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Sample records for geothermometers

  1. Geothermometer calculations for geothermal assessment

    USGS Publications Warehouse

    Reed, M.J.; Mariner, R.H.

    2007-01-01

    Geothermal exploration programs have relied on the calculation of geothermometers from hot spring chemistry as an early estimation of geothermal reservoir temperatures. Calibration of the geothermometers has evolved from experimental determinations of mineral solubility as a function of temperature to calibration from analyses of water chemistry from known depths and temperatures in thermal wells. Most of the geothermometers were calibrated from analyses of sodium-chloride type waters, and the application of some geothermometers should be restricted to waters of the chemical types that were used in their calibration. Chemical analyses must be determined to be reliable before they are used to calculate geothermometers. The USGS Geothermal Resource Assessment will rely on the silica geothermometer developed by Giggenbach that approximates the transition between chalcedony at 20??C and quartz at 200??C. Above 200??C, the assessment will rely on the quartz geothermometer. In addition, the assessment will also rely on the potassium-magnesium geothermometer.

  2. A new illite geothermometer

    SciTech Connect

    Ballantyne, Judith M.; Moore, Joseph N.

    1988-01-01

    Sericite, either as illite or illite/smectite, is ubiquitous in geothermal systems. Theoretical Ca- and Na-smectite contents of non-expanding geothermal sericites have been calculated from published electron microprobe analyses. Geothermal sericites can be modeled as solid solutions of muscovite and smectite. For those sericites that fit the model, the amount of smectite in solid solution is related to temperature by the expression TºC = 1000/(0.45LogX{sub smectite} + 2.38) – 273. The temperature dependence of illite interlayer chemistry suggests a related temperature dependence of the K, Na and Ca content of geothermal fluids. The original data used by Fournier and Truesdell (1973) to derive the empirical Na-K-Ca geothermometer for geothermal fluids can be modeled equally well by an equation incorporating the equilibrium constant for the reaction of smectite to illite: T ºC = 1.145*10{sup 3}/([0.35LogNa + 0.175LogCa – 0.75LogK] + 1.51) – 273, where the concentration units are molalities. This supports the hypothesis that illite and illite/smectite are important controls on the concentrations of Na, K and Ca in geothermal fluids.

  3. Chemical geothermometers and mixing models for geothermal systems

    USGS Publications Warehouse

    Fournier, R.O.

    1977-01-01

    Qualitative chemical geothermometers utilize anomalous concentrations of various "indicator" elements in groundwaters, streams, soils, and soil gases to outline favorable places to explore for geothermal energy. Some of the qualitative methods, such as the delineation of mercury and helium anomalies in soil gases, do not require the presence of hot springs or fumaroles. However, these techniques may also outline fossil thermal areas that are now cold. Quantitative chemical geothermometers and mixing models can provide information about present probable minimum subsurface temperatures. Interpretation is easiest where several hot or warm springs are present in a given area. At this time the most widely used quantitative chemical geothermometers are silica, Na/K, and Na-K-Ca. ?? 1976.

  4. Magnesium correction to the NaKCa chemical geothermometer

    USGS Publications Warehouse

    Fournier, R.O.; Potter, R.W., II

    1979-01-01

    Equations and graphs have been devised to correct for the adverse effects of magnesium upon the Na-K-Ca chemical geothermometer. Either the equations or graphs can be used to determine appropriate temperature corrections for given waters with calculated NaKCa temperatures > 70??C and R 50 are probably derived from relatively cool aquifers with temperatures approximately equal to the measured spring temperature, irrespective of much higher calculated Na-K-Ca temperatures. ?? 1979.

  5. Application of the TITANIQ geothermometer to ultrabasic rocks

    NASA Astrophysics Data System (ADS)

    Esteban, J. J.; Tubía, J. M.; Cuevas, J.; Gil Ibarguchi, J. I.

    2012-04-01

    The titanium-in-quartz geothermometer (TitaniQ), based on the equilibrium partitioning of Ti between rutile and quartz at P < 1 GPa (Wark and Watson, 2006), is being nowadays successfully applied to quartz-bearing crustal rocks (Liu and Santosh, 2010), mineral deposits (Focke et al., 2009) or even to quartz mylonites (Grujic et al., 2011; Baker et al., 2011). However, the strong nonlinear dependence of the Ti-in-quartz solubility upon higher pressures (> 1.5 GPa) makes necessary an independent pressure constraint to obtain accurate temperatures (Thomas et al., 2010). In order to test the TitaniQ geothermometer in ultrabasic rocks, we have analysed by electron microprobe Ti concentration of quartz inclusions within garnets from a garnet-pyroxenite of the Sierra Bermeja massif (Ronda peridotites, Betic Cordilleras). The results obtained are compared with those provided by conventional geothermobarometers. The pyroxenite shows granoblastic texture consisting of partially kelyphitized garnet and clinopyroxene. Plagioclase is present along the grain boundaries of clinopyroxene, in late veins or included within garnet. Other minor matrix minerals are rutile and quartz. Garnet compositions cover the range Py58-54Alm28-22Gro21-15And3-1Uva1-0. Garnets have inclusions of plagioclase (andesine An30-50), clinopyroxene (Ens46-42Wo52-45 Fs8-5; XJd:18-12), rutile and quartz. Clinopyroxene shows chemical variations that attest changing recrystallization conditions. Cores are closer in composition to garnet-included pyroxenes and show decrease in Al2O3 and Na2O contents and increase in CaO and MgO towards the rims. Clinopyroxene and plagioclase inclusions in garnet allow calculating the equilibrium conditions of a first Grt-Cpx-Pl assemblage. P-T were calculated iteratively using coupled thermo-barometric formulations as follows: (1) Eckert et al. (1991) and Nimis and Taylor (2000), and (2) Eckert et al. (1991) and Krogh-Ravna (2000). Although, these are one of the most reliable

  6. An empirical NaKCa geothermometer for natural waters

    USGS Publications Warehouse

    Fournier, R.O.; Truesdell, A.H.

    1973-01-01

    An empirical method of estimating the last temperature of water-rock interaction has been devised. It is based upon molar Na, K and Ca concentrations in natural waters from temperature environments ranging from 4 to 340??C. The data for most geothermal waters cluster near a straight line when plotted as the function log ( Na K) + ?? log [ ??? (Ca) Na] vs reciprocal of absolute temperature, where ?? is either 1 3 or 4 3 depending upon whether the water equilibrated above or below 100??C. For most waters tested, the method gives better results than the Na K methods suggested by other workers. The ratio Na K should not be used to estimate temperature if ??? ( MCa) MNa is greater than 1. The Na K values of such waters generally yield calculated temperatures much higher than the actual temperature at which water interacted with the rock. A comparison of the composition of boiling hot-spring water with that obtained from a nearby well (170??C) in Yellowstone Park shows that continued water-rock reactions may occur during ascent of water even though that ascent is so rapid that little or no heat is lost to the country rock, i.e. the water cools adiabatically. As a result of such continued reaction, waters which dissolve additional Ca as they ascend from the aquifer to the surface will yield estimated aquifer temperatures that are too low. On the other hand, waters initially having enough Ca to deposit calcium carbonate during ascent may yield estimated aquifer temperatures that are too high if aqueous Na and K are prevented from further reaction with country rock owing to armoring by calcite or silica minerals. The Na-K-Ca geothermometer is of particular interest to those prospecting for geothermal energy. The method also may be of use in interpreting compositions of fluid inclusions. ?? 1973.

  7. The Use of Stable Hydrogen Isotopes as a Geothermometer in Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Proskurowski, G.; Lilley, M. D.; Früh-Green, G. L.; Olson, E. J.; Kelley, D. S.

    2004-12-01

    Terrestrial geothermal work by Arnason in the 1970's demonstrated the utility of stable hydrogen isotopes as a geothermometer[1]. However, with the exception of two data points from 9°N in a study by Horibe and Craig[2], the value of this geothermometer in hydrothermal systems has never been rigorously assessed. Equilibrium fractionation factors for H2-H2O and H2-CH4 have previously been determined experimentally and theoretically over a range of temperatures and provide an expression relating alpha (fractionation) and temperature. We have measured the dD of H2(g), CH4(g) and H2O from a diverse selection of hydrothermal vent localities including Lost City, Middle Valley, Endeavour, Guaymas, Logatchev, Broken Spur, and SWIR. These samples were chosen to represent a wide range of fluid temperatures and a variety of environmental settings. We see a strong correlation between measured vent temperature and predicted vent temperature using both the hydrogen-water and the methane-hydrogen geothermometers over a temperature range of 25-400°C. In the case of the H2-H2O geothermometer, the predicted temperatures are slightly elevated with respect to the measured temperatures at the low temperature Lost City site, and are in good agreement at high temperature vent sites. The H2-CH4 geothermometer predicts temperatures that are 40-80°C elevated with respect to the measured temperature in both the low and high temperature sites. These measurements demonstrate that the hydrogen isotope geothermometer in the hydrogen-methane-water system is robust in hydrothermal systems and may be a useful tool in determining the temperature of the root zone. 1. Arnason, B., The Hydrogen-Water Isotope Thermometer Applied to Geothermal Areas In Iceland. Geothermics, 1977. 5: p. 75-80. 2. Horibe, Y. and H. Craig, D/ H fractionation in the system methane-hydrogen-water. Geochimica et Cosmochimica Acta, 1995. 59(24): p. 5209-5217.

  8. A magnesium correction for the Na-K-Ca chemical geothermometer

    USGS Publications Warehouse

    Fournier, R.O.; Potter, Robert W.

    1978-01-01

    Graphs and equations have been devised to correct for the adverse effects of magnesium upon the Na-K-Ca geothermometer. Either the graphs or equations can be used to determine temperature corrections when given waters have Na-K-Ca calculated temperatures above 70? C and values of R less than 50, where R = {Mg/(Mg + Ca + K)} x 100 in equivalents. Waters with values of R greater than 50 probably come from relatively cool aquifers with temperatures about equal to the measured spring temperature, irrespective of much higher calculated Na-K-Ca temperatures.

  9. Considerations and applications of the illite/smectite geothermometer in hydrocarbon-bearing rocks of Miocene to Mississippian age

    USGS Publications Warehouse

    Pollastro, R.M.

    1993-01-01

    Empirical relationships between clay mineral transformations and temperature provide a basis for the use of clay minerals as geothermometers. Clay-mineral geothermometry has been applied mainly to diagenetic, hydrothermal, and contact- and burial-metamorphic settings to better understand the thermal histories of migrating fluids, hydrocarbon source beds, and ore and mineral formation. Quantitatively, the most important diagenetic clay mineral reaction in sedimentary rocks is the progressive transformation of smectite to illite via mixed-layer illite/smectite (I/S). Changes in the ordering of I/S are particularly useful in the exploration for hydrocarbons because of the common coincidence between the temperatures for the conversion from random-to-ordered I/S and those for the onset of peak, or main phase, oil generation. Using three common applications, the I/S geothermometer is compared to other mineral geothermometers, organic maturation indices, and grades of indigenous hydrocarbons. -from Author

  10. Derivation and calibration of semi-empirical gas geothermometers for Mahanagdong Geothermal Project, Philippines

    SciTech Connect

    Sanchez, D.R.

    1996-12-31

    The dissolved CO{sub 2}, H{sub 2}S, and H{sub 2} gases in Mahanagdong aquifer fluids are controlled by specific gas-mineral equilibria. At temperature range of 250 to 310 {degrees}C, CO{sub 2} is buffered by clinozoisite + K-feldspar + calcite + muscovite (illite) + quartz mineral assemblage. For H{sub 2}S and H{sub 2} dissolved gases, they are more likely buffered by pyrrhotite + pyrite + magnetite mineral assemblage at similar temperature range. Calibration of five Mahanagdong (MG) gas geothermometers is presented, three of which used CO{sub 2}, H{sub 2}S, and H{sub 2} concentration in steam. The remaining two use CO{sub 2}/H{sub 2} and H{sub 2}S/H{sub 2} ratios. The calibration is based on the relation between gas content of drillhole discharges and measured aquifer temperatures. After establishing the gas content in the aquifer, gas concentrations were computed in steam after adiabatic boiling to atmospheric condition (100 {degrees}C), to obtain gas geothermometry functions. These functions could also be used in evaluating fraction of steam condensation and temperature of phase separation. A demonstration given the Mahanagdong fumarole data, indicates that there is generally a fair relation between computed temperatures using Mahanagdong gas geothermometers and the actual field trend`s temperatures.

  11. A CO2-Silica Geothermometer for Low Temperature Geothermal Resource Assessment, with Application to Resources in the Safford Basin, Arizona

    SciTech Connect

    Witcher, James C.; Stone, Claudia

    1983-11-01

    Geothermics is the study of the earth's heat energy, it's affect on subsurface temperature distribution, it's physical and chemical sources, and it's role in dynamic geologic processes. The term, geothermometry, is applied to the determination of equilibrium temperatures of natural chemical systems, including rock, mineral, and liquid phases. An assemblage of minerals or a chemical system whose phase composition is a function of temperature and pressure can be used as a geothermometer. Thus a geothermometer is useful to determine the formation temperature of rock or the last equilibrium temperature of a flowing aqueous solution such as ground water and hydrothermal fluids.

  12. Crystal size of epidotes: A potentially exploitable geothermometer in geothermal fields

    SciTech Connect

    Patrier, P.; Beaufort, D.; Touchard, G. ); Fouillac, A.M. )

    1990-11-01

    Crystal size of epidotes crystallized in quartz + epidote veins is used as the basis for a new geothermometer from the fossil geothermal field of Saint Martin (Lesser Antilles). The epidote-bearing alteration paragenesis is developed as far as 3 km from a quartz diorite pluton at temperatures of 220-350C. The length/width ratio of the epidote grains is constant for all the analyzed samples and suggests isotropic growth environments. However, the length and width of the grains vary exponentially with temperature. The obtained results offer new perspectives for simple grain-size geothermomentry but must be extended to other geologic environments to clarify the influence of different rock types.

  13. A chlorite solid solution geothermometer the Los Azufres (Mexico) geothermal system

    NASA Astrophysics Data System (ADS)

    Cathelineau, Michel; Nieva, David

    1985-11-01

    Chlorite constitutes a major hydrothermal alteration product of metamorphism of andesites, in the active geothermal system of Los Azufres (Mexico). Electron microprobe analyses performed on a set of crystals from each sample show wide variations in composition. Correlation coefficients among chemical constituents were calculated. It is shown that the tetrahedral charge is positively correlated with the octahedral vacancy and negatively with the iron content, and there is almost no correlation with the octahedral aluminium and magnesium content. A procedure is proposed to select end-members and substitution vectors, and to give a general formula for these chlorites. Their formation temperatures are estimated with great accuracy, combining results of microthermometric data on fluid inclusions from gangue minerals of chlorites (quartz, calcite), direct measurements in wells (Kuster equipment), and chemical geothermometers. Correlations between chlorite compositions, range and nature of site occupancy, and temperature are good. Formation temperatures of chlorites range from 130° C to 300° C. As no other thermodynamic parameter varies significantly in the studied field (composition of the host rocks, nature of the geothermal fluids, pressure, ...), these variations of site occupancy (mainly Al(IV) and the octahedral occupancy (6-Al(VI)-(Mg+Fe(2+)) = VAC) are considered mainly as temperature dependent. Molar fractions of each end-member show very different variations with increasing temperature: X-kaolinite decreases, and X-chamosite increases, while X-talc-3 brucite does not show significant change. From these data, activity coefficients and standard state chemical potential of major components, and molar free energy formation of chlorite have been calculated for each temperature of crystallisation.

  14. The paragonite-muscovite solvus: II. Numerical geothermometers for natural, quasibinary paragonite-muscovite pairs

    NASA Astrophysics Data System (ADS)

    Blencoe, James G.; Guidotti, Charles V.; Sassi, Francesco P.

    1994-05-01

    Three parametric (nonthermodynamic) equations have been developed to calculate final equilibration temperatures for natural, quasibinary paragonite-muscovite (Pg-Ms) pairs (mole fraction margarite in Pg < 0.05, Si/formula unit ≤ 6.2 and/or Σ(Mg + Fe 2+ + Fe 3+) ≤ 0.35 for coexistent Ms). The first two equations are paragonite-based and muscovite-based, because they yield equilibration temperatures that depend on the Na-K compositions of K-saturated Pg and Na-saturated Ms, respectively. The third equation is closure-based, because it yields equilibration temperatures that vary with the width of the gap between the Na-K compositions of coexisting Pg and Ms (i.e., the degree of solvus closure). Equilibration temperatures can be estimated, using just one of the geothermometers, or by averaging the temperatures obtained from any combination of the three equations. Comparison of the three calculated temperatures yields information on the mutual consistencies of the Na-K compositions of coexisting Pg and Ms with respect to their utility in Pg-Ms solvus thermometry. Geothermometric inconsistencies in the Na-K compositions of quasibinary Pg-Ms pairs can be caused by (1) inaccuracies in determinations of the Na-K compositions of the coexisting micas, (2) H 3O + → K + and vacancy → K + substitution in muscovite and/or paragonite (3) crystallization and preservation of quasibinary Pg-Ms pairs with metastable Na-K compositions. Due to the effects of pressure on the stability relations of Pg-Ms pairs and the K/Na ratios of Nasaturated muscovites, practical applications of Pg-Ms solvus thermometry are restricted to quasibinary Pg-Ms pairs that equilibrated at pressures between approximately 2 and 8 kbar. Within this pressure range, the utility of Pg-Ms solvus thermometry is limited thermally to approximately 300 ≤ T ≤ 700° C by (1) the decomposition of K-saturated paragonite at temperatures between approximately 580 and 700°C, and (2) steepening of the solvus limbs

  15. Empirical calibration of the clinopyroxene-garnet magnesium isotope geothermometer and implications

    NASA Astrophysics Data System (ADS)

    Li, Wang-Ye; Teng, Fang-Zhen; Xiao, Yilin; Gu, Hai-Ou; Zha, Xiang-Ping; Huang, Jian

    2016-07-01

    The large equilibrium Mg isotope fractionation between clinopyroxene and garnet observed in eclogites makes it a potential high-precision geothermometer, but calibration of this thermometer by natural samples is still limited. Here, we report Mg isotopic compositions of eclogite whole rocks as well as Mg and O isotopic compositions of clinopyroxene and garnet separates from 16 eclogites that formed at different temperatures from the Dabie orogen, China. The whole-rock δ26Mg values vary from -1.20 to +0.10 ‰. Among them, 11 samples display limited δ26Mg variations from -0.36 to -0.17 ‰, similar to those of their protoliths. The mineral separates exhibit very different δ26Mg values, from -0.39 to +0.39 ‰ for clinopyroxenes and from -1.94 to -0.81 ‰ for garnets. The clinopyroxene-garnet Mg isotope fractionation (Δ26Mgclinopyroxene-garnet = δ26Mgclinopyroxene-δ26Mggarnet) varies from 1.05 to 2.15 ‰. The clinopyroxene-garnet O isotope fractionation (Δ18Oclinopyroxene-garnet = δ18Oclinopyroxene-δ18Ogarnet) varies from -1.01 to +0.98 ‰. Equilibrium Mg isotope fractionation between clinopyroxene and garnet in the investigated samples is selected based on both the δ26Mgclinopyroxene versus δ26Mggarnet plot and the state of O isotope equilibrium between clinopyroxene and garnet. The equilibrium Δ26Mgclinopyroxene-garnet and corresponding temperature data obtained in this study, together with those available so far in literatures for natural eclogites, are used to calibrate the clinopyroxene-garnet Mg isotope thermometer. This yields a function of Δ26Mgclinopyroxene-garnet = (0.99 ± 0.06) × 106/ T 2, where T is temperature in Kelvin. The refined function not only provides the best empirically calibrated clinopyroxene-garnet Mg isotope thermometer for precise constraints of temperatures of clinopyroxene- and garnet-bearing rocks, but also has potential applications in high-temperature Mg isotope geochemistry.

  16. Toward a new < 250 °C pyrrhotite-magnetite geothermometer for claystones

    NASA Astrophysics Data System (ADS)

    Aubourg, Charles; Pozzi, Jean-Pierre

    2010-05-01

    . We interpret this trend as the appearance of magnetite. We derive a parameter PM from the warming curve of a saturated isothermal remanent magnetization acquired at 10 K (ZFC). We report on a consistent evolution of PM with temperature in the range of 40 °C to 250 °C, including natural samples, heated samples at 95 °C, and burial-like heated samples. PM first increases between ˜ 40 °C up to ˜ 85 °C, implying that pyrrhotite gradually dominates the magnetic assemblage at low temperature. For temperatures above 85 °C, PM decreases up to 250 °C, implying that the formation of magnetite gradually overshadows the magnetic input of pyrrhotite. PM values obtained from mature to overmature claystones from the Chartreuse are lower than the PM values obtained from the burial-like heated Opalinus claystones, suggesting that the formation of magnetite is driven by kinetics. The continuous trend of the PM parameter suggests that the magnetic properties of pyrrhotite-magnetite claystones can be used to infer paleo-temperatures and we propose to name this geothermometer MagEval.

  17. Evaluation of garnet-biotite geothermometers by trend surface analysis: application to the English Rive subprovince, Ontario

    SciTech Connect

    Perkins, D.; Chipera, S.J.

    1985-01-01

    The eastern Lac Seul region of the English River Subprovince (ERSP), Ontario, contains upper amphibolite/granultie facies metasediments. Widespread occurrences of garnet-biotite in pelites and psammites permit application of Gt-Bi thermometry over a 20,000 sq. km area. Trend surface analysis permits estimation of the accuracy and precision of the numerous calibrations of Gt-Bi thermometers presently available, and provides a statistical analysis of regional temperature variations. Temperatures obtained from 90 garnet cores and matrix biotites showed almost identical regional trends, regardless of the calibration used. The absolute temperature values, and the amounts of imprecision resulting from each calibration do vary greatly, however. Geothermometers based solely on 1nK/sub d/ were found to give more consistent and precise temperatures than calibrations that attempted to incorporate the effects of diluents. The Perchuk and Lavrent'eva (1983) thermometer yields the most precise and accurate results. Metamorphism and migmatization of the ERSP occurred during the Kenoran orogeny, 2.68 BYA. A thermal anticline has been preserved, with temperatures of approximately 600/sup 0/C at the north and south contacts with the Uchi and Wabigoon greenstone belts, increasing to approximately 750/sup 0/C at the center of the subprovince. A garnet-cordierite in isograd occurs at about 675/sup 0/C, and an orthopyroxene isograd at about 700/sup 0/C. Trend surface analysis is an excellent statistical tool for evaluating geothermometers and geobarometers. Application to feldspar and oxide temperatures form the Adirondacks suggests precision of +/-40/sup 0/C.

  18. Seismic heating signatures in the Japan Trench subduction plate-boundary fault zone: evidence from a preliminary rock magnetic `geothermometer'

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Dekkers, Mark J.; Zhang, Bo

    2016-04-01

    Frictional heating during earthquake rupture reveals important information on earthquake mechanisms and energy dissipation. The amount of annealing varies widely and is, as yet, poorly constrained. Here we use magnetic susceptibility versus temperature measurements during cycling to increasingly elevated temperatures to constrain the maximum temperature a slip zone has experienced. The case study comprises sheared clay cored from the Japan Trench subduction plate-boundary fault zone (décollement), which accommodated the large slip of the 2011 Mw 9.0 Tohoku-oki earthquake. The décollement was cored during the Integrated Ocean Drilling Program (IODP) Expedition 343, the Japan Trench Fast Drilling Project (JFAST). Heating signatures with estimated maximum temperatures ranging from ˜300 to over 500 °C are determined close to the multiple slip surfaces within the décollement. Since it is impossible to tie a specific slip surface to a certain earthquake, thermal evidence for the cumulative effect of several earthquakes is unveiled. This as yet preliminary rock magnetic `geothermometer' would be a useful tool to detect seismic heating along faults that experienced medium temperature rise, a range which is difficult to assess with other approaches.

  19. CO/sub 2/-silica geothermometer for low temperature geothermal resource assessment, with application to resources in the Safford Basin, Arizona

    SciTech Connect

    Witcher, J.C.; Stone, C.

    1983-11-01

    This study investigates silica-water reactions in low-temperature geothermal water in areas near Safford, southeastern Arizona, and derives a pCO2 correction for conductive silica geothermometers. Use and limitations of the technique are also discussed. Data collection, interpretation approach, and basic geochemistry, as it applies to this study, are outlined. In addition, the geology, thermal regime, geohydrology, and gross geochemistry of the Safford area are reviewed. Finally, geothermal potential, as indicated by this study and previous studies is discussed.

  20. Comparison of circulation times of thermal waters discharging from the Idaho batholith based on geothermometer temperatures, helium concentrations, and 14C measurements

    USGS Publications Warehouse

    Mariner, R.H.; Evans, William C.; Young, H.W.

    2006-01-01

    Circulation times of waters in geothermal systems are poorly known. In this study, we examine the thermal waters of the Idaho batholith to verify whether maximum system temperatures, helium concentrations, and 14C values are related to water age in these low-to-moderate temperature geothermal systems. He/N2 values of gas collected from thermal waters that circulate solely through distinct units of the Idaho batholith correlate linearly with Na-K-(4/3)Ca geothermometer temperatures, showing that both variables are excellent indicators of relative water age. Thermal waters that circulate in early Tertiary (45-50 Ma) granite of the Sawtooth batholith have 3.5 times more helium than thermal waters of the same aquifer temperature that circulate through the main Cretaceous granite (average 91 Ma). Hot spring waters circulating in hydrothermally altered parts of the batholith have very little dissolved helium and no correlation between He/N2 values and geothermometer temperatures. Thermal waters discharging from the Idaho batholith are more depleted in deuterium than modern precipitation in the area. Recharge to these geothermal systems occurred from at least 10,000 BP for the cooler systems up to about 33,000 BP for the hotter systems.

  1. The clumped isotope geothermometer in soil and paleosol carbonate

    NASA Astrophysics Data System (ADS)

    Quade, J.; Eiler, J.; Daëron, M.; Achyuthan, H.

    2013-03-01

    We studied both modern soils and buried paleosols in order to understand the relationship of temperature (T°C(47)) estimated from clumped isotope compositions (Δ47) of soil carbonates to actual surface and burial temperatures. Carbonates from modern soils with differing rainfall seasonality were sampled from Arizona, Nevada, Tibet, Pakistan, and India. T°C(47) obtained from these soils shows that soil carbonate forms in the warmest months of the year, in the late morning to afternoon, and probably in response to intense soil dewatering. T°C(47) obtained from modern soil carbonate ranges from 10.8 to 39.5 °C. On average, T°C(47) exceeds mean annual temperature by 10-15 °C due to summertime bias in soil carbonate formation, and to summertime ground heating by incident solar radiation. Secondary controls on T°C(47) are soil depth and shading. Site mean annual air temperature (MAAT) across a broad range (0-30 °C) of site temperatures is highly correlated with T°C(47) from soils, following the equation: MAAT(°C)=1.20(T°C(47)0)-21.72(r2=0.92) where T°C(47)0 is the effective air temperature at the site estimated from T°C(47). The effective air temperature represents the air temperature required to account for the T°C(47) at each site, after consideration of variations in T°C(47) with soil depth and ground heating. The highly correlated relationship in this equation should now permit mean annual temperature in the past to be reconstructed from T°C(47) in paleosol carbonate, assuming one is studying paleosols that formed in environments generally similar in seasonality and ground cover to our calibration sites. T°C(47)0 decreases systematically with elevation gain in the Himalaya, following the equation: elevation(m)=-229(T°C(47)0)+9300(r2=0.95) Assuming that temperature varied similarly with elevation in the past, this equation can be used to reconstruct paleoelevation from clumped isotope analysis of ancient soil carbonates. We also measured T°C(47) from long sequences of deeply buried (⩽5 km) paleosol carbonate in the Himalayan foreland in order to evaluate potential diagenetic resetting of clumped isotope composition. We found that paleosol carbonate faithfully records plausible soil T°C(47) down to 2.5-4 km burial depth, or ˜90-125 °C. Deeper than this and above this temperature, T°C(47) in paleosol carbonate is reset to temperatures >40 °C. We observe ˜40 °C as the upper limit for T°C(47) in modern soils from soil depths >25 cm, and therefore that T°C(47) >40 °C obtained from ancient soil carbonate indicates substantially warmer climate regimes compared to the present, or non-primary temperatures produced by resetting during diagenesis. If representative, this limits the use of T°C(47) to reconstruct ancient surface temperature to modestly buried (<3-4 km) paleosol carbonates. Despite diagenetic resetting of Δ47 values, δ18O and δ13C values of the same deeply buried paleosol carbonate appear unaltered. We conclude that solid-state reordering or recrystallization of clumping of carbon and oxygen isotopes can occur in the absence of open-system exchange of paleosol carbonate with significant quantities of water or other phases.

  2. Qrtzgeotherm: An ActiveX component for the quartz solubility geothermometer

    NASA Astrophysics Data System (ADS)

    Verma, Mahendra P.

    2008-12-01

    An ActiveX component, QrtzGeotherm, to calculate temperature and vapor fraction in a geothermal reservoir using quartz solubility geothermometry was written in Visual Basic 6.0. Four quartz solubility equations along the liquid-vapor saturation curve: (i) a quadratic equation of 1/ T and pressure, (ii) a linear equation relating log SiO 2 to the inverse of absolute temperature ( T), (iii) a polynomial of T including logarithmic terms and (iv) temperature as a polynomial of SiO 2 including logarithmic terms are programmed. The QrtzGeotherm has input parameters: (i) HRes—the reservoir enthalpy (kJ/kg), (ii) SiO2TD—silica concentration in total discharge (ppm), (iii) GeoEq—number of quartz solubility equation and (iv) TempGuess—a guess value of the reservoir temperature (°C). The reservoir enthalpy Hres is assumed to be the same as the total discharge enthalpy HR. The output parameters are (i) TempRes—reservoir temperature (°C) and (ii) VapRes—reservoir vapor fraction. The first step is to calculate the total discharge concentration of silica SiO2TD from the concentration of silica SiO2Col of separated water, sampled after N-separations of vapor and water. To use QrtzGeotherm in MS-Excel, three functions SiO2TD, GeoResTemp and GeoResVap for an N-stage separation of geothermal reservoir fluid are written in Visual Basic for Application (VBA). Similarly, a demonstration program, QrtzGeothrm, is written in Visual Basic 6.0.

  3. The fractionation of nickel between olivine and augite as a geothermometer

    USGS Publications Warehouse

    Hakli, T.A.; Wright, T.L.

    1967-01-01

    The coexisting olivine, clinopyroxene and glass of five samples collected from the Makaopuhi lava lake in Hawaii, at temperatures ranging from 1050 to 1160??C were analysed for nickel with an electron probe microanalyser. The results strongly suggest that the distribution of nickel between these three phase pairs well obeys the thermodynamic partition law, and that under favourable conditions, the distribution coefficients permit the estimation of the crystallisation temperature within an accuracy of 10-20??C. It is concluded that the application of the Makaopuhi data to plutonic and to other volcanic rocks should be carried out with caution because the effect of pressure and the changing composition of the phases upon the numerical values of the distribution coefficients is not known quantitatively. ?? 1967.

  4. Calibration of the clumped isotope geothermometer in soil carbonate in Wyoming and Nebraska, USA: Implications for paleoelevation and paleoclimate reconstruction

    NASA Astrophysics Data System (ADS)

    Hough, Brian G.; Fan, Majie; Passey, Benjamin H.

    2014-04-01

    Recent work has shown that soil carbonates typically form as the soil dries after seasonal rainfall, and therefore record seasonal aspects of climate rather than mean annual conditions. Because soil carbonate formation is closely related to the timing of local rainfall and drying, it is necessary to understand the formation seasonality and temperature, and soil water δO18 values recorded in modern soil carbonate before accurate estimates of stable isotope-based paleoelevation and paleoclimate can be made. Here we study carbonate clumped-isotope (Δ47) and oxygen isotope (δO18) compositions of modern soil carbonates and seasonal variations of soil moisture and temperature of nearby climate stations in Wyoming and western Nebraska, USA, to understand the seasonality of soil carbonate formation in semi-arid to arid temperate montane settings. We find that soil carbonate clumped-isotope temperatures (T(Δ47)) are 3-5 °C higher than mean summer air temperature and are similar to or higher than average summer soil temperature. At depths >40 cm, soil moisture dramatically decreases in early summer following the cessation of spring rains and snowmelt and shows only brief increases after major mid-late summer rain events. Soil water δO18 values calculated using carbonate δO18 and T(Δ47) values are similar to the δO18 values of local mean summer precipitation. These lines of evidence suggest that soil carbonates in our study area formed during times of soil dewatering in early summer and after major summer storm events in mid-late summer, and in or near equilibrium with mean summer precipitation δO18 values. T(Δ47) values of modern soil carbonates are inversely correlated with elevation, with a lapse rate, -4.0 °C/km, similar to the modern air and soil temperature lapse rates. Calculated soil water δO18 values also are inversely correlated with elevation, with a lapse rate of -3.7‰/km. Sample elevations can be reconstructed using both T(Δ47) values and calculated soil water δO18 values between 900 m and 2600 m in our studied area, with an accuracy of ±0.5 km or less. However, δO18 values of precipitation and soil water reflect the complex interaction of climatic, environmental, and topographic conditions prior to carbonate formation, whereas T(Δ47) values may be influenced by site-specific conditions. We suggest that both soil carbonate T(Δ47) values and calculated soil water δO18 values should be used to corroborate paleoelevation reconstruction, and the seasonal nature of soil carbonate formation should be considered when soil carbonate T(Δ47) values and δO18 values are applied for paleoclimate reconstruction.

  5. Calibration of the calcite-water oxygen-isotope geothermometer at Devils Hole, Nevada, a natural laboratory

    USGS Publications Warehouse

    Coplen, T.B.

    2007-01-01

    The ??18O of ground water (-13.54 ?? 0.05 ???) and inorganically precipitated Holocene vein calcite (+14.56 ?? 0.03 ???) from Devils Hole cave #2 in southcentral Nevada yield an oxygen isotopic fractionation factor between calcite and water at 33.7 ??C of 1.02849 ?? 0.00013 (1000 ln ??calcite-water = 28.09 ?? 0.13). Using the commonly accepted value of ???(??calcite-water)/???T of -0.00020 K-1, this corresponds to a 1000 ln ??calcite-water value at 25 ??C of 29.80, which differs substantially from the current accepted value of 28.3. Use of previously published oxygen isotopic fractionation factors would yield a calcite precipitation temperature in Devils Hole that is 8 ??C lower than the measured ground water temperature. Alternatively, previously published fractionation factors would yield a ??18O of water, from which the calcite precipitated, that is too negative by 1.5 ??? using a temperature of 33.7 ??C. Several lines of evidence indicate that the geochemical environment of Devils Hole has been remarkably constant for at least 10 ka. Accordingly, a re-evaluation of calcite-water oxygen isotopic fractionation factor may be in order. Assuming the Devils Hole oxygen isotopic value of ??calcite-water represents thermodynamic equilibrium, many marine carbonates are precipitated with a ??18O value that is too low, apparently due to a kinetic isotopic fractionation that preferentially enriches 16O in the solid carbonate over 18O, feigning oxygen isotopic equilibrium.

  6. Mixing models and ionic geothermometers applied to warm (up to 60°C) springs: Jordan Rift Valley, Israel

    NASA Astrophysics Data System (ADS)

    Mazor, E.; Levitte, D.; Truesdell, A. H.; Healy, J.; Nissenbaum, A.

    1980-01-01

    Mixing models and evaluation of SiO 2 contents of warm-water manifestations in the Jordan—Dead Sea Rift Valley indicate that these waters are fed by aquifers with estimated temperatures of up to 68°C. These calculations and Na/K ratios, concentrations of Na, K and Ca, concentrations of atmospheric Ne, Ar, Kr and Xe; and concentrations of the stable hydrogen and oxygen isotopes all indicate below-boiling temperatures. No indications are available for the existence of above-boiling geothermal systems in the Jordan Rift Valley. Slightly higher than observed temperatures are concluded for a deep component at the springs of Hammat Gader (67°C), Gofra (68°C), the Russian Garden (40°C), and the Yesha well (53-65°C). These temperatures may encourage further developments for spas and bathing installations and, to a limited extent, for space heating, but are not favorable for geothermal power generation.

  7. The calibration of a magnetic geothermometer from 50°C to 70°C in argillaceous rocks

    NASA Astrophysics Data System (ADS)

    Aubourg, Charles; Pozzi, Jean Pierre; Kars, Myriam; Janots, Dominik

    2013-04-01

    In sub-surface anoxic conditions, the microbe activity leads to a 'magnetic reset' of argillaceous rocks with the alteration of inherited iron oxides (Roberts et al., Review of Geophysics 2011). During the diagenesis, it is known that magnetic minerals (greigite, magnetite and pyrrhotite) are continuously forming. Hence, there is the possibility to use these neoformed magnetic minerals as a burial tracker (Aubourg et al., GSL; 2012). Aubourg & Pozzi (EPSL, 2010) fist proposed to use a parameter (PM) derived from rock magnetism analysis as a proxy of burial in a range 50°C to 250°C. They based their calibration curve from natural samples and laboratory heating. The evolution of PM marks two branches, up and down, with a maximum value near 90°C. Here we propose to precise the upward branch of PM evolution by studying ~600 m of argillaceous Jurassic rocks from the EST433 borehole from the Basin of Paris. We have conducted low-temperature magnetic analysis (from -263°C to 27°C) on 32 samples and derived PM parameter. The PM depth profile displays a consistent convex curve which can be explained satisfactorily by a model of nucleation-and-growth of nanoparticles of magnetite. This is in agreement with laboratory heating results obtained from Kars et al. (Gcubed, 2012). The PM evolution is compared to vitrinite reflectance data. A 1D thermal modeling suggests that burial temperature evolves from ~50°C to ~70°C (Blaise et al., 2011). Our calibration curve indicates that the production of nanoparticles of magnetite is dramatically reducing near the onset of the oil window.

  8. Fluid-inclusion technique for determining maximum temperature in calcite and its comparison to the vitrinite reflectance geothermometer

    USGS Publications Warehouse

    Barker, C.E.; Goldstein, R.H.

    1990-01-01

    The hypothesis that aqueous fluid inclusions in calcite can be used to establish maximum temperature (Tpeak) is tested. Fluid inclusion Th, mean random vitrinite reflectance (Rm), and present-day Tpeak from 46 diverse geologic systems that have been at Tpeak from 104 to 106 yr have been compiled. Present Tpeak ranged from 65 to 345??C, Th modes and means ranged from 59 to 350??C, and Rm data ranged from 0.4% to 4.6%, spanning the temperature and thermal maturity range associated with burial diagenesis, hydrothermal alteration, and low-grade metamorphism. Plots of Th and Tpeak data for systems thought to be currently at maximum temperature demonstrate close agreement between Th and present Tpeak in sedimentary basins. The relation suggests that Th of aqueous fluid inclusions in calcite may be a useful measure of maximum temperature. This study also compared Th to mean random vitrinite reflectance (Rm). Th correlates well with Rm and results in a curve similar to Rm vs. Tpeak calibrations determined by other workers. Strong correlation between Tpeak and Rm in these systems suggests that maximum temperature is the major control on thermal maturation. -after Authors

  9. Mixing models and ionic geothermometers applied to warm (up to 60°C) springs: Jordan Rift Valley, Israel

    USGS Publications Warehouse

    Mazor, E.; Levitte, D.; Truesdell, A.H.; Healy, J.; Nissenbaum, A.

