USGS Science⌕ Search

SEARCH · USGS Science

Results for “Geothermics”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46Linked to original sources

Finite-difference model of two-dimensional, single, and two-phase heat transport in a porous medium - Version I

Model documentation is presented for a two-dimensional (areal) heat-transport model capable of simulating both water- and vapor-dominated geothermal reservoirs that conform with the assumptions of the model. Finite-difference techniques are used to solve for the dependent variables pressure and enthalpy. The program is designed to simulate time-dependent problems such as those associated with geothermal reservoirs undergoing exploitation, and can treat the transition from compressed water to two-phase flow. In order to simulate more complicated field problems the present program is being extended, and therefore the model described in this report is referred to as VERSION I. A listing of the computer code is included. (Woodard-USGS)

Open-File Report↗

Preliminary catalog of earthquakes in northern Imperial Valley, California, October 1, 1976 - December 31, 1976

The northern section of the Imperial Valley region in Southern California is an area of known geothermal resources and an area of high seismicity. To study in detail the relationship between geothermal areas and earthquakes, the U.S. Geological Survey has been monitoring seismicity in the Imperial Valley with a sixteen station network since 1973. Six new stations were added to the network in November 1976. This catalog contains a description of the network and a list of preliminary data on earthquakes recorded by the network from October 1976 through December 1976

California↗

Summary of basic hydrologic data collected at Coso Hot Springs, Inyo County, California

More than 200 wells and springs were visited within a 20-mile radius of Coso Hot Springs, Calif. Hydrologic and geothermal data were collected for each well or spring site. The data includes depth, chemical quality, temperature and specific conductance of water, quantity of flow, well construction, and well logs. These data show that the normal temperature gradient in the ground is about 1.1 degrees Celsius (2 degrees Fahrenheit) per 100 feet. The temperature gradient in the thermal areas is as high as 24.4 degrees Celsius (44 degrees Fahrenheit) per 100 feet. The highest temperature measured for all the wells and springs was 142.2 degrees Celsius (288 degrees Fahrenheit). The chemical quality of water in the study area is generally good except in areas where water evaporates from land surface at Owens Valley playa or where steam escapes into the atmosphere from land surface. Computerized hydrologic and geothermal data are being stored for future use at the U.S. Geological Survey office, Laguna Niguel, Calif. (Woodard-USGS)

Open-File Report↗

Preliminary catalog of earthquakes in northern Imperial Valley, California: July 1977-September 1977

The northern section of the Imperial Valley region in southern California is an area of known geothermal resources and an area of high seismicity. To study in detail the relationship between geothermal areas and earthquakes, the U.S. Geological Survey has been monitoring seismicity in the Imperial Valley with a 16 - station network since 1973. Six new stations were added to the network in November 1976. This catalog contains a description of the network and a list of preliminary data on earthquakes recorded by the network from July 1977 through September 1977.

California↗

Electronic thermal sensor and Landsat data collection platform technology

Five Data Collection Platforms (DCP) were integrated electronically with thermal sensing systems, emplaced and operated in an analog mode at selected thermally significant volcanic and geothermal sites. The DCP's transmitted 3260 messages comprising 26,080 ambient, surface, and near-surface temperature records at an accuracy of ± 1.15 ° C for 1121 instrument days between November 14, 1972 and April 17, 1974. In harsh, windy, high-altitude volcanic environments the DCP functioned best with a small dipole antenna. Sixteen kg of alkaline batteries provided a viable power supply for the DCP systems, operated at a low-duty cycle, for 5 to 8 months. A proposed solar power supply system would lengthen the period of unattended operation of the system considerably. Special methods of data handling such as data storage via a proposed memory system would increase the significance of the twice-daily data reception enabling the DCP's to record full diurnal-temperature cycles at volcanic or geothermal sites. Refinements in the temperature-monitoring system designed and operated in experiment SR 251 included a backup system consisting of a multipoint temperature scanner, a servo mechanism and an analog-to-digital recorder. Improvements were made in temperature-probe design and in construction of corrosion-resistant seals by use of a hydrofluoric-acid-etching technique.

