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Predicted Geology of the Pahute Mesa-Oasis Valley Phase II Drilling Initiative

Description: Pahute Mesa–Oasis Valley (PM-OV) Phase II drilling will occur within an area that encompasses approximately 117 square kilometers (45 square miles) near the center of the Phase I PM-OV hydrostratigraphic framework model area. The majority of the investigation area lies within dissected volcanic terrain between Pahute Mesa on the north and Timber Mountain on the south. This area consists of a complex distribution of volcanic tuff and lava of generally rhyolitic composition erupted from nearby calderas and related vents. Several large buried volcanic structural features control the distribution of volcanic units in the investigation area. The Area 20 caldera, including its structural margin and associated caldera collapse collar, underlies the northeastern portion of the investigation area. The southern half of the investigation area lies within the northwestern portion of the Timber Mountain caldera complex, including portions of the caldera moat and resurgent dome. Another significant structural feature in the area is the west-northwest-trending Northern Timber Mountain moat structural zone, which bisects the northern portion of the investigation area and forms a structural bench. The proposed wells of the UGTA Phase II drilling initiative can be grouped into four generalized volcanic structural domains based on the stratigraphic distribution and structural position of the volcanic rocks in the upper 1,000 meters (3,300 feet) of the crust, a depth that represents the approximate planned total depths of the proposed wells.
Date: April 20, 2009
Creator: National Security Technologies, LLC
Partner: UNT Libraries Government Documents Department

UGTA Photograph Database

Description: One of the advantages of the Nevada Test Site (NTS) is that most of the geologic and hydrologic features such as hydrogeologic units (HGUs), hydrostratigraphic units (HSUs), and faults, which are important aspects of flow and transport modeling, are exposed at the surface somewhere in the vicinity of the NTS and thus are available for direct observation. However, due to access restrictions and the remote locations of many of the features, most Underground Test Area (UGTA) participants cannot observe these features directly in the field. Fortunately, National Security Technologies, LLC, geologists and their predecessors have photographed many of these features through the years. During fiscal year 2009, work was done to develop an online photograph database for use by the UGTA community. Photographs were organized, compiled, and imported into Adobe® Photoshop® Elements 7. The photographs were then assigned keyword tags such as alteration type, HGU, HSU, location, rock feature, rock type, and stratigraphic unit. Some fully tagged photographs were then selected and uploaded to the UGTA website. This online photograph database provides easy access for all UGTA participants and can help “ground truth” their analytical and modeling tasks. It also provides new participants a resource to more quickly learn the geology and hydrogeology of the NTS.
Date: April 20, 2009
Creator: National Security Technologies, LLC
Partner: UNT Libraries Government Documents Department

Geysering discharge of a geothermal wellbore at Zunil, Guatemala

Description: Within two hours after discharge began, for a production test in 1989 of well ZCQ-4, pressure variations changed from approximately sinusoidal to a cycle of sudden and complex peak discharge pressures, to 9 bar, separated by irregular pressure declines to 5 bar. Initial cycle periods of 42 minutes evolved to 150 minutes by day 20 of continuous testing, when three of four surge peaks were well separated. Chemical signatures of fluids discharged with pressure surges were distinctive. When combined with downwell pressure measurements, assignments can be made for elevations of fluid entry points. The variety of chemical signatures indicates a scarcity of interzone connectivity. These constrained discharges are suspected to derive from altered rubble zones between layered volcanic rocks.
Date: January 1, 1991
Creator: Michels, Donald E.
Partner: UNT Libraries Government Documents Department

Petrology and Geochemistry of Boninite Series Volcanic Rocks,Chichi-jima, Bonin Islands, Japan

