the material properties of the alluvial...

An investigation of vadose zone weathering processes has been undertaken on grussic saprolites developed on Californian granitoids. Preliminary results indicate strong climatic control, through infiltration, on the depth and intensity of weathering. At sites with higher infiltration, the vadose zone is comprehensively altered to grussic saprolite and saprock. Conversely, lower...

Self-potentials (SP) are sensitive to water fluxes and concentration gradients in both saturated and unsaturated geological media, but quantitative interpretations of SP field data may often be hindered by the superposition of different source contributions and time-varying electrode potentials. Self-potential mapping and close to two months of SP monitoring on a gravel bar were...

The Greater Platte River Basin area spans a central part of the Midcontinent and Great Plains from the Rocky Mountains on the west to the Missouri River on the east, and is defined to include drainage areas of the Platte, Niobrara, and Republican Rivers, the Rainwater Basin, and other adjoining areas overlying the northern High Plains aquifer. The Greater Platte River Basin contains...

The Stanford Ultra-Low Frequency Electromagnetic (ULF-EM) Monitoring Project is recording naturally varying electromagnetic signals adjacent to active earthquake faults, in an attempt to establish whether there is any variation in these signals associated with earthquakes. Our project is collaborative between Stanford University, the U.S. Geological Survey (USGS), and UC Berkeley. Lead...

What are the roles of deep Precambrian basement deformation zones in the localization of subsequent shallow-crustal deformation zones and magmas? The Paleoproterozoic Great Falls tectonic zone and its included Boulder batholith (Montana, United States) provide an opportunity to examine the importance of inherited deformation fabrics in batholith emplacement and the localization of...

The San Jacinto right-lateral strike-slip fault zone is crucial for understanding plate-boundary dynamics, regional slip partitioning, and seismic hazards within the San Andreas fault system of southern California, yet its age of initiation and long-term average slip rate are controversial. This synthesis of prior and new detailed studies in the western Salton Trough documents initiation...