Richard Zehner - Academia.edu (original) (raw)

Papers by Richard Zehner

Research paper thumbnail of Colorado Heat Flow Data from IHFC

This layer contains the heat flow sites and data of the State of Colorado compiled from the Inter... more This layer contains the heat flow sites and data of the State of Colorado compiled from the International Heat Flow Commission (IHFC) of the International Association of Seismology and Physics of the Earth's Interior (IASPEI) global heat flow database (www.heatflow.und.edu/index2.html). The data include different items: Item number, descriptive code, name of site, latitude and longitude, elevation, depth interval, number of temperature data, temperature gradient, number of conductivity measurement, average conductivity, number of heat generation measurements, average heat production, heat flow, number of individual sites, references, and date of publication.

Research paper thumbnail of New Geothermal Map Products at the Nevada Bureau of Mines and Geology as Part of the National Geothermal Data System

Recent updates to published maps, interactive maps and creation of map services have been an impo... more Recent updates to published maps, interactive maps and creation of map services have been an important component of Nevada’s contribution to the National Geothermal Data System. Updating and modernization to add new capabilities to geothermal maps is ongoing and will be presented to show how improvements benefit geothermal data users in both industrial and research applications in geothermal exploration. Examples of some of the map services will be presented.

Research paper thumbnail of Quaternary borate deposits as a geothermal exploration tool in the Great Basin

Geothermal Resources …, 2006

... Basin Mark F. Coolbaugh1, Chris Kratt2, Chris Sladek1, Richard E. Zehner1, and Lisa Shevenell... more ... Basin Mark F. Coolbaugh1, Chris Kratt2, Chris Sladek1, Richard E. Zehner1, and Lisa Shevenell1,3 ... Nevada. Samples 5/35-22bbb and 2/36-8adb are from Vandenburgh andGlancy (1970); sample WS8 is from Smith and Drever (1976). ...

Research paper thumbnail of Geothermal Site Assessment Using the National Geothermal Data System (NGDS), with Examples from the Hawthorne Ammunition Depot Area

This paper examines the features and functionality of the existing database, its integration into... more This paper examines the features and functionality of the existing database, its integration into the 50-state NGDS, and its usage in geothermal exploration and development. In particular, we examine the dataset for Hawthorne, NV, which has been supplemented extensively by ...

Research paper thumbnail of Technical Assistance from Lawrence Berkeley National Laboratory and National Energy Technology Laboratory to Elko Heat Company and the City of Wells, Nevada

Warm waters in several domestic and municipal water wells in and around the City of Wells, Nevada... more Warm waters in several domestic and municipal water wells in and around the City of Wells, Nevada, along with several hot springs a few kilometers away, suggest economical geothermal resources that could meet residential and commercial space heating demands, perhaps even geothermal electricity generation. To date, only a few low-temperature, single-user space heating applications have been developed. Under the U.S. Department of Energy’s Small Business Vouchers Pilot (SBV) Program, research teams from Lawrence Berkeley National Laboratory (LBNL) and the National Energy Technology Laboratory (NETL), in collaboration with the University of Nevada, Reno (UNR), Better Cities, and Lumos & Associates, advised the Elko Heat Company and the City of Wells in their recent drilling of a shallow geothermal gradient well, based on new field work along with a compilation and review of existing geologic, geochemical, geothermal, and geophysical data for this area. New field data include ground tem...

Research paper thumbnail of Effectiveness of 2-Meter and Geoprobe Shallow Temperature Surveys in Early Stage Geothermal Exploration

Cost-effective geothermal exploration involves a stepwise approach wherein the least expensive to... more Cost-effective geothermal exploration involves a stepwise approach wherein the least expensive tools that can advance (or reject) a property should be considered prior to more expensive techniques. Coolbaugh et al. (2007) demonstrated that shallow (2-meter) surveys were a cost-effective “direct push” tool that can identify and delineate geothermal outflow zones, prior to more expensive temperature gradient drilling. This paper evaluates the Geoprobe as another early-stage, direct push exploration tool that can collect water samples and temperature data at depths intermediate between 2 meters and typical temperature gradient drilling. In addition, the temperature relationship between surface anomalies identified by 2-meter surveys and the

Research paper thumbnail of Archuleta County CO Lineaments

This layer traces apparent topographic and air-photo lineaments in the area around Pagosa springs... more This layer traces apparent topographic and air-photo lineaments in the area around Pagosa springs in Archuleta County, Colorado. It was made in order to identify possible fault and fracture systems that might be conduits for geothermal fluids. Geothermal fluids commonly utilize fault and fractures in competent rocks as conduits for fluid flow. Geothermal exploration involves finding areas of high near-surface temperature gradients, along with a suitable plumbing system that can provide the necessary permeability. Geothermal power plants can sometimes be built where temperature and flow rates are high. To do this, georeferenced topographic maps and aerial photographs were utilized in an existing GIS, using ESRI ArcMap 10.0 software. The USA_Topo_Maps and World_Imagery map layers were chosen from the GIS Server at server.arcgisonline.com, using a UTM Zone 13 NAD27 projection. This line shapefile was then constructed over that which appeared to be through-going structural lineaments in both the aerial photographs and topographic layers, taking care to avoid manmade features such as roads, fence lines, and right-of-ways. These lineaments may be displaced somewhat from their actual location, due to such factors as shadow effects with low sun angles in the aerial photographs. Note: This shape file was constructed as an aid to geothermal exploration in preparation for a site visit for field checking. We make no claims as to the existence of the lineaments, their location, orientation, and nature.

