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D. P. Klein

Publications and source records attributed to D. P. Klein.

18 recordsLinked to original sources
USGS2012

Crustal resistivity structure from magnetotelluric soundings in the Colorado Plateau-Basin and Range provinces, central and western Arizona

Resistivity structure to about 25 km depth is defined from two-dimensional modeling of 29 magnetotelluric (MT) soundings (0.002–5 Hz) that traverse 280 km of the southwestern Colorado Plateau, transition zone, and Basin and Range provinces in Arizona. From the surface to 5 km depth, the MT model suggests structural relationships between low-resistivity sedimentary and volcanic rocks (50–300 ohm m) and high-resistivity granitic and gneissic basement (500–9000 ohm m). In the Basin and Range province, the MT model and a seismic reflection section show a generally consistent distribution of supracrustal rocks that have relatively low to moderate resistivity (MT) and relatively strong, locally coherent reflectivity. The supracrustal zone defined by these physical properties is inferred to be composed of upper plate rocks above a middle Tertiary detachment fault system which has been mapped in surrounding ranges. Some low-angle fault zones inferred from seismic reflections to extend into high resistivity basement below the supracrustal rocks are not resolved by the MT model. A low-resistivity zone with a conductance of 500 S or more is modeled in the crust at an average depth of about 15 km in the Basin and Range province and transition zone and may deepen below the southwestern part of the Colorado Plateau. In the Basin and Range province, the top of the low resistivity may correspond to a reflective layer with a 6-s two-way-travel time. This deep low-resistivity zone might be caused by a small fraction of connected hydrous solutions or silicic melts.

Journal of Geophysical Research↗
USGS2002

Geologic investigations in the Lake Valley area, Sierra County, New Mexico

At the request of the Bureau of Land Management, the U.S. Geological Survey evaluated the area of the historic Lake Valley mining district and townsite, Sierra County, New Mexico, for its potential for undiscovered mineral resources. The four chapters of this report describe the geology of the area, present the results of geophysical investigations carried out to aid in interpreting subsurface geology, describe the mining history and character of the region's ore deposits, and present geochemical data on potential for contamination from abandoned mine dumps in the mining district.

New Mexico↗
USGS1998

Geology and mineral resources of the Lake Valley area, Sierra County, New Mexico

At the request of the Bureau of Land Management, the U.S. Geological Survey assessed the Lake Valley Area of Critical Environmental Concern (ACEC), which includes the historic Lake Valley townsite and silver-manganese mining district, for undiscovered mineral resources. The Lake Valley ACEC is along the southeastern margin of the Black Range of western Sierra County, New Mexico. The Black Range contains eleven mining districts from which silver, lead, zinc, manganese, copper, gold, and tin have been recovered. As part of the study, an area of over 75 square mi (195 square km) in the area of the Lake Valley ACEC was mapped to understand ore controls and to assess mineral-resource potential. Lake Valley mining district is in Mississippian Lake Valley Formation carbonate rocks, but much of the surrounding terrane consists of volcanic rocks on the southeastern edge of the Emory cauldron which formed about 34.9 Ma. Volcanic rocks are part of the Mogollon-Datil volcanic province which include flows, breccias, ash-flow tuffs, and intrusive rhyolites. The Lake Valley mining district is located about 20 mi (32 km) south of the Late Cretaceous Laramide copper-gold porphyry intrusion at Hillsboro. It is also located at the western boundary of the Rio Grande rift basin.The Lake Valey fault is the major structural feature of the study area. Geological and geophysical data suggest the fault is composed of two segments: a southern, northwest-striking segment that may have a pre-Tertiary history and a northerly-striking segment that is part of the Emory cauldron ring fracture. The mining district is bounded by the southern, northwest-striking segment of the fault which may have up to 800 ft (240m) of normal offset. Deposit types identified in the Black Range, and for which we assess mineral potential, are Laramide porphyry, Laramide skarns, Laramide veins, gold placer, carbonate-hosted, volcanic-epithermal, and rhyolite tin; no Rio Grande Rift baritefluorite-galena deposits are known, but they are included in the assessment. The most likely deposits to be discovered in the Lake Valley district are carbonate-hosted silver-manganese deposits. These deposits could be deposited by hydrothermal fluids or be related to intrusion of Oligocene rhyolite or Laramide porphyry. An aeromagnetic high south of the district probably reflects a small felsic intrusion of unknown age. We assess the Lake Valley ACEC as having low to moderate potential for undiscovered carbonate-hosted deposits associated with volcanic rocks or Laramide porphyry plutons, and low potential for gold placer and rhyolite tin deposits.

New Mexico↗
USGS1992

The Conterminous United States Mineral Assessment Program: Background information to accompany folio of geologic, geochemical, geophysical, and mineral resource maps of the Ajo and Lukeville 1° by 2° quadrangles, Arizona

Encompassing about 21,000 km 2 in southwestern Arizona, the Ajo and Lukeville 1° by 2° quadrangles have been the subject of mineral resource investigations utilizing field and laboratory studies in the disciplines of geology, geochemistry, geophysics, and Landsat imagery. The results of these studies are published as a folio of maps, figures, and tables, with accompanying discussions. Past mineral production has been limited to copper from the Ajo Mining District. In addition to copper, the quadrangles contain potentially significant resources of gold and silver; a few other commodities, including molybdenum and evaporites, may also exist in the area as appreciable resources. This circular provides background information on the mineral deposits and on the investigations and integrates the information presented in the folio. The bibliography cites references to the geology, geochemistry, geophysics, and mineral deposits of the two quadrangles.

Arizona↗
USGS1983

Geoelectric structure of the Gila-San Francisco Wilderness Area, Graham and Greenlee Counties, Arizona, from audio-magnetotelluric data

Electromagnetic induction data using distant field sources, mostly of natural origin, in the frequency range of 4.5-27,000 Hz are analyzed to depict the geoelectric structure in an area of volcanic-rock cover located in southeastern Arizona between the Morenci and Safford porphyry copper deposits. The data for each station consist of scalar electromagnetic measurements at descrete frequencies for two-orthogonal magnetic and electric field pairs. Observations spaced about 5-km apart indicate resistivities in the range of 100-700 ohm-m for the unweathered Tertiary volcanic rocks to a depth of 200 to 500 m. Beneath this zone the data indicate resistivities in the range of 10-100 ohm-m that suggest the existence of an older volcanic rock unit. The less resistive unit appears to be displaced upward beneath Turtle Mountain, an area bounded to the northeast and southwest by mapped Basin and Range faults, and bounded to the southeast by an unmapped fault of older origin that trends northeast. Lateral changes in the resistivity of the two main geoelectric layers result in lowered resistivity in an area of known hot-springs near the confluence of the Gila and San Francisco Rivers, as well as along a north-south trending zone located on the east flank of Turtle Mountain, about 5-km (3-mi) west-northwest of the hot springs. This second anomaly is at a probable depth of 400-500 m and is interpreted to indicate a buried fault or fracture zone.

Arizona↗