    1980-01-01

    No indications are available for the existence of above-boiling geothermal systems in the Jordan Rift Valley. Slightly higher than observed temperatures are concluded for a deep component at the springs of Hammat Gader (67°C), Gofra (68°C), the Russian Garden (40°C), and the Yesha well (53–65°C). These temperatures may encourage further developments for spas and bathing installations and, to a limited extent, for space heating, but are not favorable for geothermal power generation.

  10. Application of graphite as a geothermometer in hydrothermally altered metamorphic rocks of the Merelani-Lelatema area, Mozambique Belt, northeastern Tanzania

    NASA Astrophysics Data System (ADS)

    Malisa, Elias Pausen

    1998-02-01

    Upper Precambrian pelitic and psammitic gneisses in the Mozambique Belt are usually graphite rich. The determination of crystallisation temperatures around and in the hydrothermally altered rocks of the Merelani-Lelatema mining areas, northeastern Tanzania, were made by studying the lattice parameter C of graphite. In this way, the migration of the chromophore elements giving colour to the gemstones, e.g. tanzanite, green garnet and green tourmaline in the area, can be studied. Within the hydrothermally altered zone graphite gives temperatures that range from 523°C to 880°C. These temperatures are much higher than the 390-440°C obtained through fluid inclusion studies of tanzanite, which indicates that the graphite was not hydrothermally introduced. Furthermore the hydrothermal solutions are post-metamorphic.

  11. Zircon-scale insights into the history of a Supervolcano, Bishop Tuff, Long Valley, California, with implications for the Ti-in-zircon geothermometer

    USGS Publications Warehouse

    Reid, M.R.; Vazquez, J.A.; Schmitt, A.K.

    2011-01-01

    Zircon has the outstanding capacity to record chronological, thermal, and chemical information, including the storage history of zoned silicic magma reservoirs like the one responsible for the Bishop Tuff of eastern California, USA. Our novel ion microprobe approach reveals that Bishop zircon rims with diverse chemical characteristics surround intermediate domains with broadly similar compositions. The highest Y, REE, U, and Th concentrations tend to accompany the largest excesses in Y + REE3+:P beyond what can be explained by xenotime substitution in zircon. Apparent Ti-in-zircon temperatures of <720??C for zircon rims are distinctly lower than most of the range in eruption temperatures, as estimated from FeTi-oxide equilibria and zircon solubility at quench. While permissive of crystallization of zircon at near-solidus conditions, the low Ti-in-zircon temperatures are probably better explained by sources of inaccuracy in the temperature estimates. After apparently nucleating from different melts, zircons from across the Bishop Tuff compositional spectrum may have evolved to broadly similar chemical and thermal conditions and therefore it is possible that there was no significant thermal gradient in the magma reservoir at some stage in its evolution. There is also no compelling evidence for punctuated heat ?? chemical influxes during the intermediate stages of zircon growth. Judging by the zircon record, the main volume of the erupted magma evolved normally by secular cooling but the latest erupted portion is characterized by a reversal in chemistry that appears to indicate perfusion of the magma reservoir by-or zircon entrainment in-a less evolved melt from the one in which the zircons had previously resided. ?? 2010 Springer-Verlag.

  12. Zircon-scale insights into the history of a Supervolcano, Bishop Tuff, Long Valley, California, with implications for the Ti-in-zircon geothermometer

    NASA Astrophysics Data System (ADS)

    Reid, Mary R.; Vazquez, Jorge A.; Schmitt, Axel K.

    2011-02-01

    Zircon has the outstanding capacity to record chronological, thermal, and chemical information, including the storage history of zoned silicic magma reservoirs like the one responsible for the Bishop Tuff of eastern California, USA. Our novel ion microprobe approach reveals that Bishop zircon rims with diverse chemical characteristics surround intermediate domains with broadly similar compositions. The highest Y, REE, U, and Th concentrations tend to accompany the largest excesses in Y + REE3+:P beyond what can be explained by xenotime substitution in zircon. Apparent Ti-in-zircon temperatures of <720°C for zircon rims are distinctly lower than most of the range in eruption temperatures, as estimated from FeTi-oxide equilibria and zircon solubility at quench. While permissive of crystallization of zircon at near-solidus conditions, the low Ti-in-zircon temperatures are probably better explained by sources of inaccuracy in the temperature estimates. After apparently nucleating from different melts, zircons from across the Bishop Tuff compositional spectrum may have evolved to broadly similar chemical and thermal conditions and therefore it is possible that there was no significant thermal gradient in the magma reservoir at some stage in its evolution. There is also no compelling evidence for punctuated heat ± chemical influxes during the intermediate stages of zircon growth. Judging by the zircon record, the main volume of the erupted magma evolved normally by secular cooling but the latest erupted portion is characterized by a reversal in chemistry that appears to indicate perfusion of the magma reservoir by—or zircon entrainment in—a less evolved melt from the one in which the zircons had previously resided.

  13. Experimental investigation of the alluaudite + triphylite assemblage, and development of the Na-in-triphylite geothermometer: applications to natural pegmatite phosphates

    NASA Astrophysics Data System (ADS)

    Hatert, Frederic; Ottolini, Luisa; Schmid-Beurmann, Peter

    2011-04-01

    In order to assess the stability of the primary alluaudite + triphylite assemblage, we performed hydrothermal experiments between 400 and 800°C, starting from the LiNa2Mn x Fe{3-/x 2+}Fe3+(PO4)4 compositions ( x = 1.054, 1.502, 1.745) that represent the ideal compositions of the alluaudite + triphylite assemblages from the Kibingo (Rwanda), Hagendorf-Süd (Germany), and Buranga (Rwanda) pegmatites, respectively. The pressure was maintained at 1 kbar, and the oxygen fugacity was controlled by the Ni-NiO buffer. The results of these experiments show that the alluaudite + triphylite assemblage crystallizes at 400 and 500°C, while the association alluaudite + triphylite + marićite appears at 600 and 700°C. The limit between these two domains, at ca. 550°C, corresponds to the maximum temperature that can be reached by the alluaudite + triphylite assemblages in granitic pegmatites, because marićite has never been observed in such geological environments. At 800°C, the formation of the X-phase + triphylite assemblage indicates a strong reduction of the bulk composition, according to the reaction 0.5LiM2+PO4 (triphylite) + 3Na2M2 2+Fe3+(PO4)3 (alluaudite) + 1.5H2O = 4.5NaM2+PO4 (marićite) + Li0.5Na1.5M5 2+(PO4)4 (X-phase) + H3PO4 + 0.75O2 (M2+ = Fe2+, Mn). Secondary ion mass spectrometry (SIMS) was used at our knowledge for the first time to measure Li in all the Li-bearing phosphates. A specific methodological procedure was developed with the ion microprobe to get accurate Li2O data over a wide concentration range spanning from few ppm Li up to ~11 wt%. Li2O. Our SIMS analyses of the synthesized phosphates indicate that the Li contents of alluaudites, marićites, and X-phase increase progressively with temperature, while the Li content of triphylite-type phosphates decreases due to the Li → Na substitution. The Na-exchange equilibrium between triphylite-type phosphates and alluaudite is correlated with the temperature according to the equation: ln( x {Na/Tri}/ x {Na/All}) = -7.0(7) 103/T + 5.4(9). This equation can be used to estimate the crystallization temperature of triphylite-alluaudite assemblages independently of the oxygen fugacity.

  14. Intensive parameters of enstatite chondrite metamorphism

    NASA Astrophysics Data System (ADS)

    Fogel, R. A.; Hess, P. C.; Rutherford, M. J.

    1989-10-01

    A geothermometer based on the assemblage kamacite-quartz-enstatite-oldhamite-troilite found in enstatite chondrites is described. Data obtained with the geothermometer reveal that the EL6 meteorites experienced temperatures exceeding 1000 C. These temperatures imply a metal-sulfide melting event that may have fractionated the melt from the source region.

  15. Intensive parameters of enstatite chondrite metamorphism

    NASA Technical Reports Server (NTRS)

    Fogel, Robert A.; Hess, Paul C.; Rutherford, Malcolm J.

    1989-01-01

    A geothermometer based on the assemblage kamacite-quartz-enstatite-oldhamite-troilite found in enstatite chondrites is described. Data obtained with the geothermometer reveal that the EL6 meteorites experienced temperatures exceeding 1000 C. These temperatures imply a metal-sulfide melting event that may have fractionated the melt from the source region.

  16. Interpretation of Na-K-Mg relations in geothermal waters

    USGS Publications Warehouse

    Fournier, R.O.

    1990-01-01

    When using a Na-K-???Mg triangular diagram as an aid in the interpretation of a geothermal water, the estimated temperature of last water-rock equilibration may change by as much as 50??C, depending on which of the many Na/K geothermometers one assumes is correct. A particular geothermometer may work well in one place and not in another because of differences in the mineralogy of the phases that are in contact with the reservoir fluid. The position of the full equilibrium line that is used for geothermometry and for assessing degrees of departure from equilibrium also changes as the assumed K/???Mg geothermometer equation changes. The degree of ambiguity can be evaluated by utilizing the results of all the recently published Na/K geothermometers on a single Na-K-???Mg triangular plot.

  17. Comparative study of the silica and cation geothermometry of the Malawi hot springs: Potential alternative energy source

    NASA Astrophysics Data System (ADS)

    Dulanya, Zuze; Morales-Simfors, Nury; Sivertun, Åke

    2010-06-01

    Malawi is one of the poorest countries in the world and one of the most densely populated in south-eastern Africa. Its major power source is hydro-electricity. During the past few years, the power generation capacity has been reduced, which has impacted negatively on the socio-economic development of the country. The country holds an enormous potential to generate geothermal energy due to the country's position within the Great African Rift valley. This could contribute to economic growth, poverty reduction and technological development in Malawi. The paper presents findings of research on comparisons between silica (quartz and chalcedony) and cation geothermometers (Na-K, Na-K-Ca and K-Mg) of hot springs in the Malawi Rift, in order to deduce the temperature at depth of selected hot springs. The saturation indices of most springs have a bearing on the geology of the areas where these hot springs are found. The Na-K geothermometers are, in general, higher than the Na-K-Ca geothermometer and the K-Mg geothermometer shows temperatures that are too low to be considered. The difference in the results between the different geothermometers may indicate shallow conditions of mixing with groundwater. Results also indicate that some hot springs have sufficient heat-generating capabilities and warrant further exploration work to assess their suitability for energy generation.

  18. Geothermal reservoir temperatures estimated from the oxygen isotope compositions of dissolved sulfate and water from hot springs and shallow drillholes

    USGS Publications Warehouse

    McKenzie, W.F.; Truesdell, A.H.

    1977-01-01

    The oxygen isotope compositions of dissolved sulfate and water from hot springs and shallow drillholes have been tested as a geothermometer in three areas of the western United States. Limited analyses of spring and borehole fluids and existing experimental rate studies suggest that dissolved sulfate and water are probably in isotopic equilibrium in all reservoirs of significant size with temperatures above ca. 140??C and that little re-equilibration occurs during ascent to the surface. The geothermometer is, however, affected by changes in ??18O of water due to subsurface boiling and dilution and by addition of sulfate of nearsurface origin. Methods are described to calculate the effects of boiling and dilution. The geothermometer, is applied to thermal systems of Yellowstone Park, Wyoming, Long Valley, California, and Raft River, Idaho to estimate deep reservoir temperatures of 360, 240, and 142??C, respectively. ?? 1976.

  19. The ilmenite/titano-magnetite assemblage - Kinetics of re-equilibration

    NASA Technical Reports Server (NTRS)

    Hammond, P. A.; Taylor, L. A.

    1982-01-01

    The petrogenesis of igneous and metamorphic rocks is a function of several parameters. Of these, temperature and pressure are of particular importance. Information concerning these two parameters is obtained through the use of mineral indicators. One such commonly used geothermometer/oxybarometer is that involving ilmenite/titano-magnetite. Anomalously low temperatures have been reported in cases in which the geothermometer/oxybarometer was employed. The studies suggest that low temperatures result from slow cooling rates which allows the Fe-Ti oxides to re-equilibrate. The current investigation is mainly concerned with the kinetics of the reduction of ilmenite-hematite solid solution, since this is the slower and, consequently, rate-controlling step in the re-equilibration process. The reaction rates determined for the reduction of ilmenites in the investigation are geologically rapid and must be considered when applying the considered geothermometer/oxybarometer.

  20. Estimation of Reservoir Geotemperatures from Multicomponent and Classical Geothermometry of the Bath Geothermal Reservoir: An Integrated Approach

    NASA Astrophysics Data System (ADS)

    Wishart, D. N.

    2014-12-01

    An integrated approach incorporating multicomponent and classical solute geothermometry was used to evaluate its utility to estimate the temperature of the Bath geothermal reservoir, a low-enthalpy system on the island of Jamaica. Reservoir temperatures were estimated from (1) empirical geothermometric equations; (2) simulations of solute geothermometers using SolGeo software; (3) computations of saturation indices [Log(Q/K)] of reservoir minerals from full chemically-analyzed thermal water samples over a temperature range of 25-220°C in PHREEQC; and (4) the Giggenbach Na-K-Mg geothermometer. A principal component analysis (PCA) shows strong, positive correlations between Na+, K+, and Mg2+ and is regarded as significant for these ions in their reliance as useful reservoir geoindicators. However, a negative correlation exists between Na+, K+, Mg2+ and silica (SiO2). The more realistic estimates of the geothermal reservoir temperature were provided by the Na-K and Na-K-Mg geothermometers, whereas the Na-K-Ca geothermometer overestimated reservoir temperatures. Estimated geotemperatures from silica-quartz geothermometers were the lowest. The discrepancy in estimated geotemperatures may be due to processes such as boiling, degassing, dilution, rock dissolution, and mixing during the ascent of geothermal fluids. Log (Q/K) curves cluster over a range of equilibrium temperatures closest to Na-K and Na-K-Mg geothermometers at 80-102°C. Reservoir temperatures estimated for the Bath geothermal system range between 79-118°C. Comparisons of the estimated geotemperatures using the integrated approach to geothermometry show a favorable agreement. Based on the results of this investigation, the integrated geothermometric approach provided a more reliable approach to reconstruct the fluid composition at depth and estimate the geothermal reservoir temperature.

  1. Une méthode globale d'estimation des températures des réservoirs alimentant les sources thermales. Exemple du Massif Central Français

    NASA Astrophysics Data System (ADS)

    Michard, Gil; Fouillac, Christian; Grimaud, Daniel; Denis, Jérôme

    1981-07-01

    A chemical model based on the equilibrium of water with quartz, albite, adularia, calcite, kaolinite or illite, and chlorite can explain the chemical composition of the main groups of hot springs in Massif Central. Temperature is the principal variable for determining this composition. Model temperatures generally agree with those given by classical cation geothermometers ( t ≅ 135-150° C for Vichy. La Bourboule. Evaux and Châteauneuf; t ≅ 175-180° C for Chaudes Aigues and Saint Nectaire). The model fails to represent the composition of Mont Dore waters: the high temperatures given by classical geothermometers are considered doubtful.

  2. Tularosa Basin Play Fairway Analysis: Water Chemistry

    SciTech Connect

    Adam Brandt

    2015-12-15

    This shapefile contains 409 well data points on Tularosa Basin Water Chemistry, each of which have a location (UTM), temperature, quartz and Potassium/Magnesium geothermometer; as well as concentrations of chemicals like Mn, Fe, Ba, Sr, Cs, Rb, As, NH4, HCO3, SO4, F, Cl, B, SiO2, Mg, Ca, K, Na, and Li.

  3. Tularosa Basin Play Fairway Analysis: Partial Basin and Range Heat and Zones of Critical Stress Maps

    SciTech Connect

    Adam Brandt

    2015-11-15

    Interpolated maps of heat flow, temperature gradient, and quartz geothermometers are included as TIF files. Zones of critical stress map is also included as a TIF file. The zones are given a 5km diameter buffer. The study area is only a part of the Basin and Range, but it does includes the Tularosa Basin.

  4. Occurrence of Sulphides in Sowia Dolina Near Karpacz (SW Poland) - An Example of ore Mineralization in the Contact Aureole of the Karkonosze Granite

    NASA Astrophysics Data System (ADS)

    Mochnacka, Ksenia; Oberc-Dziedzic, Teresa; Mayer, Wojciech; Pieczka, Adam; Góralski, Michał

    2007-01-01

    The authors studied the poorly-known, uneconomic sulphide mineralization site in Sowia Dolina near Karpacz. Host rocks are hornfelses of the Velká Úpa schist series, which belongs to the Izera-Kowary Unit. Ore minerals assemblage includes: pyrrhotite, pyrite, chalcopyrite, arsenopyrite, sphalerite, galena and marcasite, accompanied by ilmenite and rutile. The oldest sulphide is high-temperature pyrrhotite crystallized at about 600°C, which is in good agreement with the temperature range of contact metamorphic conditions, revealed by muscovitesillimanite transformation. Low-temperature pyrrhotite and other sulphides formed at about 390°C (arsenopyrite geothermometer) down to 265°C (pyrrhotite geothermometer), whereas fluid inclusions studies of vein quartz demonstrated the temperature range 380-150°C. Mineralization in Sowia Dolina is similar to other ore hydrothermal deposits known from the proximal or distal contact zone of the Karkonosze granite.

  5. Correlation between the silica concentration and the orifice temperature in the warm springs along the jordan-dead sea rift valley

    USGS Publications Warehouse

    Levitte, D.; Eckstein, Y.

    1978-01-01

    Analysis of twenty-one thermal springs emerging along the Jordan-Dead Sea Rift Valley in Israel indicates a very good correlation between the concentration of dissolved silica and the temperature of the spring orifice. Dissolution of quartz was identified as the apparent source of the silica in the water. Application of the silica geothermometer for mixed systems suggests that the springs in the Tiberias Lake Basin are supplied with hot water from deep reservoir (or reservoirs) at a temperature of 115??C (239??F). The same temperature was postulated earlier by the application of the Na-K-Ca hydro-geothermometer to a group of thermal springs in the same basin. The temperature of the reservoir supplying hot brines to the springs emerging along the western shore of the Dead Sea is estimated at 90??C (194??F).

  6. Thermal extraction analysis of five Los Azufres production wells

    SciTech Connect

    Kruger, Paul; Quijano, Luis

    1995-01-26

    Thermal energy extraction from five wells supplying 5-MWe wellhead generators in three zones of the Los Azufres geothermal field has been examined from production and chemical data compiled over 14-years of operation. The data, as annual means, are useful in observing small-scale changes in reservoir performance with continuous production. The chemical components are chloride for quality control and the geothermometer elements for reservoir temperatures. The flowrate and fluid enthalpy data are used to calculate the thermal extraction rates. Integration of these data provides an estimate of the total energy extracted from the zone surrounding the well. The combined production and chemical geothermometer data are used to model the produced fluid as coming from just-penetrating wells for which the annual produced mass originates from a series of concentric hemispheric shells moving out into the reservoir. Estimates are made of the drawdown distance into the reservoir and the far-field conditions.

  7. Oxygen and hydrogen isotope geochemistry of zeolites

    NASA Technical Reports Server (NTRS)

    Karlsson, Haraldur R.; Clayton, Robert N.

    1990-01-01

    Oxygen and hydrogen isotope ratios for natural samples of the zeolites analcime, chabazite, clinoptilolite, laumontite, mordenite, and natrolite have been obtained. The zeolite samples were classified into sedimentary, hydrothermal, and igneous groups. The ratios for each species of zeolite are reported. The results are used to discuss the origin of channel water, the role of zeolites in water-rock interaction, and the possibility that a calibrated zeolite could be used as a low-temperature geothermometer.

  8. Implications for geothermometry of aluminum substitution in quartz from Kings Mountain, North Carolina

    USGS Publications Warehouse

    Perry, E.C., Jr.

    1971-01-01

    The aluminum concentration of quartz from contact-metamorphosed, Al2SiO5 bearing quartzite at King's Mountain, North Carolina shows a regular variation with distance from an intrusive contact. Presumably this is the result of temperature-dependent solubility of aluminum in quartz, but critical comparison of these results with other recently published data shows that detailed calibration of this geothermometer has not yet been achieved. ?? 1971 Springer-Verlag.

  9. Techniques for the conversion to carbon dioxide of oxygen from dissolved sulfate in thermal waters

    USGS Publications Warehouse

    Nehring, N.L.; Bowen, P.A.; Truesdell, A.H.

    1977-01-01

    The fractionation of oxygen isotopes between dissolved sulfate ions and water provides a useful geothermometer for geothermal waters. The oxygen isotope composition of dissolved sulfate may also be used to indicate the source of the sulfate and processes of formation. The methods described here for separation, purification and reduction of sulfate to prepare carbon dioxide for mass spectrometric analysis are modifications of methods by Rafter (1967), Mizutani (1971), Sakai and Krouse (1971), and Mizutani and Rafter (1969). ?? 1976.

  10. Characterization of Organic Materials in the Xenolithic Clasts in Sharps (H3.4) Meteorite Using Microraman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Zolensky, M. E.; Bodnar, R. J.; Kebukawa, Y.

    2015-01-01

    Graphitization of carbon is an irreversible process which alters the structure of graphitic materials in response to the increase in metamorphic grade (temperature and/or pressure). Carbonaceous materials offer a reliable geothermometer as their Raman spectra change systematically with increasing metamorphic grade [1-3]. In this study, we identified carbonaceous materials in the xenolithic clasts in Sharps and interpreted their metamorphic history by revealing the structural organization (order) of the polyaromatic organic phases using µ-Raman spectroscopy.

  11. Characterization of Organic Materials in the Xenolithic Clasts in Sharps (H3.4) Meteorite Using Micro-Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Zolensky, M. E.; Bodnar, R. J.; Kebukawa, Y.

    2015-01-01

    Graphitization of carbon is an irreversible process which alters the structure of graphitic materials in response to the increase in metamorphic grade (temperature and/or pressure). Carbonaceous materials offer a reliable geothermometer as their Raman spectra change systematically with increasing metamorphic grade. In this study, we identified carbonaceous materials in the xenolithic clasts in Sharps and interpreted their metamorphic history by revealing the structural organization (order) of the polyaromatic organic phases using micro-Raman spectroscopy.

  12. Program and Abstracts for Clay Minerals Society 28th Annual Meeting

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This volume contains abstracts that were accepted for presentation at the annual meeting. Some of the main topics covered include: (1) fundamental properties of minerals and methods of mineral analysis; (2) surface chemistry; (3) extraterrestrial clay minerals; (4) geothermometers and geochronometers; (5) smectite, vermiculite, illite, and related reactions; (6) soils and clays in environmental research; (7) kaolinite, halloysite, iron oxides, and mineral transformations; and (8) clays in lakes, basins, and reservoirs.

  13. SE Great Basin Play Fairway Analysis

    SciTech Connect

    Adam Brandt

    2015-11-15

    This submission includes a Na/K geothermometer probability greater than 200 deg C map, as well as two play fairway analysis (PFA) models. The probability map acts as a composite risk segment for the PFA models. The PFA models differ in their application of magnetotelluric conductors as composite risk segments. These PFA models map out the geothermal potential in the region of SE Great Basin, Utah.

  14. Low-temperature geothermal assessment of the Santa Clara and Virgin River Valleys, Washington County, Utah

    SciTech Connect

    Budding, K.E.; Sommer, S.N.

    1986-01-01

    Exploration techniques included the following: (1) a temperature survey of springs, (2) chemical analyses and calculated geothermometer temperatures of water samples collected from selected springs and wells, (3) chemical analyses and calculated geothermometer temperatures of spring and well water samples in the literature, (4) thermal gradients measured in accessible wells, and (5) geology. The highest water temperature recorded in the St. George basin is 42/sup 0/C at Pah Tempe Hot Springs. Additional spring temperatures higher than 20/sup 0/C are at Veyo Hot Spring, Washington hot pot, and Green Spring. The warmest well water in the study area is 40/sup 0/C in Middleton Wash. Additional warm well water (higher than 24.5/sup 0/C) is present north of St. George, north of Washington, southeast of St. George, and in Dameron Valley. The majority of the Na-K-Ca calculated reservoir temperatures range between 30/sup 0/ and 50/sup 0/C. Anomalous geothermometer temperatures were calculated for water from Pah Tempe and a number of locations in St. George and vicinity. In addition to the known thermal areas of Pah Tempe and Veyo Hot Spring, an area north of Washington and St. George is delineated in this study to have possible low-temperature geothermal potential.

  15. Numerical modeling of thermal evolution in the contact aureole of a 0.9 m thick dolerite dike in the Jurassic siltstone section from Isle of Skye, Scotland

    NASA Astrophysics Data System (ADS)

    Wang, Dayong; Song, Yongchen; Xu, Hushan; Ma, Xiaojing; Zhao, Minglong

    2013-02-01

    In this study, we present a heat-transfer-model analysis of thermal evolution in the contact aureole of a 0.9 m thick dolerite dike in the Jurassic siltstone section from Isle of Skye, Scotland based on the constraints from the two types of vitrinite-reflectance geothermometers as well as geochemistry and burial history of host rocks. The predictions from the heat conduction models assuming the finite-time magma intrusion mechanism and pore-water volatilization can match well with both measured vitrinite reflectances and geological conditions of the host rocks. In the region where pore water volatilized and vitrinite reflectance rises with decreasing distance to the dike contact, the bomb geothermometer is consistent with the EASY%Ro model in validating the thermal evolution history of the host rocks, whereas it loses the function of temperature indicator out of the volatilization region. Possibly, the pore-water volatilization influenced the reliability of the bomb geothermometer. The computed total organic carbon contents based on the reconstructed thermal evolution history and the EASY%Ro model present the general agreement with the measured values, demonstrating the availability of the EASY%Ro model in indicating organic-matter transformation ratios at contact metamorphic conditions.

  16. Evaluation of the solute geothermometry of thermal springs and drilled wells of La Primavera (Cerritos Colorados) geothermal field, Mexico: A geochemometrics approach

    NASA Astrophysics Data System (ADS)

    Pandarinath, Kailasa; Domínguez-Domínguez, Humberto

    2015-10-01

    A detailed study on the solute geothermometry of thermal water (18 springs and 8 drilled wells) of La Primavera geothermal field (LPGF) in Mexico has been carried out by employing a geochemical database compiled from the literature and by applying all the available solute geothermometers. The performance of these geothermometers in predicting the reservoir temperatures has been evaluated by applying a geochemometrics (geochemical and statistical) method. The springs of the LPGF are of bicarbonate type and the majority have attained partial-equilibrium chemical conditions and the remaining have shown non-equilibrium conditions. In the case of geothermal wells, water is dominantly of chloride-type and, among the studied eight geothermal wells, four have shown full-equilibrium chemical conditions and another four have indicated partial-equilibrium conditions. All springs of HCO3-​ type water have provided unreliable reservoir temperatures, whereas the only one available spring of SO42- type water has provided the reservoir temperature nearer to the average BHT of the wells. Contrary to the general expected behavior, spring water of non-equilibrium and geothermal well water of partial-equilibrium chemical conditions have indicated more reliable reservoir temperatures than those of partially-equilibrated and fully-equilibrated water, respectively. Among the chemical concentration data, Li and SiO2 of two springs, SO42- and Mg of four springs, and HCO3 and Na concentrations of two geothermal wells were identified as outliers and this has been reflected in very low reservoir temperatures predicted by the geothermometers associated with them (Li-Mg, Na-Li, Na-K-Mg, SiO2 etc.). Identification of the outlier data points may be useful in differentiating the chemical characteristics, lithology and the physico-chemical and geological processes at the sample locations of the study area. In general, the solute geothermometry of the spring waters of LPGF indicated a dominantly

  17. Assessment of geothermal reservoirs by analysis of gases in thermal waters

    SciTech Connect

    Norman, D.I.; Bernhardt, C.A.

    1982-02-01

    Gases were measured in fifty-one thermal wells and springs in New Mexico including sixteen wells in the Lightning Dock geothermal area. Correlation of gases with alkali geothermometry indicates CO/sub 2/ and He increase in abundance with reservoir temperature while N/sub 2/, Ar, NO, Kr and CH/sub 4/ show slight decreases. H/sub 2/S generally occurs in waters with reservoir temperatures >100/sup 0/C, however, H/sub 2/S is not present in all high temperature waters. Gas ratios, principally CO/sub 2//N/sub 2/, CO/sub 2//Ar, CO/sub 2//CH/sub 4/, He/N/sub 2/ and He/Ar correlate better with geothermometry than abundances of individual gases. This study indicates the gas data which could be used to identify waters from reservoirs of T > 100/sup 0/C are CO/sub 2/, CO/sub 2//N/sub 2/, CO/sub 2//Ar, CO/sub 2//CH/sub 4/, He/N/sub 2/ and He/Ar in well waters as well as CO/sub 2/, CO/sub 2//CH/sub 4/, CO/sub 2//N/sub 2/, and CO/sub 2//Ar in spring waters. A geothermometer based on CO/sub 2/-CH/sub 4/ ratio is proposed. Indications are that the CO/sub 2//CH/sub 4/ geothermometer works in temperature ranges of 50 to 300/sup 0/ and nearly as well as the other chemical geothermometer. Gases and gas ratios which correlate positively with reservoir temperature show a regular zonation pattern around the hot wells in the Lightning Dock geothermal area. This agrees with other studies which indicated that the hot wells are the point of upwelling thermal waters. It is concluded that gases in waters can be a valuable exploration tool to locate favorable sites for drilling in geothermal fields.

  18. Geothermometry and kinetics in a two-spinel peridotite nodule, Colorado Plateau

    SciTech Connect

    Smith, D.; Roden, M.F.

    1981-03-01

    Compositions and zoning of minerals in a two-spinel peridotite from minette in the Navajo volcanic field on the Colorado Plateau provide unusual opportunities to compare geothermometers at low mantle temperature and to study equilibration rates. The xenolith contains pleonaste (Mg/sub .55/Fe/sub .45/Al/sub 1.62/Fe/sub .10/Cr/sub .28/O/sub 4/) and magnetite (Mg/sub. 16/Fe/sub .89/Mn/sub .01/Al/sub .18/Fe/sub 1.38/Cr/sub .32/Ti/sub .06/O/sub 4/) related by granule exsolution, together with olivine (Foyv), orthopyroxene (3.5% Al/sub 2/O/sub 3/), and clinopyroxene. Both two-spinel equilibria and several olivine-pleonaste geothermometers indicate equilibration near or below 700/sup 0/C, confirming the general accuracy and continued equilibration of these geothermometers at low temperatures. Calculated olivine-magnetite temperatures are much too high. Two-pyroxene temperatures are near 800/sup 0/C. Olivine is zoned in Ca, Fe, and Mg within 50 ..mu..m of spinel by exchange with local grain boundary melts. Gradients at pleonaste-magnetite contacts were caused by multicomponent diffusion after heating by minette; effects include slight uphill diffusion of Cr. Effective binary diffusion coefficients near 1100/sup 0/C, estimated by comparison with gradients in olivine, are near 10kaa cm/sup 2//sec for Al in magnetite and 10kab cm/sup 2//sec for Al in pleonaste; an average Mg value is in the same range. The time interval between plucking of the inclusion and minette solidification is calculated as about 60 hours, consistent with ascent times calculated assuming Newtonian viscosity for the minette magmas.

  19. The olivine-ilmenite thermometer. [partitioning effect of temperature on iron ions and magnesium

    NASA Technical Reports Server (NTRS)

    Andersen, D. J.; Lindsley, D. H.

    1979-01-01

    It is noted that the partitioning of Fe(2+) and Mg between olivine and ilmenite is temperature-dependent and can serve as a geothermometer if the activity-composition relations are determined. The paper reports on the study of the partitioning from 700-980 C at 1 kbar and 800-900 C at 13 kbar, and develops a solution model to account for the nonideality of olivine in the binary system fosterite-fayalite and for ilmenite in the ternary system ilmenite-geikielite-hematite. A comparison with crystallization experiments shows that this thermometer may be safely extrapolated to temperatures higher than those of the exchange experiments.

  20. F-Cl-OH partitioning between biotite and apatite

    NASA Astrophysics Data System (ADS)

    Zhu, Chen; Sverjensky, Dimitri A.

    1992-09-01

    An assessment of F-C1-OH partitioning between natural apatite and biotite in a variety of rocks was used to evaluate reciprocal (Mg, Fe 2+, Al VI) (F, Cl, OH) mixing properties for biotite according to the reciprocal salt solution model of WOOD and NICHOLLS (1978). Ideal mixing of F-C1-OH and Fe-Mg-Al VI in the hydroxyl and octahedral sites is assumed for biotites with dilute Cl concentrations. The reciprocal interaction parameters, in terms of Gibbs free energies, for the reactions KMg3[ AlSi3O10]( OH) 2 + KFe3[ AlSi3O10]( F) 2 = KMg3[ AlSi3O10]( F) 2 + KFe3[ AlSi3O10]( OH) 2 Phl Fann Fphl Ann and KMg3[ AlSi3O10]( Cl) 2 + KFe3[ AlSi3O10]( OH) 2 = KMg3[ AlSi3O10]( OH) 2 + KFe3[ AlSi3O10] ( Cl) 2 Clphl Ann Phl Clann are about -10 kcal/mol and -4.5 kcal/mol, respectively. These mixing properties are consistent with standard state thermodynamic properties for F and Cl endmember phases from ZHU and SVERJENSKY (1991). The approach of studying F-C1-OH partitioning between biotite and apatite permits distinguishing the reciprocal effects from the effects of temperature, pressure, and fluid composition. The resultant mixing properties are consistent with observations both in hydrothermal experiments and in natural mineral assemblages. The mixing properties presented in this study enable us now to predict F and Cl concentrations of hydrothermal fluids from the measured F and Cl concentrations in biotite with variable Fe-Mg-Al VI proportions. A case study of the Santa Rita porphyry copper deposits, New Mexico, shows that hydrothermal fluids responsible for the phyllic alteration had a salinity about 3 molal Cl -, in agreement with fluid inclusion studies. Our internally consistent standard thermodynamic properties and solid solution models also lead to recalibration of the apatite-biotite geothermometer. The revised geothermometer predicts temperatures that agree with those estimated from other independent geothermometers. The large reciprocal effects in biotite also point

  1. Chemical composition data and calculated aquifer temperature for selected wells and springs of Honey Lake Valley, California

    USGS Publications Warehouse

    Mariner, R.H.; Presser, T.S.; Evans, William C.

    1976-01-01

    Major element, minor element, and gas composition data are tabulated for 15 springs and wells in Honey Lake Valley, California. Wendel and Amedee hot springs issue Na-S04-C1 waters at boiling or near boiling temperatures; the remaining springs and wells issue Na-HC03 waters at temperatures ranging from 14 to 33 deg C. Gases escaping from the hot springs are principally nitrogen with minor amounts of methane. The geothermometers calculated from the chemical data are also tabulated for each spring. (Woodard-USGS)

  2. Hydrology and geochemistry of thermal ground water in southwestern Idaho and north-central Nevada

    SciTech Connect

    Young, H.W.; Lewis, R.E.

    1980-12-01

    The study area occupies about 14,500 square miles in southwestern Idaho and north-central Nevada. Thermal ground water occurs under artesian conditions, in discontinuous or compartmented zones, in igneous or sedimentary rocks of Tertiary age. Ground-water movement is generally northward. Temperatures of the ground water range from about 30/sup 0/ to more than 80/sup 0/C. Chemical analyses of water from 12 wells and 9 springs indicate that nonthermal waters are a calcium bicarbonate type; thermal waters are a sodium bicarbonate type. Chemical geothermometers indicate probable maximum reservoir temperatures are near 100/sup 0/C. Concentration of tritium in the thermal water water is near zero.

  3. Some petrological aspects of Imbrium stratigraphy

    NASA Technical Reports Server (NTRS)

    Ridley, W. I.

    1977-01-01

    Descriptions are given of the petrochemistry of two Apennine Front breccias, both ejected to the surface during excavation of Spur Crater. The first clast type is breccia number 15445, a spinel pyroxenite whose mineralogy and petrochemistry are consistent with the original rock type being a garnet pyroxenite. The second rock, breccia 15459, is plutonic norite, in which coarsely exsolved inverted pigeonite is associated with anorthitic plagioclase. Application of mineral geothermometers indicates crystallization of these rocks below 1100 C; hence their textures probably developed largely by solid state recrystallization during impact-metamorphism.

  4. Drilling investigation of a young magmatic intrusion beneath Inyo Dome, Long Valley Caldera, California. Progress report

    SciTech Connect

    Vogel, T.A.

    1985-01-01

    Progress to date indicates: (1) the conduit and lava flow at Obsidian Dome consist of two magma types; (2) the more mafic magma occurs at the base of Obsidian Dome and at the margins of the conduit and was emplaced first; (3) the more silicic magma occurs in the center of the conduit and in the dike; (4) the ilmenite-magnetite and orthopyroxene-augite geothermometers have not reequilibrated in the conduit or dike; (5) the more mafic magma's emplacement temperature was 974/sup 0/C compared to the silicic magma's 951/sup 0/C; and (6) trace elements are characteristic of each magma type. (ACR)

  5. Comparison of early exploration at Platanares (Honduras) and Wairakei (New Zealand)

    USGS Publications Warehouse

    Truesdell, A.H.; Glover, R.B.; Janik, C.J.; Brown, K.L.; Goff, F.

    1989-01-01

    Early exploration at Wairakei, New Zealand, is compared with the present state of exploration of Platanares, Honduras. In retrospect, geothermometer temperatures favor Platanares (e.g., 220 vs. 190??C for Na-K-Ca), but two 600-m drill holes encountered lower temperatures (160??C). Wairakei, explored before the advent of chemical geothermometry, also had disappointing early drilling results (but better than Platanares; one of the first six holes hit T > 180??C). The Wairakei drilling program was nevertheless continued at full speed and by well 20 a successful drilling strategy was discovered.

  6. Exploratory energy research program of the University of Hawaii at Manoa. Progress report

    SciTech Connect

    Not Available

    1984-01-01

    Progress is reported from the University of Hawaii on: UHM rooftop solar energy laboratory; solar pond cleansing techniques; combustion properties of biomass pyrolysis products; high-temperature solar concentrator absorber; biological abatement of hydrogen sulfide during geothermal energy production; geothermal systems on submarine rift zones of the Hawaiian chain; nitrogenous products of OTEC chlorination; interaction of hydrogen and deuterium with transition metals and their alloys at high pressures; shallow magma chambers and geothermal potential of Haleakala, Maui; effects of OTEC waste water on phytoplankton; sodium-lithium geothermometer; breaking wave forces on OTEC pipes; seismic and thermal properties on basalts. (PSB)

  7. Water chemistry of hot waters of Umut geothermal field (SW Turkey)

    NASA Astrophysics Data System (ADS)

    Avşar, Özgür; Türe, Orkun

    2014-05-01

    Umut geothermal field is located on Menderes graben which is one of the most active geothermal regions of Turkey. In order to delineate the chemistry of the waters of Umut geothermal field, fourteen samples were taken from four wells and ten from hot springs. Discharge temperatures of the waters range from 20 to 120 °C. According to the results of chemical analyses, the waters are Na+K - HCO3 type. Cation geothermometer calculations revealed a reservoir temperature greater than 200 °C for Umut geothermal field waters. Stable isotope analyses results indicates that the waters are meteoric in origin.

  8. CHEMISTRY OF LOW-TEMPERATURE GEOTHERMAL WATERS AT KLAMATH FALLS, OREGON.

    USGS Publications Warehouse

    Janik, C.J.; Truesdell, A.H.; Sammel, E.A.; White, A.F.

    1985-01-01

    Chemical and isotopic analyses of well discharges indicate that in the aquifer mixing occurs between shallow cold groundwater containing 2. 0 TU tritium and a deeper tritium-free thermal groundwaer at 100 to 120 degree C. This deeper water apparently results from the mixing of old, tritium-free cold groundwater and deep thermal groundwater at about 190 degree C and 120 mg/kg Cl. The temperature and chlorinity of the deep thermal water are based on SO//4-isotope and silica geothermometers and chloride and silica mixing models.