Open-File Report↗

Preliminary catalog of earthquakes in northern Imperial Valley, California, January 1978-March 1978

The northern section of the Imperial Valley region in southern California is an area of known geothermal resources and an area of high seismicity. To study in detail the relationship between geothermal areas and earthquakes, the U.S. Geological Survey has been monitoring seismicity in the Imperial Valley with a 16-station network sines 1973. Six new stations were added to the network in November 1976. This catalog contains a description of the network and a list of preliminary data on earthquakes recorded by the network from January 1978 through March 1978.

Open-File Report↗

Preliminary catalog of earthquakes in northern Imperial Valley, California, October 1977-December 1977

The northern section of the Imperial Valley region in southern California is an area of known geothermal resources and an area of high seismicity. To study in detail the relationship between geothermal areas and earthquakes, the U.S. Geological Survey has been monitoring seismicity in the Imperial Valley with a 16-station network since 1973. Six new stations were added to the network in November 1976. This catalog contains a description of the network and a list of preliminary data on earthquakes recorded by the network from October 1977 through December 1977.

California↗

Preliminary catalog of earthquakes in northern Imperial Valley, California, January 1, 1977 to March 31, 1977

The northern section of the Imperial Valley region in Southern California is an area of known geothermal resources and an area of high seismicity. To study in detail the relationship between geothermal areas and earthquakes, the U.S. Geological Survey has been monitoring seismicity in the Imperial Valley with a sixteen station network since 1973. Six new stations were added to the network in November 1976. This catalog contains a description of the network and a list of preliminary data on earthquakes recorded by the network from January 1977 through March 1977.

California↗

Mineral resources of the Minarets Wilderness and adjacent areas, Madera and Mono counties, California

A mineral survey of the Minarets Wilderness area and adjacent areas in the central Sierra Nevada, Calif., was conducted during 1973 through 1975. The total area covers about 620 km 2 (237 sq mi) in the Sierra and Inyo National Forests, of which about 440 km 2 (170 sq mi) are within the officially designated Minarets Wilderness. The mineral resource potential was evaluated by geological, geochemical, and geophysical studies by the U.S. Geological Survey, and by examination of mineralized rocks, prospects, and mining claims by the U.S. Bureau of Mines. The results of the survey indicate that the study area has small to moderate submarginal to paramarginal resources of copper, silver, zinc, lead, iron, and tungsten and an unevaluated potential for molybdenum resources. Limestone is present, but not of commercial quantity or quality. No other industrial minerals have been recognized in quantity. Granitic rocks have potential use as decorative stone and sand and gravel could be produced from either alluvial deposits or glacial drift. However, these commodities are more accessible elsewhere at localities closer to markets. The study area has no potential for fossil fuels, and, because of the general geologic environment, the potential for nuclear fuel minerals is considered to be low. The study area has low geothermal potential, even though it is on the western edge of the Mono-Long Valley "Known Geothermal Resource Area" (KGRA). The area is underlain by metavolcanic and metasedimentary rocks that have been intruded by granitic rocks of the Sierra Nevada batholith. Pliocene volcanic rocks are present locally. With few exceptions, the known occurrences of mineralized rock are confined to the metamorphic rocks, and the exceptions appear to be confined to plutonic rocks that are older than the Late Cretaceous granitic rocks that make up the bulk of the batholithic rocks in the study area. Although no mineral production has been recorded from prospects within the study area, mines adjacent to it have produced significant amounts of gold and tungsten. Production figures are incomplete, but mines in the Mammoth mining district (fig. 1) may have produced as much as $1 million worth of gold, silver, and other metals at the then-existing prices. The Monte Cristo mine in the Mammoth district was in production during 1978.