Research paper thumbnail of Petrology structure and tectonic setting of the Hog Heaven volcanics and their relationship to mineralization

Latite porphyry and volcanic sediments. Volcanic sediments, latite porphyry, Ravalli Group Argill... more Latite porphyry and volcanic sediments. Volcanic sediments, latite porphyry, Ravalli Group Argillites (Belt). Thin veneer of volcanic sedi ments or ashflow atop Ravalli Group (Belt). Latite porphyry and volcanic sediments. South Battle Butte Mine Latite porphyry and Ravalli Group Argillites (Belt). Martin Prospect Donald Adit Kofford Ridge Prospect Margarite Mine Volcanic sediments. Pebbly tuff, latite porphyry. Volcanic sediments and Belt paleosol Volcanic sediments (?) and Ravalli Group (Belt).

Research paper thumbnail of Favorable Geochemistry from Springs and Wells in COlorado

Citation Information: Originator: Geothermal Development Associates, Reno Nevada Originator: Unit... more Citation Information: Originator: Geothermal Development Associates, Reno Nevada Originator: United States Geological Survey (USGS) Originator: Colorado Geological Survey Publication Date: 2012 Title: Favorable Geochemistry Edition: First Publication Information: Publication Place: Reno Nevada Publisher: Geothermal Development Associates, Reno, Nevada Description: This layer contains favorable geochemistry for high-temperature geothermal systems, as interpreted by Richard "Rick" Zehner. The data is compiled from the data obtained from the USGS. The original data set combines 15,622 samples collected in the State of Colorado from several sources including 1) the original Geotherm geochemical database, 2) USGS NWIS (National Water Information System), 3) Colorado Geological Survey geothermal sample data, and 4) original samples collected by R. Zehner at various sites during the 2011 field season. These samples are also available in a separate shapefile FlintWaterSamples.shp....

Research paper thumbnail of Geothermal Potential of the Pyramid Lake Paiute Reservation, Nevada, USA: Evidence of Previously Unrecognized Moderate-Temperature (150-170°C) Geothermal Systems

At least two and possibly tbree previously unrecognized moderate-temperature (I50-165°C) geotherm... more At least two and possibly tbree previously unrecognized moderate-temperature (I50-165°C) geothermal areas have been identified during a geothermal exploration program on the Pyramid Lake Paiute Reservation (PLPR) in west-central Nevada, USA. At each of these new areas -- Pyramid Rock, the southwestern Smoke Creek Desert (SWSMD), and east Astor Pass, -- as well as at the known Needle Rocks geothermal area, hot springs andlor near-surface upwellings of hot water are associated with calcium carbonate (tufa) towers forming today in Pyramid Lake or formed in late Pleistocene Lake Lahontan. The structural controls on geothermal fluid flow are still being investigated, but the intersection of Quaternary faults appears to have localized the shallow upwelling of thermal fluids. Near-surface thermal waters, where identified, have temperatures ranging up to 49-97°C, whereas quartz and Na-K -Ca-Mg geothermometers suggest reservoir temperatures on the order of -150 to 165°C. Exploration work beg...

Research paper thumbnail of Geothermal Exploration in the Vicinity of Wells, Nevada

Geothermal activity in and around the City of Wells, Nevada, is evidenced by hot springs and the ... more Geothermal activity in and around the City of Wells, Nevada, is evidenced by hot springs and the presence of hot waters in several private and municipal wells, suggesting that this area may host a commercially-viable geothermal resource. For this reason, under the U.S. Department of Energy’s Small Business Vouchers Pilot (SBV) Program, research teams from Lawrence Berkeley National Laboratory (LBNL) and the National Energy Technology Laboratory (NETL), in collaboration with the University of Nevada, Reno (UNR), worked closely with the Elko Heat Company, the City of Wells, and Better City to review existing data and conduct field studies to site a geothermal well for district heating and other direct use applications for the Wells community. This effort started with the compilation and review of existing structural, geochemical, and geophysical information for this area. New field investigations included the measurement of ground temperatures with shallow 2-meter probes and in deeper...