  9. Lassen geothermal system

    SciTech Connect

    Muffler, L.J.P.; Nehring, N.L.; Truesdell, A.H.; Janik, C.J.; Clynne, M.A.; Thompson, J.M.

    1982-01-01

    The Lassen geothermal system consists of a central vapor-dominated reservoir underlain by hot water that discharges peripherally at lower elevations. The major thermal upflow at Bumpass Hell (elevation 2500 m) displays numerour superheated fumaroles, one of which in 1976 was 159/sup 0/C. Gas geothermometers from the fumarole areas and water geothermometers from boiling Cl-bearing waters at Morgan Hot Springs (elevation 1530 m; 8 km south of Bumpass Hell) and from 176/sup 0/C waters in a well 12 km southeast of Bumpass Hell both indicate 230 to 240/sup 0/C for the deep thermal water. With increasing distance from Bumpass Hell, gases are progressively depleted in H/sub 2/S relative to CO/sub 2/ and N/sub 2/, owing to oxidation of H/sub 2/S to pyrite, sulfur, and sulfates and to dilution with atmospheric N/sub 2/. H/sub 2/O/gas ratios and degree of superheat of fumaroles can be explained by mixing of steam of maximum enthalpy (2804 J g/sup -1/) with near-surface water and with the condensate layer overlying the vapor-dominated reservoir.

  10. Dating thermal events at Cerro Prieto using fission-track annealing

    SciTech Connect

    Sanford, S.J.; Elders, W.A.

    1981-01-01

    The duration of heating in the Cerro Prieto reservoir was estimated by relating the fading of spontaneous fission tracks in detrital apatite to observed temperatures. The rate of fading is a function of both time and temperature. The apparent fission track age of the detrital apatites then, is a function of both their source age and their time-temperature history. Data from laboratory experiments and geologic fading studies were compiled from published sources to produce lines of iso-annealing for apatite in time-temperature space. Fission track ages were calculated for samples from two wells at Cerro Prieto, one with an apparently simple and one with an apparently complex thermal history. Temperatures were estimated by empirical vitrinite reflectance geothermometry, fluid inclusion homogenization and oxygen isotope equilibrium. These estimates were compared with logs of measured borehole temperatures. The temperature in well T-366, where complete annealing first occurs, was estimated to be between 160 and 180{sup 0}C. Complete annealing at these temperatures requires 10{sup 4} and 10{sup 3} years, respectively. Well M-94 has an apparently complex thermal history. Geothermometers in this well indicate temperatures some 50 to 100{sup 0}C higher than those measured directly in the borehole. Fission tracks are partially preserved in M-94 where paleotemperatures were as high as 200{sup 0}C and are erased where geothermometers indicate temperatures of 250{sup 0}C. This implies a thermal event less than 10{sup 1} years and greater than 10{sup 0} years in duration.

  11. Geothermobarometry of Precambrian metamorphic rocks from the Tobacco Root Mountains of southwestern Montana

    SciTech Connect

    Friberg, L.M. . Dept. of Geology)

    1994-04-01

    Upper amphibolite facies metamorphic rocks of Precambrian age, located in the Spuhler Peak area of the Tobacco Root Mountains of southwestern Montana, provide the basis for comparative geothermobarometry. Twenty three samples were chosen for microprobe analyses from a stratified sequence of metapelites interlayered with amphibole schists and gneisses exposed in a cirque headwall (less than one square mile sampling area). The garnet-biotite geothermometry of Indares and Martignole (1985), for three metapelite samples, indicates an average temperature 710 [+-] 35 C at a pressure of 6,530 bars (one sample) using the modified GASP geobarometer of Newton and Haselton (1981). Geothermobarometry on the amphibole schist and gneiss samples using the hornblende-plagioclase geothermometer of Blundy and Holland (1990), for twenty samples, indicates an average temperature of 751 [+-] 47 C. The hornblende-garnet geothermometer of Graham and Powell (1984), for fifteen samples, indicates an average temperature of 628 [+-] 59 C. The total aluminum content of hornblendes from nineteen samples indicates an average pressure of 4,826 [+-] 682 bars (Johnson and Rutherford, 1988) and 6,182 [+-] 793 bars (Blundy and Holland, 1990). Variation of temperature and pressure may be explained by closure temperatures for element exchange between the minerals used in the various geothermobarometers.

  12. Continuation of the San Andreas fault system into the upper mantle: Evidence from spinel peridotite xenoliths in the Coyote Lake basalt, central California

    NASA Astrophysics Data System (ADS)

    Titus, Sarah J.; Medaris, L. Gordon; Wang, Herbert F.; Tikoff, Basil

    2007-01-01

    The Coyote Lake basalt, located near the intersection of the Hayward and Calaveras faults in central California, contains spinel peridotite xenoliths from the mantle beneath the San Andreas fault system. Six upper mantle xenoliths were studied in detail by a combination of petrologic techniques. Temperature estimates, obtained from three two-pyroxene geothermometers and the Al-in-orthopyroxene geothermometer, indicate that the xenoliths equilibrated at 970-1100 °C. A thermal model was used to estimate the corresponding depth of equilibration for these xenoliths, resulting in depths between 38 and 43 km. The lattice preferred orientation of olivine measured in five of the xenolith samples show strong point distributions of olivine crystallographic axes suggesting that fabrics formed under high-temperature conditions. Calculated seismic anisotropy values indicate an average shear wave anisotropy of 6%, higher than the anisotropy calculated from xenoliths from other tectonic environments. Using this value, the anisotropic layer responsible for fault-parallel shear wave splitting in central California is less than 100 km thick. The strong fabric preserved in the xenoliths suggests that a mantle shear zone exists below the Calaveras fault to a depth of at least 40 km, and combining xenolith petrofabrics with shear wave splitting studies helps distinguish between different models for deformation at depth beneath the San Andrea fault system.

  13. 9519 biotite granodiorite reacted in a temperature gradient

    SciTech Connect

    Charles, R.W.; Bayhurst, G.K.

    1980-10-01

    A biotite granodiorite from the Fenton Hill Hot Dry Rock (HDR) geothermal system was reacted in a controlled temperature gradient with initially distilled water for 60d. Polished rock prisms were located in the gradient at 72, 119, 161, 209, 270, and 310/sup 0/C. Scanning electron microscope and microprobe analyses show the appearance of secondary phases: Ca-montmorillonite at 72/sup 0/C and 119/sup 0/C; zeolite, either stilbite or heulandite, at 161/sup 0/C; and another zeolite, thomsonite, at higher temperatures. Solution analyses show a steady state equilibrium exists between solution and overgrowths after about 2 weeks of reaction. The chemographic relations for the system are explored in some detail indicating the divariant assemblages may be placed in a reasonable sequence in intensive variable space. These relations predict high and low temperature effects not directly observed experimentally as well as relevant univariant equilibria. Solution chemistry indicates the Na-Ca-K geothermometer more adequately predicts temperature in this system than does the silica geothermometer.

  14. Estimation of deepwater temperature and hydrogeochemistry of springs in the Takab geothermal field, West Azerbaijan, Iran.

    PubMed

    Sharifi, Reza; Moore, Farid; Mohammadi, Zargham; Keshavarzi, Behnam

    2016-01-01

    Chemical analyses of water samples from 19 hot and cold springs are used to characterize Takab geothermal field, west of Iran. The springs are divided into two main groups based on temperature, host rock, total dissolved solids (TDS), and major and minor elements. TDS, electrical conductivity (EC), Cl(-), and SO4 (2-) concentrations of hot springs are all higher than in cold springs. Higher TDS in hot springs probably reflect longer circulation and residence time. The high Si, B, and Sr contents in thermal waters are probably the result of extended water-rock interaction and reflect flow paths and residence time. Binary, ternary, and Giggenbach diagrams were used to understand the deeper mixing conditions and locations of springs in the model system. It is believed that the springs are heated either by mixing of deep geothermal fluid with cold groundwater or low conductive heat flow. Mixing ratios are evaluated using Cl, Na, and B concentrations and a mass balance approach. Calculated quartz and chalcedony geothermometer give lower reservoir temperatures than cation geothermometers. The silica-enthalpy mixing model predicts a subsurface reservoir temperature between 62 and 90 °C. The δ(18)O and δD (δ(2)H) are used to trace and determine the origin and movement of water. Both hot and cold waters plot close to the local meteoric line, indicating local meteoric origin. PMID:26733417

  15. Chemistry of thermal and nonthermal springs in the vicinity of Lassen Volcanic National Park

    USGS Publications Warehouse

    Thompson, J.M.

    1985-01-01

    Meaningful applications of water geothermometry to thermal springs in and around Lassen Volcanic National Park (LVNP) are limited to Growler Hot Spring and Morgan Hot Springs. Most hot springs located within LVNP are low-chloride, acid-sulfate waters associated with nearby steam vents. This type of hot-spring activity is characteristically found above vapor-dominated hydrothermal systems. These acid-sulfate waters are not generally useful for liquid chemical geothermometry, however, because their chemical compositions result from water-rock interaction at relatively shallow depths. Thermal waters at Drakesbad and in Little Hot Springs Valley have neutral-pH, low-Cl concentrations and have estimated Na-K-Ca and Na-Li geothermometer temperatures close to measured spring temperatures of 65 to 95??C. Hot-spring waters located south of LVNP at Growler Hot Spring, Morgan Hot Springs, and in the south-central part of LVNP in the Walker "O" No. 1 well at Terminal Geyser are rich in chloride and yield calculated geothermometer temperatures between 220 and 230??C. These thermal waters probably originate within a zone of upflow of high-enthalpy fluid inside LVNP and cool conductively during lateral flow to the south and southeast. ?? 1985.

  16. ADVANCES IN HYDROGEOCHEMICAL INDICATORS FOR THE DISCOVERY OF NEW GEOTHERMAL RESOURCES IN THE GREAT BASIN, USA

    SciTech Connect

    Simmons, Stuart F; Spycher, Nicolas; Sonnenthal, Eric; Dobson, Patrick

    2013-05-20

    This report summarizes the results of Phase I work for a go/no go decision on Phase II funding. In the first objective, we assessed the extent to which fluid-mineral equilibria controlled deep water compositions in geothermal systems across the Great Basin. Six systems were evaluated: Beowawe; Desert Peak; Dixie Valley; Mammoth; Raft River; Roosevelt. These represent a geographic spread of geothermal resources, in different geological settings and with a wide range of fluid compositions. The results were used for calibration/reformulation of chemical geothermometers that reflect the reservoir temperatures in producing reservoirs. In the second objective, we developed a reactive -transport model of the Desert Peak hydrothermal system to evaluate the processes that affect reservoir fluid geochemistry and its effect on solute geothermometry. This included testing geothermometry on “reacted” thermal water originating from different lithologies and from near-surface locations where the temperature is known from the simulation. The integrated multi-component geothermometer (GeoT, relying on computed mineral saturation indices) was tested against the model results and also on the systems studied in the first objective.

  17. Chemical, physical, and radiological quality of selected public water supplies in Florida : January-May 1979

    USGS Publications Warehouse

    Franks, Bernard J.; Irwin, G.A.

    1980-01-01

    Verde Valley--an area of complex geology where the crust of the North American plate changes from unstable to stable--is in central Arizona in the transition zone between the Basin and Range and the Colorado Plateaus tectonic provinces. Volcanism and tectonism have been progressing northeastward along the transition zone for about 20 million years. The Verde Hot Springs area is the focal point of the intersection of three major lineaments. More than 100 water samples were collected from wells and springs in the valley, and temperatures of the potential geothermal resources were calculated using two geochemical methods or geothermometers--silica and Na-K-Ca geothermometers. Because of the high concentration of dissolved magnesium in the ground water, the silica geotemperatures are considered to be more reliable than the Na-K-Ca geotemperatures. The Camp Verde and Verde Hot Springs areas contain ground water that has quartz-silica geotemperatures of between 99 and 135C and chalcedony-silica geotemperatures of between 73 and 111C. The geochemical evidence to substantiate a geothermal resource in Verde Valley is not conclusive, and further work including test drilling, should be done to verify the silica geotemperatures given in the map. (Kosco-USGS)

  18. Gas chemistry and thermometry of the Cerro Prieto, Mexico, geothermal field

    USGS Publications Warehouse

    Nehring, N.L.; D'Amore, F.

    1984-01-01

    Gas compositions of Cerro Prieto wells in 1977 reflected strong boiling in the reservoir around wells M-20 and M-25. This boiling zone appeared to be collapsing in 1982 when a number of wells in this area of the field were shut-in. In 1977 and 1982, gas compositions also showed boiling zones corresponding to faults H and L postulated by Halfman et al. (1982). Four gas geothermometers were applied, based on reservoir equilibria and calculated fugacities. The Fisher - Tropsch reaction predicted high temperatures and appeared to re-equilibrate slowly, whereas the H2S reaction predicted low temperatures and appeared to re-equilibrate rapidly. Hydrogen and NH3 reactions were intermediate. Like gas compositions, the geothermometers reflected reservoir processes, such as boiling. Surface gas compositions are related to well compositions, but contain large concentrations of N2 originating from air dissolved in groundwater. The groundwater appears to originate in the east and flow over the production field before mixing with reservoir gases near the surface. ?? 1984.

  19. Geochemistry at Momotombo, Nicaragua: one aspect in a geothermal field case history

    SciTech Connect

    Tonani, F.B.; Teilman, M.A.

    1980-09-01

    The Momotombo area was chosen for geothermal development after a number of sites were investigated in western Nicaragua. Geothermometry from several springs at Momotombo indicated subsurface temperatures might range from 153/sup 0/ to 200/sup 0/C. The geothermometers in subsequent deep exploration wells and measured temperatures were much higher, suggesting the surface thermal waters re-equilibrated with the near-surface environment. Preliminary interpretation of some 1979 flow test data shows a change in the flow regime of some wells. Other subtle changes such as correlated variations between SiO/sub 2/ and K or salinity and Mg shifts, could result from a change in flow among producing horizons. Geochemical temperatures based on the recent data ranged from 210/sup 0/ to 324/sup 0/C. The Na-K, Ca-Na, Ca-K geothermometers were used and seem adequate for monitoring the field. Comparison of the boron content in liquid and steam phases allowed estimates to be made of water-steam separation temperatures in those wells where a change in flow regime occurred. The main body of data is given in a synoptic table.

  20. Laboratory and Natural Constraints on the Temperature Limit for Preservation of the Dolomite Clumped Isotope Thermometer

    NASA Astrophysics Data System (ADS)

    Lloyd, M. K.; Eiler, J. M.

    2014-12-01

    Kinetic barriers generally inhibit intercrystalline equilibration of cations and isotopic compositions at temperatures below ~350˚C, greatly limiting the geothermometers available to study the upper 10-15 km of the crust. Calcite 'clumped' isotopes commonly appear to record homogeneous equilibrium during crystallization at surface temperatures, but kinetic models predict that reordering due to solid-state exchange among nearby carbonate groups modifies primary compositions at temperatures above ~115˚C on timescales of 10^6 - 10^8 years and fully re-equilibrates above 200˚C in most geological environments1. Slowly cooled dolomitic marbles commonly preserve apparent temperatures of ~300˚C, indicating that dolomite may have slower reordering kinetics and thus greater preservation of primary crystallization temperatures. If so, dolomite clumped isotope thermometry may be a useful geothermometer in much of the the shallow crust. We measured the kinetics of clumped isotope reordering in dolomite with heating experiments at 400-800˚C in a TZM cold seal apparatus pressurized with CO2. Results predict that no detectable reordering occurs in dolomite held at temperatures less than ~250˚C over timescales of up to 10^8 years, demonstrating the viability of the system as a shallow crustal geothermometer. The non-first order behavior observed in calcite1,2,3is exhibited by dolomite as well, albeit at higher temperatures. To test these predictions, we measured the clumped isotopic compositions of coexisting calcite and dolomite in marbles from the Notch Peak aureole, UT. Dolomite clumped isotope temperatures in the outer aureole match peak conditions predicted by thermal models up to ~275˚C, indicating that the system resisted reordering below this grade. Calcite clumped isotope temperatures are never greater than ~150˚C at all grades in the aureole; this is consistent with the ambient burial temperature in the section and indicates that all metamorphic calcite was fully

  1. Constraining chemical geothermometry with reactive transport models: An example study of the Dixie Valley geothermal area

    NASA Astrophysics Data System (ADS)

    Wanner, C.; Peiffer, L.; Spycher, N.; Sonnenthal, E. L.; Iovenitti, J. L.; Kennedy, B. M.

    2012-12-01

    In this study, 1D and 2D reactive transport simulations of the Dixie Valley geothermal area (Nevada, USA) were performed using Toughreact [1] to evaluate the fluid flow pathways and rates of equilibration of hydrothermal fluids. Modeling studies were combined with new multicomponent geothermometry, which is being used to estimate the temperature of geothermal reservoirs based on chemical analysis of geothermal springs. The concept is based on the assumption of chemical equilibrium between the thermal fluid and minerals of the reservoir rock [2]. If re-equilibration occurs between the reservoir at depth and the surface, then the 'deep' chemical signature of the fluid is lost and the obtained reservoir temperature is underestimated. The simulations were run for a vertical cross-section that has been structurally and geologically characterized. Model calibration was performed using available site information such as chemical analysis of geothermal springs, isotherms inferred from geothermal wells and results of a previous flow simulation study [3]. Model runs included the simulation of typical near-surface processes such as dilution, mixing and salt leaching occurring at the Dixie Valley geothermal area. Each reactive transport model produced 'synthetic' waters that were processed using the multicomponent chemical geothermometer code GeoT [4]. This code computes the saturation indices of reservoir minerals as a function of the temperature. Reservoir temperature is inferred when mineral saturation indices all cluster around zero. GeoT results were also compared with classical solute geothermometers (silica, Na-K-(Ca), K-Mg) [5]. Simulation results reveal that a minimum vertical fluid velocity on the order of a meter per day is needed to preserve the geochemical signature of a geothermal reservoir and to predict its temperature. The simulations also show that deep geochemical signatures are well preserved if fracture surfaces are partially coated by secondary minerals

  2. Electron Spin Resonance (ESR) Studies of Returned Comet Nucleus Samples

    NASA Technical Reports Server (NTRS)

    Tsay, Fun-Dow; Kim, Soon Sam; Liang, Ranty H.

    1997-01-01

    Electron Spin Resonance (ESR) studies have been carried out on organic and inorganic free radicals generated by gamma-ray and/or UV-irradiation and trapped in ice matrices. It is suggested that the concentration of these free radicals together with their thermal stability can be used as an accurate built-in geothermometer and radiation probe for returned comet nucleus sample studies. ESR studies have also been carried out on paramagnetic (Mn(2+), Ti(3+), and Fe(3+)) and ferromagnetic (ferric oxide and metallic iron) centers known to be present in terrestrial and extraterrestrial samples. The presence or absence of these magnetic centers coupled with their characteristic ESR lineshape can be used to investigate the shock effects, quenching/cooling rate and oxidation-reduction conditions in the formation and subsequent evolution of returned comet nucleus samples.

  3. Isotopic studies of epigenetic features in metalliferous sediment, Atlantis II Deep, Red Sea

    USGS Publications Warehouse

    Zierenberg, Robert A.; Shanks, Wayne C., III

    1988-01-01

    The unique depositional environment of the Atlantis II Deep brine pool in the Red Sea produces a stratiform metalliferous deposit of greater areal extent than deposits formed by buoyant-plume systems typical of the midocean ridges because of much more efficient metal entrapment. Isotopic analyses of strontium, sulfur, carbon, and oxygen from the metalliferous sediments indicate that three major sources contribute dissolved components to the hydrothermal system: seawater, Miocene evaporites, and rift-zone basalt. An areally restricted magnetite-hematite-pyroxene assemblage formed at high temperatures, possibly in response to hydrothermal convection initiated by intrusion of basalt into the metalliferous sediment. A correlation between smectite Fe/(Fe+Mg) ratios and oxygen isotope temperatures suggests that smectite is a potentially important chemical geothermometer, and confirms geochemical calculations indicating that Mg-rich smectite is more stable than Fe-rich smectite at elevated temperatures.

  4. Colorado's hydrothermal resource base: an assessment

    SciTech Connect

    Pearl, R.H.

    1981-01-01

    As part of its effort to more accurately describe the nations geothrmal resource potential, the US Department of Energy/Division of Geothermal Energy contracted with the Colorado Geological survey to appraise the hydrothermal (hot water) geothermal resources of Colorado. Part of this effort required that the amount of energy that could possibly be contained in the various hydrothermal systems in Colorado be estimated. The findings of that assessment are presented. To make these estimates the geothermometer reservoir temperatures estimated by Barrett and Pearl (1978) were used. In addition, the possible reservoir size and extent were estimated and used. This assessment shows that the total energy content of the thermal systems in Colorado could range from 4.872 x 10{sup 15} BTU's to 13.2386 x 10{sup 15} BTU's.

  5. Paleotemperature regime studies of the Barents Sea sediments through spontaneous fission-track analysis

    SciTech Connect

    Il`chenko, V.L.

    1995-09-01

    The results obtained are compared to earlier data on vitrinite reflectance and the catagenetic alteration grade of disseminated organic matter studied in samples from the same boreholes and stratigraphic intervals. Accessory apatite from terricrenous sediments is usable as a geothermometer of higher sensitivity than that based on epigenetic alterations of organic matter. The fission-track analysis data on the paleothermal history of terrigenous sediments from the South Barents Depression are presented. Apatite from six offshore boreholes in the South Barents shelf (Severo-Guliaev, Kurentsov, Murman, Severo-Kil`din, Shtokman, and Ludlov fields) is studied. Paleotemperature values lying within or beyond the upper limit of the oil-productive thermal interval are considered important factors stimulating the generation of hydrocarbons.

  6. Boundary Creek thermal areas of Yellowstone National Park: II, thermal water analyses

    SciTech Connect

    Thompson, J.M.; Hutchinson, R.A.

    1980-09-01

    Water samples from 28 thermal springs, 2 non-thermal springs, and 2 creeks from the Boundary Creek Thermal Areas (BCTA) in the southwestern corner of Yellowstone National Park were analyzed to help establish a chemical water-quality base line prior to possible geothermal exploitation of the Island Park Geothermal Area (IPGA). The springs, situated at the southwestern end of the Madison Plateau, are the Yellowstone Park thermal waters nearest to the IPGA and might respond to geothermal exploitation in the IPGA. Water temperatures ranging from 50/sup 0/ to 90/sup 0/C and low Cl concentrations (< 110 mgL/sup -1/) characterize spring waters in the BCTA. They are chemically distinct from the major geysers and hot springs in Yellowstone Park. The Na-K-Ca and silica geothermometers are in general agreement, usually within 10/sup 0/C, and indicate reservoir temperatures of 150 to 170/sup 0/C.

  7. Gas Geochemistry of the Dogger Geothermal Aquifer (Paris Basin, France)

    SciTech Connect

    Criaud, A.; Fouillac, C.; Marty, B.; Brach, M.; Wei, H.F.

    1987-01-20

    The low enthalpy program developed in the Paris Basin provides the opportunity for studying the gas geochemistry of the calcareous aquifer of the Dogger. Hydrocarbons and CO{sub 2} are mainly biogenic, He displays high concentrations. He, Ar and N{sub 2} have multiple origins (radioactive decay, atmospheric migration, biochemical processes). The distribution of the gases in the zones of the basin varies in relation to the general chemistry, sedimentology and hydrodynamics. The gas geothermometers do not apply to this environment but useful estimations of the redox potential of the fluid can be derived from CO{sub 2}/CH{sub 4} and N{sub 2}/NH{sub 4}{sup +} ratios. H{sub 2} and H{sub 2}S are involved in corrosion processes and scaling in the pipes. 12 refs., 3 figs., 2 tabs.

  8. An evaluation of the geothermal potential of the Tecuamburro Volcano area of Guatemala

    SciTech Connect

    Heiken, G.; Duffield, W.

    1990-09-01

    Radiometric ages indicate that the Tecuamburro Volcano and three adjacent lava domes grew during the last 38,300 years, and that a 360-m-wide phreatic crater, Laguna Ixpaco, was formed near the base of these domes about 2900 years ago. Laguna Ixpaco is located within the Chupadero crater, from which pyroxene pumice deposits were erupted 38,300 years ago. Thus, the likelihood is great for a partly molten or solid-but-still-hot near-surface intrusion beneath the area. Fumaroles and hot springs issue locally from the Tecuamburro volcanic complex and near Laguna Ixpaco. Analyses of gas and fluid samples from these and other nearby thermal manifestations yield chemical-geothermometer temperatures of about 150{degree} to 300{degree}C, with the highest temperatures at Ixpaco. The existence of a commercial-grade geothermal reservoir beneath the Ixpaco area seems likely. 84 refs., 70 figs., 12 tabs.

  9. Hydrologic model based on deep test data from the Walker O No. 1 well, Terminal Geyser, California

    SciTech Connect

    Beall, J.J.

    1981-10-01

    The Shasta Forest No. 1 Well (renamed Walker O No. 1) at Terminal Geyser, California, was reentered and deepened from 1258 to 4008 feet. Temperature logs indicate the well penetrated a laterally flowing thermal aquifer between 1400 and 2200 feet. Large amounts of drilling fluids were lost in that zone. Maximum temperature in the well (10 months after drilling) was 348/sup 0/F at 2000 feet. A large reversed temperature gradient zone occurs below 2400 feet. Bottom hole temperature is 256/sup 0/F. After completion, the well was flowed for about five hours with nitrogen injection at 2000 feet. Samples taken throughout the flow indicate that fluids lost during drilling were not completely recovered. Salinity increased steadily during the flow period. Ratios of Na, K, and Ca were nearly constant, however, and application of Na-K and Na-K-Ca geothermometers indicate these fluids were in equilibrium with rocks at a temperature of 448-449/sup 0/F.

  10. The Geyser Bight geothermal area, Umnak Island, Alaska

    SciTech Connect

    Motyka, R.J. ); Nye, C.J. Univ. of Alaska, Fairbanks, AK . Geophysical Inst.); Turner, D.L. . Geophysical Inst.); Liss, S.A. )

    1993-08-01

    The Geyser Bight geothermal area contains one of the hottest and most extensive areas of thermal springs in Alaska, and is the only site in the state with geysers. Heat for the geothermal system is derived from crustal magma associated with Mt. Recheshnoi volcano. Successive injections of magma have probably heated the crust to near its minimum melting point and produced the only high-SiO[sub 2] rhyolites in the oceanic part of the Aleutian arc. At least two hydrothermal reservoirs are postulated to underlie the geothermal area and have temperatures of 165 and 200 C, respectively, as estimated by geothermometry. Sulfate-water isotope geothermometers suggest a deeper reservoir with a temperature of 265 C. The thermal spring waters have relatively low concentrations of Cl (600 ppm) but are rich in B (60 ppm) and As (6 ppm). The As/Cl ratio is among the highest reported for geothermal waters. 41 refs., 12 figs., 8 tabs.

  11. Conditions of origin of natural diamonds of peridotite affinity

    NASA Technical Reports Server (NTRS)

    Boyd, F. R.; Finnerty, A. A.

    1980-01-01

    Studies of mineral inclusions in natural diamonds and rare diamondiferous xenoliths from kimberlites show that most diamonds are associated with a dunite or harzburgite paragenesis. The diamondiferous periodites and dunites have predominantly coarse or tabular textures that suggest low-temperature (less than 1100 C) equilibration. Application of the K(D) Fe/Mg(Ga/Ol) geothermometer of O'Neill and Wood to analytical data for the minerals in these rocks shows that most have equilibrated below 1100 C. Application of this thermometer to pairs of olivine and garnet crystals included in individual diamonds indicates that the diamonds have crystallized in the range 900-1300 C, with a majority of estimated equilibration temperatures falling in the range below 1150 C. Comparison of these estimates of equilibration temperature with the zone of invariant vapor composition solidus for kimberlite and garnet lherzolite determined by Eggler and Wendlandt (1979) suggests that many diamonds may have formed in subsolidus events.

  12. Studies of quaternary saline lakes-I. Hydrogen isotope fractionation in saline minerals

    USGS Publications Warehouse

    Matsuo, S.; Friedman, I.; Smith, G.I.

    1972-01-01

    Borax, gaylussite, nahcolite and trona were synthesized in aqueous solution at temperatures ranging from 8?? to 35??C. Except for borax, deuterium was always depleted in these hydrated minerals relative to the solutions from which they were crystallized. In borax, no significant fractionation was found. The fractionation factor of D H for the trona-water system exhibited a marked temperature dependence. By combining the deuterium contents of trona and the solution from which trona was crystallized, the following thermometer scale was obtained: In ( D H) trona ( D H)water = 1.420 ?? 104 T2 + 23.56 T (1). An attempt to establish a geothermometer based on C13 C12 fractionation between carbonate minerals and carbonate ions in aqueous solution was not successful. ?? 1972.

  13. Chemistry and isotopes of deep geothermal saline fluids in the Upper Rhine Graben: Origin of compounds and water-rock interactions

    NASA Astrophysics Data System (ADS)

    Pauwels, Hélène; Fouillac, Christian; Fouillac, Anne-Marie

    1993-06-01

    Deep boreholes (⩽870 m) in the Upper Rhine Graben produce medium-temperature (120-150°C) saline fluids that circulate through the granitic basement and/or the overlying sedimentary rocks. The salinity of these deep fluids, sampled from both the granite and the sedimentary rock, can be explained by a three-step model: (1) evaporation of seawater which produces a primary brine; li(2) mixing between a dilute fluid and the primary brine; and (3) dissolution of halite by the later fluid. The thermal waters sampled at shallower depths are the result of mixing of the deep saline fluid and surface water. Geothermometer calculations indicate that some of the deep fluids did reach high temperatures (up to 220-260°C). During cooliug, reactions between fluid and rock took place, but the fluids did not have enough time to reach complete equilibrium with the surrounding rock.

  14. WEN-1: first successful well in the Wendel-Amedee KGRA

    SciTech Connect

    Juncal, R.W.; Gertsch, W.D.; Johnson, K.R.

    1982-10-01

    Field exploration activities initiated by GeoProducts Corp. in 1977 culminated in the successful completion of a deep production well in Sept. 1981. The well was drilled to a depth of 5823' and completed in a fractured, dominantly granodiorite lithology. A broad fault zone with associated fracturing occurs at approximately 5300'-5335' and serves as the main production zone. Well testing has indicated a highly productive well with no immediate boundaries. Long term testing was conducted at a constant artesian flow rate of 670 gpm with a maximum downhole temperature during flow of 251 F. The thermal fluid is a Na-SO/sub 4/-Cl type of low salinity. Various geothermometers suggest that the fluid originates from a reservoir in the 275-310 F range. Further study and refinement of the system model is ongoing in preparation for future deep drilling.

  15. An approach for geochemical assessment of Chipilapa geothermal field

    SciTech Connect

    Nieva, D.; Verma, M.P.; Portugal, E.; Torres, V.

    1993-01-28

    It presents a systematic methodology to evaluate the reservoir characteristics of Chipilapa- Ahuachapan geothermal field through the highly diluted natural manifestations (springs and domestic wells) in its surroundings. The manifestations are classified in three main groups according to their mechanism of formation: high salinity water (HSW), medium salinity water (MSW), and Sulfated Water (SW). The reservoir temperature at Chipilapa geothermal field is around 220°C which is estimated with application of various chemical geothermometers. The isotopic studies indicate that the heating of local meteoric water with the separated steam of deep reservoir fluids is a dominating process in the formation of springs and domestic wells fluids. The process of formation of primary and secondary vapor explains the isotopic composition of fumaroles.

  16. Metamorphic conditions in the Ashe Metamorphic Suite, North Carolina Blue Ridge

    SciTech Connect

    McSween, H.Y. Jr. ); Abbott, R.N.; Raymond, L.A. )

    1989-12-01

    Taconian metamorphism of mafic rocks in the Ashe Metamorphic Suite can be characterized by reference to an isograd corresponding to the reaction bio + epi = hbl + gar, which separates rocks into two zones of low-variance assemblages. Temperatures and pressures estimated from mineral exchange geothermometers and a barometer suggest that this reaction occurred at approximately 600-650C and 7.5 kbar. Phase equilibria between biotite and hornblende, as well as the sharpness of the mapped isograd, indicate that the reaction is discontinuous. Inferred differences in metamorphic grade between Ashe amphibolites and mafic dikes in the underlying basement suggest that these units are in faulted contact. Isograd patterns in pelitic rocks suggest an elongated domal uplift that developed after metamorphism and thrusting, the core of which is exposed in the adjacent Grandfather Mountain window.

  17. Improved Geothermometry Through Multivariate Reaction-path Modeling and Evaluation of Geomicrobiological Influences on Geochemical Temperature Indicators: Final Report

    SciTech Connect

    Mattson, Earl; Smith, Robert; Fujita, Yoshiko; McLing, Travis; Neupane, Ghanashyam; Palmer, Carl; Reed, David; Thompson, Vicki

    2015-03-01

    The project was aimed at demonstrating that the geothermometric predictions can be improved through the application of multi-element reaction path modeling that accounts for lithologic and tectonic settings, while also accounting for biological influences on geochemical temperature indicators. The limited utilization of chemical signatures by individual traditional geothermometer in the development of reservoir temperature estimates may have been constraining their reliability for evaluation of potential geothermal resources. This project, however, was intended to build a geothermometry tool which can integrate multi-component reaction path modeling with process-optimization capability that can be applied to dilute, low-temperature water samples to consistently predict reservoir temperature within ±30 °C. The project was also intended to evaluate the extent to which microbiological processes can modulate the geochemical signals in some thermal waters and influence the geothermometric predictions.

  18. Evolution and present state of the hydrothermal system in Long Valley caldera ( USA).

    USGS Publications Warehouse

    Sorey, M.L.

    1985-01-01

    Hydrothermal activity was more intense in the past and probably involved fluid circulation to depths of several km or more with heat supplied by the Long Valley magma chamber. The present-day hydrothermal system in Long Valley appears to consist of 2 principal zones in which hot water flows laterally from W to E at depths of less than 1 km within and around the resurgent dome. Maximum measured temperatures within these zones are near 170oC, but esimates from chemical geothermometers and extrapolation of a high-temperature gradient measured in a recent drill hole indicate that a source reservoir at temperatures near 240o may exist at greater depths within the Bishop Tuff beneath the W moat. -from Author

  19. IIb trioctahedral chlorite from the Barberton greenstone belt: crystal structure and rock composition constraints with implications to geothermometry

    NASA Astrophysics Data System (ADS)

    Xie, Xiaogang; Byerly, Gary R.; Ferrell, Ray E., Jr.

    geothermometers can not be applied to all BGB samples. However, the empirical chlorite geothermometer based on AlIV of chlorite may be applicable to chlorites formed under metamorphic conditions because it can predict the chemical composition of the chlorite from basaltic and dacitic samples in this study. An estimated temperature of about 320°C for the greenschist metamorphism of the greenstone belt through this geothermometer is consistent with that obtained by other geothermometers.

  20. Chemistry and geothermometry of brine produced from the Salton Sea Scientific drill hole, Imperial Valley, California

    USGS Publications Warehouse

    Thompson, J.M.; Fournier, R.O.

    1988-01-01

    The December 29-30, 1985, flow test of the State 2-14 well, also known as the Salton Sea Scientific drill hole, produced fluid from a depth of 1865-1877 m at a reservoir temperature of 305????5??C. Samples were collected at five different flashing pressures. The brines are Na-Ca-K-Cl-type waters with very high metal and low SO4 and HCO3 contents. Compositions of the flashed brines were normalized relative to the 25??C densities of the solutions, and an ionic charge balance was achieved by adjusting the Na concentration. Calculated Na/K geothermometer temperatures, using equations suggested by different investigators, range from 326?? to 364??C. The Mg/K2 method gives a temperature of about 350??C, Mg/Li2 about 282??, and Na/Li 395??-418??C. -from Authors

  1. The timing and mechanism of depletion in Lewisian granulites

    NASA Technical Reports Server (NTRS)

    Cohen, A. S.; Onions, R. K.; Ohara, M. J.

    1988-01-01

    Large Ion Lithophile (LIL) depletion in Lewisian granulites is discussed. Severe depletions in U, Th, and other LIL have been well documented in Lewisan mafic and felsic gneisses, but new Pb isotopic analyses show little or no depletion in lithologies with high solidus temperatures, such as peridotite. This suggests that LIL transport in this terrane took place by removal of partial melts rather than by pervasive flooding with externally derived CO2. The Pb and Nd isotopic data gathered on these rocks show that the depletion and granulite metamorphism are distinct events about 250 Ma apart. Both fluid inclusions and cation exchange geothermometers date from the later metamorphic event and therefore have little bearing on the depletion event, suggesting a note of caution for interpretations of other granulite terranes.

  2. Preliminary evaluation of thermal and nonthermal waters at selected sites in Panama, Central America. Evaluacion preliminar de aguas termales y no termales de sitios seleccionados en Panama, Centroamerica

    SciTech Connect

    Shevenell, L.

    1989-11-01

    Thirty-one thermal and nonthermal water samples were collected in Panama by the Instituto de Recursos Hidraulicos y Electrificacion and analyzed by the Earth and Space Sciences Division at Los Alamos National Laboratory to evaluate the geothermal potential of four different areas. Chemical and isotopic analyses were performed on each sample. Because samples from several areas were submitted, the chemistry of the samples is varied, with total dissolved solids of thermal fluids ranging from 900 to nearly 10,000 mg/{ell}. All water samples studied are meteoric in origin, and none of the thermal waters exhibit an {sup 18}O enrichment, which is characteristic of high-temperature isotopic, exchange between water and rock. At all four areas, calculated geothermometer temperatures within a reservoir of less than 160{degrees}C. 4 refs., 4 figs., 6 tabs.

  3. A Review of Methods Applied by the U.S. Geological Survey in the Assessment of Identified Geothermal Resources

    USGS Publications Warehouse

    Williams, Colin F.; Reed, Marshall J.; Mariner, Robert H.

    2008-01-01

    The U. S. Geological Survey (USGS) is conducting an updated assessment of geothermal resources in the United States. The primary method applied in assessments of identified geothermal systems by the USGS and other organizations is the volume method, in which the recoverable heat is estimated from the thermal energy available in a reservoir. An important focus in the assessment project is on the development of geothermal resource models consistent with the production histories and observed characteristics of exploited geothermal fields. The new assessment will incorporate some changes in the models for temperature and depth ranges for electric power production, preferred chemical geothermometers for estimates of reservoir temperatures, estimates of reservoir volumes, and geothermal energy recovery factors. Monte Carlo simulations are used to characterize uncertainties in the estimates of electric power generation. These new models for the recovery of heat from heterogeneous, fractured reservoirs provide a physically realistic basis for evaluating the production potential of natural geothermal reservoirs.

  4. Chemical and isotopic prediction of aquifer temperatures in the geothermal system at Long Valley, California

    USGS Publications Warehouse

    Fournier, R.O.; Sorey, M.L.; Mariner, R.H.; Truesdell, A.H.

    1979-01-01

    Temperatures of aquifers feeding thermal springs and wells in Long Valley, California, estimated using silica and Na-K-Ca geothermometers and warm spring mixing models, range from 160/dg to about 220??C. This information was used to construct a diagram showing enthalpy-chloride relations for the various thermal waters in the Long Valley region. The enthalpy-chloride information suggests that a 282 ?? 10??C aquifer with water containing about 375 mg chloride per kilogram of water is present somewhere deep in the system. That deep water would be related to ??? 220??C Casa Diablo water by mixing with cold water, and to Hot Creek water by first boiling with steam loss and then mixing with cold water. Oxygen and deuterium isotopic data are consistent with that interpretation. An aquifer at 282??C with 375 mg/kg chloride implies a convective heat flow in Long Valley of 6.6 ?? 107 cal/s. ?? 1979.