California↗

Preliminary catalog of earthquakes in northern Imperial Valley, California, October 1978-December 1978

The northern section of the Imperial Valley region in southern California is an area of known geothermal resources and high seismicity. To investigate the relationship between geothermal areas and earthquakes in the Imperial Valley, a 16-station seismic network was established in early 1973 by the U. S. Geological Survey. Six more stations were added to the network in November 1976. This catalog contains a description of the network and a list of preliminary data on earthquakes detected and recorded by the network from October 1978 through December 1973.

California↗

Preliminary catalog of earthquakes in northern Imperial Valley, California, July 1978 - September 1978

The northern section of the Imperial Valley region in southern California is an area of known geothermal resources and high seismicity. To investigate the relationship between geothermal areas and earthquakes in the Imperial Valley, a 16-station seismic network was established in early 1973 by the U. S. Geological Survey. Six more stations were added to the network in November 1976. This catalog contains a description of the network and a list of preliminary data on earthquakes detected and recorded by the network from July 1978 through September 1978.

California↗

Supplemental data from the Ennis and other thermal-springs areas, Southwestern Montana, 1978-80

Hydrogeologic data were collected principally during 1978-80 in eight hot-spring areas, in the Marysville geothermal test well, in the Butte Mine and in the Bitterroot and Missoula River valleys to provide a basis for evaluating the geothermal potential of the areas. Measurements are tabulated for subsurface temperatures, water levels, rates of flow, and the chemical composition of water and gas in wells and test holes. Most of the data are for the area near Ennis Hot Springs.

Montana↗

Potential hydrologic effects of developing coal and other geo-energy resources of Oregon; a review

Southwestern Oregon has several hundred million tons of good-quality minable coal. Because of the dip of the coal beds, the only economical method of mining would be by underground methods. In addition, minor occurrences of low-quality coal have been noted at more than 20 sites in both western and northeastern Oregon. About 2 million acres are now under lease for petroleum and gas exploration across the State. Natural gas was discovered in northwestern Oregon in 1979, and current production is about 17 million cubic feet per day from five wells. Thirteen Known Geothermal Resource Areas in several parts of the State cover 432,000 acres, and more than 420,000 acres are under lease for geothermal exploration. No hydrologic impacts have been noted from exploration and production of coal or other geoenergy resources in Oregon. (USGS)

Open-File Report↗

Heat-flow measurements at shot points along the 1978 Saudi Arabia seismic deep-refraction line; Part II, Discussion and interpretation

The heat-flow profile across the Arabian Shield from Ar Riyad to Ad Darb and across the Red Sea is examined for compatibility with the lithospheric structure of the area as deduced from geologic and other geophysical data. Broad continental uplift associated with Red Sea rifting is symmetric about the Red Sea axis, and geologic and geochronologic evidence indicate that uplift has occurred mainly in the interval 25-13 Ma (mega-annum) ago. Thermal-profile changes in the upper mantle resulting from an influx of hot material associated with rifting yield the correct order of magnitude of uplift, and this mechanism is suggested as the explanation for the regional doming. A lithospheric section, constructed from seismic refraction, gravity, and regional geologic data, provides the framework for construction of thermal models. Thermal gradient measurements were made in drill holes at five shot points. Geotherms for the Shield, which assume a radiogenic heat-source distribution that decreases exponentially with depth, yield temperatures of about 450?C at a depth of 40 km (base of the crust) for shot points 2 (Sabhah) and 3. The geotherm for shot point 4 (near Bishah) yields a distinctly higher temperature (about 580?C) for the same depth. Static models used to model the heat flow in the oceanic crust of the Red Sea shelf and coastal plain either yield too small a heat flow to match the observed heat flow or give lithosphere thicknesses that are so thin as to be improbable. Dynamic (solid-state accretion) models, which account for mantle flow at the base of the lithosphere, adequately match the observed heat-flow values. In the deep-water trough of the Red Sea, which is presently undergoing active sea-floor spreading, classical models of heat flow for a moving slab with accretion at the spreading center are adequate to explain the average heat-flow level. At shot point 5 (Ad Darb), the anomalous heat flow of 2 HFU (heat-flow units) can be explained in terms of a Shield component (0.8-1.0 HFU) and a component related to heating by the abutting oceanic crust a few kilometers away for periods exceeding 10 Ma. Analytical results are included for: 1) the cooling of a static sheet with an initial temperature distribution characteristic of a moving slab in a sea-floor spreading environment, and 2) the heating of a homogeneous quarter-space at its vertical boundary.