Description: An Eocene submarine boninite series volcanic center isexposed on the island of Chichi-jima, Bonin Islands, Japan. Five rocktypes, boninite, bronzite andesite, dacite, quartz dacite, and rhyolite,were distinguished within the boninite volcanic sequence on the basis ofpetrographic and geochemical observations. Boninite lavas contain highmagnesium, nickel, and chromium contentsindicative of primitive melts,but have high silica contents relative to other mantle-derived magmas.All boninite series lavas contain very low incompatible elementconcentrations, and concentrations of high-field strength elements inprimitive boninite lavas are less than half of those found in depletedmid-ocean ridge basalts. Abundances of large-ion lithophile elements arerelatively high in boninite series lavas, similar to the enrichmentsobserved in many island arc lavas. Trends for both major and traceelement data suggest that the more evolved lavas of the boninite magmaseries were derived primarily through high-level fractionalcrystallization of boninite. Textural features, such as resorption andglomeroporphyrocrysts, and reverse chemical zonations suggest that magmamixing contributed to the development of the quartz dacitelavas.
Date: January 1, 1977
Creator: Dobson, Patrick F.; Blank, Jennifer G.; Maruyama, Shigenori & Liou, J.G.
Partner: UNT Libraries Government Documents Department

Coupled Analysis of Change in Fracture Permeability during the Cooling Phase of the Yucca Mountain Drift Scale Test

Description: This paper presents results from a coupled thermal, hydrological and mechanical analysis of thermally-induced permeability changes during heating and cooling of fractured volcanic rock at the Drift Scale Test at Yucca Mountain, Nevada. The analysis extends the previous analysis of the four-year heating phase to include newly available data from the subsequent four year cooling phase. The new analysis of the cooling phase shows that the measured changes in fracture permeability follows that of a thermo-hydro-elastic model on average, but at several locations the measured permeability indicates (inelastic) irreversible behavior. At the end of the cooling phase, the air-permeability had decreased at some locations (to as low as 0.2 of initial), whereas it had increased at other locations (to as high as 1.8 of initial). Our analysis shows that such irreversible changes in fracture permeability are consistent with either inelastic fracture shear dilation (where permeability increased) or inelastic fracture surface asperity shortening (where permeability decreased). These data are important for bounding model predictions of potential thermally-induced changes in rock-mass permeability at a future repository at Yucca Mountain.
Date: June 1, 2008
Creator: Rutqvist, Jonny; Rutqvist, J.; Freifeld, B.; Tsang, Y.W.; Min, K.B. & Elsworth, D.
Partner: UNT Libraries Government Documents Department

A synthesis and review of geomorphic surfaces of the boundary zone Mt. Taylor to Lucero uplift area, West-Central New Mexico

Description: The Mt. Taylor volcanic field and Lucero uplift of west-central New Mexico occur in a transitional-boundary zone between the tectonically active Basin-and Range province (Rio Grande rift) and the less tectonically active Colorado plateau. The general geomorphology and Cenozoic erosional history has been discussed primarily in terms of a qualitative, descriptive context and without the knowledge of lithospheric processes. The first discussion of geomorphic surfaces suggested that the erosional surface underlying the Mt. Taylor volcanic rocks is correlative with the Ortiz surface of the Rio Grande rift. In 1978 a study supported this hypothesis with K-Ar dates on volcanic rocks within each physiographic province. The correlation of this surface was a first step In the regional analysis of the boundary zone; however, little work has been done to verify this correlation with numerical age dates and quantitatively reconstruct the surface for neotectonic purposes. Those geomorphic surfaces inset below and younger than the ``Ortiz`` surface have been studied. This report provides a summary of this data as well as unpublished data and a conceptual framework for future studies related to the LANL ISR project.
Date: January 1, 1989
Creator: Wells, S.G.
Partner: UNT Libraries Government Documents Department