Research paper thumbnail of Papua New Guinea Country Update

Papua New Guinea (PNG) is an emerging economy which stands at the threshold of economic prosperit... more Papua New Guinea (PNG) is an emerging economy which stands at the threshold of economic prosperity but is constrained by the lack of access to reliable electricity. Located within the “ring of fire”, PNG has numerous active volcanoes and known geothermal systems. There are currently 55 MWe (gross) of geothermal power installed at Lihir Gold Mine in New Ireland Province. However, there have not been any additional power plants constructed in the past five years, mostly due to lack of adequate legislation and government support. The high cost of diesel and fuel oil, and the unpredictable nature of hydro power stations, has renewed strong interest in geothermal power. This paper is an overview of the current status of geothermal in PNG and progress being made to support further development.

Research paper thumbnail of Colorado Potential Geothermal Pathways

This layer contains the weakened basement rocks. Isostatic gravity was utilized to identify struc... more This layer contains the weakened basement rocks. Isostatic gravity was utilized to identify structural basin areas, characterized by gravity low values reflecting weakened basement rocks. Together interpreted regional fault zones and basin outlines define geothermal "exploration fairways", where the potential exists for deep, superheated fluid flow in the absence of Pliocene or younger volcanic units.

Research paper thumbnail of Geologic bibliography of the Mount Hayes Quadrangle, Alaska

Open-File Report, 1980

Brooks, A. H., 1906, The geography and geology o f Alaska, a summary o f e x i s t i n g knowledg... more Brooks, A. H., 1906, The geography and geology o f Alaska, a summary o f e x i s t i n g knowledge, w i t h a s e c t i o n on c l i m a t e b y Cleveland Abbe, J r. , and a t o p o g r a p h i c map and d e s c r i p t i o n t h e r e o f , b y R. U.

Research paper thumbnail of Geologic map of the southern part of Mount Hayes Quadrangle, Alaska

Research paper thumbnail of Preliminary geologic map of the Mount Hayes quadrangle, eastern Alaska Range, Alaska

Open-File Report, 1992

A suite of alkalic mafic and associated plutonic rocks occurs north of the Denali fault in the Wi... more A suite of alkalic mafic and associated plutonic rocks occurs north of the Denali fault in the Windy terrane, and in the Hayes Glacier and southern Jarvis Creek Glacier subterranes of the Yukon-Tanana terrane. The suite consists of lamprophyre, alkalic gabbro, alkalic diorite, and monzonite, and diorite in dikes,

Research paper thumbnail of Geologic maps of the eastern Alaska Range, Alaska (44 quadrangles, 1:63,360 scale), with descriptions and interpretations of map units

Limestone to marble composed of calcite with minor quartz, plagioclase, and sericite. Local skarn... more Limestone to marble composed of calcite with minor quartz, plagioclase, and sericite. Local skarn, devel oped in lenses up to 1 m thick along diabase-marble contact, composed of fine-to medium-grained schis tose calcite and minor epidote, hornblende, wollastonite, garnet, and clinopyroxene. Volcanic sandstone composed of fine-grained, rounded to subangular clasts of twinned and zoned plagio clase and minor quartz in matrix predominantly of chlorite. Authigenic analcite replaces and cements clasts in some calcareous sandstone. Calcareous volcanic graywacke composed of abundant twinned and zoned plagioclase clasts up to 1.5 mm long in a fine-grained, sparsely fossiliferous matrix of calcite and minor epidote and white mica. Presence of graded bedding, poor sorting, and slump structures indicates sedimentary and volcaniclastic strata depos ited from turbidity currents in a low-energy environment below wave base located near active volcanic vents (Bond, 1973, 1976). Andesite has intergranular to ophitic porphyritic texture. Composed of twinned and zoned plagioclase phenocrysts locally resorbed and sparse glomerocrysts up to 3.5 mm long and local hornblende phenocrysts up to 2 mm long, in a fine-grained to felty groundmass of plagioclase, quartz, and white mica. Locally amygdules filled with clinozoisite and chlorite. Andesite tuff composed of angular to subangular plagioclase fragments in matrix predominantly of clay minerals, opaque minerals, and locally abundant calcite. Hornblende(?) completely replaced by chlorite. Diabase composed of fine-grained plagioclase and clinopyroxene and minor opaque minerals, chlorite, and epidote. Relict minerals are plagioclase and sparse hornblende, quartz, clinopyroxene, and opaque minerals. Metamorphic minerals are chlorite, epidote, calcite, and white mica. Dacitic to rhyodacitic ash to lapilli tuffs, green to gray, mainly broken plagioclase, quartz, K-feldspar, and lithic fragments in matrix of very-fine-grained aggregate of quartz, feldspar, chlorite and local leucoxene. Plagioclase commonly twinned. Pumice fragments preserved as irregular platelets and disks of chlorite with porous or tubular texture. Lithic fragments angular; composed of a variety of volcanic rocks exhibiting por phyritic, trachytic, pilotaxitic, glassy, microvesicular, and scoriaceous textures. Locally stratified due to var iation in grain size, color, and grading. Local normal and double grading. A 200-m-thick, unstratified lapilli tuff in northwest Mount Hayes A-3 Quadrangle exhibits distinctive large aerial extent, lack of K-feldspar, and coarse pumice fragments ranging from less than 1 cm to nearly 1 m long (Bond, 1976). Green to grayish green debris-flow deposits composed of poorly sorted angular fragments, from 5 to 20 cm across and locally imbricate, in a matrix of sand, silt, and mud. Angular fragments composed of volcanic rock fragments, plagioclase, quartz, and fossil debris. Matrix mainly microcrystalline quartz, fine chlorite, and/or sericite, and leucoxene. Individual beds range in thickness from a few centimeters to about 18 m. Upper parts of beds often graded, with thin, laminated tops (Bond, 1976). Gray, brown, or green poorly sorted sandstone and graywacke beds, from 2 cm to more than 1 m thick; inter bedded with subordinate, massive or laminated, silty claystones from a few centimeters to a few meters thick. Beds graded but lack internal current features such as crossbedding, convoluted bedding, parallel lamination, or ripple-drift lamination. Grain size ranges from pebbles to fine sand. Clasts mainly angular to subangular. Clasts composed of andesitic(?) fragments, plagioclase, and quartz. Volcanic rock fragments exhibit pyroclastic, pilotaxitic, trachytic, glassy, and sparse scoriaceous and pumiceous textures. Matrix chiefly a dark, microcrystalline aggregate of chlorite and leucoxene and minor amounts of quartz and feld spar (Bond, 1976). Unit metamorphosed to lower greenschist facies. Well exposed in south-central and southeastern Mount Hayes Quadrangle, south of Denali fault and Broxson Gulch thrust, and north of Eureka Creek fault. Under lies Eagle Creek Formation. Overlies volcaniclastic rocks member (P*sl). P*sl VOLCANICLASTIC ROCKS MEMBER-Dark gray, dark green, and maroon volcanic and volcaniclastic rocks. Chiefly volcanic flows interbedded with lapilli tuff, volcanic breccia, graywacke, argillite, and lime stone to marble. Local massive to bedded conglomerate, graywacke, and siltstone. Volcaniclastic rocks con tain abundant volcanic rock fragments and relict pumice, exhibiting trachytic, scoriaceous, and relict glassy textures. Limestone to marble