Open-File Report↗

Laboratory investigations of the physics of steam flow in a porous medium

Experiments were carried out in the laboratory to test a theory of transient flow of pure steam in a uniform porous medium. This theory is used extensively in modeling pressure-transient behavior in vapor-dominated geothermal systems. Transient, superheated steam-flow experiments were run by bringing a cylinder of porous material to a uniform initial pressure, and then making a step increase in pressure at one end of the sample, while monitoring the pressure-transient breakthrough at the other end. It was found in experiments run at 100?, 125?, and 146?C that the time required for steam-pressure transients to propagate through an unconsolidated material containing sand, silt, and clay was 10 to 25 times longer than predicted by theory. It is hypothesized that the delay in the steam-pressure transient was caused by adsorption of steam in the porous sample. In order to account for steam adsorption, a sink term was included in the conservation of mass equation. In addition, energy transfer in the system has to be considered because latent heat is released when steam adsorption occurs, increasing the sample temperature by as much as 10?C. Finally, it was recognized that the steam pressure was a function of both the temperature and the amount of adsorption in the sample. For simplicity, this function was assumed to be in equilibrium adsorption isotherm, which was determined by experiment. By solving the modified mass and energy equations numerically, subject to the empirical adsorption isotherm relationship, excellent theoretical simulation of the experiments was achieved. The experiments support the hypothesis that adsorption of steam can strongly influence steam pressure-transient behavior in porous media; the results suggest that the modified steam-flow theory, which includes steam adsorption terms, should be used in modeling steam flow in vapor-dominated geothermal systems.

Open-File Report↗

Lake Ellen kimberlite, Michigan, U.S.A.

The recently discovered Lake Ellen kimberlite, in northern Michigan, indicates that bedrock sources of diamonds found in glacial deposits in the Great Lakes area could lie within the northern U.S. Magnetic surveys show a main kimberlite 200 m in diameter and an adjacent body 25 x 90 m(?). The kimberlite cuts Proterozoic volcanic rocks that overlie Archean basement, but is post-Ordovician in age based on abundant Ordovician(?) dolomite inclusions. Xenocrysts and megacrysts are ilmenite (abundant, 12.5-19% MgO), pyropealmandine and Cr-pyrope (up to 9.3% Cr2O3), Cr-diopside (up to 4.5% Cr2O3), olivine (Fo 91), enstatite and phlogopite. The kimberlite contains fragments of crustal schist and granulite, as well as disaggregated crystals and rare xenoliths of eclogites, garnet pyroxenites and garnet peridotites from a heterogeneous upper mantle. Eclogites, up to 3 cm size, show granoblastic equant or tabular textures and consist of jadeitic cpx (up to 8.4% Na20, 15.3% Al2O3), pyrope-almandine, ? rutile ? kyanite ? sanidine ? sulfide. Garnet pyroxenite contains pyrope--(0.44% Cr2O3) + cpx (0.85% Na2O, 0.53% Cr2O3) + Mg-Al spinel. Mineral compositions of rare composite xenocrysts of garnet + cpx are distinctively peridotitic, pyroxenitic or eclogitic. Calculated temperatures of equilibration are 920-1060 ?C for the eclogites and 820-910?C for the garnet pyroxenite using the Ellis-Green method. Five peridotite garnet-clinopyroxene composite xenocrysts have calculated temperatures of 980-1120?C using the Lindsley-Dixon 20 kb solvus. Spinel pyroxenite and clinopyroxene-orthopyroxene composites have lower calculated temperatures of 735?C and 820-900?C, respectively. Kyanite-bearing eclogites must have formed at pressures greater than 18-20 kb. Using the present shield geotherm with a heat flow value of 44mW/m 2 for the time of kimberlite emplacement, the eclogite temperatures imply pressures of 35-48 kb (105-140 km) and the garnet pyroxenite temperatures indicate pressures of 24-29 kb (75-90 km). Temperatures of two peridotitic garnet-cpx composite xenocrysts if on a shield geotherm, imply pressures within the diamond stability field.