Completion Report for Well ER-12-2

Description: Well ER-12-2 was drilled for the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office, in support of the Nevada Environmental Restoration Project at the Nevada Test Site, Nye County, Nevada. The well was drilled from November 2002 to January 2003 as part of a hydrogeologic investigation program for the Yucca Flat Corrective Action Unit. The overall purpose of the well was to gather subsurface data to better characterize the hydrogeology in the northwestern portion of Yucca Flat. The well was drilled to total measured depth of 2,097.9 meters. The 131.1-centimeter-diameter borehole was left open (i.e., uncased) below the base of the intermediate casing at 901.6 meters. A piezometer string was installed outside the surface casing to a depth of 176.4 meters to monitor a zone of perched water. Data gathered during and shortly after hole construction include composite drill cuttings samples collected every 3 meters, sidewall core samples from 7 depths, various geophysical logs, and water level measurements. These data indicate that the well penetrated, in descending order, 137.5 meters of Quaternary and Tertiary alluvium, 48.8 meters of Tertiary volcanic rocks, 289.6 meters of Mississippian Chainman Shale, and 1,622.5 meters of Mississippian and Upper Devonian Eleana Formation consisting of shale, argillite, sandstone, quartzite, and limestone. Forty-seven days after the well was drilled the water level inside the main hole was tagged at the depth of 65.43 meters, and the water level inside the piezometer string was tagged at 127.14 meters.
Date: November 2004
Creator: Bechtel Nevada
Partner: UNT Libraries Government Documents Department

Modeling Approach/Strategy for Corrective Action Unit 97, Yucca Flat and Climax Mine, Revision 0

Description: The objectives of the UGTA corrective action strategy are to predict the location of the contaminant boundary for each CAU, develop and implement a corrective action, and close each CAU. The process for achieving this strategy includes modeling to define the maximum extent of contaminant transport within a specified time frame. Modeling is a method of forecasting how the hydrogeologic system, including the underground test cavities, will behave over time with the goal of assessing the migration of radionuclides away from the cavities and chimneys. Use of flow and transport models to achieve the objectives of the corrective action strategy is specified in the FFACO. In the Yucca Flat/Climax Mine system, radionuclide migration will be governed by releases from the cavities and chimneys, and transport in alluvial aquifers, fractured and partially fractured volcanic rock aquifers and aquitards, the carbonate aquifers, and in intrusive units. Additional complexity is associated with multiple faults in Yucca Flat and the need to consider reactive transport mechanisms that both reduce and enhance the mobility of radionuclides. A summary of the data and information that form the technical basis for the model is provided in this document.
Date: August 2003
Creator: Willie, Janet
Partner: UNT Libraries Government Documents Department

Statistical Analysis and Geologic Evaluation of Laboratory-Derived Physical Property Data for Selected Nevada Test Site Core Samples of Non-Zeolitized Tuffs

Description: A statistical analysis and geologic evaluation of recently acquired laboratory-derived physical property data are being performed to better understand and more precisely correlate physical properties with specific geologic parameters associated with non-zeolitized tuffs at the Nevada Test Site. Physical property data include wet and dry bulk density, grain density (i.e., specific gravity), total porosity, and effective porosity. Geologic parameters utilized include degree of welding, lithology, stratigraphy, geographic area, and matrix mineralogy (i.e., vitric versus devitrified). Initial results indicate a very good correlation between physical properties and geologic parameters such as degree of welding, lithology, and matrix mineralogy. However, physical properties appear to be independent of stratigraphy and geographic area, suggesting that the data are transferrable with regards to these two geologic parameters. Statistical analyses also indicate that the assumed grain density of 2.65 grams per cubic centimeter used to calculate porosity in some samples is too high. This results in corresponding calculated porosity values approximately 5 percent too high (e.g., 45 percent versus 40 percent), which can be significant in the lower porosity rocks. Similar analyses and evaluations of zeolitic tuffs and carbonate rock physical properties data are ongoing as well as comparisons to geophysical log values.
Date: April 20, 2009
Creator: National Security Technologies, LLC
Partner: UNT Libraries Government Documents Department