  5. Assessment of geothermal resources at Newcastle, Utah

    USGS Publications Warehouse

    Blackett, Robert E.; Shubat, Michael A.; Chapman, David S.; Forster, Craig B.; Schlinger, Charles M.

    1989-01-01

    Integrated geology, geophysics, and geochemistry studies in the Newcastle area of southwest Utah are used to develop a conceptual geologic model of a blind, moderate-temperature hydrothermal system. Studies using 12 existing and 12 new, thermal gradient test holes, in addition to geologic mapping, gravity surveys, and other investigations have helped define the thermal regime. Preliminary results indicate that the up-flow region is located near the west-facing escarpment of an adjacent mountain range, probably related to the bounding range-front fault. Chemical geothermometers suggest equilibration temperatures ranging from 140??C to 170??C. The highest temperature recorded in the system is 130??C from an exploration well drilled by the Unocal Corporation.

  6. Valid garnet biotite (GB) geothermometry and garnet aluminum silicate plagioclase quartz (GASP) geobarometry in metapelitic rocks

    NASA Astrophysics Data System (ADS)

    Wu, Chun-Ming; Cheng, Ben-He

    2006-06-01

    At present there are many calibrations of both the garnet-biotite (GB) thermometer and the garnet-aluminum silicate-plagioclase-quartz (GASP) barometer that may confuse geologists in choosing a reliable thermometer and/or barometer. To test the accuracy of the GB thermometers we have applied the various GB thermometers to reproduce the experimental data and data from natural metapelitic rocks of various prograde sequences, inverted metamorphic zones and thermal contact aureoles. We have concluded that the four GB thermometers (Perchuk, L.L., Lavrent'eva, I.V., 1983. Experimental investigation of exchange equilibria in the system cordierite-garnet-biotite. In: Saxena, S.K. (ed.) Kinetics and equilibrium in mineral reactions. Springer-Verlag New York, Berlin, Heidelberg. pp. 199-239.; Kleemann, U., Reinhardt, J., 1994. Garnet-biotite thermometry revised: the effect of Al VI and Ti in biotite. European Journal of Mineralogy 6, 925-941.; Holdaway, M.J., 2000. Application of new experimental and garnet Margules data to the garnet-biotite geothermometer. American Mineralogist 85, 881-892., Model 6AV; Kaneko, Y., Miyano, T., 2004. Recalibration of mutually consistent garnet-biotite and garnet-cordierite geothermometers. Lithos 73, 255-269. Model B) are the most valid and reliable of this kind of thermometer. More specifically, we prefer the Holdaway (Holdaway, M.J., 2000. Application of new experimental and garnet Margules data to the garnet-biotite geothermometer. American Mineralogist 85, 881-892.) and the Kleemann and Reinhardt (Kleemann, U., Reinhardt, J., 1994. Garnet-biotite thermometry revised: the effect of Al VI and Ti in biotite. European Journal of Mineralogy 6, 925-941.) calibrations due to their small errors in reproducing the experimental temperatures and good accuracy in successfully discerning the systematic temperature changes of the different sequences. In addition, after applying the GASP barometer to 335 natural metapelitic samples containing one kind

  7. Crystallization temperature determination of Itokawa particles by plagioclase thermometry with X-ray diffraction data obtained by a high-resolution synchrotron Gandolfi camera

    NASA Astrophysics Data System (ADS)

    Tanaka, Masahiko; Nakamura, Tomoki; Noguchi, Takaaki; Nakato, Aiko; Ishida, Hatsumi; Yada, Toru; Shirai, Kei; Fujimura, Akio; Ishibashi, Yukihiro; Abe, Masanao; Okada, Tatsuaki; Ueno, Munetaka; Mukai, Toshifumi

    2014-02-01

    The crystallization temperatures of Itokawa surface particles recovered by the space probe Hayabusa were estimated by a plagioclase geothermometer using sodic plagioclase triclinicity. The Δ131-index required for the thermometer, which is the difference in X-ray diffraction peak positions between the 131 and 13¯1 reflections of plagioclase, was obtained by a high-resolution synchrotron Gandolfi camera developed for the third generation synchrotron radiation beamline, BL15XU at SPring-8. Crystallization temperatures were successfully determined from the Δ131-indices for four particles. The observed plagioclase crystallization temperatures were in a range from 655 to 660 °C. The temperatures indicate crystallization temperatures of plagioclases in the process of prograde metamorphism before the peak metamorphic stage.

  8. Multicomponent Equilibrium Models for Testing Geothermometry Approaches

    SciTech Connect

    Cooper, D. Craig; Palmer, Carl D.; Smith, Robert W.; McLing, Travis L.

    2013-02-01

    Geothermometry is an important tool for estimating deep reservoir temperature from the geochemical composition of shallower and cooler waters. The underlying assumption of geothermometry is that the waters collected from shallow wells and seeps maintain a chemical signature that reflects equilibrium in the deeper reservoir. Many of the geothermometers used in practice are based on correlation between water temperatures and composition or using thermodynamic calculations based a subset (typically silica, cations or cation ratios) of the dissolved constituents. An alternative approach is to use complete water compositions and equilibrium geochemical modeling to calculate the degree of disequilibrium (saturation index) for large number of potential reservoir minerals as a function of temperature. We have constructed several “forward” geochemical models using The Geochemist’s Workbench to simulate the change in chemical composition of reservoir fluids as they migrate toward the surface. These models explicitly account for the formation (mass and composition) of a steam phase and equilibrium partitioning of volatile components (e.g., CO2, H2S, and H2) into the steam as a result of pressure decreases associated with upward fluid migration from depth. We use the synthetic data generated from these simulations to determine the advantages and limitations of various geothermometry and optimization approaches for estimating the likely conditions (e.g., temperature, pCO2) to which the water was exposed in the deep subsurface. We demonstrate the magnitude of errors that can result from boiling, loss of volatiles, and analytical error from sampling and instrumental analysis. The estimated reservoir temperatures for these scenarios are also compared to conventional geothermometers. These results can help improve estimation of geothermal resource temperature during exploration and early development.

  9. Delineating Spatial Patterns in the Yellowstone Hydrothermal System using Geothermometry

    NASA Astrophysics Data System (ADS)

    King, J.; Hurwitz, S.; Lowenstern, J. B.

    2015-12-01

    Yellowstone National Park is unmatched with regard to its quantity of active hydrothermal features. Origins of thermal waters in its geyser basins have been traced to mixing of a deep parent water with meteoric waters in shallow local reservoirs (Fournier, 1989). A mineral-solution equilibrium model was developed to calculate water-rock chemical re-equilibration temperatures in these shallow reservoirs. We use the GeoT program, which uses water composition data as input to calculate saturation indices of selected minerals; the "best-clustering" minerals are then statistically determined to infer reservoir temperatures (Spycher et al., 2013). We develop the method using water composition data from Heart Lake Geyser Basin (HLGB), for which both chemical and isotopic geothermometers predict a reservoir water temperature of 205°C ± 10°C (Lowenstern et al., 2012), and minerals found in drill cores in Yellowstone's geyser basins. We test the model for sensitivity to major element composition, pH, Total Inorganic Carbon (TIC) and selected minerals to optimize model parameters. Calculated temperatures are most accurate at pH values below 9.0, and closely match the equilibrium saturation indices of quartz, stilbite, microcline, and albite. The model is optimized with a TIC concentration that is consistent with the mass of diffuse CO2 flux in HLGB (Lowenstern et al., 2012). We then use water compositions from other thermal basins in Yellowstone in search of spatial variations in reservoir temperatures. We then compare the calculated temperatures with various SiO2 and cation geothermometers.

  10. Empirical garnet muscovite geothermometry in metapelites

    NASA Astrophysics Data System (ADS)

    Wu, Chun-Ming; Wang, Xin-She; Yang, Chong-Hui; Geng, Yuan-Sheng; Liu, Fu-Lai

    2002-05-01

    Two empirical garnet-muscovite geothermometers, assuming no ferric iron (Model A) and 50% ferric iron (Model B) in muscovite, respectively, were calibrated under the physical conditions of P=3.0-14.0 kbar and T=530-700 °C. The input temperatures and pressures were determined by simultaneously applying the garnet-biotite thermometer [Am. Mineral. 85 (2000) 881.] and the GASP geobarometer [Am. Mineral. 86 (2001) 1117.] to natural metapelites. To confirm internal thermodynamic consistency, Holdaway's [Am. Mineral. 85 (2000) 881.] garnet mixing properties were adopted. Muscovite was treated as a symmetric Fe-Mg-Al VI ternary solid solution, and its Margules parameters were derived in this work. The resulting two formulae reproduced the input garnet-biotite temperatures well within ±50 °C, and gave identical results for a great body of natural samples. Moreover, they successfully distinguished the systematic changes of temperatures of different grade rocks from a prograde sequence, inverted metamorphic zone, and thermal contact aureole. Pressure estimation has almost no effect on the two formalisms of the garnet-muscovite geothermometer. Assuming analytical error of ±5% for the relevant components of both garnet and muscovite, the total random uncertainty of the two formulations will generally be within ±5 °C. The two thermometers derived in this work may be used as practical tools to metamorphic pelites under the conditions of 480 to 700 °C, low- to high-pressure, in the composition ranges Xalm=0.51-0.82, Xpyr=0.04-0.22, and Xgros=0.03-0.24 in garnet, and Fe tot=0.03-0.17, and Mg=0.04-0.14 atoms p.f.u. in muscovite.

  11. Chemical and mineralogical data and processing methods management system prototype with application to study of the North Caucasus Blybsky Metamorphic Complexes metamorphism PT-condition

    NASA Astrophysics Data System (ADS)

    Ivanov, Stanislav; Kamzolkin, Vladimir; Konilov, Aleksandr; Aleshin, Igor

    2014-05-01

    There are many various methods of assessing the conditions of rocks formation based on determining the composition of the constituent minerals. Our objective was to create a universal tool for processing mineral's chemical analysis results and solving geothermobarometry problems by creating a database of existing sensors and providing a user-friendly standard interface. Similar computer assisted tools are based upon large collection of sensors (geothermometers and geobarometers) are known, for example, the project TPF (Konilov A.N., 1999) - text-based sensor collection tool written in PASCAL. The application contained more than 350 different sensors and has been used widely in petrochemical studies (see A.N. Konilov , A.A. Grafchikov, V.I. Fonarev 2010 for review). Our prototype uses the TPF project concept and is designed with modern application development techniques, which allows better flexibility. Main components of the designed system are 3 connected datasets: sensors collection (geothermometers, geobarometers, oxygen geobarometers, etc.), petrochemical data and modeling results. All data is maintained by special management and visualization tools and resides in sql database. System utilities allow user to import and export data in various file formats, edit records and plot graphs. Sensors database contains up to date collections of known methods. New sensors may be added by user. Measured database should be filled in by researcher. User friendly interface allows access to all available data and sensors, automates routine work, reduces the risk of common user mistakes and simplifies information exchange between research groups. We use prototype to evaluate peak pressure during the formation of garnet-amphibolite apoeclogites, gneisses and schists Blybsky metamorphic complex of the Front Range of the Northern Caucasus. In particular, our estimation of formation pressure range (18 ± 4 kbar) agrees on independent research results. The reported study was

  12. Mineralogy and geothermometry of high-temperature rhyolites from the central and western Snake River Plain

    USGS Publications Warehouse

    Honjo, N.; Bonnichsen, B.; Leeman, W.P.; Stormer, J.C., Jr.

    1992-01-01

    Voluminous mid-Miocene rhyolitic ash-flow tuffs and lava flows are exposed along the northern and southern margins of the central and western Snake River Plain. These rhyolites are essentially anhydrous with the general mineral assemblage of plagioclase ??sanidine ?? quartz + augite + pigeonite ?? hypersthene ?? fayalitic olivine + Fe-Ti oxides + apatite + zircon which provides an opportunity to compare feldspar, pyroxene, and Fe-Ti oxide equilibration temperatures for the same rocks. Estimated pyroxene equilibration temperatures (based on the geothermometers of Lindsley and coworkers) range from 850 to 1000??C, and these are well correlated with whole-rock compositions. With the exception of one sample, agreement between the two-pyroxene thermometers tested is well within 50??C. Fe-Ti oxide geothermometers applied to fresh magnetite and ilmenite generally yield temperatures about 50 to 100??C lower than the pyroxene temperatures, and erratic results are obtained if these minerals exhibit effects of subsolidus oxidation and exsolution. Results of feldspar thermometry are more complicated, and reflect uncertainties in the thermometer calibrations as well as in the degree of attainment of equilibrium between plagioclase and sanidine. In general, temperatures obtained using the Ghiorso (1984) and Green and Usdansky (1986) feldspar thermometers agree with the pyroxene temperatures within the respective uncertainties. However, uncertainties in the feldspar temperatures are the larger of the two (and exceed ??60??C for many samples). The feldspar thermometer of Fuhrman and Lindsley (1988) produces systematically lower temperatures for many of the samples studied. The estimated pyroxene temperatures are considered most representative of actual magmatic temperatures for these rhyolites. This range of temperatures is significantly higher than those for rhyolites from many other suites, and is consistent with the hypothesis that the Snake River Plain rhyolitic magmas formed

  13. A thermodynamic model for di-trioctahedral chlorite from experimental and natural data in the system MgO-FeO-Al2O3-SiO2-H2O: applications to P- T sections and geothermometry

    NASA Astrophysics Data System (ADS)

    Lanari, Pierre; Wagner, Thomas; Vidal, Olivier

    2014-02-01

    We present a new thermodynamic activity-composition model for di-trioctahedral chlorite in the system FeO-MgO-Al2O3-SiO2-H2O that is based on the Holland-Powell internally consistent thermodynamic data set. The model is formulated in terms of four linearly independent end-members, which are amesite, clinochlore, daphnite and sudoite. These account for the most important crystal-chemical substitutions in chlorite, the Fe-Mg, Tschermak and di-trioctahedral substitution. The ideal part of end-member activities is modeled with a mixing-on-site formalism, and non-ideality is described by a macroscopic symmetric (regular) formalism. The symmetric interaction parameters were calibrated using a set of 271 published chlorite analyses for which robust independent temperature estimates are available. In addition, adjustment of the standard state thermodynamic properties of sudoite was required to accurately reproduce experimental brackets involving sudoite. This new model was tested by calculating representative P- T sections for metasediments at low temperatures (<400 °C), in particular sudoite and chlorite bearing metapelites from Crete. Comparison between the calculated mineral assemblages and field data shows that the new model is able to predict the coexistence of chlorite and sudoite at low metamorphic temperatures. The predicted lower limit of the chloritoid stability field is also in better agreement with petrological observations. For practical applications to metamorphic and hydrothermal environments, two new semi-empirical chlorite geothermometers named Chl(1) and Chl(2) were calibrated based on the chlorite + quartz + water equilibrium (2 clinochlore + 3 sudoite = 4 amesite + 4 H2O + 7 quartz). The Chl(1) thermometer requires knowledge of the (Fe3+/ΣFe) ratio in chlorite and predicts correct temperatures for a range of redox conditions. The Chl(2) geothermometer which assumes that all iron in chlorite is ferrous has been applied to partially recrystallized

  14. Hydrogeochemical evaluation of conventional and hot dry rock geothermal resource potential in the Clear Lake region, California

    SciTech Connect

    Goff, F.; Adams, A.I.; Trujillo, P.E.; Counce, D.

    1993-05-01

    Chemistry, stable isotope, and tritium contents of thermal/mineral waters in the Clear Lake region were used to evaluate conventional and hot dry rock (HDR) geothermal potential for electrical generation. Thermal/mineral waters of the Clear Lake region are broadly classified as thermal meteoric and connate types based on chemical and isotopic criteria. Ratios of conservative components such as B/Cl are extremely different among all thermal/mineral waters of the Clear Lake region except for clusters of waters emerging from specific areas such as the Wilbur Springs district and the Agricultural Park area south of Mt. Konocti. In contrast ratios of conservative components in large, homogeneous geothermal reservoirs are constant. Stable isotope values of Clear Lake region waters show a mixing trend between thermal meteoric and connate (generic) end-members. The latter end-member has enriched {delta}D as well as enriched {delta}{sup 18}O, from typical high-temperature geothermal reservoir waters. Tritium data indicate most Clear Lake region waters are mixtures of old and young fluid components. Subsurface equilibration temperature of most thermal/mineral waters of the Clear Lake region is {le}150{degree}C based on chemical geothermometers but it is recognized that Clear Lake region waters are not typical geothermal fluids and that they violate rules of application of many geothermometers. The combined data indicate that no large geothermal reservoir underlies the Clear Lake region and that small localized reservoirs have equilibration temperatures {le}150{degree}C (except for Sulphur Bank mine). HDR technologies are probably the best way to commercially exploit the known high-temperatures existing beneath the Clear Lake region particularly within and near the main Clear Lake volcanic field.

  15. Geochemistry of thermal/mineral waters in the Clear Lake region, California, and implications for hot dry rock geothermal development

    SciTech Connect

    Goff, F.; Adams, A.I.; Trujillo, P.E.; Counce, D.; Mansfield, J.

    1993-02-01

    Thermal/mineral waters of the Clear Lake region are broadly classified as thermal meteoric and connote types based on chemical and isotopic criteria. Ratios of conservative components such as B/Cl are extremely different among all thermal/mineral waters of the Clear Lake region except for clusters of waters emerging from specific areas such as the Wilbur Springs district and the Agricultural Park area south of Mt. Konocti. In contrast, ratios of conservative components in large, homogeneous geothermal reservoirs are constant. Stable isotope values of Clear Lake region waters show a mixing trend between thermal meteoric and connote end-members. The latter end-member has enriched [delta]D as well as enriched d[sup l8]O, very different from typical high-temperature geothermal reservoir waters. Tritium data and modeling of ages indicate most Clear Lake region waters are 500 to > 10,000 yr., although mixing of old and young components is implied by the data. The age of end-member connate water is probably > 10,000 yr. Subsurface equilibration temperature of most thermal/mineral waters of the Clear Lake region is [le] 150[degrees]C based on chemical geothermometers but it is recognized that Clear Lake region waters are not typical geothermal fluids and that they violate rules of application of many geothermometers. The combined data indicate that no large geothermal reservoir underlies the Clear Lake region and that small localized reservoirs have equilibration temperatures [le] 150[degrees]C (except for Sulphur Bank Mine). Hot dry rock technologies are the best way to commercially exploit the known high temperatures existing beneath the Clear Lake region, particularly within the main Clear Lake volcanic field.

  16. Geochemical Characterization and Geothermometry of the Geothermal Springs of Northwest India

    NASA Astrophysics Data System (ADS)

    Zamudio, K. D.; Klemperer, S. L.; Sastry, S. R.; Harinarayana, T.

    2014-12-01

    The Himalayan collision zone between India and Asia hosts an active geothermal province that spans the border from India into Tibet. Despite significant exploration, commercial development thus far in India is limited to modest use of hot water for heating greenhouses. We sampled nine hot springs in Northwest India, from the Karakoram Fault, across the Indus-Yarlung Suture Zone, to the Main Central Thrust. We analyzed major cation and anion chemistry using ICP-OES. Calcium ranges from 1-220 ppm, potassium from 4-110 ppm, magnesium from 0-60 ppm and sodium from 70-440 ppm. These values are similar to samples analyzed by the Geological Survey of India in previous decades. Preliminary reservoir temperatures calculated using the Fournier & Potter Na-K-Ca-Mg geothermometer range from 100-260°C. No correlations with geologic structure or location across the Himalayan orogen are apparent, and springs located within a few tens of km of each other have apparent temperatures differing by a factor of two. However, these classical geothermometers are subject to large uncertainty in cases where gas has been lost or where there has been dilution of the waters from depth with surface waters. We will use Lawrence Berkeley National Laboratory's multicomponent geothermometry code, GeoT, to improve the temperature estimation for each geothermal site. Even if reservoir temperatures are not high enough for electricity generation, these springs have the potential to provide cheap heating and cooling for the local communities. We plan to collect additional water samples in neighboring Tibet in the future.

  17. Distinguishing and understanding thermogenic and biogenic sources of methane using multiply substituted isotopologues

    NASA Astrophysics Data System (ADS)

    Stolper, D. A.; Martini, A. M.; Clog, M.; Douglas, P. M.; Shusta, S. S.; Valentine, D. L.; Sessions, A. L.; Eiler, J. M.

    2015-07-01

    Sources of methane to sedimentary environments are commonly identified and quantified using the stable isotopic compositions of methane. The methane "clumped-isotope geothermometer", based on the measurement of multiply substituted methane isotopologues (13CH3D and 12CH2D2), shows promise in adding new constraints to the sources and formational environments of both biogenic and thermogenic methane. However, questions remain about how this geothermometer behaves in systems with mixtures of biogenic and thermogenic gases and different biogenic environments. We have applied the methane clumped-isotope thermometer to a mixed biogenic-thermogenic system (Antrim Shale, USA) and to biogenic gas from gas seeps (Santa Barbara and Santa Monica Basin, USA), a pond on the Caltech campus, and methanogens grown in pure culture. We demonstrate that clumped-isotope based temperatures add new quantitative constraints to the relative amounts of biogenic vs. thermogenic gases in the Antrim Shale indicating a larger proportion (∼50%) of thermogenic gas in the system than previously thought. Additionally, we find that the clumped-isotope temperature of biogenic methane appears related to the environmental settings in which the gas forms. In systems where methane generation rates appear to be slow (e.g., the Antrim Shale and gas seeps), microbial methane forms in or near both internal isotopic equilibrium and hydrogen-isotope equilibrium with environmental waters. In systems where methane forms rapidly, microbial methane is neither in internal isotopic equilibrium nor hydrogen-isotope equilibrium with environmental waters. A quantitative model of microbial methanogenesis that incorporates isotopes is proposed to explain these results.

  18. Assessment of the geothermal resources of the Socialist Republic of Vietnam

    SciTech Connect

    Flynn, T.; Tien, Phan Cu; Schochert, D.; Quy, Hoang Huu

    1997-12-31

    More than 125 thermal springs, with temperatures greater than 30{degrees}C have been identified and catalogued by the General Department of Geology of Vietnam. Subsurface data are limited and fewer than 10 areas have been identified, on the basis of chemical geothermometers, as capable of supporting electric power production. Six sites in south-central Vietnam have recently been selected for exploration to determine their development potential for electrical power generation. Selected criteria included surface features, chemical geothermometers, proximity to regional faults trends, and regional requirements for electric power. Site visits were conducted to a total of eight areas in south central Vietnam where collateral economic developments suggest the need for a local, reliable source of electricity. Physical and visual information on geothermal springs and wells in Vietnam was compared to Nevada`s geothermal resources. Surface geothermal manifestations in Vietnam appear remarkably similar to those in Nevada. Outcrops adjacent to the geothermal areas indicate that Mesozoic-age granites are the most likely basement rocks. Quaternary basalts mapped throughout the study area may be responsible for the thermal anomaly. Initial exploration efforts will focus on three of the six sites, which together may be able to produce 40 to 60 MWe. A cooperative research program with selected Vietnamese governmental agencies includes geologic mapping, surface geophysical and geochemical surveys, and a graduated schedule of drilling programs, ranging in depth from 100 to 1,000 m. Results will be used to define a detailed, deep drilling and testing program at the three prime sites. Development of geothermal power in this region will boost local economic recovery and add stability to the national electric grid.

  19. Generation of Primary Kilauea Magmas: Constraints on Pressure, Temperature and Composition of Melts

    NASA Astrophysics Data System (ADS)

    Gudfinnsson, G. H.; Presnall, D. C.

    2004-12-01

    Picrite glasses from the submarine extension of Kilauea, Puna Ridge, which contain up to 15.0 wt% MgO, are the most magnesian glass samples reported from Hawaii. Their compositions form a distinct olivine fractionation trend. A comparison of this trend with phase relations of garnet lherzolite in the CaO-MgO-Al2O3-SiO2 (CMAS) and CaO-MgO-Al2O3-SiO2-Na2O-FeO (CMASNF) system indicates that melts parental to the Hawaiian picrites are produced by melting of a garnet lherzolite source at a pressure of 5 ± 1 GPa. The primary melt composition for Kilauea proposed by Clague et al. (1995), which has 18.4 wt% MgO, is close to the expected 5 GPa melt composition. By using the pressure-independent CMASNF geothermometer (Gudfinnsson and Presnall, 2001), we obtain a temperature of formation of 1450° C for the most magnesian Puna Ridge glass after correction for the presence of 0.4 wt% H2O and 0.7 wt% CO2. This assumes that the glass is not much modified after separation from the lherzolite source. However, comparison with phase relations in the CMAS system strongly suggests that the most magnesian Puna Ridge glasses are the product of some olivine fractionation, and therefore give temperature considerably lower than that of the source. When applied to the proposed Kilauea primary melt composition of Clague et al. (1995), the CMASNF geothermometer gives a melting temperature of 1596° C or about 1565° C after correction for the presence of volatiles. This compares well with the anhydrous solidus temperature of 1600 ± 15° C at 5 GPa for the fertile KR4003 lherzolite (Lesher et al., 2003), which has the complete garnet lherzolite phase assemblage present at the solidus at this pressure. This consistency supports use of phase relations from the CMAS system and the CMASNF geothermometer to the Puna Ridge picrite compositions. With the pressure and temperature of melting known, one can calculate the potential temperature of the Hawaiian mantle, provided certain conditions are met

  20. Untangling the History of Oceanic Peridotites Using Spinel Oxybarometry

    NASA Astrophysics Data System (ADS)

    Birner, S.; Warren, J. M.; Cottrell, E.; Davis, F. A.

    2014-12-01

    Comprehensive knowledge of the oxygen fugacity of the upper mantle is critical to understanding the processes associated with melt production, interaction, and extraction. Thus, it is important to understand how fO2 changes during a peridotite's thermal and petrologic history in the asthenospheric and lithospheric mantle, as metamorphic subsolidus reequilibration can result in changes to recorded fO2. A case study of Tongan forearc peridotites highlights the heterogeneity seen in mantle peridotites. We analyzed two dredges located 250 km apart along the trench: one dredge ranges in fO2 from 0.5 to 1 log unit above the QFM buffer, similar to analyses of supra-subduction zone xenoliths (e.g. Brandon and Draper, 1996; Wood and Virgo, 1989) while the other dredge ranges from QFM-0.75 to QFM+0.25 and exhibits high spinel Cr# (ranging from 0.45 to 0.75). Systematics between fO2, Ti concentration, olivine forsterite content, and Cr# within each dredge allow us to differentiate between the effects of melt extraction, melt interaction, and cooling. Because the spinel oxybarometry equation is dependent on temperature, it is important to be able to accurately determine the temperature recorded by peridotites. Though many geothermometers are available for mantle rocks, we assert that geothermometers based on Fe-Mg exchange between olivine and spinel are the most applicable to fO2 calculations, because the oxygen fugacity recorded by a mantle assemblage is primarily controlled by this exchange. Additionally, preliminary analyses of diffusion profiles across olivine-spinel grain boundaries provide insight into the cooling of peridotite in the oceanic lithosphere and its effects on oxygen fugacity. Mg-Fe exchange between olivine and spinel is controlled by the distribution coefficient, KD, which is dependent on both temperature and the proportion of Cr to other trivalent cations in spinel. We see an increase in olivine forsterite content towards the olivine-spinel interface

  1. Rutile geochemistry and its potential use in quantitative provenance studies

    NASA Astrophysics Data System (ADS)

    Zack, T.; von Eynatten, H.; Kronz, A.

    2004-10-01

    Rutile is among the most stable detrital minerals in sedimentary systems. Information contained in rutile is therefore of prime importance, especially in the study of mature sediments, where most diagnostic minerals are no longer stable. In contrast to zircon, rutile provides information about the last metamorphic cycle as rutile is not stable at greenschist facies conditions. Several known geochemical characteristics of rutile can be used to retrace provenance. The lithology of source rocks can be determined using Nb and Cr contents in rutile, because the most important source rocks for rutile, metapelites and metabasites, imprint a distinct Nb and Cr signature in rutiles. Since Zr in rutile, coexisting with zircon and quartz, is extremely temperature dependent, this relationship can be used as a geothermometer. Metapelites always contain zircon and quartz, thus the Nb and Cr signatures of metapelites indicate rutiles that can be used for thermometry. The result is effectively a single-mineral geothermometer, which is to our knowledge the first of its kind in provenance studies. Several other trace elements are variably enriched in rutile, but the processes creating these variations are so far not understood. In a case study, Al, Si, V, Cr, Fe, Zr, Nb and W contents in rutiles were obtained by electron microprobe from three sediment samples from Upstate New York. A Pleistocene glacial sand, whose source was granulite-facies rocks of the southern Adirondacks, has detrital rutile geochemical signatures which are consistent with the local Geology; a predominantly metapelitic source with a minor metabasitic contribution. Calculated temperatures for the metapelitic rutiles from the glacial sand are consistent with a predominantly granulite-facies source. The two other samples are from Paleozoic clastic wedges deposited in the foreland of the Taconian and Acadian orogenies. Here several geochemical patterns of detrital rutiles are comparable to rutiles derived from the

  2. The Hydrogeochemistry of Qingshui Geothermal Field, Northeastern Taiwan.

    NASA Astrophysics Data System (ADS)

    Yu-Wen, Chen; Cheng-Kuo, Lin; Wayne, Lin; Yu-Te, Chang; Pei-Shan, Hsieh

    2015-04-01

    The Qingshui geothermal field is located at the upstream valley of Lanyang Creek, northeastern Taiwan. It is renowned as a geothermal field. The previous studies demonstrated a higher geothermal gradient, 100oC/km warmer than a normal geotherm. However, Qingshui geothermal field has not been well developed due to the higher mining costs. In the recent years, the Taiwan government has been focusing on developing alternative and renewable energy and initiated a 10 year project, Nation Energy Program. This study is part of this project In general, it is very difficult to collect deep downhole samples without considerable change of hydro- and gas- chemistry of water under high temperature and pressure. A new sampling tool, GTF Sampler, was designed by the research team, Green Energy and Environment Laboratories, Industrial Technology Research Institute. This tool can simultaneously collect high quality geothermal water and gas sample and moreover, the sampling depth can reach up to 800 meters. Accordingly, a more accurate measurements can be conducted in the laboratory. In this study, 10 geothermal samples were collected and measured. The results demonstrate that geothermal water samples are characterized with Na(K)-HCO3 water type and located at the mature water area in Giggenbach Na-K-Mg diagram. Several geothermometers, including silica and cation geothermometry, were used to estimate potential temperature in the geothermal reservoir systems. In general, the geothermoters of Na-K and Na-K-Ca obtain reservoir temperatures between 120-190oC and 130-210oC, respectively, but the silica geothermometer indicates a lower reservoir temperature between 90 and 170oC. There is no big difference among them. It is worth to note that all calculated temperatures are lower than those of in-situ downhole measurements; therefore, more detailed and advanced researches would be needed for the inconsistency. To examine the argument about igneous heat source in the previous studies, rare

  3. Peak temperature in intracratonic basins constrained by magnetic studies:Example of the Illinois Basin

    NASA Astrophysics Data System (ADS)

    Uz, E.; Ferre, E. C.; Rimmer, S.; Morse, D. G.; Crockett, J. E.

    2012-12-01

    Deciphering the thermal evolution of a package of sedimentary rocks through time constitutes an essential element in exploration for oil and gas. Classic geothermometers based on illite crystallinity, vitrinite reflectance, the Rock-Eval method or conodont coloration index are limited to rocks containing sufficient amounts of one of the index materials. Magnetic approaches to geothermometry have intrinsic advantages due to the quasi-ubiquitous presence of magnetically remanent grains in sedimentary environments. Previous attempts to correlate burial temperature with magnetic properties focused on the low-field bulk magnetic susceptibility Km (Hrouda et al., 2003) or on the low-temperature magnetic parameter PM in pyrrhotite-magnetite assemblages (MagEval method of Aubourg and Pozzi, 2010). We simultaneously investigate the variation of an array of magnetic parameters with temperature. These parameters include low-field magnetic susceptibility, saturation isothermal magnetic remanence, saturation magnetization, coercitive force and coercivity of magnetic remanence. Tracking multiple magnetic parameters offers the advantage of being sensitive not only to heating-induced mineralogical changes but also to heating-induced magnetic domain changes. This multi-parameter method also has the benefit of being applicable to a broad range of sedimentary lithologies. To demonstrate the principles of this method we begin examining intracontinental basins because they are broadly undeformed and their thermal histories remain, in general, relatively simple. Igneous intrusions and basinal hydrothermal fluids may, however, complicate matters. The Illinois Basin, an oil- and gas-producing basin, provides an accessible test area for the geothermometric tests. The Mount Simon Sandstone constitutes the first lithological unit investigated because it sits at the deepest level in the basin and is therefore likely to have recorded the highest burial temperatures. The proposed method

  4. Exploration of the Upper Hot Creek Ranch Geothermal Resource, Nye County, Nevada

    SciTech Connect

    Dick Benoit; David Blackwell

    2006-01-01

    The Upper Hot Creek Ranch (UHCR) geothermal system had seen no significant exploration activity prior to initiation of this GRED III project. Geochemical geothermometers calculated from previously available but questionable quality analyses of the UHCR hot spring waters indicated possible subsurface temperatures of +320 oF. A complex Quaternary and Holocene faulting pattern associated with a six mile step over of the Hot Creek Range near the UHCR also indicated that this area was worthy of some exploration activity. Permitting activities began in Dec. 2004 for the temperature-gradient holes but took much longer than expected with all drilling permits finally being received in early August 2005. The drilling and geochemical sampling occurred in August 2005. Ten temperature gradient holes up to 500’ deep were initially planned but higher than anticipated drilling and permitting costs within a fixed budget reduced the number of holes to five. Four of the five holes drilled to depths of 300 to 400’ encountered temperatures close to the expected regional thermal background conditions. These four holes failed to find any evidence of a large thermal anomaly surrounding the UHCR hot springs. The fifth hole, located within a narrow part of Hot Creek Canyon, encountered a maximum temperature of 81 oF at a depth of 105’ but had cooler temperatures at greater depth. Temperature data from this hole can not be extrapolated to greater depths. Any thermal anomaly associated with the UHCR geothermal system is apparently confined to the immediate vicinity of Hot Creek Canyon where challenges such as topography, a wilderness study area, and wetlands issues will make further exploration time consuming and costly. Ten water samples were collected for chemical analysis and interpretation. Analyses of three samples of the UHCR thermal give predicted subsurface temperatures ranging from 317 to 334 oF from the Na-K-Ca, silica (quartz), and Na-Li geothermometers. The fact that all

  5. Exploration of the Upper Hot Creek Ranch Geothermal Resource, Nye County, Nevada

    SciTech Connect

    Dick Benoit; David Blackwell

    2005-10-31

    The Upper Hot Creek Ranch (UHCR) geothermal system had seen no significant exploration activity prior to initiation of this GRED III project. Geochemical geothermometers calculated from previously available but questionable quality analyses of the UHCR hot spring waters indicated possible subsurface temperatures of +320 oF. A complex Quaternary and Holocene faulting pattern associated with a six mile step over of the Hot Creek Range near the UHCR also indicated that this area was worthy of some exploration activity. Permitting activities began in Dec. 2004 for the temperature-gradient holes but took much longer than expected with all drilling permits finally being received in early August 2005. The drilling and geochemical sampling occurred in August 2005. Ten temperature gradient holes up to 500’ deep were initially planned but higher than anticipated drilling and permitting costs within a fixed budget reduced the number of holes to five. Four of the five holes drilled to depths of 300 to 400’ encountered temperatures close to the expected regional thermal background conditions. These four holes failed to find any evidence of a large thermal anomaly surrounding the UHCR hot springs. The fifth hole, located within a narrow part of Hot Creek Canyon, encountered a maximum temperature of 81 oF at a depth of 105’ but had cooler temperatures at greater depth. Temperature data from this hole can not be extrapolated to greater depths. Any thermal anomaly associated with the UHCR geothermal system is apparently confined to the immediate vicinity of Hot Creek Canyon where challenges such as topography, a wilderness study area, and wetlands issues will make further exploration time consuming and costly. Ten water samples were collected for chemical analysis and interpretation. Analyses of three samples of the UHCR thermal give predicted subsurface temperatures ranging from 317 to 334 oF from the Na-K-Ca, silica (quartz), and Na-Li geothermometers. The fact that all

  6. Model for origin and evolution of water at volcanoes in São Miguel, Azores (Portugal), based on geochemical and isotopic data set

    NASA Astrophysics Data System (ADS)

    Woitischek, Julia; Dietzel, Martin; Virgílio Cruz, J.; Inguaggiato, Salvatore; Leis, Albrecht; Böttcher, Michael E.

    2016-04-01

    A conceptual model is presented to better constrain the origin and evolution of discharges at Sete Cidades, Fogo and Furnas Volcano, using geochemical and isotopic analyses of rock and water as well as recalculated gas composition. The evolution of thermal water clearly reveals that Na-HCO3 and Na-SO4 type of springs have their origin in meteoric water as isotope data are close to the local meteoric water line (δ 18OH2O =-3 ± 1 ‰ V-SMOW; δ DH2O= -13 ± 7 ‰ V-SMOW) with exception of a Na-Cl spring named Ferraria, Sete Cidades area (δ 18OH2O = 0.45 ‰ V-SMOW ; δ DH2O= 4.18 ‰ V-SMOW). Analysed solutions are chemical evolved by evaporation, uptake of volcanic gas, leaching of local basaltic rocks, precipitation of solids, partly admixture of sea water and/or biological activity. Following the individual concentrations supports this model e.g.: HCO3 concentration and the recalculated isotopic composition of gaseous CO2 (δ 13CCO_2 = -4 ± 2.5 ‰ V-PDB) reflect evolved magmatic CO2 uptake and the subsequent leaching progress; High SO42- concentration of up to 16.5 mmol L-1 with δ 34SSO4 = 0.35 ± 0.3 ‰ (V-CDT) reflects magmatic origin which mainly control water chemistry of boiling pools of both Fogo and Furnas lake; δ 18OSO4 = 10.5 ‰ (V-SMOW) suggests organic origin and fits together with the observation of stromatolitic structures in the related precipitates; Molar Mg/Caratio (≈ 0.77) of all thermal discharges reflects leaching of analysed local basalt (Mg/Ca≈ 0.78). Furthermore, shallow and evolved outgassing effects can be distinguished. Equilibrium temperatures for various minerals given in SI vs. T plots and further geothermometers (e.g. Na-K, Na-K-Ca geothermometers) were discussed to estimate temperatures of reservoirs.

  7. Accessory Mineral U-Pb Ti-Zr Thermochronology of the Deep Crust of Zealandia: Rift, Breakup and Drift from 90-20 Ma

    NASA Astrophysics Data System (ADS)

    Beinlich, A.; Palin, J.; Cooper, A. F.