Research paper thumbnail of With contributions for selected areas from

dggs.alaska.gov

... George Plafker, and Donald H. Richter, for assisting in part of the bedrock geologic mapping,... more ... George Plafker, and Donald H. Richter, for assisting in part of the bedrock geologic mapping, and L. David Carter, Thomas D. Hamilton, and ... We appreciate the excellent discussions and field tours provided by Clint Nauman and Steven Newkirk of some of the massive sulfide ...

Research paper thumbnail of Assessment of Exploration Bias in Data-Driven Predictive Models and the Estimation of Undiscovered Resources

Natural Resources Research, 2007

The spatial distribution of discovered resources may not fully mimic the distribution of all such... more The spatial distribution of discovered resources may not fully mimic the distribution of all such resources, discovered and undiscovered, because the process of discovery is biased by accessibility factors (e.g., outcrops, roads, and lakes) and by exploration criteria. In data-driven predictive models, the use of training sites (resource occurrences) biased by exploration criteria and accessibility does not necessarily translate to a biased predictive map. However, problems occur when evidence layers correlate with these same exploration factors. These biases then can produce a data-driven model that predicts known occurrences well, but poorly predicts undiscovered resources. Statistical assessment of correlation between evidence layers and map-based exploration factors is difficult because it is difficult to quantify the “degree of exploration.” However, if such a degree-of-exploration map can be produced, the benefits can be enormous. Not only does it become possible to assess this correlation, but it becomes possible to predict undiscovered, instead of discovered, resources. Using geothermal systems in Nevada, USA, as an example, a degree-of-exploration model is created, which then is resolved into purely explored and unexplored equivalents, each occurring within coextensive study areas. A weights-of-evidence (WofE) model is built first without regard to the degree of exploration, and then a revised WofE model is calculated for the “explored fraction” only. Differences in the weights between the two models provide a correlation measure between the evidence and the degree of exploration. The data used to build the geothermal evidence layers are perceived to be independent of degree of exploration. Nevertheless, the evidence layers correlate with exploration because exploration has preferred the same favorable areas identified by the evidence patterns. In this circumstance, however, the weights for the “explored” WofE model minimize this bias. Using these revised weights, posterior probability is extrapolated into unexplored areas to estimate undiscovered deposits.

Research paper thumbnail of Prediction and discovery of new geothermal resources in the Great Basin: Multiple evidence of a large undiscovered resource base

Geothermal Resources …, 2006

... Mark F. Coolbaugh1, Gary L. Raines2, Richard E. Zehner1, Lisa Shevenell1,3, and Colin F. Will... more ... Mark F. Coolbaugh1, Gary L. Raines2, Richard E. Zehner1, Lisa Shevenell1,3, and Colin F. Williams4 ... Coolbaugh, MF, Faulds, JE, Kratt, C., Oppliger, GL, Shevenell, LA, Calvin, WM, Ehni, WJ, and Zehner, RE, 2006b, Geothermal Potential of the Pyramid Lake Paiute Reservation ...