Primary carbonatite melt from deeply subducted oceanic crust

Description: Partial melting in the Earth's mantle plays an important part in generating the geochemical and isotopic diversity observed in volcanic rocks at the surface. Identifying the composition of these primary melts in the mantle is crucial for establishing links between mantle geochemical 'reservoirs' and fundamental geodynamic processes. Mineral inclusions in natural diamonds have provided a unique window into such deep mantle processes. Here they provide exper8imental and geochemical evidence that silicate mineral inclusions in diamonds from Juina, Brazil, crystallized from primary and evolved carbonatite melts in the mantle transition zone and deep upper mantle. The incompatible trace element abundances calculated for a melt coexisting with a calcium-titanium-silicate perovskite inclusion indicate deep melting of carbonated oceanic crust, probably at transition-zone depths. Further to perovskite, calcic-majorite garnet inclusions record crystallization in the deep upper mantle from an evolved melt that closely resembles estimates of primitive carbonatite on the basis of volcanic rocks. Small-degree melts of subducted crust can be viewed as agents of chemical mass-transfer in the upper mantle and transition zone, leaving a chemical imprint of ocean crust that can possibly endure for billions of years.
Date: July 1, 2008
Creator: Walter, M.J.; Bulanova, G.P.; Armstrong, L.S.; Keshav, S.; Blundy, J.D.; Gudfinnesson, G. et al.
Partner: UNT Libraries Government Documents Department

Sediment transport time measured with U-Series isotopes: Resultsfrom ODP North Atlantic Drill Site 984

Description: High precision uranium isotope measurements of marineclastic sediments are used to measure the transport and storage time ofsediment from source to site of deposition. The approach is demonstratedon fine-grained, late Pleistocene deep-sea sediments from Ocean DrillingProgram Site 984A on the Bjorn Drift in the North Atlantic. The sedimentsare siliciclastic with up to 30 percent carbonate, and dated by sigma 18Oof benthic foraminifera. Nd and Sr isotopes indicate that provenance hasoscillated between a proximal source during the last three interglacialperiods volcanic rocks from Iceland and a distal continental sourceduring glacial periods. An unexpected finding is that the 234U/238Uratios of the silicate portion of the sediment, isolated by leaching withhydrochloric acid, are significantly less than the secular equilibriumvalue and show large and systematic variations that are correlated withglacial cycles and sediment provenance. The 234U depletions are inferredto be due to alpha-recoil loss of234Th, and are used to calculate"comminution ages" of the sediment -- the time elapsed between thegeneration of the small (<_ 50 mu-m) sediment grains in the sourceareas by comminution of bedrock, and the time of deposition on theseafloor. Transport times, the difference between comminution ages anddepositional ages, vary from less than 10 ky to about 300 to 400 ky forthe Site 984A sediments. Long transport times may reflect prior storagein soils, on continental shelves, or elsewhere on the seafloor. Transporttime may also be a measure of bottom current strength. During the mostrecent interglacial periods the detritus from distal continental sourcesis diluted with sediment from Iceland that is rapidly transported to thesite of deposition. The comminution age approach could be used to dateQuaternary non-marine sediments, soils, and atmospheric dust, and may beenhanced by concomitant measurement of 226Ra/230Th, 230Th/234U, andcosmogenic nuclides.
Date: June 5, 2006
Creator: DePaolo, Donald J.; Maher, Kate; Christensen, John N. & McManus,Jerry
Partner: UNT Libraries Government Documents Department

Geophysical Evidence for the Availability of Geothermal Energy in New Britian

Description: This paper combines some of the results and interpretations of geological mapping, seismic refraction, marine seismic, and gravity surveys to show that large tracts of New Britain could be favorable targets for geothermal power development. It is shown that the fractured and faulted lithosphere is associated with grabens and rifts in which mantle material has risen to within 10 to 15 km from the surface. The grabens and rifts are marked by volcanism in which the dominant volcanic rocks are olivine--and tholeiitic--basalts, with a sprinkling of more acid volcanics ranging from dacite to andesite. Following A. Rittman the basalts are believed to have originated in the asthenosphere when the lithosphere was broken up under a tensional stress regime; the acid volcanics were formed by magmatic differentiation within the crust. it was argued that ideal geothermal reservoirs are capped with altered ash deposits or other nonpermeable volcanics. To feed such reservoirs conduits are required which are naturally located on fault or shear zones. The two areas selected as favorable for future geothermal power development are located between Talasea and Lolobau Is., say around Hoskins; and near Rabaul, between Matupi Harbor and Matupi. As a type area, the rift between the Gazelle Peninsula and New Ireland resembles the Afar triangle, at the northern end of the Great Valley Rift system of Africa.
Date: January 1, 1974
Creator: Wiebenga, W. A. & Furumoto, A. S.
Partner: UNT Libraries Government Documents Department