    2006-12-01

    Cenozoic alkaline mafic volcanics of eastern Otago were made famous in classic petrology and petrography texts coauthored by Francis Turner. Several locales have yielded mantle and crustal xenoliths including the Pigroot "mafic phonolite". Here, among abundant spinel lherzolite xenoliths, we discovered an undeformed cumulate gabbro composed of intermediate plagioclase and pargasitic amphibole with augite, ilmenite, magnetite, titanite (sphene) and accessory zircon and apatite. Major and trace elements indicate the rock crystallised from primitive alkaline magma, whereas the mineral assemblage indicates equilibration under amphibolite facies conditions at 5-9 kbar. Accessory mineral U-Pb Ti-Zr thermochronology by LA-ICP-MS on grain separates and in thin section reveals a T-t path that began with zircon crystallisation at 90±2 Ma (^{208}Pb-corrected 206Pb/238U, n=37, mswd=9.9) and 710±20°C (Ti-zircon geothermometer of Watson et al. 2006). Titanite dates (207Pb-corrected 206Pb/238U, n=49) and temperatures (Zr-titanite geothermometer of Hayden et al. 2006 at 7 kbar) form a linear array (r2=0.6) extending from 85 Ma, 830°C to 34 Ma, 760°C. The slope of this T-t array is inconsistent with diffusive loss of Pb and Zr from titanite (Cherniak, pers.comm.) and, together with REE data and reaction textures, indicates prolonged growth at the expense of plagioclase and ilmenite. Apatite U-Pb isotope data projected from the measured 207Pb/206Pb in plagioclase give a lower intercept age of 20±3 Ma (n=17, mswd=1.5) which overlaps the K-Ar age of the phonotephrite host lava (Coombs, pers.comm.). This remarkable xenolith records 1) crystallisation of alkaline mafic magma in the deep crust during early rifting of Zealandia from Gondwana around 90 Ma, 2) heating during continued lithospheric thinning 90-85 Ma, 3) slow cooling (≤2°C/my) for 50 my following continental breakup at 85 Ma, and 4) transport to the surface and thermal quenching at 20 Ma. Slow cooling of the deep

  8. Infrared Spectroscopy for Rapid Characterization of Drill Core and Cutting Mineralogy

    NASA Astrophysics Data System (ADS)

    Calvin, W. M.; Kratt, C.; Kruse, F. A.

    2009-12-01

    Water geochemistry can vary with depth and location within a geothermal reservoir, owing to natural factors such as changing rock type, gas content, fluid source and temperature. The interaction of these variable fluids with the host rock will cause well known changes in alteration mineral assemblages that are commonly factored into the exploration of hydrothermal systems for economic metals, but are less utilized with regard to mapping borehole geology for geothermal energy production. Chemistry of geothermal fluids and rock alteration products can impact production factors such as pipeline corrosion and scaling and early studies explored the use of both silica and chlorites as geothermometers. Infrared spectroscopy is particularly good at identifying a wide variety of alteration minerals, especially in discrimination among clay minerals, with no sample preparation. The technique has been extensively used in the remote identification of materials, but is not commonly used on drill core or chips. We have performed several promising pilot studies that suggest the power of the technique to sample continuously and provide mineral logs akin to geophysical ones. We have surveyed a variety of samples, including drill chip boards, boxed core, and drill cuttings from envelopes, sample bottles and chip trays. This work has demonstrated that core and drill chips can be rapidly surveyed, acquiring spectra every few to tens of cm of section, or the vertical resolution of the chip tray (typically 10 feet). Depending on the sample type we can acquire spectral data over thousands of feet depth at high vertical resolution in a fraction of the time that is needed for traditional analytical methods such as XRD or TEM with better accuracy than traditional geologic drill or chip logging that uses visual inspection alone. We have successfully identified layered silicates such as illite, kaolinite, montmorillonite chlorite and prehnite, zeolites, opal, calcite, jarosite and iron oxides

  9. Subseafloor phase equilibria in high-temperature hydrothermal fluids of the Lucky Strike Seamount (Mid-Atlantic Ridge, 37°17‧N)

    NASA Astrophysics Data System (ADS)

    Pester, Nicholas J.; Reeves, Eoghan P.; Rough, Mikaella E.; Ding, Kang; Seewald, Jeffrey S.; Seyfried, William E.

    2012-08-01

    As part of an integrated study conducted at the Lucky Strike Seamount (Mid-Atlantic Ridge, 37°17'N) in 2008, gas-tight sampling devices were used to collect high-temperature (˜300 °C) hydrothermal fluids issuing from sulfide structures distributed throughout the vent field located in the summit depression. Compared with previous observations from 1993 to 1997, the most substantial changes in vent fluid compositions are dramatically increased CO2 concentrations (˜5×, up to 133 mmol/L) and the observation of vent fluids enriched in dissolved chloride relative to seawater. Combined with an increase in δ13C values by ˜4‰ in 2008, the elevated CO2 indicates replenishment of the magmatic heat source and may be indicative of a recent magmatic event. The additional supporting fluid chemistry is, however, similar to that of the previous sampling intervals, necessitating a reassessment of the subseafloor controls on vent fluid chemistry at Lucky Strike in the context of recently obtained geophysical data that provides the depth/extent of a steady-state magma chamber. Two-phase behavior is indicated by the chloride variability in the vent fluids; and comparison with experimental data for the associated chloride-dependent partitioning of minor/trace elements suggests the possibility of a similar source fluid for all the vent structures, while limiting the likelihood of shallow phase separation and subseafloor mixing for the hydrothermal end-members. A recently calibrated Fe/Mn geothermometer indicates minimum subseafloor equilibration temperatures of 350-385 °C. However, constraints imposed by dissolved Si/Cl in conjunction with geophysical observations are consistent with peak reaction conditions at temperatures of 430-475 °C and pressures near the top of the axial magma chamber (˜410-480 bars), where magmatic CO2 becomes entrained in the circulating fluids. The distance between the magma chamber and the seafloor at Lucky Strike is substantially greater than at

  10. Geothermobarometry of Spinel Peridotites from Southern British Columbia: Implications for the Thermal Conditions in the Upper Mantle

    NASA Astrophysics Data System (ADS)

    Ghent, E. D.; Greenfield, A. R.; Russell, J. K.

    2012-12-01

    Spinel lherzolite xenoliths within by alkali basalt volcanic rocks exposed at Rayfield River and Big Timothy Mountain, south-central British Columbia represent samples of the underlying lithospheric mantle. Electron microprobe analysis shows that most xenoliths comprise compositionally homogeneous grains of olivine, orthopyroxene, clinopyroxene and spinel. We applied the following geothermometers: orthopyroxene-clinopyroxene, spinel-orthopyroxene, and spinel-olivine to these rocks. Temperatures calculated using the Brey and Köhler calibration of two-pyroxene thermometry (Brey and Köhler 1990) were constrained in pressure by being required to lie on a model geotherm developed for this region of B.C following the methods of Harder and Russell (2006). The geotherm is constrained to produce a temperature at the Moho (33 km) of 825 ± 25 C in order to match the lowest temperature peridotite xenoliths recovered in this study. The simultaneous solution of the model geotherm and the pressure-dependent Brey- Köhler two-pyroxene thermometry removed the need for adopting an arbitrary pressure - although the overall effect of pressure on the temperature calculations is negligible (~2°C for 100 MPa). We take these temperatures to represent peak mantle lithosphere temperatures. Fourteen Rayfield River xenoliths return average two-pyroxene temperatures between 841 and 961 °C corresponding to depths of 34-42 km. Orthopyroxene-spinel and olivine-spinel results are 889 ± 60°C and 825 ± 88°C, respectively. Five Big Timothy xenoliths have two-pyroxene temperature that span 840 to 1057 °C (Mean 970 ± 64°C) corresponding to depths of 34-48 km. Orthopyroxene-spinel and olivine-spinel temperatures are 844 ± 63°C and 896 ± 232°C, respectively. We argue that this range in temperatures does not represent closure temperatures imposed during cooling either in the mantle or during transport by the lavas. The temperature ranges are due to differences in calibration of the

  11. A geochemical reconnaissance of the Alid volcanic center and geothermal system, Danakil depression, Eritrea

    USGS Publications Warehouse

    Lowenstern, J. B.; Janik, C.J.; Fournier, R.O.; Tesfai, T.; Duffield, W.A.; Clynne, M.A.; Smith, James G.; Woldegiorgis, L.; Weldemariam, K.; Kahsai, G.

    1999-01-01

    Geological and geochemical studies indicate that a high-temperature geothermal system underlies the Alid volcanic center in the northern Danakil depression of Eritrea. Alid is a very late-Pleistocene structural dome formed by shallow intrusion of rhyolitic magma, some of which vented as lavas and pyroclastic flows. Fumaroles and boiling pools distributed widely over an area of ~10 km2 on the northern half of Alid suggest that an active hydrothermal system underlies much of that part of the mountain. Geothermometers indicate that the fumarolic gases are derived from a geothermal system with temperatures >225??C. The isotopic composition of condensed fumarolic steam is consistent with these temperatures and implies that the source water is derived primarily from either lowland meteoric waters or fossil Red Sea water, or both. Some gases vented from the system (CO2, H2S and He) are largely magmatic in origin. Permeability beneath the volcanic center may be high, given the amount of intrusion-related deformation and the active normal faulting within the Danakil depression.Geological and geochemical studies indicate that a high-temperature geothermal system underlies the Alid volcanic center in the northern Danakil depression of Eritrea. Alid is a very late-Pleistocene structural dome formed by shallow intrusion of rhyolitic magma, some of which vented as lavas and pyroclastic flows. Fumaroles and boiling pools distributed widely over an area of approx. 10 km2 on the northern half of Alid suggest that an active hydrothermal system underlies much of that part of the mountain. Geothermometers indicate that the fumarolic gases are derived from a geothermal system with temperatures >225??C. The isotopic composition of condensed fumarolic steam is consistent with these temperatures and implies that the source water is derived primarily from either lowland meteoric waters or fossil Red Sea water, or both. Some gases vented from the system (CO2, H2S and He) are largely

  12. Subaerial and sublacustrine hydrothermal activity at Lake Rotomahana

    NASA Astrophysics Data System (ADS)

    Stucker, Valerie K.; de Ronde, Cornel E. J.; Scott, Bradley J.; Wilson, Nathaniel J.; Walker, Sharon L.; Lupton, John E.

    2016-03-01

    Lake Rotomahana is a crater lake in the Okataina Volcanic Centre (New Zealand) that was significantly modified by the 1886 Tarawera Rift eruption. The lake is host to numerous sublacustrine hydrothermal vents. Water column studies were conducted in 2011 and 2014 along with sampling of lake shore hot springs and crater lakes in Waimangu Valley to complement magnetic, seismic, bathymetric and heat flux surveys. Helium concentrations below 50 m depth are higher in 2014 compared to 2011 and represent some of the highest concentrations measured, at 6 × 10- 7 ccSTP/g, with an end-member 3He/4He value of 7.1 RA. The high concentrations of helium, when coupled with pH anomalies due to high dissolved CO2 content, suggest the dominant chemical input to the lake is derived from magmatic degassing of an underlying magma. The lake shore hot spring waters show differences in source temperatures using a Na-K geothermometer, with inferred reservoir temperatures ranging between 197 and 232 °C. Water δ18O and δD values show isotopic enrichment due to evaporation of a steam heated pool with samples from nearby Waimangu Valley having the greatest enrichment. Results from this study confirm both pre-1886 eruption hydrothermal sites and newly created post-eruption sites are both still active.

  13. Apacheta, a new geothermal prospect in Northern Chile

    SciTech Connect

    Urzua, Luis; Powell, Tom; Cumming, William B.; Dobson, Patrick

    2002-05-24

    The discovery of two high-temperature fumaroles, with gas geochemistry compatible with an economic geothermal system, established Apacheta as one of the most attractive geothermal exploration prospects in northern Chile. These remote fumaroles at 5,150 m elevation were first sampled in 1999 by ENAP and its partners, following up on the reports of a CODELCO water exploration well that flowed small amounts of dry steam at 4,540 m elevation in the valley 4.5 km east of the fumaroles. The prospect is associated with a Plio-Pleistocene volcanic complex located within a NW-trending graben along the axis of the high Andes. The regional water table is 4,200 masl. There are no hot springs, just the 88 degrees C steam well and the 109 degrees and 118 degrees C fumaroles with gas compositions that indicate reservoir temperatures of greater than or equal to 250 degrees C, using a variety of gas geothermometers. An MT-TDEM survey was completed in 2001-2002 by Geotermica del Norte (SDN), an ENAP-C ODELCO partnership, to explore the Apacheta geothermal concession. The survey results indicated that base of the low resistivity clay cap has a structural apex just west of the fumaroles, a pattern typically associated with shallow permeability within a high temperature geothermal resource. SGN plans to drill at least one exploration well in 2002-03 to characterize a possible economic resource at Apacheta.

  14. Three-Dimensional Geologic Characterization of Geothermal Systems: Astor Pass, Nevada, USA

    SciTech Connect

    Siler, Drew L; Mayhew, Brett; Faulds, James E

    2012-09-30

    Geothermal systems in the Great Basin, USA, are controlled by a variety of fault intersection and fault interaction areas. Understanding the specific geometry of the structures most conducive to geothermal circulation is crucial in order to both mitigate the costs of geothermal exploration (especially drilling) and to identify blind geothermal systems (no surface expression). Astor Pass, Nevada, one such blind geothermal system, lies near the boundary between two distinct structural domains, the Walker Lane and the Basin and Range, and exhibits characteristics of each setting. Both northwest-striking, left-stepping dextral faults of the Walker Lane and kinematically linked northerly striking normal faults associated with the Basin and Range are present at Astor Pass. Previous studies identified a blind geothermal system controlled by the intersection of northwest-striking dextral and north-northwest-striking normal faults. Wells drilled into the southwestern quadrant of the fault intersection yielded 94˚C fluids, with geothermometers suggesting significantly higher maximum temperatures. Additional data, including reprocessed 2D seismic data and petrologic analysis of well cuttings, were integrated with existing and reinterpreted geologic maps and cross-sections to aid construction of a 3D geologic model. This comprehensive 3D integration of multiple data sets allows characterization of the structural setting of the Astor Pass blind geothermal system at a level of detail beyond what independent data interpretation can provide. Our analysis indicates that the blind geothermal system is controlled by two north- to northwest-plunging fault intersections.

  15. Electron Spin Resonance (ESR) studies of returned comet nucleus samples

    NASA Technical Reports Server (NTRS)

    Tsay, Fun-Dow; Kim, Soon Sam; Liang, Ranty H.

    1989-01-01

    The most important objective of the Comet Nucleus Sample Returm Mission is to return samples which could reflect formation conditions and evolutionary processes in the early solar nebula. It is expected that the returned samples will consist of fine-grained silicate materials mixed with ices composed of simple molecules such as H2O, NH3, CH4 as well as organics and/or more complex compounds. Because of the exposure to ionizing radiation from cosmic-ray, gamma-ray, and solar wind protons at low temperature, free radicals are expected to be formed and trapped in the solid ice matrices. The kind of trapped radical species together with their concentration and thermal stability can be used as a dosimeter as well as a geothermometer to determine thermal and radiation histories as well as outgassing and other possible alternation effects since the nucleus material was formed. Since free radicals that are known to contain unpaired electrons are all paramagnetic in nature, they can be readily detected and characterized in their native form by the Electron Spin Resonance (ESR) method. In fact, ESR has been shown to be a non-destructive, highly sensitive tool for the detection and characterization of paramagnetic, ferromagnetic, and radiation damage centers in terrestrial and extraterrestrial geological samples. The potential use of ESR as an effective method in the study of returned comet nucleus samples, in particular, in the analysis of fine-grained solid state icy samples is discussed.

  16. Structural controls of hot-spring systems on southwestern Montana

    USGS Publications Warehouse

    Chadwick, Robert A.; Leonard, Robert Benjamin

    1979-01-01

    Thermal waters that issue as hot (more than 38C) springs in southwestern Montana appear to circulate to depth along Cenozoic block faults, deep fractures penetrating the dominantly crystalline rock crust, or major structural lineaments. At individual hot springs, rising thermal waters are transmitted along conduits formed by the intersection of a major fault with other faults, fracture zones, anticlinal axes (which may be faulted or fractures), or sedimentary aquifers. Step faults and other intra-valley faults may influence circulation at some springs. At others, fracture zones alone may provide the necessary vertical permeability. Normal regional heat apparently is sufficient to maintain the hydrothermal systems without enhancement from cooling igneous bodies. The thermal gradient normally is higher in low thermal conductivity sediments of the block-fault valleys than the 30C per kilometer average for crystalline rock. To attain reservoir temperatures of 60 to 120C indicated by chemical geothermometers, waters would have to circulate to depths of about 2 to 4 kilometers in crystalline rock and about 1 to 2 kilometers in valley sediments. (Kosco-USGS)

  17. Carbon-rich aggregates in type 3 ordinary chondrites - Characterization, origins, and thermal history

    NASA Technical Reports Server (NTRS)

    Brearley, Adrian J.

    1990-01-01

    Carbon-rich aggregates from three type 3.4-3.6 ordinary chondrites and two chondritic clasts have been characterized in detail, using TEM techniques. The aggregates in all the meteorites studied range in size from 5-1000 microns and consist of a fine scale intergrowth of poorly graphitized carbon, amorphous carbon, Fe,Ni metal, and minor chromite. Contrary to previous reports, well-crystallized graphite and magnetite are absent. The association of Fe,Ni metal and carbonaceous material suggests that the original carbonaceous material may have formed by Fischer-Tropsch (FT) type reactions at low temperatures (less than 400 K), possibly in the solar nebula. This carbonaceous material probably consisted of a complex mixture of hydrocarbons, kerogen-like material, and other complex organic molecules. The aggregates were subsequently accreted onto the ordinary chondrite parent bodies and underwent planetary thermal processing which resulted in the catalytic graphitization of hydrocarbons, in the presence of Fe,Ni metal, to produce poorly graphitized carbon. None of the meteorites studied experienced temperatures sufficiently high to produce crystalline, ordered graphite. Using the empirical geothermometer of Rietmeijer and Mackinnon (1985), the measured d(002) spacings of poorly graphitized carbon show that graphitization occurred at temperatures between 300 and 450 C. This range of temperatures is significantly lower than the generally quoted metamorphic temperatures for type 3.4-3.6 ordinary chondrites (about 450-500 C).

  18. Diagenesis of the Oseberg Sandstone Reservoir (North Sea): An example of integration of core, formation fluid and geochemical modelling studies

    SciTech Connect

    Girard, J.P.; Sanjuan, B.; Czernichowski-Lauriol, I.; Fouillac, C.

    1996-12-31

    A detailed multidisciplinary integrated study of the Middle Jurassic Oseberg reservoir in 20 wells of the Oseberg field, Norwegian North Sea, was carried out in collaboration with Norsk Hydro and Oseberg partners. The objectives were to reconstruct the tinting, conditions and spatial variation of diagenetic transformations; to characterize the nature and origin of diagenetic fluids; and to develop a geochemical model of the observed diagenesis. The 20-60 m thick Oseberg Formation occurs at depths of 2.5 to 3.2 km, and at present temperatures of 100 to 125{degrees}C. The detrital assemblage is mainly composed of quartz, K-feldspar, albite, muscovite and lithic clay clasts, and is very homogeneous throughout the field. The diagenetic sequence includes: minor siderite and pyrite, K-feldspar rims, ankerite, pervasive feldspar dissolution, abundant vermiform kaolinite, quartz overgrowths, poikilotopic ferroan calcite, and dickite. Diagenetic temperatures were derived from fluid inclusions in ankerite, quartz and calcite, and combined with the modelled burial/thermal history to constrain approximate ages and duration of diagenetic events. Isotopic compositions of carbonates and kaolinite indicate that meteoric water and seawater were two major constituents of diagenetic fluids. Present formation waters are fairly similar chemically and isotopically at reservoir scale and represent mixing of three end members: seawater ({approximately}54%), meteoric water ({approximately}40%) and primary evaporative brine ({approximately}6%). Stability diagrams and chemical geothermometers indicate that formation fluids are close to equilibrium with the host sandstone at present reservoir temperatures.

  19. Subsurface temperatures and surface heat flow in the Michigan Basin and their relationships to regional subsurface fluid movement

    USGS Publications Warehouse

    Vugrinovich, R.

    1989-01-01

    Linear regression of 405 bottomhole temperature (BHT) measurements vs. associated depths from Michigan's Lower Peninsula results in the following equation relating BHT and depth: BHT(??C) = 14.5 + 0.0192 ?? depth(m) Temperature residuals, defined as (BHT measured)-(BHT calculated), were determined for each of the 405 BHT's. Areas of positive temperature residuals correspond to areas of regional groundwater discharge (determined from maps of equipotential surface) while areas of negative temperature residuals correspond to areas of regional groundwater recharge. These relationships are observed in the principal aquifers in rocks of Devonian and Ordovician age and in a portion of the principal aquifer in rocks of Silurian age. There is a similar correspondence between high surface heat flow (determined using the silica geothermometer) and regional groundwater discharge areas and low surface heat flow and regional groundwater recharge areas. Post-Jurassic depositional and tectonic histories suggest that the observed coupling of subsurface temperature and groundwater flow systems may have persisted since Jurassic time. Thus the higher subsurface palaeotemperatures (and palaeogeothermal gradients) indicated by recent studies most likely pre-date the Jurassic. ?? 1989.

  20. Vertical movements of crust, uplift of lithosphere, and isostatic unroofing: case histories from the Ozark dome and northern Appalachians

    SciTech Connect

    Friedman, G.M.

    1987-05-01

    Evidence of former deep burial of Ordovician to Devonian strata of the Ozark dome and northern Appalachians has been obtained from petrographic and geochemical studies of carbonates and coal-bearing rocks. In diagenetic minerals of the carbonate rocks, fluid inclusion homogenization temperatures and delta/sup 18/O values indicate paleotemperatures of 100 to 200/sup 0/C. The geothermometers used also include vitrinite reflectance, level of organic metamorphism (LOM), Staplin kerogen alteration index, and conodont alteration index (CAI). Maximum depths of burial were calculated from the estimated paleotemperatures assuming a geothermal gradient of about 25/sup 0/C/km. Strata of the Silurian of the northern Appalachian basin and of the Ordovician of the Ozark dome are interpreted to have reached maximum burial depths of 5 and 4.3 km, respectively; Devonian strata in the Catskill Mountains of New York had former burial depths of about 6.5 km; Lower Ordovician carbonate sequences of the northern Appalachian basin were buried to more than 7 km; Middle Ordovician strata from the same basin had paleodepths of approximately 5 km, and Devonian strata, 4.5 to 5 km. If these strata were formerly buried much more deeply than previously thought, then unexpectedly large amounts of uplift and erosion, ranging from 4.3 to 7 km, must also have occurred to bring these strata to the present land surface. The occurrence of such large-scale vertical movements of the crust and lithosphere needs to be recognized in paleogeographic reconstructions.

  1. Experimental examination of two-pyroxene graphical thermometers using natural pyroxenes with application to metaigneous pyroxenes from the Adirondack Mountains, New York

    NASA Astrophysics Data System (ADS)

    Nabelek, P. I.; Lindsley, D. H.; Bohlen, S. R.

    1987-09-01

    Clinopyroxene with exsolved orthopyroxene and coexisting orthopyroxene with exsolved clinopyroxene (inverted pigeonite) in metaigneous rocks from the Adirondacks, New York, were experimentally homogenized at temperatures near those inferred for their original crystallization. The purposes were several: (1) to test the graphical two-pyroxene geothermometer of Lindsley (1983); (2) to test the hypothesis of Bohlen and Essene (1978) that these were originally igneous pyroxenes; and (3) to test whether modal recombination of complexly exsolved pyroxenes yields realistic compositions. Experiments on Fe-rich compositions at 930° and 870° C (1 GPa) are compatible with the graphical thermometer of Lindsley (1983); however, this graphical thermometer yields apparent temperatures approximately 50° C too high for experiments at 1050° C and 1100° C (0 MPa). This suggests that at intermediate Mg/Fe the augite isotherms for these temperatures lie at lower wollastonite compositions than shown by Lindsley. The results are, however, in good agreement with isotherms derived from the solution model of Davidson (1985). When these isotherms are applied to a variety of terrestrial and lunar igneous rocks and the metaigneous rocks from the Adirondacks, temperatures given by augite and pigeonite compositions from coexisting pairs are similar. Comparison of the experimentally homogenized compositions with modally recombined compositions of Bohlen and Essene (1978) show that discrepancies between augite and pigeonite temperatures may nevertheless arise if pyroxene grains formed by granular exsolution are not correctly reintegrated.

  2. Thermal springs in the Salmon River basin, central Idaho

    SciTech Connect

    Young, H.W.; Lewis, R.E.

    1982-02-01

    The Salmon River basin within the study area occupies an area of approximately 13,000 square miles in central Idaho. Geologic units in the basin are igneous, sedimentary, and metamorphic rocks; however, granitic rocks of the Idaho batholith are predominant. Water from thermal springs ranges in temperature from 20.5/sup 0/ to 94.0/sup 0/ Celsius. The waters are slightly alkaline and are generally a sodium carbonate or bicarbonate type. Dissolved-solids concentrations are variable and range from 103 to 839 milligrams per liter. Estimated reservoir temperatures determined from the silicic acid-corrected silica, sodium-potassium-calcium, and sulfate-water isotope geothermometers range from 30/sup 0/ to 184/sup 0/ Celsius. Tritium concentrations in sampled thermal waters are near zero and indicate the waters are at least 100 years old. Stable-isotope data indicate it is unlikely that a single hot-water reservoir supplies hot springs in the basin. Thermal springs discharged at least 15,800 acre-feet of water in 1980. Associated convective heat flux is 2.7 x 10/sup 7/ calories per second.

  3. Geothermal hydrology of Warner Valley, Oregon: a reconnaissance study

    SciTech Connect

    Sammel, E.A.; Craig, R.W.

    1981-01-01

    Warner Valley and its southern extension, Coleman Valley, are two of several high-desert valleys in the Basin and Range province of south-central Oregon that contain thermal waters. At least 20 thermal springs, defined as having temperatures of 20/sup 0/C or more, issue from Tertiary basaltic flows and tuffs in and near the valleys. Many shallow wells also produce thermal waters. The highest measured temperature is 127/sup 0/C, reported from a well known as Crump geyser, at a depth of 200 meters. The hottest spring, located near Crump geyser, has a surface temperature of 78/sup 0/C. The occurrence of these thermal waters is closely related to faults and fault intersections in the graben and horst structure of the valleys. Chemical analyses show that the thermal waters are of two types: sodium chloride and sodium bicarbonate waters. Chemical indicators show that the geothermal system is a hot-water rather than a vapor-dominated system. Conductive heat flow in areas of the valley unaffected by hydrothermal convection is probably about 75 milliwatts per square meter. The normal thermal gradient in valley-fill dpeosits in these areas may be about 40/sup 0/C per kilometer. Geothermometers and mixing models indicate that temperatures of equilibration are at least 170/sup 0/C for the thermal components of the hotter waters. The size and location of geothermal reservoirs are unknown.

  4. The metapelitic garnet biotite muscovite aluminosilicate quartz (GBMAQ) geobarometer

    NASA Astrophysics Data System (ADS)

    Wu, Chun-Ming; Zhao, Guochun C.

    2007-09-01

    In this contribution we have empirically calibrated the garnet-biotite-muscovite-aluminosilicate-quartz (GBMAQ) barometer using low- to medium-high-pressure, mid-grade metapelites. Application of the barometer suggests that the GBMAQ and GASP barometers show quite similar pressure estimates. Furthermore, metapelites within thermal contact aureole or very limited geographic area show no meaningful pressure diversity determined by the GBMAQ and GASP barometers which is the geological reality. The random error of the GBMAQ barometer is expected to be around ± 0.8 kbar, and this barometer shows no systematic bias with respect to either pressure, or temperature, or Al VI in muscovite, or Fe in biotite, or Fe in garnet. The GBMAQ barometer is thermodynamically consistent with the garnet-biotite geothermometer because they share the same activity models of both garnet and biotite. This barometer is especially useful for assemblages with Ca-poor garnet or Ca-poor plagioclase or plagioclase-absent metapelites. Application of this barometer beyond the calibration ranges, i.e., P- T range and chemical ranges of the minerals, is not encouraged.

  5. Oxygen isotope fractionation between analcime and water - An experimental study

    NASA Technical Reports Server (NTRS)

    Karlsson, Haraldur R.; Clayton, Robert N.

    1990-01-01

    The oxygen isotope fractionation between analcime and water is studied to test the feasibility of using zeolites as low-temperature thermometers. The fractionation of oxygen isotopes between natural analcime and water is determined at 300, 350, and 400 C, and at fluid pressures ranging from 1.5 to 5.0 kbar. Also, isotope ratios for the analcime framework, the channel water, and bulk water are obtained. The results suggest that the channel water is depleted in O-18 relative to bulk water by a constant value of about 5 percent, nearly independent of temperature. The analcime-water fractionation curve is presented, showing that the exchange has little effect on grain morphology and does not involve recrystallization. The exchange is faster than any other observed for a silicate. The exchange rates suggest that zeolites in active high-temperature geothermal areas are in oxygen isotopic equilibrium with ambient fluids. It is concluded that calibrated zeolites may be excellent low-temperature oxygen isotope geothermometers.

  6. Fe-isotope fractionation in magmatic-hydrothermal mineral deposits: A case study from the Renison Sn-W deposit, Tasmania

    NASA Astrophysics Data System (ADS)

    Wawryk, Christine M.; Foden, John D.

    2015-02-01

    We present 50 new iron isotopic analyses of source granite and mineral separates from the Renison tin deposit in western Tasmania. The aim of the study is to characterise the composition of minerals within a tin deposit associated with a reduced, S-type magma. We have analysed bulk samples of granite, and separates of pyrrhotite, pyrite, arsenopyrite, magnetite, chalcopyrite and siderite by multi-collector inductively coupled mass spectrometry. The isotopic compositions of mineral separates are consistent with theoretical predictions of equilibrium fractionation based on Mössbauer spectroscopy and other parametric calculations. Mineral-mineral pairs yield temperatures of formation that are in agreement with prior detailed fluid inclusion studies, but are spatially inconsistent with declining fluid temperatures with distance from the causative intrusion, limiting the use of Fe isotopes as a potential geothermometer, at least in this case. Comparison of our data with published data from other deposits clearly demonstrates that pyrite, magnetite and chalcopyrite from the hottest ore fluids (>300-400 °C) at Renison are isotopically heavier than minerals sampled from a deposit formed at similar temperatures, but associated with a more oxidised and less differentiated intrusion.

  7. Oxygen isotope fractionation factors between anhydrite and water from 100 to 550°C

    NASA Astrophysics Data System (ADS)

    Chiba, Hitoshi; Kusakabe, Minoru; Hirano, Shin-Ichi; Matsuo, Sadao; Somiya, Shigeyuki

    1981-03-01

    Oxygen isotope exchange between anhydrite and water was studied from 100 to 550°C, using the partial equilibrium method. The exchange rate was extremely low in NaCl solution. In the lower-temperature range, acid solutions were used to produce sufficient reaction to determine the oxygen isotope fractionation factors. The fractionation factors obtained in the present study are definitely different from those given by Lloyd [8]. They are similar to those for the HSO 4--water system studied by Mizutani and Rafter [19], and are consistently 2‰ higher than those of the barite-water system by Kusakabe and Robinson [5]. The temperature dependence of the oxygen isotope fractionation factors was calculated by the least squares method in which the weight was taken to be inversely proportional to the experimental error. The fractionation is given by: 10 3lnαanhydrite-water=3.21×(10 3/T) 2-4.72 Available δ 18O values of natural anhydrite were used to test the validity of this expression. It is shown that this newly revised geothermometer can be successfully applied to natural hydrothermal anhydrite.

  8. Evaluation of thermobarometers for garnet peridotites

    NASA Technical Reports Server (NTRS)

    Finnerty, A. A.; Boyd, F. R.

    1984-01-01

    Twenty-one geothermometers and six geobarometers are evaluated for accuracy and precision for garnet lherzolites, with a suite of well-equilibrated xenoliths from kimberlites of northern Lesotho. Accuracy was tested by comparison of P-T estimates for a diamond-bearing and a graphite-bearing xenolith with the experimentally determined diamond-graphite univariant curve and by comparison of P-T estimates for phlogopite-bearing xenoliths to the high-temperature stability limit of phlogopite. Precision was evaluated by measuring the scatter of P-T estimates for each of four xenoliths from a wide range of P and T when many point analyses of the constituent minerals are used for P-T estimation. Most satisfactory is a thermobarometer composed of the uncorrected diopside-enstatite miscibility gap of Lindsley and Dixon (1976), combined with the uncorrected isopleths for aluminum in enstatite coexisting with pyrope of MacGregor (1974). The inflection observed in the northern Lesotho paleogeotherm cannot be an artifact of the method of temperature estimation.

  9. Hydrogeochemistry and preliminary reservoir model of the Platanares Geothermal System, Honduras, Central America

    SciTech Connect

    Goff, F.; Shevenell, L.; Janik, C.J.; Truesdell, A.H.; Grigsby, C.O.; Paredes, R.

    1986-01-01

    A detailed hydrogeochemical investigation has been performed at Platanares, Honduras in preparation for shallow geothermal exploration drilling. Platanares is not associated with any Quaternary volcanism but lies in a tectonic zone of late Tertiary to Quaternary extension. Thermal fluids are characterized by pH between 7 and 10, Cl < 40 mg/l, HCO/sub 3/ > SO/sub 4/ > Cl, B less than or equal to 17 mg/l, Li less than or equal to 4 mg/l and As less than or equal to 1.25 mg/l. Various geochemical indicators show that mixing of hot and cold end-member fluids is an important hydrologic process at this site. Geothermometers indicate the geothermal system equilibrated at roughly 225/sup 0/C while trace element chemistry indicates the reservoir resides in Cretaceous red beds of the Valle de Angeles Group. Based on the discharge rates of thermal features, the minimum power output of the Platanares geothermal site is about 45 MW (thermal).

  10. Thermal springs in the Payette River basin, west-central Idaho

    SciTech Connect

    Lewis, R.E.; Young, H.W.

    1980-10-01

    The Payette River basin, characterized by steep, rugged mountains and narrow river valleys, occupies an area of about 3300 square miles in west-central Idaho. Predominant rock types in the basin include granitic rocks of the Idaho batholith and basalt flows of the Columbia River Basalt Group. Waters from thermal springs in the basin, temperatures of which range from 34/sup 0/ to 86/sup 0/ Celsius, are sodium bicarbonate type and are slightly alkaline. Dissolved-solids concentrations range from 173 to 470 milligrams per liter. Reservoir temperatures determined from the sodium-potassium-calcium, silicic acid-corrected silica, and sulfate-water isotope geothermometers range from 53/sup 0/ to 143/sup 0/ Celsius. Tritium, present in concentrations between 0 and 2 tritium units, indicate that sampled thermal waters are at least 100 years and possibly more than 1000 years old. Stable-isotope data indicate it is unlikely any of the nonthermal waters sampled are representative of precipitation that recharges the thermal springs in the basin. Thermal springs discharged about 5700 acre-feet of water in 1979. Associated convective heat flux is 1.1 x 10/sup 7/ calories per second.

  11. Validation of Multicomponent Equilibrium Geothermometry at Four Geothermal Power Plants

    SciTech Connect

    Ghanashyam Neupane; Jeffrey S Baum; Earl D Mattson; Gregory L Mines; Carl D Palmer; Robert W Smith

    2001-01-01

    This paper evaluates our ability to predict geothermal reservoir temperatures using water compositions measured from surface hot springs or shallow subsurface wells at four geothermal sites prior to the startup of geothermal energy production using RTEst, a multicomponent equilibrium geothermometer we have developed and are testing. The estimated reservoir temperatures of these thermal expressions are compared to measured bottom-hole temperatures of production wells at Raft River, ID; Neal Hot Springs, OR; Roosevelt Hot Springs, UT; and Steamboat Springs, NV geothermal sites. In general, temperatures of the producing reservoir estimated from the composition of water from surface expressions/shallow wells using RTEst are similar to the measured bottom-hole temperatures. For example, estimates for the Neal Hot Springs system are within ±10 ºC of the production temperatures. However, some caution must be exercised in evaluating RTEst predictions. Estimated temperature for a shallow Raft River well (Frazier well) is found to be slightly lower (ca. 15 ºC) than the bottom-hole temperatures from the geothermal plant production wells. For the Raft River system, local geology and fluid mixing model indicate that the fluid source for this shallow well may not have originated from the production reservoir. Similarly, RTEst results for Roosevelt Hot springs and Steamboat Springs geothermal areas were found consistent with the reservoir temperatures obtained from deep wells. These results suggest that the RTEst could be a valuable tool for estimating temperatures and evaluation geothermal resources.

  12. The use of Ahuachapan fluid chemistry to indicate natural state conditions and reservoir processes during exploitation

    SciTech Connect

    Treusdell, A.H. ); Aunzo, Z.; Bodvarsson, G. ); Alonso, J.; Campos, A. )

    1989-01-01

    Chemical analyses of production fluids from Ahuachapan, El Salvador, have been used to indicate natural state reservoir fluid temperatures and chloride concentrations and reservoir processes resulting from exploitation. Geothermometer temperatures (Na--K--Ca and SiO{sub 2}) and calculated aquifer Cl for early flows show a gradient from about 265{degree}C and 9000 ppM Cl in the western part of the well field to 235{degree}C and 6000 ppM Cl in the eastern part. The geochemical temperatures are 10--20{degree}C higher than early downhole measurements. Since exploitation started, pressures have declined over most of the drilled area with boiling and excess-enthalpy discharges in the eastern and western parts. In the center of the field, a number of wells show mixing with cooler, less-saline water. These wells are nearly coincident with a major NE-SW oriented fault that may be the conduit for downward recharge of cooler fluids from an overlying aquifer. 12 refs., 9 figs., 1 tab.

  13. Temperature constraints on the Ginkgo flow of the Columbia River Basalt Group

    NASA Astrophysics Data System (ADS)

    Ho, Anita M.; Cashman, Katharine V.

    1997-05-01

    This study provides the first quantitative estimate of heat loss for a Columbia River Basalt Group flow. A glass composition-based geothermometer was experimentally calibrated for a composition representative of the 500-km-long Ginkgo flow of the Columbia River Basalt Group to measure temperature change during transport. Melting experiments were conducted on a bulk sample at 1 atm between 1200 and 1050 °C. Natural glass was sampled from the margin of a feeder dike near Kahlotus, Washington, and from pillow basalt at distances of 120 km (Vantage, Washington), 350 km (Molalla, Oregon), and 370 km (Portland, Oregon). Ginkgo basalt was also sampled at its distal end at Yaquina Head, Oregon (500 km). Comparison of the glass MgO content, K2O in plagioclase, and measured crystallinities in the experimental charges and natural samples tightly constrains the minimum flow temperature to 1085 ± 5 °C. Glass and plagioclase compositions indicate an upper temperature of 1095 ± 5 °C; thus the maximum temperature decrease along the flow axis of the Ginkgo is 20 °C, suggesting cooling rates of 0.02 0.04 °C/km. These cooling rates, substantially lower than rates observed in active and historic flows, are inconsistent with turbulent flow models. Calculated melt temperatures and viscosities of 240 750 Pa · s allow emplacement either as a fast laminar flow under an insulating crust or as a slower, inflated flow.

  14. Chemical Analyses of Ground Water in the Carson Desert near Stillwater, Churchill County, Nevada, 2005

    USGS Publications Warehouse

    Fosbury, DeEtta; Walker, Mark; Stillings, Lisa L.