Research paper thumbnail of Colorado Heat Flow Data from IHFC

This layer contains the heat flow sites and data of the State of Colorado compiled from the Inter... more This layer contains the heat flow sites and data of the State of Colorado compiled from the International Heat Flow Commission (IHFC) of the International Association of Seismology and Physics of the Earth's Interior (IASPEI) global heat flow database (www.heatflow.und.edu/index2.html). The data include different items: Item number, descriptive code, name of site, latitude and longitude, elevation, depth interval, number of temperature data, temperature gradient, number of conductivity measurement, average conductivity, number of heat generation measurements, average heat production, heat flow, number of individual sites, references, and date of publication.

Research paper thumbnail of New Geothermal Map Products at the Nevada Bureau of Mines and Geology as Part of the National Geothermal Data System

Recent updates to published maps, interactive maps and creation of map services have been an impo... more Recent updates to published maps, interactive maps and creation of map services have been an important component of Nevada’s contribution to the National Geothermal Data System. Updating and modernization to add new capabilities to geothermal maps is ongoing and will be presented to show how improvements benefit geothermal data users in both industrial and research applications in geothermal exploration. Examples of some of the map services will be presented.

Research paper thumbnail of Quaternary borate deposits as a geothermal exploration tool in the Great Basin

Geothermal Resources …, 2006

... Basin Mark F. Coolbaugh1, Chris Kratt2, Chris Sladek1, Richard E. Zehner1, and Lisa Shevenell... more ... Basin Mark F. Coolbaugh1, Chris Kratt2, Chris Sladek1, Richard E. Zehner1, and Lisa Shevenell1,3 ... Nevada. Samples 5/35-22bbb and 2/36-8adb are from Vandenburgh andGlancy (1970); sample WS8 is from Smith and Drever (1976). ...

Research paper thumbnail of Geothermal Site Assessment Using the National Geothermal Data System (NGDS), with Examples from the Hawthorne Ammunition Depot Area

This paper examines the features and functionality of the existing database, its integration into... more This paper examines the features and functionality of the existing database, its integration into the 50-state NGDS, and its usage in geothermal exploration and development. In particular, we examine the dataset for Hawthorne, NV, which has been supplemented extensively by ...

Research paper thumbnail of Technical Assistance from Lawrence Berkeley National Laboratory and National Energy Technology Laboratory to Elko Heat Company and the City of Wells, Nevada

Warm waters in several domestic and municipal water wells in and around the City of Wells, Nevada... more Warm waters in several domestic and municipal water wells in and around the City of Wells, Nevada, along with several hot springs a few kilometers away, suggest economical geothermal resources that could meet residential and commercial space heating demands, perhaps even geothermal electricity generation. To date, only a few low-temperature, single-user space heating applications have been developed. Under the U.S. Department of Energy’s Small Business Vouchers Pilot (SBV) Program, research teams from Lawrence Berkeley National Laboratory (LBNL) and the National Energy Technology Laboratory (NETL), in collaboration with the University of Nevada, Reno (UNR), Better Cities, and Lumos & Associates, advised the Elko Heat Company and the City of Wells in their recent drilling of a shallow geothermal gradient well, based on new field work along with a compilation and review of existing geologic, geochemical, geothermal, and geophysical data for this area. New field data include ground tem...

Research paper thumbnail of Effectiveness of 2-Meter and Geoprobe Shallow Temperature Surveys in Early Stage Geothermal Exploration

Cost-effective geothermal exploration involves a stepwise approach wherein the least expensive to... more Cost-effective geothermal exploration involves a stepwise approach wherein the least expensive tools that can advance (or reject) a property should be considered prior to more expensive techniques. Coolbaugh et al. (2007) demonstrated that shallow (2-meter) surveys were a cost-effective “direct push” tool that can identify and delineate geothermal outflow zones, prior to more expensive temperature gradient drilling. This paper evaluates the Geoprobe as another early-stage, direct push exploration tool that can collect water samples and temperature data at depths intermediate between 2 meters and typical temperature gradient drilling. In addition, the temperature relationship between surface anomalies identified by 2-meter surveys and the

Research paper thumbnail of Archuleta County CO Lineaments

This layer traces apparent topographic and air-photo lineaments in the area around Pagosa springs... more This layer traces apparent topographic and air-photo lineaments in the area around Pagosa springs in Archuleta County, Colorado. It was made in order to identify possible fault and fracture systems that might be conduits for geothermal fluids. Geothermal fluids commonly utilize fault and fractures in competent rocks as conduits for fluid flow. Geothermal exploration involves finding areas of high near-surface temperature gradients, along with a suitable plumbing system that can provide the necessary permeability. Geothermal power plants can sometimes be built where temperature and flow rates are high. To do this, georeferenced topographic maps and aerial photographs were utilized in an existing GIS, using ESRI ArcMap 10.0 software. The USA_Topo_Maps and World_Imagery map layers were chosen from the GIS Server at server.arcgisonline.com, using a UTM Zone 13 NAD27 projection. This line shapefile was then constructed over that which appeared to be through-going structural lineaments in both the aerial photographs and topographic layers, taking care to avoid manmade features such as roads, fence lines, and right-of-ways. These lineaments may be displaced somewhat from their actual location, due to such factors as shadow effects with low sun angles in the aerial photographs. Note: This shape file was constructed as an aid to geothermal exploration in preparation for a site visit for field checking. We make no claims as to the existence of the lineaments, their location, orientation, and nature.