A Hydrostratigraphic Model and Alternatives for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 97: Yucca Flat-Climax Mine, Lincoln and Nye Counties, Nevada

Description: A new three-dimensional hydrostratigraphic framework model for the Yucca Flat-Climax Mine Corrective Action Unit was completed in 2005. The model area includes Yucca Flat and Climax Mine, former nuclear testing areas at the Nevada Test Site, and proximal areas. The model area is approximately 1,250 square kilometers in size and is geologically complex. Yucca Flat is a topographically closed basin typical of many valleys in the Basin and Range province. Faulted and tilted blocks of Tertiary-age volcanic rocks and underlying Proterozoic and Paleozoic sedimentary rocks form low ranges around the structural basin. During the Cretaceous Period a granitic intrusive was emplaced at the north end of Yucca Flat. A diverse set of geological and geophysical data collected over the past 50 years was used to develop a structural model and hydrostratigraphic system for the basin. These were integrated using EarthVision? software to develop the 3-dimensional hydrostratigraphic framework model. Fifty-six stratigraphic units in the model area were grouped into 25 hydrostratigraphic units based on each unit's propensity toward aquifer or aquitard characteristics. The authors organized the alluvial section into 3 hydrostratigraphic units including 2 aquifers and 1 confining unit. The volcanic units in the model area are organized into 13 hydrostratigraphic units that include 8 aquifers and 5 confining units. The underlying pre-Tertiary rocks are divided into 7 hydrostratigraphic units, including 3 aquifers and 4 confining units. Other units include 1 Tertiary-age sedimentary confining unit and 1 Mesozoic-age granitic confining unit. The model depicts the thickness, extent, and geometric relationships of these hydrostratigraphic units (''layers'' in the model) along with the major structural features (i.e., faults). The model incorporates 178 high-angle normal faults of Tertiary age and 2 low-angle thrust faults of Mesozoic age. The complexity of the model area and the non-uniqueness of some of the interpretations incorporated into the ...
Date: January 1, 2006
Creator: Nevada, Geotechnical Sciences Group Bechtel
Partner: UNT Libraries Government Documents Department

Saturated Zone Plumes in Volcanic Rock: Implications for Yucca Mountain

Description: This paper presents a literature survey of the occurrences of radionuclide plumes in saturated, fractured rocks. Three sites, Idaho National laboratory, Hanford, and Oak Ridge are discussed in detail. Results of a modeling study are also presented showing that the length to width ratio of a plume starting within the repository footprint at the Yucca Mountain Project site, decreases from about 20:1 for the base case to about 4:1 for a higher value of transverse dispersivity, indicating enhanced lateral spreading of the plume. Due to the definition of regulatory requirements, this lateral spreading does not directly impact breakthrough curves at the 18 km compliance boundary, however it increases the potential that a plume will encounter reducing conditions, thus significantly retarding the transport of sorbing radionuclides.
Date: February 14, 2006
Creator: Kelkar, S.; Roback, R.; Robinson, B.; Srinivasan, G.; Jones, C. & Reimus, P.
Partner: UNT Libraries Government Documents Department

A comparative simulation study of coupled THM processes and their effect on fractured rock permeability around nuclear waste repositories

Description: This paper presents an international, multiple-code, simulation study of coupled thermal, hydrological, and mechanical (THM) processes and their effect on permeability and fluid flow in fractured rock around heated underground nuclear waste emplacement drifts. Simulations were conducted considering two types of repository settings: (a) open emplacement drifts in relatively shallow unsaturated volcanic rock, and (b) backfilled emplacement drifts in deeper saturated crystalline rock. The results showed that for the two assumed repository settings, the dominant mechanism of changes in rock permeability was thermal-mechanically-induced closure (reduced aperture) of vertical fractures, caused by thermal stress resulting from repository-wide heating of the rock mass. The magnitude of thermal-mechanically-induced changes in permeability was more substantial in the case of an emplacement drift located in a relatively shallow, low-stress environment where the rock is more compliant, allowing more substantial fracture closure during thermal stressing. However, in both of the assumed repository settings in this study, the thermal-mechanically-induced changes in permeability caused relatively small changes in the flow field, with most changes occurring in the vicinity of the emplacement drifts.
Date: October 23, 2008
Creator: Rutqvist, Jonny; Barr, Deborah; Birkholzer, Jens T.; Fujisaki, Kiyoshi; Kolditz, Olf; Liu, Quan-Shen et al.
Partner: UNT Libraries Government Documents Department