    2008-01-01

    This report presents the chemical analyses of ground-water samples collected in 2005 from domestic wells located in the Stillwater area of the Carson Desert (fig. 1). These data were evaluated for evidence of mixing with nearby geothermal waters (Fosbury, 2007). That study used several methods to identify mixing zones of ground and geothermal waters using trace elements, chemical equilibria, water temperature, geothermometer estimates, and statistical techniques. In some regions, geothermal sources influence the chemical quality of ground water used for drinking water supplies. Typical geothermal contaminants include arsenic, mercury, antimony, selenium, thallium, boron, lithium, and fluoride (Webster and Nordstrom, 2003). The Environmental Protection Agency has established primary drinking water standards for these, with the exception of boron and lithium. Concentrations of some trace metals in geothermal water may exceed drinking water standards by several orders of magnitude. Geothermal influences on water quality are likely to be localized, depending on directions of ground water flow, the relative volumes of geothermal sources and ground water originating from other sources, and depth below the surface from which water is withdrawn. It is important to understand the areal extent of shallow mixing of geothermal water because it may have adverse chemical and aesthetic effects on domestic drinking water. It would be useful to understand the areal extent of these effects.

  15. Hydrology and geochemistry of thermal ground water in southwestern Idaho and north-central Nevada

    SciTech Connect

    Young, H.W.; Lewis, R.E.

    1982-01-01

    Chemical analyses of water from 12 wells and 9 springs indicate that nonthermal waters are a calcium bicarbonate type; thermal waters are a sodium carbonate or bicarbonate type. Chemical geothermometers indicate probable maximum reservoir temperatures are near 100/sup 0/ Celsius. Concentration of tritium in the thermal water is near zero. Depletion of stable isotopes in the hot waters relative to present-day meteoric waters indicates recharge to the system probably occurred when the climate averaged 3/sup 0/ to 5/sup 0/ Celsius colder than at present. Temperatures about 3.5/sup 0/ Celsius colder than at present occurred during periods of recorded Holocene glacial advances and indicate a residence time of water in the system of at least several thousand years. Residence time calculated on the basis of reservoir volume and thermal-water discharge is 3400 to 6800 years for an effective reservoir porosity of 0.05 and 0.10, respectively. Preliminary analyses of carbon-14 determinations indicate an age of the hot waters of about 18,000 to 25,000 years. The proposed conceptual model for the area is one of an old system, where water has circulated for thousands, even tens of thousands, of years. Within constraints imposed by the model described, reservoir thermal energy for the geothermal system in southwestern Idaho and north-central Nevada is about 130 x 10/sup 18/ calories.

  16. Diffusion of Ca and Mg in Calcite

    SciTech Connect

    Cygan, R.T.; Fisler, D.K.

    1999-02-10

    The self-diffusion of Ca and the tracer diffusion of Mg in calcite have been experimentally measured using isotopic tracers of {sup 25}Mg and {sup 44}Ca. Natural single crystals of calcite were coated with a thermally-sputtered oxide thin film and then annealed in a CO{sub 2} gas at one atmosphere total pressure and temperatures from 550 to 800 C. Diffusion coefficient values were derived from the depth profiles obtained by ion microprobe analysis. The resultant activation energies for Mg tracer diffusion and Ca self-diffusion are respectively: E{sub a}(Mg) = 284 {+-} 74 kJ/mol and E{sub a}(Ca) = 271 {+-} 80 kJ/mol. For the temperature ranges in these experiments, the diffusion of Mg is faster than Ca. The results are generally consistent in magnitude with divalent cation diffusion rates obtained in previous studies and provide a means of interpreting the thermal histories of carbonate minerals, the mechanism of dolomitization, and other diffusion-controlled processes. The results indicate that cation diffusion in calcite is relatively slow and cations are the rate-limiting diffusing species for the deformation of calcite and carbonate rocks. Application of the calcite-dolomite geothermometer to metamorphic assemblages will be constrained by cation diffusion and cooling rates. The direct measurement of Mg tracer diffusion in calcite indicates that dolomitization is unlikely to be accomplished by Mg diffusion in the solid state but by a recrystallization process.

  17. BACA Project: geothermal demonstration power plant. Final report

    SciTech Connect

    Not Available

    1982-12-01

    The various activities that have been conducted by Union in the Redondo Creek area while attempting to develop the resource for a 50 MW power plant are described. The results of the geologic work, drilling activities and reservoir studies are summarized. In addition, sections discussing the historical costs for Union's involvement with the project, production engineering (for anticipated surface equipment), and environmental work are included. Nineteen geothermal wells have been drilled in the Redondo Creek area of the Valles Caldera: a prominent geologic feature of the Jemez mountains consisting of Pliocene and Pleistocene age volcanics. The Redondo Creek area is within a complex longitudinal graben on the northwest flank of the resurgent structural dome of Redondo Peak and Redondo Border. The major graben faults, with associated fracturing, are geologically plausible candidates for permeable and productive zones in the reservoir. The distribution of such permeable zones is too erratic and the locations too imprecisely known to offer an attractive drilling target. Log analysis indicates there is a preferred mean fracture strike of N31W in the upper portion of Redondo Creek wells. This is approximately perpendicular to the major structure in the area, the northeast-striking Redondo Creek graben. The geothermal fluid found in the Redondo Creek reservoir is relatively benign with low brine concentrations and moderate H/sub 2/S concentrations. Geothermometer calculations indicate that the reservoir temperature generally lies between 500/sup 0/F and 600/sup 0/F, with near wellbore flashing occurring during the majority of the wells' production.

  18. Alabama Tin Belt. Metallogenesis and mineral resource evaluation. Final report for the 1983-1984 project year

    SciTech Connect

    Green, N.L.; Tompa, B.; Gomolka, J.; Wade, G.; Usdansky, S.I.

    1986-03-01

    The Alabama Tin Belt covers an area of approximately 180 km/sup 2/ within the Tallapoosa lithotectonic block of the Northern Alabama Piedmont. In the second year of this three year project, efforts continued towards detailing the distribution and petrogenesis of tin-bearing peraluminous granitoids in central Coosa County. In particular, mapping, structural analysis and petrographical/petrological studies have been used to examine the geologic settings, geochemical and mineralogical variations, crystallization conditions and nature of source rock(s) of selected granitic plutons and related pegmatite bodies in the vicinity of Rockford, Alabama. Thermobarometeric techniques (a ternary feldspar thermobarometer and a plagioclase-muscovite geothermometer), that could be used in conjunction with compositions of constituent minerals to yield reasonable estmates of granite crystallization and alteration temperatures, were also developed. Preliminary results provide evidence that: (1) the granitoids possess characteristics possibly derived from both sedimentary (S-type) and igneous (I-type) sources; (2) feldspars of the tin-bearing pegmatites possess extremely high Rb and Cs concentrations; (3) the peraluminous granitoids crystallized under varying oxygen fugacity conditions at temperatures of 510 to 710/sup 0/ and pressures greater than 6 kbar; and, (4) the Rockford Pluton occupies the core of a post-D/sub 1/, antiformal structure that is overturned to the northwest.

  19. Comparative thermometry on pelitic rocks and marbles of the Llano uplift, Texas

    SciTech Connect

    Letargo, C.M.R.; Lamb, W.M. . Dept. of Geology)

    1992-01-01

    The Llano Uplift in central Texas is a Grenville-aged metamorphic complex consisting of amphibolite facies assemblages whose development has been attributed to the emplacement of granite plutons between 1.0--1.1 Ga. Temperatures have been obtained from garnet-biotite, garnet-ilmenite, and calcite-dolomite pairs as well as from various silicate equilibria. Application of these geothermometers yield consistent results and are thus indicative of peak conditions attending the amphibolite facies metamorphism. Temperature determined using garnet-biotite and garnet-ilmenite thermometry compare favorably with calcite-dolomite temperatures obtained from marbles in contact with granite plutons in the southeastern part of the uplift. The highest calcite-dolomite temperatures of [approximately]600 C are obtained from marbles containing an isobarically invariant assemblage consisting of calcite + dolomite + diopside + tremolite + forsterite. At pressures of 2--3 kbar, this isobarically invariant assemblage will be stable at a temperature range of [approximately]600--650 C. Also in close proximity to granites in the southeast uplift is the assemblage muscovite + quartz + k-feldspar + sillimanite [approximately] andalusite which indicate T 650 C and P 2.5 kbar. Assemblages consisting of garnet + sillimanite + quartz + plagioclase (GASP) and garnet + rutile + ilmenite + plagioclase + quartz (GRIPS) are currently being studied to provide additional constraints on pressures of amphibolite facies metamorphism.

  20. Temperature fluctuation of the Iceland mantle plume through time

    NASA Astrophysics Data System (ADS)

    Spice, Holly E.; Fitton, J. Godfrey; Kirstein, Linda A.

    2016-02-01

    The newly developed Al-in-olivine geothermometer was used to find the olivine-Cr-spinel crystallization temperatures of a suite of picrites spanning the spatial and temporal extent of the North Atlantic Igneous Province (NAIP), which is widely considered to be the result of a deep-seated mantle plume. Our data confirm that start-up plumes are associated with a pulse of anomalously hot mantle over a large spatial area before becoming focused into a narrow upwelling. We find that the thermal anomaly on both sides of the province at Baffin Island/West Greenland and the British Isles at ˜61 Ma across an area ˜2000 km in diameter was uniform, with Al-in-olivine temperatures up to ˜300°C above that of average mid-ocean ridge basalt (MORB) primitive magma. Furthermore, by combining our results with geochemical data and existing geophysical and bathymetric observations, we present compelling evidence for long-term (>107 year) fluctuations in the temperature of the Iceland mantle plume. We show that the plume temperature fell from its initial high value during the start-up phase to a minimum at about 35 Ma, and that the mantle temperature beneath Iceland is currently increasing.

  1. Results of investigation at the Miravalles geothermal field, Costa Rica. Resultados de las investigaciones en el campo geotermico de Miravalles, Costa Rica; Parte 2, Muestreo de fluidos pozo abajo

    SciTech Connect

    Grigsby, C.O.; Goff, F.; Trujillo, P.E. Jr.; Counce, D.A.; Dennis, B.; Kolar, J.; Corrales, R.; Instituto Costarricense de Electricidad, San Jose )

    1989-10-01

    Samples of the geothermal fluids in the Miravalles, Costa Rica, geothermal system were collected from production wellbores using downhole fluid samplers, from flowing wellheads using miniseparators, and from hot springs that discharge in the area. The reservoir fluid at Miravalles is a neutral-chloride-type water, but fumaroles and acid-sulfate springs are present within the main thermal area, and there are bicarbonate-rich hot springs that are clearly related to the neutral-chloride reservoir fluids. Dissolved gases are primarily a mixture of CO{sub 2} with air, but samples collected in the fumarolic areas also contain H{sub 2}S. Water-stable isotope analyses suggest local meteoric recharge, and the reservoir fluid shows oxygen isotopic shifts of about 2.5% due to high-temperature oxygen exchange between water and rock. Chemical geothermometer temperatures are consistent with the measured downhole temperature of 220{degrees} to 255{degrees}C. This pattern of neutral-chloride reservoir fluids with acid-sulfate springs near the source region and bicarbonate-rich chloride hot springs at the periphery of the system suggests a lateral outflow type of hydrothermal system. In addition to the geochemical evidence, temperature profiles from several of the wells show temperature reversals that are characteristic of lateral outflow plumes. We find no evidence for the underlying, higher temperature (300{degrees}C) system, which has been suggested by other investigators. 24 refs., 14 figs., 6 tabs.

  2. Geothermal resources in the Banbury Hot Springs area, Twin Falls County, Idaho

    USGS Publications Warehouse

    Lewis, R.E.; Young, Harold William

    1982-01-01

    Thermal water 30.0 degrees to 72.0 degrees Celsius is produced from 26 wells and 2 springs in the vicinity of Banbury Hot Springs near Buhl, Idaho. Thermal water is used for residence heating, catfish and tropical fish production, greenhouse operation, swimming pools, and therapeutic baths. In 1979, 10,300 acre-feet of thermal water was utilized; heat discharged convectively from the geothermal system was about 1.1 x 107 calories per second. Decline in artesian head and discharge apparent in recorder charts from two wells may represent seasonal fluctuations or may reflect reservoir response to development of the resource. The thermal waters sampled are sodium carbonate or bicarbonate in character and slightly alkaline. Mixing of hot (72 degrees Celsius) water with local cooler ground water can be shown from various relations among stable isotopes, chloride, and enthalpy. On the basis of concentration of tritium, the age of most of the water sampled is at least 100 years and perhaps more than 1,000 years. Some water (33 degrees Celsius) may be as young as 29 years. On the basis of silica, sodium-potassium-calcium, and sulfate-water geothermometers, the best estimate of the maximum reservoir temperature for the thermal water is between 70 degrees and 100 degrees Celsius.

  3. Geothermal resources in the Banbury Hot Springs area, Twin Falls County, Idaho

    USGS Publications Warehouse

    Lewis, R.E.; Young, H.W.

    1980-01-01

    Thermal water (30.0 to 72.0 degrees Celsius) is produced from 26 wells and 2 springs in the vicinity of Banbury Hot Springs near Buhl, Idaho. Thermal water is used for space heating of private residences, catfish and tropical fish production, greenhouse operation, swimming pools, and therapeutic baths. In 1979, 10 ,300 acre-feet of thermal water was utilized; heat discharged convectively from the geothermal system was about 1.09 x 10 to the 7th power calories per second. Decline in artesian head and discharge apparent in recorder charts from two wells may represent seasonal fluctuations or may reflect aquifer response to development of the resource. Thermal waters sampled are sodium bicarbonate in character and slightly alkaline. Mixing of a hot (72 degrees Celsius) water with local, cooler ground water can be shown from various relations between stable isotopes, chloride, and enthalpy. On the basis of concentration of trituim , age of the waters sampled is at least 100 years an perhaps more than 1,000 years. One water (33 degress Celsius) may be as young as 29 years. On the basis of silica, sodium-potassium-calcium, and sulfate-water geothermometers, best estimate of the maximum reservoir temperature for the thermal waters is between about 70 and 100 degrees Celsius. (USGS)

  4. The Domuyo volcanic system: An enormous geothermal resource in Argentine Patagonia

    NASA Astrophysics Data System (ADS)

    Chiodini, Giovanni; Liccioli, Caterina; Vaselli, Orlando; Calabrese, Sergio; Tassi, Franco; Caliro, Stefano; Caselli, Alberto; Agusto, Mariano; D'Alessandro, Walter

    2014-03-01

    A geochemical survey of the main thermal waters discharging in the southwestern part of the Domuyo volcanic complex (Argentina), where the latest volcanic activity dates to 0.11 Ma, has highlighted the extraordinarily high heat loss from this remote site in Patagonia. The thermal water discharges are mostly Na-Cl in composition and have TDS values up to 3.78 g L- 1 (El Humazo). A simple hydrogeochemical approach shows that 1,100 to 1,300 kg s- 1 of boiling waters, which have been affected by shallow steam separation, flow into the main drainage of the area (Rio Varvarco). A dramatic increase of the most conservative species such as Na, Cl and Li from the Rio Varvarco from upstream to downstream was observed and related solely to the contribution of hydrothermal fluids. The equilibrium temperatures of the discharging thermal fluids, calculated on the basis of the Na-K-Mg geothermometer, are between 190 °C and 230 °C. If we refer to a liquid originally at 220 °C (enthalpy = 944 J g- 1), the thermal energy release can be estimated as high as 1.1 ± 0.2 GW, a value that is much higher than the natural release of heat in other important geothermal fields worldwide, e.g., Mutnovsky (Russia), Wairakei (New Zealand) and Lassen Peak (USA). This value is the second highest measured advective heat flux from any hydrothermal system on Earth after Yellowstone.

  5. Chemical and isotopic data for water from thermal springs and wells of Oregon

    SciTech Connect

    Mariner, R.H.; Swanson, J.R.; Orris, G.J.; Presser, T.S.; Evans, W.C.

    1981-01-01

    The thermal springs of Oregon range in composition from dilute NaHCO/sub 3/ waters to moderately saline CO/sub 2/-charged NaCl-NaHCO/sub 3/ waters. Most of the thermal springs are located in southeastern or southcentral Oregon, with a few in northeastern Oregon and near the contact of the Western Cascades with the High Cascades. Thermal springs in the central and northern parts of the Cascades generally issue moderately saline NaCl waters. Farther south in the Cascades, the thermal waters are high in CO/sub 2/ as well as chloride. Most thermal springs in northeastern Oregon issue dilute NaHCO/sub 3/ waters of high pH (>8.5). These waters are similar to the thermal waters which issue from the Idaho batholith, farther east. Most of the remaining thermal waters are Na mixed-anion waters. Based on the chemical geothermometers, Mickey Srpings, Hot Borax Lake, Alvord Hot Springs, Neal Hot Springs, Vale Hot Springs, Crump Well, Hunters (Lakeview) Hot Springs, and perhaps some of the springs in the Cascades are associated with the highest temperature systems (>150/sup 0/C).

  6. Contribution à l'étude du métamorphisme des gisements cupro-cobaltifères stratiformes du Sud-Shaba, Zaire. Le district minier de Lwishia

    NASA Astrophysics Data System (ADS)

    Cluzel, D.

    The late precambrian copper-bearing strata of southern Shaba ('Série des mines') have undergone metamorphism during the latest proterozoic to early paleozoic times. Structural, textural and crystallochemical analysis of this metamorphic event shows a very peculair evolution. During a first phase, prior to folding, a static recrystallization is accompanied by several chemical chanes such as Na, then KMg metasomatism. This hydrothermal character is due to 'hydrostatic' stress conditions and fluid circulation linked with surrounding evaporites. During this prograde stage of metamorphism, kyanite + carbonate + sulphide paragenesis suggest low water partial pressure and high pH-low Eh conditions. Geothermometers and fluid inclusions indicate moderate to medium temperatures (300-400°C). Sparse synergetic CuCo sulphide mineralization is overconcentrated to its present disposition. A second hydrothermal event following the main folding phase is probably linked with halokinetic or halotectonic structures. It is essentially retrograde with oxidizing and low-temperature (200°C) conditions, resulting in the total leaching of evaporites and the forming of clay minerals, such as kandites or smectites.

  7. Petrological and Geochemical Evolution, during the last 40,000 years of the Tacana Volcano Chiapas, Mexico

    NASA Astrophysics Data System (ADS)

    Mora, J.; Macias, J.; Garcia-palomo, A.; Espindola, J.; Manetti, P.; Vaselli, O.

    2001-12-01

    The Tacaná Volcanic Complex (TVC) is located in SW Chiapas, Mexico. Its highest peak constitutes a marker of the international border with Guatemala. Fieldwork aided by photo interpretation has allowed us to recognize three different volcanic centers at the TVC: Chichuj (EVCh; 3,800 masl.), Tacaná, which gives name to the complex (EVT; 4,060 masl), and San Antonio (EVSA; 3,700 masl). The volcanic deposits from these three centers consist mainly of block-and-ash flows, lavas, and summit domes. In this work were analyzed selected samples of lava flows, lava domes, and juvenile clasts from the most recent pyroclastic flows. The lava flows and the domes have andesitic-dacitic composition, and the juvenile clasts are andesitic. Basaltic andesite enclaves found in the 2000 yr BP Mixcun pyroclastic flow are the most basic of all analyzed products in the CVT (andesitic basalt). All the products are porphyritic with phenocrysts of plagioclase, orthopyroxene and clinopyroxene, and amphibole. Using two pyroxenes and ilmenite-titanomagnetite geothermometers, we estimated the temperature of crystallization, which varies between 910o and 950oC. The geochemical data (majors elements, trace elements and isotopes) shows that crystal fractionation was the principal process of evolution, with a small assimilation of granitic crustal rocks.

  8. Not so hot "hot spots" in the oceanic mantle.

    PubMed

    Bonath, E

    1990-10-01

    Excess volcanism and crustal swelling associated with hot spots are generally attributed to thermal plumes upwelling from the mantle. This concept has been tested in the portion of the Mid-Atlantic Ridge between 34 degrees and 45 degrees (Azores hot spot). Peridotite and basalt data indicate that the upper mantle in the hot spot has undergone a high degree of melting relative to the mantle elsewhere in the North Atlantic. However, application of various geothermometers suggests that the temperature of equilibration of peridotites in the mantle was lower, or at least not higher, in the hot spot than elsewhere. The presence of H(2)O-rich metasomatized mantle domains, inferred from peridotite and basalt data, would lower the melting temperature of the hot spot mantle and thereby reconcile its high degree ofmelting with the lack of a mantle temperature anomaly. Thus, some so-called hot spots might be melting anomalies unrelated to abnormally high mantle temperature or thermal plumes. PMID:17808242

  9. New evidence on the hydrothermal system in Long Valley caldera, California, from wells, fluid sampling, electrical geophysics, and age determinations of hot-spring deposits

    USGS Publications Warehouse

    Sorey, M.L.; Suemnicht, G.A.; Sturchio, N.C.; Nordquist, G.A.

    1991-01-01

    Data collected since 1985 from test drilling, fluid sampling, and geologic and geophysical investigations provide a clearer definition of the hydrothermal system in Long Valley caldera than was previously available. This information confirms the existence of high-temperature (> 200??C) reservoirs within the volcanic fill in parts of the west moat. These reservoirs contain fluids which are chemically similar to thermal fluids encountered in the central and eastern parts of the caldera. The roots of the present-day hydrothermal system (the source reservoir, principal zones of upflow, and the magmatic heat source) most likely occur within metamorphic basement rocks beneath the western part of the caldera. Geothermometer-temperature estimates for the source reservoir range from 214 to 248??C. Zones of upflow of hot water could exist beneath the plateau of moat rhyolite located west of the resurgent dome or beneath Mammoth Mountain. Lateral flow of thermal water away from such upflow zones through reservoirs in the Bishop Tuff and early rhyolite accounts for temperature reversals encountered in most existing wells. Dating of hot-spring deposits from active and inactive thermal areas confirms previous interpretations of the evolution of hydrothermal activity that suggest two periods of extensive hot-spring discharge, one peaking about 300 ka and another extending from about 40 ka to the present. The onset of hydrothermal activity around 40 ka coincides with the initiation of rhyolitic volcanism along the Mono-Inyo Craters volcanic chain that extends beneath the caldera's west moat. ?? 1991.

  10. I/S and C/S mixed layers, some indicators of recent physical-chemical changes in active geothermal systems: The case study of Chipilapa (El Salvador)

    SciTech Connect

    Beaufort, D.; Papapanagiotou, P.; patrier, P.; Fouillac, A.M.; Traineau, H.

    1996-01-24

    I/S and C/S mixed layers from the geothermal field of Chipilapa (El Salvador) have been studied in details in order to reevaluate their potential use as indicator of the thermodynamic conditions in which they were formed. It is funded that overprinting of clay bearing alteration stages is common. For a given alteration stage, the spatial variation of I/S and C/S mixed layer ininerals is controlled by kinetics of mixed layer transformation and not only by temperature. Clay geo-thermometers cannot give reliable results because the present crystal-chemical states of the I/S and C/S mixed layers is not their initial state, it was aquired during the overall hydrothermal history which post dated the nucleation of smectitic clay material at high temperature. Occurrences of smectites or smectite-rich mixed layers at high temperature in reservoirs is a promising guide for reconstruct the zones in which boiling or mixing of non isotherinal fluids occurred very recently or still presently.

  11. Geothermal resources of the Western Arm of the Black Rock Desert, northwestern Nevada; Part II, Aqueous geochemistry and hydrology

    USGS Publications Warehouse

    Welch, A.H.; Preissler, A.M.

    1990-01-01

    The western arm of the Black Rock Desert, Nevada, includes several distinct hydrothermal systems, some of which exceed 150 C and may exceed 200 C at depth, determined on the basis of chemical geothermometry. The cation composition of the thermal water appears to be controlled by aluminosilicate minerals that are common in other active geothermal systems. Estimates of the equilibrium temperatures at which some mineral pairs are stable, when compared with the more commonly applied geothermometer estimates, indicate that thermodynamic data may be useful for estimating deep aquifer temperatures. Thermal water at Great Boiling and Mud Springs, which has a chloride concentration of about 2,000 mg/L and a total dissolved-solids concentration of 4 ,500 mg/L, appears to have been affected by shallow evapotranspiration in an adjacent playa prior to deep circulation. This model of recharge within the basin floor is distinctly different from models proposed for most other geothermal systems in the northern Great Basin. (USGS)

  12. New geochemical investigations in Platanares and Azacualpa geothermal sites (Honduras)

    NASA Astrophysics Data System (ADS)

    Barberi, Franco; Carapezza, Maria Luisa; Cioni, Roberto; Lelli, Matteo; Menichini, Matia; Ranaldi, Massimo; Ricci, Tullio; Tarchini, Luca

    2013-05-01

    Platanares and Azacualpa geothermal sites of Honduras are located in an inner part of the Caribbean Plate far from the active volcanic front of Central America. Here geology indicates that there are not the conditions for the occurrence of shallow magmatic heat sources for high-enthalpy geothermal resources. Geothermal perspectives are related to the possibility of a deep circulation of meteoric water along faults and the storage of the heated fluid in fractured permeable reservoirs. Geochemical geothermometers indicate a temperature for the deeper part of the geothermal reservoir close to 200 °C for Platanares and of 150-170 °C for Azacualpa. Calcite scaling, with subordinate silica deposition has to be expected in both sites. CO2 soil flux investigations have been carried out in both areas and reveal the presence of positive anomalies likely corresponding to the presence at depth of fractured degassing geothermal reservoirs. Compared with the geothermal areas of Central Italy whose reservoirs are hosted in carbonate rocks, e.g. Latera (Chiodini et al., 2007), the CO2 soil flux measured in Honduras is significantly lower (mean of 17 g/m2day at Platanares and of 163 g/m2day at Azacualpa) probably because of the dominant silicate nature of the deep reservoirs.

  13. Water information bulletin No. 30 geothermal investigations in Idaho

    SciTech Connect

    Mitchell, J.C.; Johnson, L.L.; Anderson, J.E.; Spencer, S.G.; Sullivan, J.F.

    1980-06-01

    There are 899 thermal water occurrences known in Idaho, including 258 springs and 641 wells having temperatures ranging from 20 to 93/sup 0/C. Fifty-one cities or towns in Idaho containing 30% of the state's population are within 5 km of known geothermal springs or wells. These include several of Idaho's major cities such as Lewiston, Caldwell, Nampa, Boise, Twin Falls, Pocatello, and Idaho Falls. Fourteen sites appear to have subsurface temperatures of 140/sup 0/C or higher according to the several chemical geothermometers applied to thermal water discharges. These include Weiser, Big Creek, White Licks, Vulcan, Roystone, Bonneville, Crane Creek, Cove Creek, Indian Creek, and Deer Creek hot springs, and Raft River, Preston, and Magic Reservoir areas. These sites could be industrial sites, but several are in remote areas away from major transportation and, therefore, would probably be best utilized for electrical power generation using the binary cycle or Magma Max process. Present uses range from space heating to power generation. Six areas are known where commercial greenhouse operations are conducted for growing cut and potted flowers and vegetables. Space heating is substantial in only two places (Boise and Ketchum) although numerous individuals scattered throughout the state make use of thermal water for space heating and private swimming facilities. There are 22 operating resorts using thermal water and two commercial warm-water fish-rearing operations.

  14. Hydrous pyrolysis in the field: closed-system diagenesis at high fluid flow

    SciTech Connect

    Hutcheon, I.; Abercrombie, H.; Shevalier, M.; Nahnybida, C.

    1989-03-01

    Diagenetic processes are studied by observing natural systems or by experimental hydrous pyrolysis of water-organic-rock mixtures. Steam-enhanced recovery is similar to hydrous pyrolysis but is done in a previously undisturbed geological setting with mass, time, and temperature closer to natural diagenetic systems. Chemical and isotopic compositions of produced water and gas were determined for wellhead samples obtained from quartz-rich and lithic reservoirs. Estimates of reservoir temperature were made using the silica and Na-K geothermometers and agree with temperatures estimated from /sup 13/C//sup 13/C partitioning between bicarbonate and CO/sub 2/. Temperature and fluid composition data are portrayed on activity diagrams and show that minerals (illite, chalcedony, chlorite, analcime, and smectite) rapidly reach equilibrium with waters. Mineral reactions inferred from produced waters are different in quartz-rich and lithic reservoirs and agree with mineral reactions observed in post-steam cores. Carbon isotopic data indicate that carbonate minerals are the source of produced CO/sub 2/. Comparison of the buffering potential of aqueous carbonate species, carbonate minerals, organic acids, and silicate hydrolysis shows that silicates have the greatest potential to buffer pH. The authors data are consistent with pH control by silicate hydrolysis and indicate that silicate-carbonate reactions may be a major source of CO/sub 2/ during diagenesis. More generally, their results show that a diagenetic system of high fluid flow can be approximated by closed-system behavior.

  15. Evaluation of low-temperature geothermal potential in north-central Box Elder County, Utah

    SciTech Connect

    Davis, M.C.; Kolesar, P.T.

    1984-12-01

    The low-temperature geothermal resources of north-central Box Elder County, Utah were assessed. Exploration techniques used included chemical analyses of water from wells and springs, temperature surveys, and temperature-depth measurements in unused wells within the study area. The highest water temperatures (31/sup 0/, 30/sup 0/, and 29/sup 0/C) recorded in this research were located in three separate geographic regions, suggesting that no single warm water occurrence dominates the study area. Total dissolved solid (TDS) concentrations ranged from 294 to 11,590 mg/l. Areas of warm water occurrences generally had TDS values of greater than 1100 mg/l. Reservoir temperatures were estimated using chemical geothermometers. Calculated temperatures ranged between 50/sup 0/ and 100/sup 0/C. Temperature-depth measurements were logged in 16 unused wells. Thermal gradients calculated from the profiles ranged from isothermal to 267/sup 0/C/km. The background gradient for the study area appears to be slightly above the average Basin and Range gradient of 35/sup 0/C/km. The highest gradients were calculated for the area approximately eight kilometers west of Snowville, Utah, which is also an area of warm water. 61 refs., 15 figs., 6 tabs.

  16. The influence of kinetics on the oxygen isotope composition of calcium carbonate

    NASA Astrophysics Data System (ADS)

    Watkins, James M.; Nielsen, Laura C.; Ryerson, Frederick J.; DePaolo, Donald J.

    2013-08-01

    Paleotemperature reconstructions rely on knowledge of the equilibrium separation of oxygen isotopes between aqueous solution and calcium carbonate. Although oxygen isotope separation is expected on theoretical grounds, the temperature-dependence remains uncertain because other factors, such as slow exchange of isotopes between dissolved CO2-species and water, can obscure the temperature signal. This is problematic for crystal growth experiments on laboratory timescales and for interpreting the oxygen isotope composition of crystals formed in natural settings. We present results from experiments in which inorganic calcite is precipitated in the presence of 0.25 μM dissolved bovine carbonic anhydrase (CA). The presence of dissolved CA accelerates oxygen isotope equilibration between the dissolved carbon species CO2, H2CO3, HCO3-, CO32- and water, thereby eliminating this source of isotopic disequilibrium during calcite growth. The experimental results allow us to isolate, for the first time, kinetic oxygen isotope effects occurring at the calcite-water interface. We present a framework of ion-by-ion growth of calcite that reconciles our new measurements with measurements of natural cave calcites that are the best candidate for having precipitated under near-equilibrium conditions. Our findings suggest that isotopic equilibrium between calcite and water is unlikely to have been established in laboratory experiments or in many natural settings. The use of CA in carbonate precipitation experiments offers new opportunities to refine oxygen isotope-based geothermometers and to interrogate environmental variables other than temperature that influence calcite growth rates.

  17. Hydrogeochemistry and reservoir model of Fuzhou geothermal field, China

    NASA Astrophysics Data System (ADS)

    Huang, H. F.; Goff, Fraser

    1986-03-01

    Fuzhou geothermal field is a low- to intermediate-temperature geothermal system consisting of meteoric water that circulates deeply along faults. The area of the field is about 9 km 2 but it is elongated in a NNW-trending direction. Fluids in the field are controlled by a series of four NNW extensional faults in Cretaceous granitic basement (Fuzhou fault zone). These faults feed warm waters into overlying permeable Quaternary sediments. The hydrothermal system consists of north and south parts whose chemical compositions are subtly different. In the northern part the system discharges sulfate/chloride waters with relatively low chloride concentrations, but in the south the system discharges chloride waters having relatively high chloride concentrations. Maximum wellhead temperatures are 97°C, which agrees with the chalcedony geothermometer in many cases. Based on the solubility of quartz, the deep-reservoir temperature cannot exceed 123 to 131°C. From heat and mass balance calculations, we conclude that the present total extracted capacity of fluid from the reservoir (20,000 tons/day) could be doubled without noticeable drawdown. We estimate the recoverable heat in the reservoir to be about 1.71 × 10 11 MJ.

  18. Regional geothermal exploration in north central New Mexico. Final report

    SciTech Connect

    Icerman, L.

    1984-02-01

    A broad-based geothermal resource reconnaissance study covering Bernalillo, Los Alamos, Rio Arriba, San Miguel, Sandoval, Santa Fe, Taos, Torrance, and Valencia counties in north central New Mexico was conducted from June 15, 1981, through September 30, 1983. Specific activities included the compilation of actual temperature, bottom-hole temperature gradient, and geotemperature data; tabulation of water chemistry data; field collection of temperature-depth data from existing wells; and drilling of temperature gradient holes in the Ojo Caliente, San Ysidro, Rio Puerco, and Polvadera areas. The data collected were used to perform: (1) a regional analysis of the geothermal energy potential of north central New Mexico; (2) two site-specific studies of the potential relationship between groundwater constrictions and geothermal resources; (3) an evaluation of the geothermal energy potential at Santa Ana Pueblo; (4) a general analysis of the geothermal energy resources of the Rio Grande Rift, including specific data on the Valles Caldera; and (5) an evaluation of the use of geothermometers on New Mexico groundwaters. Separate abstracts were prepared for individual chapters.

  19. Sub-continental lithospheric mantle structure beneath the Adamawa plateau inferred from the petrology of ultramafic xenoliths from Ngaoundéré (Adamawa plateau, Cameroon, Central Africa)

    NASA Astrophysics Data System (ADS)

    Nkouandou, Oumarou F.; Bardintzeff, Jacques-Marie; Fagny, Aminatou M.

    2015-11-01

    Ultramafic xenoliths (lherzolite, harzburgite and olivine websterite) have been discovered in basanites close to Ngaoundéré in Adamawa plateau. Xenoliths exhibit protogranular texture (lherzolite and olivine websterite) or porphyroclastic texture (harzburgite). They are composed of olivine Fo89-90, orthopyroxene, clinopyroxene and spinel. According to geothermometers, lherzolites have been equilibrated at 880-1060 °C; equilibrium temperatures of harzburgite are rather higher (880-1160 °C), while those of olivine websterite are bracketed between 820 and 1010 °C. The corresponding pressures are 1.8-1.9 GPa, 0.8-1.0 GPa and 1.9-2.5 GPa, respectively, which suggests that xenoliths have been sampled respectively at depths of 59-63 km, 26-33 km and 63-83 km. Texture and chemical compositional variations of xenoliths with temperature, pressure and depth on regional scale may be ascribed to the complex history undergone by the sub-continental mantle beneath the Adamawa plateau during its evolution. This may involve a limited asthenosphere uprise, concomitantly with plastic deformation and partial melting due to adiabatic decompression processes. Chemical compositional heterogeneities are also proposed in the sub-continental lithospheric mantle under the Adamawa plateau, as previously suggested for the whole Cameroon Volcanic Line.

  20. Geochemistry of water and gas discharges from the Mt. Amiata silicic complex and surrounding areas (central Italy)

    NASA Astrophysics Data System (ADS)

    Minissale, A.; Magro, G.; Vaselli, O.; Verrucchi, C.; Perticone, I.

    1997-12-01

    reliability of geothermometers in liquid phase, which understimate the real temperatures of the discovered geothermal fields. More reliable temperatures are envisaged by using gas composition-based geothermometers. Bulk composition of the 67 gas samples studied seems to be the result of a continuous mixing between a N 2-rich component of meteoric origin related to the Ca-SO 4 aquifer and a deep CO 2-rich component rising largely along the boundaries of the geothermal systems. Nitrogen-rich gas samples have nearly atmospheric N 2/Ar (=83) and 15N/ 14N ( δ=0‰) ratios whereas CO 2-rich samples show anomalously high δ15N values (up to +6.13 ‰), likely related to N 2 from metamorphic schists lying below the carbonate formations. On the basis of average 13C/ 12C isotopic ratio ( δ13C around 0‰), CO 2 seems to originate mainly from thermometamorphic reactions in the carbonate reservoir and/or in carbonate layers embedded in the underlying metamorphic basement. Distribution of 3He/ 4He isotopic ratios indicates a radiogenic origin of helium in a tectonic environment that, in spite of the presence of many post-orogenic basins and mantle-derived magmatics, can presently be considered in a compressive phase.

  1. Fluid-aided incorporation of Y into almandine-pyrope garnet via coupled dissolution-reprecipitation

    NASA Astrophysics Data System (ADS)

    Harlov, D. E.

    2009-12-01

    In nature almandine-pyrope garnet is a well-known host for a variety of trace elements including (Y+HREE), Sr, HFSE, as well as LREE such as Sm and Nd; all of which have important roles with regard to various geological processes (Kohn, 2009, GCA, 73, 170). For example, Y exchange between xenotime and garnet has been empirically calibrated as a geothermometer (Pyle and Spear, 2000, CMP, 138, 51). Sm/Nd and Lu/Hf dating, using garnet, is a well-known geochronometer (Thöni et al., 2008, Chem Geol, 254, 216). In general, REE + HFSE + Sr have been used to chart garnet growth and subsequently the evolution of the host rock (Konrad-Schmolke et al., 2008, EPSL, 272, 488). Incorporation of Y into garnet is probably the most widely studied trace element. These studies range from stress-induced redistribution of Y in garnet (Røhr et al, 2007, Am Mineral, 92, 1276) to Y zoning during garnet growth (Zeh, 2005, J Petrol, 47, 2335). While the incorporation of Y into garnet has generally been thought to occur either via diffusion or during garnet growth, more recent workers have suggested that incorporation of Y could also be fluid-aided. Fluid-aided incorporation of Y into garnet has been tested in the piston-cylinder apparatus (CaF2 assemblies, cylindrical graphite ovens) at 1000 MPa and 900 °C (8 days duration). Here, 10 mg of 50-200 µm size, inclusion-free, gem quality, fragments of the Gore Mountain garnet (Alm40-49, Py37-43, Gr13-16, Sp1) plus 5 mg 2N NaOH and 2 mg Y2O3 were loaded into a 3 mm diameter, 1 cm long, Au capsule that was then arc-welded shut and placed vertically in the CaF2 assembly such that the NiCr thermocouple tip came halfway up along the Au capsule length. Examination of the garnet fragments after the experiment indicates both high Y mobility and the partial alteration of the garnet in the form of a remobilized Y3Al5O12 component enriching those areas of the garnet along the grain rim. The enriched areas take the form of a series of intergrowths with

  2. An Excel-based tool for evaluating and visualizing geothermometry data

    NASA Astrophysics Data System (ADS)

    Hora, J. M.; Wörner, G.; Kronz, A.

    2012-12-01

    Most geothermometers are based on exchange of chemical components between two phases that are in equilibrium with one another. In cases where (a) pairs of minerals in mutual grain contact are difficult to find, (b) the sample has experienced multiple generations of crystal growth resulting in zoning along mutual grain contact, (c) has multiple populations of crystals that each preserve a point along a P-T-t path, or (d) exsolution is present, identification of equilibrium pairs of analyses is challenging. All of these problems are exacerbated where the element(s) of interest diffuse slowly, yet these systems are among the most useful because they have the advantage of being resistant to resetting by later thermal events. By relaxing the requirement that thermometry be done only on analyses across a mutual grain boundary, the problem changes from that of having a dearth of data to that of having large data sets that possibly include a significant proportion of meaningless pairs of analyses that need to be filtered out. We present a method using Microsoft Excel that allows large amounts of data to be handled in a compact form-factor, and provides a calculation and visualization tool that: (1) can be adapted for use with any thermometer involving two phases, (2) facilitates quick comparison of equilibrium and apparent temperature results from all possible equilibrium pairs in a sample, (3) identifies populations of mineral pairs that may have experienced similar P-T conditions in the case of an open system, and (4) shows whether resulting temperature estimations predominantly depend on observed compositional variability in one of the two phases. In contrast to a traditional data table where all samples and associated calculations are presented either in columns or rows, our approach is to array our calculations in a grid. Model inputs relating to one phase are arrayed vertically, and inputs related to the other phase are arrayed horizontally along the left and top

  3. Trace element signatures in quartz reveal crystallization histories of Katmai magmas: a combined electron microprobe/cathodoluminescence study

    NASA Astrophysics Data System (ADS)

    Payne, A. L.; Eichelberger, J. C.