Research paper thumbnail of Petrology structure and tectonic setting of the Hog Heaven volcanics and their relationship to mineralization

Latite porphyry and volcanic sediments. Volcanic sediments, latite porphyry, Ravalli Group Argill... more Latite porphyry and volcanic sediments. Volcanic sediments, latite porphyry, Ravalli Group Argillites (Belt). Thin veneer of volcanic sedi ments or ashflow atop Ravalli Group (Belt). Latite porphyry and volcanic sediments. South Battle Butte Mine Latite porphyry and Ravalli Group Argillites (Belt). Martin Prospect Donald Adit Kofford Ridge Prospect Margarite Mine Volcanic sediments. Pebbly tuff, latite porphyry. Volcanic sediments and Belt paleosol Volcanic sediments (?) and Ravalli Group (Belt).

Research paper thumbnail of Favorable Geochemistry from Springs and Wells in COlorado

Citation Information: Originator: Geothermal Development Associates, Reno Nevada Originator: Unit... more Citation Information: Originator: Geothermal Development Associates, Reno Nevada Originator: United States Geological Survey (USGS) Originator: Colorado Geological Survey Publication Date: 2012 Title: Favorable Geochemistry Edition: First Publication Information: Publication Place: Reno Nevada Publisher: Geothermal Development Associates, Reno, Nevada Description: This layer contains favorable geochemistry for high-temperature geothermal systems, as interpreted by Richard "Rick" Zehner. The data is compiled from the data obtained from the USGS. The original data set combines 15,622 samples collected in the State of Colorado from several sources including 1) the original Geotherm geochemical database, 2) USGS NWIS (National Water Information System), 3) Colorado Geological Survey geothermal sample data, and 4) original samples collected by R. Zehner at various sites during the 2011 field season. These samples are also available in a separate shapefile FlintWaterSamples.shp....

Research paper thumbnail of Geothermal Potential of the Pyramid Lake Paiute Reservation, Nevada, USA: Evidence of Previously Unrecognized Moderate-Temperature (150-170°C) Geothermal Systems

At least two and possibly tbree previously unrecognized moderate-temperature (I50-165°C) geotherm... more At least two and possibly tbree previously unrecognized moderate-temperature (I50-165°C) geothermal areas have been identified during a geothermal exploration program on the Pyramid Lake Paiute Reservation (PLPR) in west-central Nevada, USA. At each of these new areas -- Pyramid Rock, the southwestern Smoke Creek Desert (SWSMD), and east Astor Pass, -- as well as at the known Needle Rocks geothermal area, hot springs andlor near-surface upwellings of hot water are associated with calcium carbonate (tufa) towers forming today in Pyramid Lake or formed in late Pleistocene Lake Lahontan. The structural controls on geothermal fluid flow are still being investigated, but the intersection of Quaternary faults appears to have localized the shallow upwelling of thermal fluids. Near-surface thermal waters, where identified, have temperatures ranging up to 49-97°C, whereas quartz and Na-K -Ca-Mg geothermometers suggest reservoir temperatures on the order of -150 to 165°C. Exploration work beg...

Research paper thumbnail of Geothermal Exploration in the Vicinity of Wells, Nevada

Geothermal activity in and around the City of Wells, Nevada, is evidenced by hot springs and the ... more Geothermal activity in and around the City of Wells, Nevada, is evidenced by hot springs and the presence of hot waters in several private and municipal wells, suggesting that this area may host a commercially-viable geothermal resource. For this reason, under the U.S. Department of Energy’s Small Business Vouchers Pilot (SBV) Program, research teams from Lawrence Berkeley National Laboratory (LBNL) and the National Energy Technology Laboratory (NETL), in collaboration with the University of Nevada, Reno (UNR), worked closely with the Elko Heat Company, the City of Wells, and Better City to review existing data and conduct field studies to site a geothermal well for district heating and other direct use applications for the Wells community. This effort started with the compilation and review of existing structural, geochemical, and geophysical information for this area. New field investigations included the measurement of ground temperatures with shallow 2-meter probes and in deeper...

Research paper thumbnail of Papua New Guinea Country Update

Papua New Guinea (PNG) is an emerging economy which stands at the threshold of economic prosperit... more Papua New Guinea (PNG) is an emerging economy which stands at the threshold of economic prosperity but is constrained by the lack of access to reliable electricity. Located within the “ring of fire”, PNG has numerous active volcanoes and known geothermal systems. There are currently 55 MWe (gross) of geothermal power installed at Lihir Gold Mine in New Ireland Province. However, there have not been any additional power plants constructed in the past five years, mostly due to lack of adequate legislation and government support. The high cost of diesel and fuel oil, and the unpredictable nature of hydro power stations, has renewed strong interest in geothermal power. This paper is an overview of the current status of geothermal in PNG and progress being made to support further development.