Compilation of modal analyses of volcanic rocks from the Nevada Test Site area, Nye County, Nevada

Description: Volcanic rock samples collected from the Nevada Test Site, Nye County, Nevada, between 1960 and 1985 were analyzed by thin section to obtain petrographic mode data. In order to provide rapid accessibility to the entire database, all data from the cards were entered into a computerized database. This computer format will enable workers involved in stratigraphic studies in the Nevada Test Site area and other locations in southern Nevada to perform independent analyses of the data. The data were compiled from the mode cards into two separate computer files. The first file consists of data collected from core samples taken from drill holes in the Yucca Mountain area. The second group of samples were collected from measured sections and surface mapping traverses in the Nevada Test Site area. Each data file is composed of computer printouts of tables with mode data from thin section point counts, comments on additional data, and location data. Tremendous care was taken in transferring the data from the cards to computer, in order to preserve the original information and interpretations provided by the analyzer. In addition to the data files above, a file is included that consists of Nevada Test Site petrographic data published in other US Geological Survey and Los Alamos National Laboratory reports. These data are presented to supply the user with an essentially complete modal database of samples from the volcanic stratigraphic section in the Nevada Test Site area. 18 refs., 4 figs.
Date: October 1, 1990
Creator: Page, W.R.
Partner: UNT Libraries Government Documents Department

Chemical changes associated with zeolitization of the tuffaceous beds of Calico Hills at Yucca Mountain, Nevada

Description: The chemistry of the tuffaceous beds of Calico Hills was examined in samples collected over a 100{sup 2} km area south of the Timber Mountain-Oasis Valley caldera complex to determine regional geochemical patterns during zeolitization. Samples of 58 vitric and zeolitic tuffs were analyzed for 48 elements by a combination of x-ray fluorescence, atomic absorption spectrophotometry, and neutron activation analysis. Major and trace element concentrations for zeolitic tuffs vary significantly from those for vitric tuffs. Complex, geographically-controlled patterns of elemental enrichment and depletion in the zeolitic tuffs are found for Na, K, Ca, Mg, U, Rb, Sr, Ba and Cs. Vitric and zeolitic tuffs generally have the same SiO{sub 2} contents on an anhydrous basis, but minor net silica gain or loss has occurred in some samples. Zeolitic tuffs from the northern part of the study area, adjacent to the caldera complex, are notably K-rich and Na- and U-poor compared to zeolitic tuffs to the south. The compositions of the K-rich zeolitic tuffs are similar to those found in other areas of the western US where volcanic rocks are affected by potassium metasomatism. Alteration of vitric tuffs took place in an open chemical system and geographic control of major element compositions probably reflects regional variations in groundwater chemistry during alteration. The K-rich zeolitic tuffs in the northern part of the study area were probably altered by hydrothermal fluids whereas tuffs further south were altered by lower-temperature groundwaters.
Date: March 1, 1992
Creator: Broxton, D.E.
Partner: UNT Libraries Government Documents Department