    2009-12-01

    Trace concentrations of Ti4+ and Al3+ which substitute for Si4+ in the quartz lattice reflect conditions in the melt at the time of crystallization, and zones enriched in these ions show distinctive cathodoluminescent signatures. Ti content of quartz has been shown to be an effective metric for crystallization temperatures, as calibrated by the TitaniQ geothermometer (Wark and Watson, 2006). Al concentrations in quartz show a less consistent connection with crystallization temperature and may have a positive correlation to crystal growth rate (Dennen et al., 1970; Müller et al., 2002). Ti and Al concentrations were measured by electron probe microanalysis (EPMA) and corresponding cathodoluminescence (CL) images were made for quartz grains from three magmatic rock suites of the Katmai region of the Alaska Peninsula: (1) high-silica rhyolite from the Novarupta lava dome; (2) the Mageik rhyolite sills, suggested as an analog for Novarupta's feeder (Lowenstern and Mahood, 1991); and (3) the Pinnacle Porphyry granodiorite, which has mingled field relations with the Mageik sills. Ti data was applied to the TitaniQ geothermometer to reveal the thermal histories of the three Katmai magmatic systems. Quartz from each of the three rock suites shows a distinctive crystallization history. Weak oscillatory CL zoning and constant (within error) Ti concentrations across Novarupta quartz suggest continuous growth at small degrees of undercooling at a minimum temperature of ~770-800°C, consistent with previously reported Fe-Ti oxide temperatures (Hildreth, 1983; Coombs and Gardner, 2001). Late-stage dissolution was followed by growth of very thin Al-rich, high-intensity CL rims, perhaps reflecting subsequent rapid growth during dome emplacement. Euhedral quartz of the Mageik sills has cores enriched in both Ti and Al, yielding minimum temperatures of ~900°C, and possibly representing rapid growth. Dark CL rims low in Ti likely represent continued growth to subsolidus

  4. Geochemistry and geothermometry of non-volcanic hot springs in West Malaysia

    NASA Astrophysics Data System (ADS)

    Baioumy, Hassan; Nawawi, Mohd; Wagner, Karl; Arifin, Mohd Hariri

    2015-01-01

    . However, the possible mixing of the original hot waters with near surface cold water is evident from the clear disagreement between the silica and cation geothermometers as well as the disequilibrium with their associated host rocks as indicated from the plot of studied hot springs in the Na-K-Mg ternary diagram and saturation indices calculations. Quartz geothermometers gave equilibrium temperatures ranging from 93 °C in the Ayer Hangat hot spring to 154 °C in the Lojing hot spring. This requires 398 to 649 kJ/kg energy to heat the water suggesting an intermediate enthalpy. These results also pointed out that some of the studied hot springs have potential to generate adequate heat, which could be harnessed for energy generation upon further work to prove their viability.

  5. Chemical and stable-radiogenic isotope compositions of Polatlı-Haymana thermal waters (Ankara, Turkey)

    NASA Astrophysics Data System (ADS)

    Akilli, Hafize; Mutlu, Halim

    2016-04-01

    Complex tectono-magmatic evolution of the Anatolian land resulted in development of numerous geothermal areas through Turkey. The Ankara region in central Anatolia is surrounded by several basins which are filled with upper Cretaceous-Tertiary sediments. Overlying Miocene volcanics and step faulting along the margins of these basins played a significant role in formation of a number of low-enthalpy thermal waters. In this study, chemical and isotopic compositions of Polatlı and Haymana geothermal waters in the Ankara region are investigated. The Polatlı-Haymana waters with a temperature range of 24 to 43 °C are represented by Ca-(Na)-HCO3 composition implying derivation from carbonate type reservoir rocks. Oxygen-hydrogen isotope values of the waters are conformable with the Global Meteoric Water Line and point to a meteoric origin. The carbon isotopic composition in dissolved inorganic carbon (DIC) of the studied waters is between -21.8 and -1.34 permil (vs. VPDB). Marine carbonates and organic rocks are the main sources of carbon. There is a high correlation between oxygen (3.7 to 15.0 permil; VSMOW) and sulfur (-9.2 to 19.5 permil; VCDT) isotope compositions of sulfate in waters. The mixing of sulfate from dissolution of marine carbonates and terrestrial evaporite units is the chief process behind the observed sulfate isotope systematics of the samples. 87Sr/86Sr ratios of waters varying from 0.705883 to 0.707827 are consistent with those of reservoir rocks. The temperatures calculated by SO4-H2O isotope geothermometry are between 81 and 138 °C nearly doubling the estimates from chemical geothermometers.

  6. Eocene to Oligocene retrogression and recrystallization of the Stak eclogite in northwest Himalaya

    NASA Astrophysics Data System (ADS)

    Kouketsu, Yui; Hattori, Kéiko; Guillot, Stéphane; Rayner, Nicole

    2016-01-01

    Highly retrogressed eclogite is present in the Stak massif located on the northern edge of the Indian continental margin in northern Pakistan. Garnet in foliated samples contains omphacite inclusions (Xjd = 0.33-0.40) and quartz inclusions and latter retain Raman spectroscopic evidence for high residual pressures up to 0.52 GPa. These garnet grains do not show apparent compositional zoning. By contrast, one sample contains euhedral grains of garnet with quartz inclusions that show residual pressures as low as 0.25 GPa. These garnet grains do not contain omphacite inclusions, and show different compositional zoning compared to the omphacite-bearing garnet. The metamorphic condition of this sample was estimated to be 1.0-1.4 GPa/650-710 °C using residual pressure values of quartz inclusions in garnets and the garnet-clinopyroxene geothermometer. The U-Pb ages of zircon grains range from 158 to 28 Ma with a cluster between at ca. 32 Ma, which is younger than that of the peak ultrahigh-pressure metamorphic ages of eclogitic massifs in the northwestern Himalaya, e.g. Kaghan and Tso Morari. We suggest that the retrogressed eclogitic rocks in the Stak massif were heated by nearby Nanga Parbat Haramosh massif at ca. 32 Ma, subsequent to peak eclogite facies conditions. During this heating, part of the eclogite was largely recrystallized to form euhedral garnet grains. These results suggest that the Stak massif resided at a lower crustal depth while other ultrahigh-pressure massifs were exhumed in western Himalaya.

  7. Hidrogeochemistry of Maguarichi's thermal waters, Chihuahua, México

    NASA Astrophysics Data System (ADS)

    Villalobos-Aragon, A.; Rascon-Oaxaca, E.; Espejel-Garcia, V. V.

    2012-12-01

    The surface expression of the Piedras de Lumbre Geothermal Zone comprises hot springs and steaming fumaroles, which occur in the vicinity of fractures within the rhyolites related to the Sierra Madre Occidental. Waters from hot springs and fumaroles were sampled in order to classify their temperature, hydrogeochemical behavior and origin. Maguarichi, is located in the southwestern part of the mexican state of Chihuahua, in the high Sierra Tarahumara, 350 km southwest from Chihuahua City. Previous work characterized the water as having a sulfate-chloride and sodium-chloride composition, and a temperature (calculated with geothermometers) of 130°C. In 2001, after close to ten years of geological, geochemical and geophysical work made by the Mexican Federal Electrical Commission (CFE), a small geothermal power plant was installed at a cost of US$1.3 million. This small (300 kW) binary-cycle unit supplied energy to the nearby Maguarichi village, 6 kilometers away. The unit was dismantled in 2007 when the electric grid reached the village. In 2012, after a visit by the Mexican president, a plan to develop this area as a touristic attraction is under way. In order to determine the hydrogeochemistry of the thermal waters, two sampling expeditions (October 2011 and May 2012) were performed and the preliminary results show that samples have temperatures ranging from 80°C to 98°C, with major ion and heavy element concentrations below the maximum permissible levels for human consumption waters (NOM-127-SSA1-1994). Sulfate values range from 198 to 222 mg/l, while arsenic ranges from 0.009 to 0.015mg/l. By using H and O stable isotopes we expect to determine the origin of this waters (meteoric or magmatic).

  8. Reconstruction and geochemical modelling of the diagenetic history of the middle Jurassic Oseberg sandstone reservoir, Oseberg Field, Norwegian North Sea

    SciTech Connect

    Girard, J.P.; Sanjuan, B.; Fouillac, C.

    1995-08-01

    A detailed multidisciplinary integrated study of the Middle Jurassic Oseberg reservoir in 13 wells of the Oseberg field, Norwegian North Sea, was carried out in order to (1) reconstruct precisely the timing, conditions and spatial variation of diagenetic transformations (2) characterize the nature and origin of the diagenetic fluids, and (3) develop a geochemical model of the observed diagenesis. The 20-60 in thick Oseberg Formation occurs at depths of 2.5 to 3.2 km, and at present temperatures ranging from 100 to 125{degrees}C. The detrital assemblage is mainly composed of quartz, K-feldspar, albrite, muscovite and lithic clay clasts, and is very homogeneous throughout the study area. The chronological sequence of diagenetic phases established from petrographic observations includes: minor siderite and pyrite, K-feldspar overgrowths, ankerite, feldspar dissolution, vermiform, kaolinite, quartz overgrowths, poikilotopic Fe-rich calcite, dickite. Diagenetic temperatures were determined from fluid inclusions in ankerite, quarts and calcite. Combination with modelled burial/thermal history permitted to constrain approximate ages and duration of major diagenetic events. Isotopic compositions of diagenetic cements indicate that meteoric water was (and still is) a major constituant of diagenetic fluids. Present formation waters are fairly similar chemically and isotopically at reservoir scale and represent mixing of three endmembers: seawater, meteoric water and primary evaporative brine. Stability diagrams and chemical geothermometers suggest that formation fluids are close to equilibrium with the host sandstone at present reservoir temperatures. Geochemical modelling of the diagenetic evolution of water-reservoir interactions was carried out using the EQ3/6 code and the Allan{sup TM}/Neptunix integrated simulator system. Results emphasize the importance of circulations of large volumes of fluid within the reservoir throughout the diagenetic history.

  9. Generation and evolution of hydrothermal fluids at Yellowstone: Insights from the Heart Lake Geyser Basin

    USGS Publications Warehouse

    Lowenstern, J. B.; Bergfeld, D.; Evans, William C.; Hurwitz, S.

    2012-01-01

    We sampled fumaroles and hot springs from the Heart Lake Geyser Basin (HLGB), measured water and gas discharge, and estimated heat and mass flux from this geothermal area in 2009. The combined data set reveals that diverse fluids share an origin by mixing of deep solute-rich parent water with dilute heated meteoric water, accompanied by subsequent boiling. A variety of chemical and isotopic geothermometers are consistent with a parent water that equilibrates with rocks at 205°C ± 10°C and then undergoes 21% ± 2% adiabatic boiling. Measured diffuse CO2 flux and fumarole compositions are consistent with an initial dissolved CO2 concentration of 21 ± 7 mmol upon arrival at the caldera boundary and prior to southeast flow, boiling, and discharge along the Witch Creek drainage. The calculated advective flow from the basin is 78 ± 16 L s−1 of parent thermal water, corresponding to 68 ± 14 MW, or –1% of the estimated thermal flux from Yellowstone. Helium and carbon isotopes reveal minor addition of locally derived crustal, biogenic, and meteoric gases as this fluid boils and degasses, reducing the He isotope ratio (Rc/Ra) from 2.91 to 1.09. The HLGB is one of the few thermal areas at Yellowstone that approaches a closed system, where a series of progressively boiled waters can be sampled along with related steam and noncondensable gas. At other Yellowstone locations, steam and gas are found without associated neutral Cl waters (e.g., Hot Spring Basin) or Cl-rich waters emerge without significant associated steam and gas (Upper Geyser Basin).

  10. Petrology, geochemistry, and petrogenesis of ultramafic xenoliths from 1800-1801 Kaupulehu flow, Hualalai Volcano, Hawaii

    SciTech Connect

    Chen, C.H.

    1986-01-01

    The 1800-1801 Kaupulehu alkalic flow on Hualalai Volcano, Hawaii, contains abundant xenoliths of dunite, wehrlite, and olivine-clinopyroxenite with minor gabbro, troctolite, anorthosite, and websterite. The petrography and mineral chemistry of forty-six dunite, wehrlite, and olivine-clinopyroxenite xenoliths have been studied; eight were selected for determination of trace element concentrations and isotopic ratios of separated clinopyroxenes. Temperatures of equilibrium obtained from both olivine-spinel and pyroxene geo-thermometers range from 1000 C to 1200 C for these ultramafic xenoliths. A depth of 8-25 km is suggested for the formation of these ultramafic xenoliths. The rarity of othopyroxene, presence of clinopyroxene, Fe-rich olivine and clinopyroxene compositions, and high TiO content in spinel and clinopyroxene indicate that these xenoliths have a cumulate origin and are not residues from partial melting. Sr and Nd isotopic ratios from clinopyroxene are different from those of most Mid-Ocean Ridge Basalts. Rare earth element (REE) concentrations in liquid that equilibrated with xenolith clinopyroxenes have light rare earth element (LREE) enriched patterns with (Ce/Yb)n between 4 and 10. Similar olivine, spinel, and clinopyroxene compositions in xenoliths and Hawaiian basalts as well as good agreement of their Sr and Nd isotopic ratios suggests a genetic relationship between Hualalai ultramafic xenoliths and Hawaiian basalts. Some xenoliths possibly are cumulates from alkalic or tholeiitic basalts. However, Hualalai tholeiitic basalts are excluded due to their different /sup 3/He//sup 4/He values and REE patterns. The magmas that crystallized the Mg-rich (>Fo/sub 87/) dunites with high REE contents are similar in Sr and Nd isotopic values to Hualalai 1800-1801 alkalic basalts but have higher REE and Sr contents.

  11. Implications of ground water chemistry and flow patterns for earthquake studies.

    PubMed

    Guangcai, Wang; Zuochen, Zhang; Min, Wang; Cravotta, Charles A; Chenglong, Liu

    2005-01-01

    Ground water can facilitate earthquake development and respond physically and chemically to tectonism. Thus, an understanding of ground water circulation in seismically active regions is important for earthquake prediction. To investigate the roles of ground water in the development and prediction of earthquakes, geological and hydrogeological monitoring was conducted in a seismogenic area in the Yanhuai Basin, China. This study used isotopic and hydrogeochemical methods to characterize ground water samples from six hot springs and two cold springs. The hydrochemical data and associated geological and geophysical data were used to identify possible relations between ground water circulation and seismically active structural features. The data for delta18O, deltaD, tritium, and 14C indicate ground water from hot springs is of meteoric origin with subsurface residence times of 50 to 30,320 years. The reservoir temperature and circulation depths of the hot ground water are 57 degrees C to 160 degrees C and 1600 to 5000 m, respectively, as estimated by quartz and chalcedony geothermometers and the geothermal gradient. Various possible origins of noble gases dissolved in the ground water also were evaluated, indicating mantle and deep crust sources consistent with tectonically active segments. A hard intercalated stratum, where small to moderate earthquakes frequently originate, is present between a deep (10 to 20 km), high-electrical conductivity layer and the zone of active ground water circulation. The ground water anomalies are closely related to the structural peculiarity of each monitoring point. These results could have implications for ground water and seismic studies in other seismogenic areas. PMID:16029173

  12. Approaches for Multicomponent Equilibrium Geothermometry as a Tool for Geothermal Resource Exploration

    NASA Astrophysics Data System (ADS)

    Smith, R. W.; Palmer, C. D.; Cooper, D.

    2012-12-01

    Geothermometry is an important tool to estimate deep reservoir temperature from the geochemical composition of shallower and cooler waters. The underlying assumption of geothermometry is that the shallow waters maintain a chemical signature that reflects equilibrium in the deeper reservoir. Many of the geothermometers used in practice are based on empirical observations and correlation between water temperatures and composition using a subset (typically silica, cations or cation ratios) of the dissolved constituents. An alternative approach is to use complete water compositions and equilibrium geochemical modeling to calculate the degree of disequilibrium (Saturation Index) for large number of potential reservoir mineral as a function of temperature. Key to applying this approach is to define the often unknown primary/secondary mineral assemblage controlling equilibrium in the deep reservoir and to apply develop parameter optimization approaches to estimate the likely conditions (e.g., temperature, PCO2) to which the water was exposed in the deep subsurface. Selection of mineral assemblages can be addressed by a combination of practical (e.g., taking into account common alteration mineral assemblages) as well as theoretical (limiting the number of minerals by the phase rule) considerations. Because the values of Saturation Indexes are a function of reaction stoichiometry, simultaneous interpretation requires that values be weighted or normalized. The approach used here is to write reaction in terms of thermodynamic components and then divide the saturation index by the total count of components in the reaction (e.g., 1 for quartz, 2 for calcite, 5 for albite, and 7 for muscovite). This approach is tested against both synthetic and field derived data sets to estimate reservoir temperatures which are compared to actual temperatures or temperatures estimated from commonly employed approaches for geothermometry.

  13. Thermal state and implications for eruptive styles of the intra-Plinian and climactic ignimbrites of the 4.6 ka Fogo A eruption sequence, São Miguel, Azores

    NASA Astrophysics Data System (ADS)

    Pensa, A.; Giordano, G.; Cas, R. A. F.; Porreca, M.

    2015-11-01

    The 4.6 ka Fogo A Plinian eruption was a caldera-forming volcanic event on São Miguel Island, Azores. The deposit succession is very complex, composed of a thick trachytic Plinian fallout deposit interstratified with two intra-Plinian ignimbrites (named "pink ignimbrite" and "black ignimbrite" sequentially). The succession ends with a main ignimbrite (named "dark brown ignimbrite"), which represents the deposit of complete collapse of the eruption column and the end of the eruption. In this work, emplacement temperatures of the three ignimbrites are estimated by study of partial thermal remanent magnetization (pTRM) of lithic clasts. A total of 140 oriented lithic clasts were collected from 15 localities distributed along the northern and southern flanks of Fogo volcano. The paleomagnetic data reveal different emplacement temperatures and thermal histories that were experienced by each ignimbrite. The results indicate the presence of five different paleomagnetic behaviours that suggest emplacement temperatures of 350-400 °C for the first (pink) intra-Plinian ignimbrite, temperatures higher than 580-600 °C for the second (black) intra-Plinian ignimbrite and 250-370 °C for the last (dark brown) climactic ignimbrite. The thermal history experienced by each pyroclastic flow and its ignimbrite deposit was also assessed by the use of the magnetite-ilmenite geothermometer to determine the pre-eruptive magma temperature (estimated to be around 900 °C). We interpret the different emplacement temperatures of the Fogo A ignimbrites as being due to a combination of factors. These include (i) collapse from different heights of the eruption column and the resultant different amounts of air entrainment into the gas-particle mixture, (ii) variable content of lithic clasts and (iii) different types of juvenile clasts in the ignimbrites.

  14. Chemical and isotopic compositions of thermal waters in Anatolia, Turkey: A link to fluid-mineral equilibria

    NASA Astrophysics Data System (ADS)

    Mutlu, Halim; Gülec, Nilgün; Hilton, David R.

    2015-04-01

    The complex magmato-tectonic setting of Turkey has resulted in the occurrence of numerous geothermal fields with distinct chemical and isotopic fluid compositions. We evaluate the data on these fluids in terms of water-rock interaction, mineral equilibrium conditions and reservoir temperatures of each geothermal field. The Ca-HCO3 rich nature of most waters is ascribed to derivation from carbonate-type reservoir rocks. SO4-type waters are found in areas where the reservoir is partly comprised of evaporite units. Na-Cl type waters are characteristic for the coastal areas of west Anatolia. Chemical geothermometer applications estimate average reservoir temperatures of 180 °C for the western Anatolian region, 120 °C for the Balıkesir region, 130 °C for the eastern Anatolian region, 140 °C for the North Anatolian Fault Zone and 70 °C for the Eskişehir region. For most of the waters, chalcedony controls the silica solubility and the majority of waters are equilibrated with calcite and chalcedony minerals. Oxygen and hydrogen isotope compositions (-13.5 to -4 permil (VSMOW) and -95.4 to -23 permil (VSMOW), respectively) are generally conformable with Global Meteoric Water Line (GMWL); however, stable isotope systematics of geothermal waters close to the coast are consistent with the Mediterranean Meteoric Water Line (MMWL). Carbon and sulfur isotope compositions (δ13C (VPDB): -17.7 to +5.6 permil and δ34S (VCDT): -5.5 to +45.7 permil) suggest marine carbonates and terrestrial evaporite units as the main source of dissolved carbon and sulfate in the waters.

  15. Shallow submarine hydrothermal activity with significant contribution of magmatic water producing talc chimneys in the Wakamiko Crater of Kagoshima Bay, southern Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Yamanaka, Toshiro; Maeto, Kotaro; Akashi, Hironori; Ishibashi, Jun-Ichiro; Miyoshi, Youko; Okamura, Kei; Noguchi, Takuroh; Kuwahara, Yoshihiro; Toki, Tomohiro; Tsunogai, Urumu; Ura, Tamaki; Nakatani, Takeshi; Maki, Toshihiro; Kubokawa, Kaoru; Chiba, Hitoshi

    2013-05-01

    Active hydrothermal venting from shallow seafloor (200-m depth) with talc chimneys has been discovered at the Wakamiko Crater floor in the Aira Caldera, southern Kyushu, Japan. The major chemical composition of the fluids suggests that the fluids are supplied from a single reservoir. The fluid is characterized by a low chloride concentration, low δD value, and a high δ18O value, suggesting that the endmember hydrothermal fluid is a mixture of seawater and andesitic water and possibly contribution of meteoric water and/or phase separation. Such noticeable magmatic input may be supported by high helium isotopic ratio (6.77 RA) of fumarolic gas discharging from the crater. Silica and alkaline geothermometers indicate that the fluid-rock interaction in the reservoir occurs in the temperature range of 230 to 250 °C. The high alkalinity and high ammonium and dissolved organic matter concentrations in the fluid indicate interaction of the fluid with organic matter in sedimentary layers. At least three hydrothermal vents have been observed in the crater. Two of these have similar cone-shaped chimneys. The chimneys have a unique mineralogy and consist dominantly of talc (kerolite and hydrated talc) with lesser amounts of carbonate (dolomite and magnesite), anhydrite, amorphous silica, and stibnite. The precipitation temperature estimated from δ18O values of talc was almost consistent with the observed fluid temperature. Geochemical modeling calculations also support the formation of talc and carbonate upon mixing of the endmember hydrothermal fluid with seawater and suggest that the talc chimneys are currently growing from venting fluid.

  16. Paleogeothermal record of the Emeishan mantle plume: evidences from borehole Ro data in the Sichuan basin, SW China

    NASA Astrophysics Data System (ADS)

    Hu, S.

    2013-12-01

    The Emeishan basalt province located in the southwest of China is widely accepted to be a result of the eruption of a mantle plume at the time of middle-late Permian. If it was a mantle plume, the ambient sedimentary rocks must be heated up during the development of the mantle plume and this thermal effect must be recorded by some geothermometers in the country rocks. The vitrinite reflectance (Ro) data as a maximum paleotemperature recorder from boreholes in Sichuan basin was employed to expose the thermal regime related to the proposed Emeishan mantle plume. The Ro profiles from boreholes which drilled close to the Emeishan basalts shows a ';dog-leg' (break) style at the unconformity between the middle and the upper Permian, and the Ro profiles in the lower subsection (pre-middle Permian) shows a significantly higher slopes (gradients) than those in the upper subsection. In contrast, those Ro profiles from boreholes far away from the center of the basalt province have no break at the uncomformity. Based on the chemical kinetic model of Ro, the paleo-temperature gradients for the upper and the lower subsections in different boreholes, as well as the erosion at the unconformity between the middle and the upper Permian, were reconstructed to reveal the variations of the temperature gradients and erosion thickness with geological time and space. Both the thermal regime and the erosion thickness together with their spatial variation (structure) provide strong geothermal evidence for the existence of the Emeishan mantle plume in the middle-late Permian.

  17. On the Future of Thermochemical Databases, the Development of Solution Models and the Practical Use of Computational Thermodynamics in Volcanology, Geochemistry and Petrology: Can Innovations of Modern Data Science Democratize an Oligarchy?

    NASA Astrophysics Data System (ADS)

    Ghiorso, M. S.

    2014-12-01

    Computational thermodynamics (CT) has now become an essential tool of petrologic and geochemical research. CT is the basis for the construction of phase diagrams, the application of geothermometers and geobarometers, the equilibrium speciation of solutions, the construction of pseudosections, calculations of mass transfer between minerals, melts and fluids, and, it provides a means of estimating materials properties for the evaluation of constitutive relations in fluid dynamical simulations. The practical application of CT to Earth science problems requires data. Data on the thermochemical properties and the equation of state of relevant materials, and data on the relative stability and partitioning of chemical elements between phases as a function of temperature and pressure. These data must be evaluated and synthesized into a self consistent collection of theoretical models and model parameters that is colloquially known as a thermodynamic database. Quantitative outcomes derived from CT reply on the existence, maintenance and integrity of thermodynamic databases. Unfortunately, the community is reliant on too few such databases, developed by a small number of research groups, and mostly under circumstances where refinement and updates to the database lag behind or are unresponsive to need. Given the increasing level of reliance on CT calculations, what is required is a paradigm shift in the way thermodynamic databases are developed, maintained and disseminated. They must become community resources, with flexible and assessable software interfaces that permit easy modification, while at the same time maintaining theoretical integrity and fidelity to the underlying experimental observations. Advances in computational and data science give us the tools and resources to address this problem, allowing CT results to be obtained at the speed of thought, and permitting geochemical and petrological intuition to play a key role in model development and calibration.

  18. Water-rock interaction processes in the Triassic sandstone and the granitic basement of the Rhine Graben: Geochemical investigation of a geothermal reservoir

    NASA Astrophysics Data System (ADS)

    Aquilina, L.; Pauwels, H.; Genter, A.; Fouillac, C.

    1997-10-01

    Saline fluids have been collected in the Rhine Graben over the last two decades, both from the Triassic sandstone aquifer and the granitic basement down to a depth of 3500m. Their salinities and location are compared in order to distinguish the respective influences of temperature and host-rock mineralogy in the water-rock interaction processes. The comparison shows that sulphates in the sedimentary formations were dissolved by the fluids, which also led to Br enrichment. Mica dissolution has strongly increased the Rb and Cs contents, which then provide an indication of the degree of water-rock interaction. The Sr isotopic ratios are used to compare the fluids with the granite minerals. Two relationships are revealed for the fluids in the sandstone and the granite, one related to widespread mica dissolution, which could have affected both the Buntsandstein and the granite, and the other to subsequent plagioclase dissolution, which is observed only in the granite. Computations showed that 12.5g of mica and 1.658 of plagioclase per liter of fluid have been dissolved. The nature of these two relationships suggests two different evolutions for the fluids and the individualization of the two reservoirs during the graben's history. The cation concentrations are mainly controlled by temperature, and are independent of the type of host rock. Equilibrium with the rock mainly caused Ca and K concentration variations, which has induced clear CaK and Ca-δ 18O, K-δ 18O correlations. Geothermometric computations indicate that with increasing depth, the cations, the silica and the δ 18O(SO 4) geothermometers evolve towards a value close to 230δC. This demonstrates the existence of a hot reservoir in the granite of the graben, at a depth estimated at 4.5-5 km.

  19. Changes in illite crystallinity within an ancient tectonic boundary thrust caused by thermal, mechanical, and hydrothermal effects: an example from the Nobeoka Thrust, southwest Japan

    NASA Astrophysics Data System (ADS)

    Fukuchi, Rina; Fujimoto, Koichiro; Kameda, Jun; Hamahashi, Mari; Yamaguchi, Asuka; Kimura, Gaku; Hamada, Yohei; Hashimoto, Yoshitaka; Kitamura, Yujin; Saito, Saneatsu

    2014-12-01

    Illite crystallinity (IC), the full width at half maximum of the illite (001) peak in clay-fraction X-ray diffraction (XRD), is a common geothermometer widely applied to various tectonic settings. Paleotemperature estimation using IC presents methodological ambiguity because IC is not only affected by background temperature but also by mechanical, hydrothermal, and surface weathering effects. To clarify the influences of these effects on IC in the fault zone, we analyzed the IC and the illite 001 peak intensity of continuous borehole core samples from the Nobeoka Thrust, a fossilized tectonic boundary thrust in the Shimanto Belt, the Cretaceous-Paleogene Shimanto accretionary complex in southwest Japan. We also carried out grinding experiments on borehole core samples and sericite standard samples as starting materials and investigated the effect of mechanical comminution on the IC and illite peak intensity of the experimental products. We observed the following: (1) the paleotemperatures of the hanging wall and footwall of the Nobeoka Thrust are estimated to be 288°C to 299°C and 198°C to 249°C, respectively, which are approximately 20°C to 30°C lower than their previously reported temperatures estimated by vitrinite reflectance; (2) the fault core of the Nobeoka Thrust does not exhibit IC decrease; (3) the correlation of IC and illite peak intensity in the hanging wall damage zone were well reproduced by the grinding experiment, suggesting that the effect of mechanical comminution increases toward the fault core and; (4) the abrupt increase in IC value accompanied by high illite peak intensity is explained by hydrothermal alterations including plagioclase breakdown and the formation of white micas. Our results indicate that IC has potential for quantifying the effects of mechanical comminution and hydrothermal alteration within a fault zone.

  20. 13C-18O bonding (Δ47) in deep-sea corals: a calibration study

    NASA Astrophysics Data System (ADS)

    Kimball, J. B.; Tripati, A.; Dunbar, R. B.; Eagle, R.

    2013-12-01

    Deep-sea corals are a potentially valuable archive of temperature in intermediate and deep waters, regions for which a paucity of temperature data exists. These archives could give valuable insight into the natural variability of areas of the ocean that play an active role in large-scale climate dynamics. Due to significant 'vital effects' (i.e., non-equilibrium mineral compositions) in δ18O, however, deep-sea coral have been challenging to develop as a paleotemperature proxy. Clumped-isotope paleothermometry is a new method that may circumvent some of the known complications with δ18O paleotemperature analysis in deep-sea coral. This geothermometer is based on the ordering of heavy 13C-18O ';clumps' in carbonate minerals. Initial calibration studies have shown that the method is independent from the solution chemistry of the precipitating fluids as well as 'vital effects' in deep-sea corals and other types of carbonates. Some kinetic effects have been observed in tropical corals and speleothems. Here we report new data in order to further develop clumped isotopes as a paleothermometer in deep-sea corals as well as to investigate taxon-specific effects. 13C-18O bond ordering was analyzed in live-collected scleractinian (Enallopsammia sp.) and gorgonian (Isididae and Coralliidae) deep-sea corals. We determined mass 47 anomalies in samples (Δ47), which refers to the parts per thousand excess of 13C-18O-16O in CO2 produced on acid digestion of a sample, relative to the amount predicted to be present if isotopes were randomly distributed amongst all CO2 isotopologues. Measured Δ47 values were compared to in situ temperatures and the relationship between Δ47 and temperature was determined for each group to investigate taxon-specific effects.

  1. Favorable Geochemistry from Springs and Wells in COlorado

    DOE Data Explorer

    Zehner, Richard E.

    2012-02-01

    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. Data from all samples were reportedly collected using standard water sampling protocols (filtering through 0.45 micron filter, etc.) Sample information was standardized to ppm (micrograms/liter) in spreadsheet columns. Commonly-used cation and silica geothermometer temperature estimates are included. Spatial Domain: Extent: Top: 4515595.841032 m Left: 149699.513964 m Right: 757959.309388 m Bottom: 4104156.435530 m Contact Information: Contact Organization: Geothermal Development Associates, Reno, Nevada Contact Person: Richard “Rick” Zehner Address: 3740 Barron Way City: Reno State: NV Postal Code: 89511 Country: USA Contact Telephone: 775-737-7806 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System 1984 (WGS ’1984) Prime Meridian: Greenwich

  2. Comments on Evaluation of thermobarometers for garnet peridotites' by A. A. Finnerty and F. R. Boyd

    SciTech Connect

    Ganguly, J. )

    1992-02-01

    In order to evaluate the accuracy of a given combination of thermo-barometer, Finnerty and Boyd (1984) calculated the P-T conditions of two control samples of garnet lherzolite xenoliths, namely BD 2125 and PHN 1569. The importance of the samples lies in the fact that BD 2125 is diamond bearing, whereas PHN 1569 is graphite bearing. The alumina solubility in orthopyroxene (OPx) coexisting with garnet (Gt) is sensitive to both pressure and temperature changes and has thus been used widely, in combination with various geothermometers, for the thermo-barometry of garnet lherzolite xenoliths. Finnerty and Boyd (1984) concluded that the experimental calibrations of alumina solubility in OPx by Akella (1976) and Lane and Ganguly (1980) are as precise as, but probably less accurate than MC74 barometer,' where MC74 referred to the experimental calibration of alumina solubility in OPx by McGregor (1974) in the system MgSiO{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2} (MAS) based on synthesis experiments from glass of appropriate compositions. This conclusion on the accuracy of the above barometers was based on their observation that the use of only MC74 placed the calculated P-T conditions of the control samples in the right field with respect to the diamond-graphite equilibrium boundary, while those of Akella (1976; AK76) and Lane and Ganguly (1980; LG80) yielded P-T conditions that did not exactly satisfy the latter constraint, but were within 2 kb of the phase boundary. While it is clear from thermodynamic considerations that an unambiguous test of the accuracy of the calibrations cannot be carried out without making corrections for the effects of the additional components which are present in the natural samples but not in the experimental charges, the calculations of Finnerty and Boyd (1984) using LG80 are grossly erroneous.

  3. Physical characteristics and quality of water from selected springs and wells in the Lincoln Point-Bird Island area, Utah Lake, Utah

    USGS Publications Warehouse

    Baskin, R.L.; Spangler, L.E.; Holmes, W.F.

    1994-01-01

    From February 1991 to October 1992, the U.S. Geological Survey, in cooperation with the Central Utah Water Conservancy District, investigated the hydrology of the Lincoln Point - Bird Island area in the southeast part of Utah Lake, Utah. The investigation included measurements of the discharge of selected springs and measurements of the physical and chemical characteristics of water from selected springs and wells in the LincolnPoint - Bird Island area. This report contains data for twenty-one distinct springs in the study area including two springs beneath the surface of Utah Lake at Bird Island. Data from this study, combined with data from previous studies, indicate that the location of springs in the Lincoln Point - Bird Island area probably is controlled by fractures that are the result of faulting. Measured discharge of springs in the Lincoln Point - Bird Island area ranged from less than 0.01 cubic foot per second to 0.84 cubic foot per second. Total discharge in the study area, including known unmeasured springs and seeps, is estimated to be about 5 cubic feet per second. Reported and measured temperatures of water from springs and wells in the Lincoln Point - Bird Island area ranged from 16.0 degrees Celsius to 36.5 degrees Celsius. Dissolved-solids con-centrations ranged from 444 milligrams per liter to 7,932 milligrams per liter, and pH ranged from 6.3 to 8.1. Physical and chemical characteristics of spring and well water from the west side of Lincoln Point were virtually identical to the physical and chemical characteristics of water from the submerged Bird Island springs, indicating a similar source for the water. Water chemistry, isotope analyses, and geothermometer calculations indicate deep circulation of water discharging from the springs and indicate that the source of recharge for the springs at Lincoln Point and Bird Island does not appear to be localized in the LincolnPoint - Bird Island area.

  4. Using High Pressure Thermal Vessel For Mineral Solubility Experiments in Geothermal System

    NASA Astrophysics Data System (ADS)

    Liu, H. L.; Huang, Y. H.; Chen, H. F.; Song, S. R.

    2014-12-01

    Due to the serious scaling problems of the production in pipeline, Qingshui geothermal power plants closed after 12 years in the past. Because the pressure reduced in the process of upwelling, the hot spring from the reservoir will scaling CaCO3 immediately by large CO2 escape. This result will cause the space of pipeline reduced. On the other hand, as the temperature decreases, the SiO2 scaled in the part of heat exchanger. This study chose the Hongchailin and Qingshui IC-21 well as objects to simulate, and the Szeleng sandstone and the Lushan slate are the target layer of drilling well, respectively. We use pure water and saturated water pressure in our experiments. Besides, the previous studies showed that temperature of reservoir in Qingshui site was not over 300℃, so we set 300℃ as the upper limit temperature. The pressure was less than 800 bar by calculated the rock density of target layer. The original rock sample were placed in first autoclave, and added pure water in the second autoclave. Then we heat the first autoclave to reach the target temperature, and make the pressure saturated over water vapor pressure. After 72 hours the saturated water were leaked into the second autoclave. As the temperature cooling down, we removed the water from second autoclave and diluted the water. Finally, the Na+, K+, Mg+2, Ca+2 ions were analyzed by ICP. We want to get the maximum solubility of calcite and amorphous silica in equilibrium with sandstone and slate, and then check whether the method of geothermometer calculated is reasonable or not by calculated the concentration of Na+, K+, Si+4 in hot spring.

  5. Prefeasibility geothermal assessment of Platanares, Department of Copan, Honduras

    SciTech Connect

    Goff, S.; Goff, F.; Heiken, G.; Duffield, W.A.; Truesdell, A.H.; Laughlin, A.W.; Flores, W.

    1989-01-01

    The Platanares geothermal system is located in a region of active Quaternary tectonism in western Honduras. Although the geothermal area is partially blanketed by Miocene ignimbrites (14.5 m.y.), there are no nearby Quaternary volcanic rocks to act as a young magmatic heat source. No acid-sulfate waters, indicative of vapor-dominated conditions, exist in the area. Hot spring activity is most vigorous along a 2 km stretch of the Quebrada del Agua Caliente fault zone. Natural discharge is high (/approximately/3300 l/min), temperatures range from 35 to 100/degree/C, pH ranges from 7 to 9, and totally dissolved solids are low (/approximately/1100 mg/kg). Chemical geothermometers indicate a subsurface reservoir temperature of about 225/degree/C. Three exploration core holes (7.8 cm diameter) have been drilled to a maximum depth of 680 m and maximum temperature of 165/degree/C. Two holes produce copious amounts of water under artesian conditions (/approximately/500 l/min max; 5 bars flowing) from fractured red beds of Cretaceous to Eocene age (Valle de Angeles Group). Maximum power output is /approximately/4.5 MW (thermal) but CO/sub 2/ released during flashing formed some aragonite scale in one hole. The third core hole has an ''apparent'' conductive gradient of 139/degree/C/km at 400 m. Downward continuation of this gradient implies that the minimum depth to the geothermal resource (225/degree/C) is 1.5 to 2.0 km. 13 refs., 4 figs.

  6. Water-rock interaction processes in the Triassic sandstone and the granitic basement of the Rhine Graben: Geochemical investigation of a geothermal reservoir

    SciTech Connect

    Aquilina, L.; Pauwels, H.; Genter, A.; Fouillac, C.