Research paper thumbnail of Colorado Potential Geothermal Pathways

This layer contains the weakened basement rocks. Isostatic gravity was utilized to identify struc... more This layer contains the weakened basement rocks. Isostatic gravity was utilized to identify structural basin areas, characterized by gravity low values reflecting weakened basement rocks. Together interpreted regional fault zones and basin outlines define geothermal "exploration fairways", where the potential exists for deep, superheated fluid flow in the absence of Pliocene or younger volcanic units.

Research paper thumbnail of Geologic bibliography of the Mount Hayes Quadrangle, Alaska

Open-File Report, 1980

Brooks, A. H., 1906, The geography and geology o f Alaska, a summary o f e x i s t i n g knowledg... more Brooks, A. H., 1906, The geography and geology o f Alaska, a summary o f e x i s t i n g knowledge, w i t h a s e c t i o n on c l i m a t e b y Cleveland Abbe, J r. , and a t o p o g r a p h i c map and d e s c r i p t i o n t h e r e o f , b y R. U.

Research paper thumbnail of Geologic map of the southern part of Mount Hayes Quadrangle, Alaska

Research paper thumbnail of Preliminary geologic map of the Mount Hayes quadrangle, eastern Alaska Range, Alaska

Open-File Report, 1992

A suite of alkalic mafic and associated plutonic rocks occurs north of the Denali fault in the Wi... more A suite of alkalic mafic and associated plutonic rocks occurs north of the Denali fault in the Windy terrane, and in the Hayes Glacier and southern Jarvis Creek Glacier subterranes of the Yukon-Tanana terrane. The suite consists of lamprophyre, alkalic gabbro, alkalic diorite, and monzonite, and diorite in dikes,

Research paper thumbnail of Geologic maps of the eastern Alaska Range, Alaska (44 quadrangles, 1:63,360 scale), with descriptions and interpretations of map units

Limestone to marble composed of calcite with minor quartz, plagioclase, and sericite. Local skarn... more Limestone to marble composed of calcite with minor quartz, plagioclase, and sericite. Local skarn, devel oped in lenses up to 1 m thick along diabase-marble contact, composed of fine-to medium-grained schis tose calcite and minor epidote, hornblende, wollastonite, garnet, and clinopyroxene. Volcanic sandstone composed of fine-grained, rounded to subangular clasts of twinned and zoned plagio clase and minor quartz in matrix predominantly of chlorite. Authigenic analcite replaces and cements clasts in some calcareous sandstone. Calcareous volcanic graywacke composed of abundant twinned and zoned plagioclase clasts up to 1.5 mm long in a fine-grained, sparsely fossiliferous matrix of calcite and minor epidote and white mica. Presence of graded bedding, poor sorting, and slump structures indicates sedimentary and volcaniclastic strata depos ited from turbidity currents in a low-energy environment below wave base located near active volcanic vents (Bond, 1973, 1976). Andesite has intergranular to ophitic porphyritic texture. Composed of twinned and zoned plagioclase phenocrysts locally resorbed and sparse glomerocrysts up to 3.5 mm long and local hornblende phenocrysts up to 2 mm long, in a fine-grained to felty groundmass of plagioclase, quartz, and white mica. Locally amygdules filled with clinozoisite and chlorite. Andesite tuff composed of angular to subangular plagioclase fragments in matrix predominantly of clay minerals, opaque minerals, and locally abundant calcite. Hornblende(?) completely replaced by chlorite. Diabase composed of fine-grained plagioclase and clinopyroxene and minor opaque minerals, chlorite, and epidote. Relict minerals are plagioclase and sparse hornblende, quartz, clinopyroxene, and opaque minerals. Metamorphic minerals are chlorite, epidote, calcite, and white mica. Dacitic to rhyodacitic ash to lapilli tuffs, green to gray, mainly broken plagioclase, quartz, K-feldspar, and lithic fragments in matrix of very-fine-grained aggregate of quartz, feldspar, chlorite and local leucoxene. Plagioclase commonly twinned. Pumice fragments preserved as irregular platelets and disks of chlorite with porous or tubular texture. Lithic fragments angular; composed of a variety of volcanic rocks exhibiting por phyritic, trachytic, pilotaxitic, glassy, microvesicular, and scoriaceous textures. Locally stratified due to var iation in grain size, color, and grading. Local normal and double grading. A 200-m-thick, unstratified lapilli tuff in northwest Mount Hayes A-3 Quadrangle exhibits distinctive large aerial extent, lack of K-feldspar, and coarse pumice fragments ranging from less than 1 cm to nearly 1 m long (Bond, 1976). Green to grayish green debris-flow deposits composed of poorly sorted angular fragments, from 5 to 20 cm across and locally imbricate, in a matrix of sand, silt, and mud. Angular fragments composed of volcanic rock fragments, plagioclase, quartz, and fossil debris. Matrix mainly microcrystalline quartz, fine chlorite, and/or sericite, and leucoxene. Individual beds range in thickness from a few centimeters to about 18 m. Upper parts of beds often graded, with thin, laminated tops (Bond, 1976). Gray, brown, or green poorly sorted sandstone and graywacke beds, from 2 cm to more than 1 m thick; inter bedded with subordinate, massive or laminated, silty claystones from a few centimeters to a few meters thick. Beds graded but lack internal current features such as crossbedding, convoluted bedding, parallel lamination, or ripple-drift lamination. Grain size ranges from pebbles to fine sand. Clasts mainly angular to subangular. Clasts composed of andesitic(?) fragments, plagioclase, and quartz. Volcanic rock fragments exhibit pyroclastic, pilotaxitic, trachytic, glassy, and sparse scoriaceous and pumiceous textures. Matrix chiefly a dark, microcrystalline aggregate of chlorite and leucoxene and minor amounts of quartz and feld spar (Bond, 1976). Unit metamorphosed to lower greenschist facies. Well exposed in south-central and southeastern Mount Hayes Quadrangle, south of Denali fault and Broxson Gulch thrust, and north of Eureka Creek fault. Under lies Eagle Creek Formation. Overlies volcaniclastic rocks member (P*sl). P*sl VOLCANICLASTIC ROCKS MEMBER-Dark gray, dark green, and maroon volcanic and volcaniclastic rocks. Chiefly volcanic flows interbedded with lapilli tuff, volcanic breccia, graywacke, argillite, and lime stone to marble. Local massive to bedded conglomerate, graywacke, and siltstone. Volcaniclastic rocks con tain abundant volcanic rock fragments and relict pumice, exhibiting trachytic, scoriaceous, and relict glassy textures. Limestone to marble