Origin of a sanidine-coesite grospydite

Description: A grospydite xenolith from the Roberts Victor kimberlite pipe in South Africa presents an unusual phase assemblage of clinopyroxene, garnet, kyanite, coesite, and sanidine. The rock as previously described (Smyth and Hatton, 1977) consists of 50% omphocitic clinopyroxene, 28% garnet (Gr/sub 50/Py/sub 28/Alm/sub 22/), 9% kyanite, 65 coesite, and 1% sanidine (Or/sub 99/). Assuming the addition of three additional compatible phases (phlogopite, enstatite, and H/sub 2/O vapor) and a simplified chemistry of the phases present, a Schreinemakers thermodynamic analysis was attempted in order to estimate the pressure and temperature of equilibrium of the rock. Four reactions involving six components are likely to have determined an invariant point for the assemblage: (1) Kyn + 2 Cpx reversible Cos + Gt + En; (2) 3 Cos + Phl reversible San + 3 En + H/sub 2/O; (3) 3 Kyn + 6 Cpx + Phl reversible San + 3 Gt + 6 En + H/sub 2/O; and (4) 6 Cos + 3 gt + Phl reversible San + 3 Kyn + 6 Cpx + H/sub 2/O. Using tabulated as well as estimated thermodynamic data for the phases, the calculated values for equilibrium temperatures and pressures for the reactions yield an invariant point for the assemblage at a depth of about 160 km (40 kbars) and a temperature of about 1060/sup 0/C. This point likely represents a subsolidus recrystallization stage of origin.
Date: January 1, 1982
Creator: Wohletz, K.H. & Smyth, J.R.
Partner: UNT Libraries Government Documents Department

Final report, intermediate-depth, hole No. 1-78-U1, Socorro Prospect, New Mexico

Description: During the period May 19, 1977 to July 22, 1977, fourteen heat flow boreholes were completed on the Socorro Prospect, New Mexico. Rock types encountered ranged from unconsolidated Quaternary alluvium to dense volcanic rocks. Depths of the holes were from 60 to 440 feet with an average total depth of 288 feet. Geothermal gradients from the fourteen boreholes ranged from 0.32 to 7.58 F/100 ft. Thermal conductivity values of 3.6 to 7.5 mcal/cm-sec C were obtained from a total of 76 samples of drill cuttings. Individual heat flow values range from 0.3 to 5.4 HFU (1 HFU-1 {micro}cal/cm{sup 2}-sec). The linearity of the gradients for these holes suggests that heat transport in the shallow subsurface penetrated by these boreholes is predominantly by conduction; however, the magnitude of the heat flow for eight of the boreholes indicates that they are disturbed by groundwater movement. Based on published data as well as the results of the present survey, a value of about 2.5 HFU is probably representative of the background heat flow in the area of the Socorro Prospect. The heat flow determination of 5.4 HFU in borehole No. 5-77-B20 could indicate a prospect of commercial quality. Heat flow values greater than 3 HFU require either melting within the shallow crust or convective transport of heat by water or magma. This heat flow value, therefore, supports the observation of modern uplift in the Socorro area over a postulated magma chamber situated at a depth of 11 {+-} miles. Based on the data collected during this exploration project, they recommend that a second phase program of more closely-spaced heat flow boreholes be drilled on the Socorro Prospect to determine the lateral extent of the high heat flow zone characterized by hole No. 5-77-B20.
Date: November 1, 1977
Creator: Quiett, Steve & Combs, Jim
Partner: UNT Libraries Government Documents Department

Application of magnetic method to assess the extent of high temperature geothermal reservoirs

Description: The extent of thermally altered rocks in high temperature geothermal reservoirs hosted by young volcanic rocks can be assessed from magnetic surveys. Magnetic anomalies associated with many geothermal field in New Zealand and Indonesia can be interpreted in terms of thick (up to 1 km) demagnetized reservoir rocks. Demagnetization of these rocks has been confirmed by core studies and is caused by hydrothermal alteration produced from fluid/rock interactions. Models of the demagnetized Wairakei (NZ) and Kamojang (Indonesia) reservoirs are presented which include the productive areas. Magnetic surveys give fast and economical investigations of high temperature prospects if measurements are made from the air. The magnetic interpretation models can provide important constraints for reservoir models. Magnetic ground surveys can also be used to assess the extent of concealed near surface alteration which can be used in site selection of engineering structures.
Date: January 26, 1995
Creator: Soengkono, S. & Hochstein, M.P.
Partner: UNT Libraries Government Documents Department