Open-File Report↗

Garnet peridotites from Williams kimberlites, north-central Montana, U.S.A

Two Williams kimberlites, 250x350m and 37x390m, in the eastern part of a swarm of 30 middle Eocene alnoitic diatremes in north-central Montana, USA, contain xenoliths of garnet-bearing lherzolites, harzburgites and dunites, in addition to spinel peridotites and upper and lower crustal amphibolites and granulites. Colluvial purple, red, and pink garnets are dominantly Mg- and Cr-rich, indicating their derivation From peridotites or megacrysts, and have CaO and Cr 2 O 3 contents that fall in the lherzolite trend. Temperatures were calculated by the Lindsley-Dixon 20 kb method for lherzolites and by the O'Neill-Wood method for harzburgites and dunites, and pressures were calculated by the MacGregor method, or were assumed to be 50 kb for dunites. Most peridotites equilibrated at 1220-1350°C and 50-60 kb, well above a 44mW/m 2 shield geotherm and on or at higher P than the graphite-diamond boundary. Four lherzolites are low T-P (830-990°C, 23-42 kb) and are close to the shield geotherm. All four low T-P lherzolites have coarse textures whereas the high T-P cluster has both coarse and porphyroclastic textures, indicating a range of conditions of deformation and recrystallization in a restricted high T-P range. The tiny size (0.01-0.2 mm) of granulated and euhedral olivines in several xenoliths shows that deformation was occurring just prior to incorporation in kimberlite and that ascent was rapid enough (40-70 km/hr) to retard Further coarsening of fine-grained olivine. For other high T-P peridotites, cessation of deformation and beginning of recrystallization before or during inclusion in kimberlite is suggested by larger (up to 3mm) euhedral olivines in a matrix of fine granulated olivine or by optical continuity of large and nearby small olivines. Two low T-P lherzolites contain distinctive, phlogopite-rimmed, 5-8mm clots of moderate-Cr garnet + Cr-spinel + Cr-diopside + enstatite that are inferred to have formed by reaction of an initial high-Cr garnet brought into the garnet + spinel stability Field. This suggests a reduction in pressure and temperature prior to inclusion in the kimberlite, followed by metasomatic introduction of phlogopite. These textural and compositional variations of peridotites seem most compatible with kimberlite generation and ascent during dynamic diapiric perturbation of the upper mantle.

Montana↗

Arsenic and chloride data for five stream sites in the Madison River drainage, Montana, 1988

Enriched geothermal waters in Yellowstone National Park contribute large quantities of arsenic to the Madison River. Because arsenic may be acutely or chronically toxic to humans when ingested, it is of concern in the upper Missouri River basin where the water is used for domestic purposes. In passage of water downstream, concentrations of arsenic in the Madison and Missouri Rivers are diluted by tributary inflows. However, insufficient information existed to describe concentrations during runoff at specific locations. As a result, a monitoring network was established to better define arsenic concentrations during the 1988 peak runoff and during periods prior to and following the runoff. In addition to arsenic, samples were analyzed for chloride because of its association with geothermal water and specific conductance because it is a surrogate measure of dissolved-solids concentration. This report presents data acquired during 1988 at five sampling stations in the Madison River drainage. (USGS)

Open-File Report↗