Research paper thumbnail of With contributions for selected areas from

dggs.alaska.gov

... George Plafker, and Donald H. Richter, for assisting in part of the bedrock geologic mapping,... more ... George Plafker, and Donald H. Richter, for assisting in part of the bedrock geologic mapping, and L. David Carter, Thomas D. Hamilton, and ... We appreciate the excellent discussions and field tours provided by Clint Nauman and Steven Newkirk of some of the massive sulfide ...

Research paper thumbnail of Assessment of Exploration Bias in Data-Driven Predictive Models and the Estimation of Undiscovered Resources

Natural Resources Research, 2007

The spatial distribution of discovered resources may not fully mimic the distribution of all such... more The spatial distribution of discovered resources may not fully mimic the distribution of all such resources, discovered and undiscovered, because the process of discovery is biased by accessibility factors (e.g., outcrops, roads, and lakes) and by exploration criteria. In data-driven predictive models, the use of training sites (resource occurrences) biased by exploration criteria and accessibility does not necessarily translate to a biased predictive map. However, problems occur when evidence layers correlate with these same exploration factors. These biases then can produce a data-driven model that predicts known occurrences well, but poorly predicts undiscovered resources. Statistical assessment of correlation between evidence layers and map-based exploration factors is difficult because it is difficult to quantify the “degree of exploration.” However, if such a degree-of-exploration map can be produced, the benefits can be enormous. Not only does it become possible to assess this correlation, but it becomes possible to predict undiscovered, instead of discovered, resources. Using geothermal systems in Nevada, USA, as an example, a degree-of-exploration model is created, which then is resolved into purely explored and unexplored equivalents, each occurring within coextensive study areas. A weights-of-evidence (WofE) model is built first without regard to the degree of exploration, and then a revised WofE model is calculated for the “explored fraction” only. Differences in the weights between the two models provide a correlation measure between the evidence and the degree of exploration. The data used to build the geothermal evidence layers are perceived to be independent of degree of exploration. Nevertheless, the evidence layers correlate with exploration because exploration has preferred the same favorable areas identified by the evidence patterns. In this circumstance, however, the weights for the “explored” WofE model minimize this bias. Using these revised weights, posterior probability is extrapolated into unexplored areas to estimate undiscovered deposits.

Research paper thumbnail of Prediction and discovery of new geothermal resources in the Great Basin: Multiple evidence of a large undiscovered resource base

Geothermal Resources …, 2006

... Mark F. Coolbaugh1, Gary L. Raines2, Richard E. Zehner1, Lisa Shevenell1,3, and Colin F. Will... more ... Mark F. Coolbaugh1, Gary L. Raines2, Richard E. Zehner1, Lisa Shevenell1,3, and Colin F. Williams4 ... Coolbaugh, MF, Faulds, JE, Kratt, C., Oppliger, GL, Shevenell, LA, Calvin, WM, Ehni, WJ, and Zehner, RE, 2006b, Geothermal Potential of the Pyramid Lake Paiute Reservation ...