    1997-10-01

    Saline fluids have been collected in the Rhine Graben over the last two decades, both from the Triassic sandstone aquifer and the granitic basement down to a depth of 3500m. Their salinities and location are compared in order to distinguish the respective influences of temperature and host-rock mineralogy in the water-rock interaction processes. The comparison shows that sulphates in the sedimentary formations were dissolved by the fluids, which also led to Br enrichment. Mica dissolution has strongly increased the Rb and Cs contents, which then provide an indication of the degree of water-rock interaction. The Sr isotopic ratios are used to compare the fluids with the granite minerals. Two relationships are revealed for the fluids in the sandstone and the granite, one related to widespread mica dissolution, which could have affected both the Buntsandstein and the granite, and the other to subsequent plagioclase dissolution, which is observed only in the granite. Computations showed that 12.5g of mica and 1.65g of plagioclase per liter of fluid have been dissolved. The nature of these two relationships suggests two different evolutions for the fluids and the individualization of the two reservoirs during the graben`s history. The cation concentrations are mainly controlled by temperature, and are independent of the type of host rock. Equilibrium with the rock mainly caused Ca and K concentration variations, which has induced clear Ca-K and Ca-{delta}{sup 18}O, K-{delta}{sup 18}O correlations. Geothermometric computations indicate that with increasing depth, the cations, the silica and the {delta}{sup 18}O (SO{sub 4}) geothermometers evolve towards a value close to 230{degrees}C. This demonstrates the existence of a hot reservoir in the granite of the graben, at a depth estimated at 4.5-5 km. 59 refs., 11 figs., 6 tabs.

  7. Scaling Tendency of Geothermal Waters Armutlu Peninsula, Northwestern Turkey

    NASA Astrophysics Data System (ADS)

    Ertekin, Can

    2015-04-01

    Prediction of scaling tendencies from geothermal waters is important for taking necessary precautions to prevent or control the scale formation. This study contains scaling tendency of geothermal outlets occurring through Armutlu Peninsula in Northwestern Turkey. The E-W trending region stretches into the Marmara Sea (ca. 117 km E-W by 45 km N-S) and is bounded to the north and the south by North Anatolian Fault Zone (NAFZ). The two branches of NAFZ traversing the peninsula control not only active seismicity but also geothermal discharges of the region. Widespread basement rocks across the peninsula including metamorphic assemblage of granitic and volcanic rocks host geothermal fluids. The two distinctive geothermal discharges (Armutlu and Yalova) take place through lineaments appurtenant to the northern branch of NAFZ. Their discharge temperatures of 65 ° C (Yalova) and 70 ° C (Armutlu) are the highest of the region. According to their water chemical results, scaling tendency were computed by using WATCH for different temperature steps under the assumptions of single-stage adiabatic boiling and equilibrium degassing. To evaluate their scaling tendencies, mean geothermal reservoir temperatures were computed by using chemical geothermometers. Scaling tendencies were plotted for calcite, amorphous silica and quartz minerals for different temperature values including reservoir temperatures. Their scaling behavior reveals that oversaturation with calcite and quartz minerals are rapidly attained for the geothermal fluids (Yalova and Armutlu) at relatively lower temperatures. Regarding amorphous silica, they are completely undersaturated. Besides, Langelier Saturation Index (LSI) and Ryznar Stability Index (RSI) were calculated. Their results depict scale formation due to being positive LSI and less than 6.0 of RSI values.

  8. Geospeedometry and the metamorphic history of the Late Cretaceous Chiwaukum Schist, west central Washington state

    SciTech Connect

    Evans, D.A. . Div. of Geological and Planetary Sciences); Lasaga, A.C.; Ague, J.J.; Brandon, M.T. . Dept. of Geology and Geophysics)

    1993-04-01

    The Chiwaukum Schist on the NE side of the Late Cretaceous Mount Stuart batholith (MSB) shows evidence of a low-P contact metamorphism, followed by a higher-P amphibolite-facies regional metamorphism (Evans and Berti, 1986). Samples were collected from this contact zone in order to quantify the time-temperature history of the schist using the geospeedometry method of Lasaga (1983). Pseudomorphic textures and garnet-aluminosilicate-plagioclase (GASP) geobarometry within some samples show an increase in pressure during crystal growth, consistent with the interpretation of Evans and Berti (1986), that regional metamorphism followed intrusion of the MSB. Geospeedometry exploits the kinetics of diffusion associated with the thermo-barometric exchange reactions in order to determine the retrograde cooling history of a metamorphic rock. This technique was applied using Fe-Mg diffusion between garnet and biotite as defined by that geothermometer. Modeling results indicate that the region was exhumed and cooled from about 22 km and 610 C to about 8 km and 525 C, in a period of about 2.5 Myr. The average exhumation rate is 5.6 km/Myr. These results are consistent with existing isotopic ages, which indicate that the northeast MSB was intruded at about 95 Ma (K/Ar hornblende and U/Pb zircon) and that the Chiwaukum Schist cooled through temperatures of about 350 C at 86 to 83 Ma (K/Ar muscovite). Rapid unroofing appears to follow shortly after the climax of crustal thickening within the Cascade metamorphic core and may be related to erosional and/or tectonic denudation within a mountainous collisional orogen.

  9. Thermal maturation of carbonaceous material from Mbuji-Mayi Supergroup (Kasai, Democratic Republic of Congo).

    NASA Astrophysics Data System (ADS)

    Baludikay, Blaise K.; Storme, Jean-Yves; Baudet, Daniel; François, Camille; Javaux, Emmanuelle

    2016-04-01

    The Mbuji-Mayi Supergroup is a sedimentary sequence in DRC unaffected by regional metamorphism. It consists of two distinct successions: a lower, ~500 m thick siliciclastic sequence of the BI Group and an upper, ~1000 m thick carbonate sequence with stromatolitic build-ups and black shales of the BII Group directly overlain by basaltic lavas [1]. Radiometric data suggest a Latest Meso- to Early Neoproterozoic age [2, 3, 4, and 5]. A well preserved and diversified microfossil assemblage is reported including 54 taxa belonging to 32 genera. The potential Late Mesoproterozoic-Tonian index fossil Trachyhystrichosphaera aimika, is reported for the first time in central Africa, and co-occurs with other eukaryotes and prokaryotes [6]. Thermal maturation calculated on macerate residues, using geothermometer for low-grade metamorphism [7] reveals thermal palaeoenvironments of organic matter, ranging from 180 to 279° C (average = 249 ± 37 °C). The range of thermal maturity is similar, in both microfossils and amorphous organic matter. Raman reflectance (RmcRo %), which is also an index indicative of maturity [8], ranges from 1.05 to 2.55 % (average = 2.01 ± 0.42 %). So, organic matter from Mbuji-Mayi is likely into a maturation stage corresponding to oil window. References: [1] Raucq (1957) Ann. MRAC, série 8, Sc. géol. 18, 427. [2] Cahen & Snelling (1966) Publ. C., Amsterdam. [3] Cahen et al. (1984) Clarendon Press, Oxford. [4] Delpomdor et al. (2013) Pal.3 389, 4-34. [5] François et al. (in preparation). [6] Baludikay et al. (in review) Prec. Res. [7] Kouketsu et al. (2014) Island Arc 23, 33-50. [8] Liu et al. (2013) Geochemistry, Chi. Sc. Bul. 58 (11), 1285-1298.

  10. Influence of vegetation type and site-to-site variability on soil carbonate clumped isotope records, Andean piedmont of Central Argentina (32-34°S)

    NASA Astrophysics Data System (ADS)

    Ringham, Mallory C.; Hoke, Gregory D.; Huntington, Katharine W.; Aranibar, Julieta N.

    2016-04-01

    The clumped isotope geothermometer estimates the formation temperature (T (Δ47)) of carbonates and has great potential to enhance the extraction of environmental data from pedogenic (soil) carbonate in the geologic record. However, the influence of vegetation type and site-specific conditions on carbonate formation processes and T (Δ47) records remains poorly understood. This study examines the potential for variability in T (Δ47) data between nearby, same elevation sites with different C3/C4 biomass. Pedogenic carbonates (undercoatings and nodules) were collected from five modern soil pits in the semi-arid eastern Andean piedmont of Argentina under a summer precipitation regime. Three pits were instrumented with temperature and moisture sensors to 1 m depth, and a fourth was instrumented with additional soil CO2 and atmospheric (temperature, relative humidity, insolation, and rainfall) sensors. T (Δ47) values (mean: 30 ± 6 °C (±1SE)) are invariant with depth and are statistically indistinguishable between the four instrumented sites, though a 10 °C difference between our T (Δ47) values and those of a nearby Peters et al. (2013, EPSL) study suggests the potential for significant site-to-site variability, likely due to local soil hydrology. The results of this study suggest that deeper (≥40 cm) T (Δ47) values are consistent with carbonate formation during the early part of soil drying immediately after large mid-summer rainstorms. Carbonate formation ≤ 40 cm depth may be biased to soil drying after small, frequent precipitation events occurring throughout the spring, summer, and fall months, averaging to shallow summer T (Δ47) values and resulting in a near-isothermal T (Δ47) profile.

  11. Geochemical features of the geothermal fluids from the Mapamyum non-volcanic geothermal system (Western Tibet, China)

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Chen, Xiaohong; Shen, Licheng; Wu, Kunyu; Huang, Mingzhi; Xiao, Qiong

    2016-06-01

    Mapamyum geothermal field (MGF) in western Tibet is one of largest geothermal areas characterized by the occurrence of hydrothermal explosions on the Tibetan Plateau. The geochemical properties of hydrothermal water in the MGF system were investigated to trace the origin of the solutes and to determine the equilibrium temperatures of the feeding reservoir. The study results show that the geochemistry of hydrothermal waters in the MGF system is mainly of the Na-HCO3 type. The chemical components of hydrothermal waters are mainly derived from the minerals in the host rocks (e.g., K-feldspar, albite, Ca-montmorillonite, and Mg-montmorillonite). The hydrothermal waters are slightly supersaturated or undersaturated with respect to aragonite, calcite, dolomite, chalcedony and quartz (saturation indices close to 0), but are highly undersaturated with respect to gypsum and anhydrite (saturation indices < 0). Mixing models and Na-K-Mg ternary diagrams show that strong mixing between cold meteoric water and deeply-seated thermal fluids occurred during the upward flowing process. δD and δ18O data confirm that the meteoric water acts as the water source of the geothermal waters. An ~ 220 °C equilibrated reservoir temperature of hydrothermal spring waters was calculated via both the Na-K-Mg ternary diagrams and the cationic chemical geothermometers. The logpCO2 of hydrothermal waters in the MGF system ranges from - 2.59 to - 0.57 and δ13C of the total dissolved inorganic carbon ranges from - 5.53‰ to - 0.94‰, suggesting that the carrier CO2 in hydrothermal water are mainly of a magmatic or metamorphic CO2 origin.

  12. Occurrence of Tourmaline in Metasedimentary Rocks of the Isua Supracrustal Belt, Greenland: Implications for Ribose Stabilization in Hadean Marine Sediments

    NASA Astrophysics Data System (ADS)

    Mishima, Shinpei; Ohtomo, Yoko; Kakegawa, Takeshi

    2016-06-01

    Abiotic formation of RNA was important for the emergence of terrestrial life, but the acknowledged difficulties of generating and stabilizing ribose have often raised questions regarding how the first RNA might have formed. Previous researchers have proposed that borate could have stabilized ribose; however, the availability of borate on the early Earth has been the subject of intense debate. In order to examine whether borate was available on the early Earth, this study examined metasedimentary rocks from the Isua Supracrustal Belt. Garnet, biotite, and quartz comprise the major constituents of the examined rocks. Field relationships and the chemical compositions of the examined rocks suggest sedimentary origin. The present study found that garnet crystals contain a number of inclusions of tourmaline (a type of borosilicate mineral). All tourmaline crystals are Fe-rich and categorized as schorl. Both garnet and tourmaline often contain graphite inclusions and this close association of tourmaline with garnet and graphite has not been recognized previously. Garnet-biotite and graphite geothermometers suggest that the tourmaline in garnet experienced peak metamorphic conditions (~500 °C and 5 kbar). The mineralogical characteristics of the tourmaline and the whole rock composition indicate that the tourmaline formed authigenically in the sediment during diagenesis and/or early metamorphism. Clay minerals in modern sediments have the capability to adsorb and concentrate borate, which could lead to boron enrichment during diagenesis, followed by tourmaline formation under metamorphic conditions. Clay minerals, deposited on the early Archean seafloor, were the precursors of the garnet and biotite in the examined samples. The studied tourmaline crystals were most likely formed in the same way as modern tourmaline in marine sediments. Therefore, boron enrichment by clays must have been possible even during the early Archean. Thus, similar enrichment could have been

  13. Occurrence of Tourmaline in Metasedimentary Rocks of the Isua Supracrustal Belt, Greenland: Implications for Ribose Stabilization in Hadean Marine Sediments.

    PubMed

    Mishima, Shinpei; Ohtomo, Yoko; Kakegawa, Takeshi

    2016-06-01

    Abiotic formation of RNA was important for the emergence of terrestrial life, but the acknowledged difficulties of generating and stabilizing ribose have often raised questions regarding how the first RNA might have formed. Previous researchers have proposed that borate could have stabilized ribose; however, the availability of borate on the early Earth has been the subject of intense debate. In order to examine whether borate was available on the early Earth, this study examined metasedimentary rocks from the Isua Supracrustal Belt. Garnet, biotite, and quartz comprise the major constituents of the examined rocks. Field relationships and the chemical compositions of the examined rocks suggest sedimentary origin. The present study found that garnet crystals contain a number of inclusions of tourmaline (a type of borosilicate mineral). All tourmaline crystals are Fe-rich and categorized as schorl. Both garnet and tourmaline often contain graphite inclusions and this close association of tourmaline with garnet and graphite has not been recognized previously. Garnet-biotite and graphite geothermometers suggest that the tourmaline in garnet experienced peak metamorphic conditions (~500 °C and 5 kbar). The mineralogical characteristics of the tourmaline and the whole rock composition indicate that the tourmaline formed authigenically in the sediment during diagenesis and/or early metamorphism. Clay minerals in modern sediments have the capability to adsorb and concentrate borate, which could lead to boron enrichment during diagenesis, followed by tourmaline formation under metamorphic conditions. Clay minerals, deposited on the early Archean seafloor, were the precursors of the garnet and biotite in the examined samples. The studied tourmaline crystals were most likely formed in the same way as modern tourmaline in marine sediments. Therefore, boron enrichment by clays must have been possible even during the early Archean. Thus, similar enrichment could have been

  14. Water geochemistry of the Lucero Uplift, New Mexico: geothermal investigation of low-temperature mineralized fluids

    SciTech Connect

    Goff, F.; McCormick, T.; Gardner, J.N.; Trujillo, P.E.; Counce, D.; Vidale, R.; Charles, R.

    1983-04-01

    A detailed geochemical investigation of 27 waters of the Lucero uplift, central New Mexico, was performed to determine if the fluids originate from a high-temperature geothermal system along the Rio Grande rift. Two types of mineralized water issue from the Lucero region: a relatively saline (high-Cl, high-SO/sub 4/) type and a relatively dilute (low-Cl, high-SO/sub 4/) type. Emergence temperatures of both types range from 12 to 26/sup 0/C. Chemical data and thermodynamic and geothermometer calculations all indicate that both water types are in equilibrium with carbonate and evaporite minerals found in local Colorado Plateau rocks at surface temperatures or slightly higher. Stable isotope data do not indicate high-temperature rock-water interaction. Although evidence is seen for mixing between mineralized waters and dilute surface waters, no evidence for mixing of a deep hot fluid and surface waters is seen. Dilute mineral waters, which issue from a large area of Chinle Formation on the west side of the Lucero uplift, may be useful for low-temperature geothermal applications with appropriate design of equipment. Saline mineral waters, which leak from a zone of faulted and folded rocks along the Comanche fault zone, do not appear to have much, if any, geothermal potential due to their low-temperature, restricted distribution, and high concentration of dissolved solids. No evidence that saline mineral waters are associated with Quaternary faults of the Rio Grande rift or Quaternary basaltic volcanism within the immediate area is seen.

  15. Session 10: The Cerro Prieto Geothermal Field, Mexico: The Experiences Gained from Its Exploration and Development

    SciTech Connect

    Lippman, M.J.; Goldstein, N.E.; Halfman, S.E.; Witherspoon, P.A.

    1983-12-01

    The Cerro Prieto case study demonstrated the value of a multidisciplinary effort for exploring and developing a geothermal field. There was no problem in recognizing the geothermal potential of the Cerro Prieto area because of the many obvious surface manifestations. However, the delineation of the geothermal reservoir at depth was not so straightforward. Wells drilled near the abundant surface manifestations only produced fluids of relatively low enthalpy. Later it was determined that these zones of high heat loss corresponded to discharge areas where faults and fractures allowed thermal fluids to leak to the surface, and not to the main geothermal reservoir. The early gravity and seismic refraction surveys provided important information on the general structure of the area. Unaware of the existence of a higher density zone of hydrothermally altered sediments capping the geothermal reservoir, CFE interpreted a basement horst in the western part of the field and hypothesized that the bounding faults were controlling the upward flow of thermal fluids. Attempting to penetrate the sedimentary column to reach the ''basement horst'', CFE discovered the {alpha} geothermal reservoir (in well M-5). The continuation of the geothermal aquifer (actually the {beta} reservoir) east of the original well field was later confirmed by a deep exploration well (M-53). The experience of Cerro Prieto showed the importance of chemical ratios, and geothermometers in general, in establishing the subsurface temperatures and fluid flow patterns. Fluid chemical and isotopic compositions have also been helpful to determine the origin of the fluids, fluid-production mechanisms and production induced effects on the reservoir.

  16. New geochemical and isotopic insights to evaluate the geothermal resource of the hydrothermal system of Rosario de la Frontera (Salta, northern Argentina)

    NASA Astrophysics Data System (ADS)

    Chiodi, A.; Tassi, F.; Báez, W.; Maffucci, R.; Invernizzi, C.; Giordano, G.; Corrado, S.; Bicocchi, G.; Vaselli, O.; Viramonte, J. G.; Pierantoni, P. P.

    2015-03-01

    In this study, the chemical and isotopic composition of thermo-mineral springs from the Rosario de la Frontera hydrothermal system was used to construct a conceptual model describing the source regions the thermal fluids and the chemical-physical processes controlling the chemistry of waters and dissolved gases during their underground circulation. The main hydrothermal reservoir, hosted within the Cretaceous Pirgua Subgroup deposits, is fed by meteoric water and shows a Na-HCO3 composition produced by water-rock interactions involving sedimentary formations mostly consisting of conglomerates and sandstones, which are interbedded with alkaline volcanic rocks and shales and limestone deposits. This aquifer also receives significant contributions of crustal CO2 and He from mantle degassing, the latter being likely favored by the regional tectonic assessment that is characterized by a deep detachment (at about 10 km depth) in the basement of the Santa Bárbara thick-skinned thrust system and a thinned lithosphere. The uprising thermal fluids mix with a relatively high salinity Na-Cl dominated aquifer produced by the interaction of meteoric water with the Tertiary Anta Formation evaporite. The temperatures of the hydrothermal reservoir, estimated with water geothermometers, are up to 130 °C, which are consistent with the thickness of the hydrothermal circuit (2700-3000 m) and the relatively high local geothermal gradient (~ 40 °C/km). These results suggest that the heat stored in the fluid phase of RFHS is up to ~ 1 × 1018 J, a value significantly higher (20%) than that previously estimated assuming an average reservoir temperature of 90 °C.

  17. Geothermal GIS coverage of the Great Basin, USA: Defining regional controls and favorable exploration terrains

    USGS Publications Warehouse

    Coolbaugh, M.F.; Sawatzky, D.L.; Oppliger, G.L.; Minor, T.B.; Raines, G.L.; Shevenell, L.; Blewitt, G.; Louie, J.N.

    2003-01-01

    A geographic information system (GIS) of geothermal resources, built last year for the state of Nevada, is being expanded to cover the Great Basin, USA. Data from that GIS is being made available to industry, other researchers, and the public via a web site at the Great Basin Center for Geothermal Energy, Reno, Nevada. That web site features a search engine, supports ArcExplorer?? for on-line map construction, and provides downloadable data layers in several formats. Though data collection continues, preliminary analysis has begun. Contour maps of geothermal temperatures, constructed using geothermometer temperatures calculated from a Great Basin geochemical database compiled by the Geo-Heat Center, reveal distinctive trends and patterns. As expected, magmatic-type and extensional-type geothermal systems have profoundly different associations, with magmatic-type systems following major tectonic boundaries, and extensional-type systems associating with regionally high heat flow, thin crust, active faulting, and high extensional strain rates. As described by earlier researchers, including Rowen and Wetlaufer (1981) and Koenig and McNitt (1983), high-temperature (> 100??C) geothermal systems appear to follow regional northeast trends, most conspicuously including the Humboldt structural zone in Nevada, the "Black Rock-Alvord Desert" trend in Oregon and Nevada, and the "Newcastle-Roosevelt" trend in Utah and Nevada. Weights-of-evidence analyses confirm a preference of high-temperature geothermal systems for young northeast-trending faults, but the distribution of geothermal systems correlates even better with high rates of crustal extension, as measured from global positioning system (GPS) stations in Nevada. A predictive map of geothermal potential based only on areas of high extensional strain rates and high heat flux does an excellent job of regionally predicting the location of most known geothermal systems in Nevada, and may prove useful in identifying blind

  18. Deciphering the thermal and mixing history of the Pleistocene rhyolite magma chamber at Augustine Volcano

    NASA Astrophysics Data System (ADS)

    Nadeau, P. A.; Webster, J. D.; Mandeville, C. W.; Monteleone, B.; Shimizu, N.; Goldoff, B. A.

    2015-12-01

    Recent activity at Augustine Volcano, located in Cook Inlet, Alaska, has been dominated by intermediate composition lavas and relatively small explosions. Earlier in Augustine's history, however, a thick (~30 m) rhyolite fall was erupted ca. 25 ka, containing at least three distinct rhyolite lithologies. Numerous studies have documented evidence of magma mixing in the more recently-erupted material. Here we attempt to evaluate similar mixing events that may have affected the 25 ka rhyolitic magma prior to its eruption. Basaltic to basaltic-andesitic deposits are found interbedded with the rhyolite at Augustine, so at least two magmas were present in Augustine's plumbing system at the same or nearly the same time. Hints at interactions between two or more magmas are also evident on a smaller scale. Xenocrysts of olivine and clinopyroxene are present in the rhyolite, each with mafic melt inclusions. Additionally, two of the three rhyolitic lithologies studied contain high-aluminum amphiboles that are compositionally similar to amphiboles from mafic enclaves entrained during the 2006 eruption and thus may be xenocrystic. To further investigate possible heating by secondary melts and the history of mixing, we use the titanium-in-quartz geothermometer (TitaniQ) on chemical zonation in quartz phenocrysts. We find that most quartz has a distinct 3-zone pattern, though one lithology also contains some complex zoning patterns in phenocryst cores, perhaps suggesting a xenocrystic origin. Additionally, we examine relationships between trace elements in the silicate melt inclusions from a variety of phenocryst types to determine if there is evidence for input of additional magma of different compositions. Finally, we apply results of a preliminary investigation of the mineralogy of a high-phosphorus dacite that stratigraphically overlies the rhyolite to assess their similarity and the degree of mixing, if any, that may have led to the transition from rhyolitic to dacitic magma.

  19. Thermally induced cation redistribution in Fe-bearing oxy-dravite and potential geothermometric implications

    NASA Astrophysics Data System (ADS)

    Bosi, Ferdinando; Skogby, Henrik; Hålenius, Ulf

    2016-05-01

    Iron-bearing oxy-dravite was thermally treated in air and hydrogen atmosphere at 800 °C to study potential changes in Fe, Mg and Al ordering over the octahedrally coordinated Y and Z sites and to explore possible applications to intersite geothermometry based on tourmaline. Overall, the experimental data (structural refinement, Mössbauer, infrared and optical absorption spectroscopy) show that heating Fe-bearing tourmalines results in disordering of Fe over Y and Z balanced by ordering of Mg at Y, whereas Al does not change appreciably. The Fe disorder depends on temperature, but less on redox conditions. The degree of Fe3+-Fe2+ reduction is limited despite strongly reducing conditions, indicating that the f O2 conditions do not exclusively control the Fe oxidation state at the present experimental conditions. Untreated and treated samples have similar short- and long-range crystal structures, which are explained by stable Al-extended clusters around the O1 and O3 sites. In contrast to the stable Al clusters that preclude any temperature-dependent Mg-Al order-disorder, there occurs Mg diffusion linked to temperature-dependent exchange with Fe. Ferric iron mainly resides around O2- at O1 rather than (OH)-, but its intersite disorder induced by thermal treatment indicates that Fe redistribution is the driving force for Mg-Fe exchange and that its diffusion rates are significant at these temperatures. With increasing temperature, Fe progressively disorders over Y and Z, whereas Mg orders at Y according to the order-disorder reaction: YFe + ZMg → ZFe + YMg. The presented findings are important for interpretation of the post-crystallization history of both tourmaline and tourmaline host rocks and imply that successful tourmaline geothermometers may be developed by thermal calibration of the Mg-Fe order-disorder reaction, whereas any thermometers based on Mg-Al disorder will be insensitive and involve large uncertainties.

  20. Rare-element granitic pegmatite of Miocene age emplaced in UHP rocks from Visole, Pohorje Mountains (Eastern Alps, Slovenia): accessory minerals, monazite and uraninite chemical dating

    NASA Astrophysics Data System (ADS)

    Uher, Pavel; Janák, Marian; Konečný, Patrik; Vrabec, Mirijam

    2014-04-01

    The granitic pegmatite dike intruded the Cretaceous UHP rocks at Visole, near Slovenska Bistrica, in the Pohorje Mountains (Slovenia). The rock consists mainly of K-feldspar, albite and quartz, subordinate muscovite and biotite, while the accessory minerals include spessartine-almandine, zircon, ferrocolumbite, fluorapatite, monazite- (Ce), uraninite, and magnetite. Compositions of garnet (Sps48-49Alm45-46Grs + And3-4 Prp1.5-2), metamict zircon with 3.5 to 7.8 wt. % HfO2 [atom. 100Hf/(Hf + Zr) = 3.3-7.7] and ferrocolumbite [atom. Mn/(Mn + Fe) = 0.27-0.43, Ta/(Ta + Nb) = 0.03-0.46] indicate a relatively low to medium degree of magmatic fractionation, characteristic of the muscovite - rare-element class or beryl-columbite subtype of the rare-element class pegmatites. Monazite-(Ce) reveals elevated Th and U contents (≤11 wt. % ThO2, ≤5 wt. % UO2). The monazite-garnet geothermometer shows a possible precipitation temperature of ~495 ± 30 °C at P~4 to 5 kbar. Chemical U-Th-Pb dating of the monazite yielded a Miocene age (17.2 ± 1.8 Ma), whereas uraninite gave a younger (~14 Ma) age. These ages are comtemporaneous with the main crystallization and emplacement of the Pohorje pluton and adjacent volcanic rocks (20 to 15 Ma), providing the first documented evidence of Neogene granitic pegmatites in the Eastern Alps. Consequently, the Visole pegmatite belongs to the youngest rare-element granitic pegmatite populations in Europe, together with the Paleogene pegmatite occurrences along the Periadriatic (Insubric) Fault System in the Alps and in the Rhodope Massif, as well as the Late Miocene to Pliocene pegmatites in the Tuscany magmatic province (mainly on the Island of Elba).

  1. Fluid inclusion gas chemistry as a potential minerals exploration tool: Case studies from Creede, CO, Jerritt Canyon, NV, Coeur d'Alene district, ID and MT, southern Alaska mesothermal veins, and mid-continent MVT's

    USGS Publications Warehouse

    Landis, G.P.; Hofstra, A.H.

    1991-01-01

    Recent advances in instrumentation now permit quantitative analysis of gas species from individual fluid inclusions. Fluid inclusion gas data can be applied to minerals exploration empirically to establish chemical (gas composition) signatures of the ore fluids, and conceptually through the development of genetic models of ore formation from a framework of integrated geologic, geochemical, and isotopic investigations. Case studies of fluid inclusion gas chemistry from ore deposits representing a spectrum of ore-forming processes and environments are presented to illustrate both the empirical and conceptual approaches. We consider epithermal silver-gold deposits of Creede, Colorado, Carlin-type sediment-hosted disseminated gold deposits of Jerritt Canyon, Nevada, metamorphic silver-base-metal veins of the Coeur d'Alene district, Idaho and Montana, gold-quartz veins in accreted terranes of southern Alaska, and the mid-continent base-metal sulfide deposits of Mississippi Valley-Type (MVT's). Variations in gas chemistry determine the redox state of the ore fluids, provide compositional input for gas geothermometers, characterize ore fluid chemistry (e.g., CH4CO2, H2SSO2, CO2/H2S, organic-rich fluids, gas-rich and gas-poor fluids), identify magmatic, meteoric, metamorphic, shallow and deep basin fluids in ore systems, locate upwelling plumes of magmatic-derived volatiles, zones of boiling and volatile separation, interfaces between contrasting fluids, and important zones of fluid mixing. Present techniques are immediately applicable to exploration programsas empirical studies that monitor fluid inclusion gas threshold concentration levels, presence or absence of certain gases, or changes in gas ratios. We suggest that the greater contribution of fluid inclusion gas analysis is in the integrated and comprehensive chemical dimension that gas data impart to genetic models, and in the exploration concepts based on processes and environments of ore formation derived from

  2. Hydrogeochemical characteristics and genetic implications of Edipsos thermal springs, north Euboea, Greece

    NASA Astrophysics Data System (ADS)

    Kelepertsis, Akindynos; Tziritis, Evangelos; Kelepertzis, Eustratios; Leontakianakos, Giorgos; Pallas, Kostas

    2009-09-01

    Edipsos area, situated in northern Euboea, has been well known since ancient times for the existence of thermal springs. In order to assess the hydrogeochemical conditions, thermal and cold water samples were collected and analyzed by ICP method for major and trace elements. The results revealed the direct impact of seawater, a process which is strongly related to the major tectonic structures of the area. Seawater impact was confirmed by the Cl/Br and Na/Cl ionic ratios, as well as from statistical processing and graphical interpretation of the analytical results, which classified the sampled waters into three groups (two for cold waters and one for the thermal ones). Trace element ranges for thermal waters are: As (44-84 ppb), Pb (23-154 ppb), Ag (1-2 ppb), Mn (31-680 ppb), Cu (61-97 ppb), Cs (66-244 ppb), Se (0-76 ppb), Li (732-3269 ppb), Fe (0-1126 ppb), Sr (14000-34100 ppb), B (4300-9600 ppb). Compared with the chemical composition of other thermal springs from the Hellenic Volcanic Arc, Edipsos thermal waters are enriched in Ca2+, Na+, Cl-, SO4 2-, Li, B and K+, reflecting the influence from seawater. Cold waters are free of heavy metals compared with other natural waters and are characterized by good quality based on the major element chemistry. Finally, several geothermometers were applied in order to assess the reservoir temperatures, but none of them appear to be applicable, mainly due to the impact of seawater on the initial hydrogeochemistry of the geothermal fluids.

  3. Hydrochemistry and geothermometrical modeling of low-temperature Panticosa geothermal system (Spain)

    NASA Astrophysics Data System (ADS)

    Asta, Maria P.; Gimeno, Maria J.; Auqué, Luis F.; Gómez, Javier; Acero, Patricia; Lapuente, Pilar

    2012-08-01

    The chemical characteristics of the low-temperature geothermal system of Panticosa (Spain) were investigated in order to determine the water temperature at the reservoir and to identify the main geochemical processes that affect the water composition during the ascent of the thermal waters. In general, the studied waters are similar to other geothermal systems in the Pyrenees, belonging to the group of granite-related alkaline thermal waters (high pH, low total dissolved solids, very low magnesium concentration, and sodium as the dominant cation). According to the alkaline pH of these waters, they have a very low CO2 partial pressure, bicarbonate is the dominant anion and silica is partially ionized as H3SiO4-. The unusually active acid-base pairs (HCO3-/CO32 - and, mainly, H4SiO4/H3SiO4-) act as homogeneous pH buffers and contribute to the total alkalinity in these alkaline waters. On the basis of the study of the conservative elements, a mixing process between a hot and a cold end-member has been identified. Additionally, in order to determinate the water temperature at the reservoir, several geothermometric techniques have been applied, including both geothermometrical modeling and classical geothermometrical calculations. The geothermometrical modeling seems to indicate that thermal waters re-equilibrate with respect to calcite and kaolinite during their ascent to the surface. Modeling results suggest that these thermal waters would be in equilibrium with respect to albite, K-feldspar, quartz, calcite, kaolinite and zoisite at a similar temperature of 90 ± 20 °C in the reservoir, which is in good agreement with the results obtained by applying the classical geothermometers.

  4. Constraints of C-O-S isotope compositions and the origin of the Ünlüpınar volcanic-hosted epithermal Pb-Zn ± Au deposit, Gümüşhane, NE Turkey

    NASA Astrophysics Data System (ADS)

    Akaryali, Enver; Akbulut, Kübra

    2016-03-01

    The Eastern Pontide Orogenic Belt (EPOB) constitutes one of the best examples of the metallogenic provinces in on the Alpine-Himalayan belt. This study focuses on the genesis of the Ünlüpınar Pb-Zn ± Au deposit in the southern part of the Eastern Pontide Orogenic Belt. The main lithological units in the study area are the Early Carboniferous Kurtoğlu Metamorphic Complex the Late Carboniferous Köse Granitoid and the Early-Middle Jurassic Şenköy Formation. The studied deposit is hosted by the Şenköy Formation, which consists predominantly of basaltic-andesitic rocks and associated pyroclastic rocks that are calc-alkaline in composition. Silicic, sulfidic, argillic, chloritic, hematitic, carbonate and limonite are the most obvious alteration types observed in the deposit site. Ore microscopy studies exhibit that the mineral paragenesis in deposits includes pyrite, chalcopyrite, sphalerite, galena, gold, quartz and calcite. Electron microprobe analyses conducted on sphalerite indicate that the Zn/Cd ratio varies between 84 and 204, and these ratios point at a hydrothermal deposit related to granitic magmas. Fluid inclusion studies in calcite and quartz show that the homogenization temperature of the studied deposit ranges between 90-160 °C and 120-330 °C respectively. The values of sulfur isotope analysis of pyrite, sphalerite and galena minerals vary between 1.6‰ and 5.7‰, and the results of oxygen and carbon isotope analysis range between 8.4‰ and 18‰ and -5‰ and -3.6‰, respectively. The average formation temperature of the ore was calculated as 264 °C with a sulfur isotope geothermometer. All of the data indicate that the Ünlüpınar deposit is an epithermal vein-type mineralization that was formed depending on the granitic magmatism.

  5. The bulk isotopic composition of hydrocarbons in subaerial volcanic-hydrothermal emissions from different tectonic settings

    NASA Astrophysics Data System (ADS)

    Fiebig, J.; Tassi, F.; Vaselli, O.; Viveiros, M. F.; Silva, C.; Lopez, T. M.; D'Alessandro, W.; Stefansson, A.

    2015-12-01

    Assuming that methane and its higher chain homologues derive from a common source, carbon isotope patterns have been applied as a criterion to identify occurrences of abiogenic hydrocarbons. Based on these, it has been postulated that abiogenic hydrocarbon production occurs within several (ultra)mafic environments. More evolved volcanic-hydrothermal systems may also provide all the prerequisites necessary for abiogenic hydrocarbon production, such as availability of inorganic CO2, hydrogen and heat. We have investigated the chemical and isotopic composition of n-alkanes contained within subaerial hydrothermal discharges emitted from a range of hot spot, subduction and rift-related volcanoes to determine the origin of hydrocarbons in these systems. Amongst these are Nisyros (Greece), Vesuvio, Campi Flegrei, Ischia, Pantelleria and Vulcano (all Italy), Mt. Mageik and Trident (USA), Copahue (Argentina), Teide (Spain), Furnas and Fogo (Portugal). The carbon isotopic composition of methane emitted from these sites varies from -65 to -8‰ , whereas δ13C of ethane and propane exhibit a much narrower variation from -17‰ to -31‰. Methane that occurs most enriched in 13C is also characterized by relatively positive δD values ranging up to -80‰. Carbon isotope reversals between methane and ethane are only observed for locations exhibiting δ13C-CH4 values > -20‰, such as Teide, Pantelleria, Trident and Furnas. At Furnas, δ13C-CH4 varies by 50‰ within a relatively short distance of <50m between two vents, whereas δ13C-C2H6 varies by less than 2‰ only. For some of the investigated locations apparent carbon isotopic temperatures between methane and CO2 are in agreement with those derived from gas concentration geothermometers. At these locations methane, however seems to be in disequilibrium with ethane and propane. These findings imply that methane on the one hand and the C2+ hydrocarbons on the other hand often might derive from distinct sources.

  6. Development of the archean crust in the medina mountain area, wind river range, wyoming (U.S.A.)

    USGS Publications Warehouse

    Koesterer, M.E.; Frost, C.D.; Frost, B.R.; Hulsebosch, T.P.; Bridgwater, D.; Worl, R.G.

    1987-01-01

    Evidence for an extensive Archean crustal history in the Wind River Range is preserved in the Medina Mountain area in the west-central part of the range. The oldest rocks in the area are metasedimentary, mafic, and ultramafic blocks in a migmatite host. The supracrustal rocks of the Medina Mountain area (MMS) are folded into the migmatites, and include semi-pelitic and pelitic gneisses, and mafic rocks of probable volcanic origin. Mafic dikes intrude the older migmatites but not the MMS, suggesting that the MMS are distinctly younger than the supracrustal rocks in the migmatites. The migmatites and the MMS were engulfed by the late Archean granite of the Bridger, Louis Lake, and Bears Ears batholiths, which constitutes the dominant rock of the Wind River Range. Isotopic data available for the area include Nd crustal residence ages from the MMS which indicate that continental crust existed in the area at or before 3.4 Ga, but the age of the older supracrustal sequence is not yet known. The upper age of the MMS is limited by a 2.7 Ga RbSr age of the Bridger batholith, which was emplaced during the waning stages of the last regional metamorphism. The post-tectonic Louis Lake and Bears Ears batholiths have ages of 2.6 and 2.5 Ga, respectively (Stuckless et al., 1985). At least three metamorphic events are recorded in the area: (1) an early regional granulite event (M1) that affected only the older inclusions within the migmatites, (2) a second regional amphibolite event (M2) that locally reached granulite facies conditions, and (3) a restricted, contact granulite facies event (M3) caused by the intrusion of charnockitic melts associated with the late Archean plutons. Results from cation exchange geobarometers and geothermometers yield unreasonablu low pressures and temperatures, suggesting resetting during the long late Archean thermal evenn. ?? 1987.

  7. Generation and evolution of hydrothermal fluids at Yellowstone: Insights from the Heart Lake Geyser Basin

    NASA Astrophysics Data System (ADS)

    Lowenstern, J. B.; Bergfeld, D.; Evans, W. C.; Hurwitz, S.

    2012-01-01

    We sampled fumaroles and hot springs from the Heart Lake Geyser Basin (HLGB), measured water and gas discharge, and estimated heat and mass flux from this geothermal area in 2009. The combined data set reveals that diverse fluids share an origin by mixing of deep solute-rich parent water with dilute heated meteoric water, accompanied by subsequent boiling. A variety of chemical and isotopic geothermometers are consistent with a parent water that equilibrates with rocks at 205°C ± 10°C and then undergoes 21% ± 2% adiabatic boiling. Measured diffuse CO2 flux and fumarole compositions are consistent with an initial dissolved CO2 concentration of 21 ± 7 mmol upon arrival at the caldera boundary and prior to southeast flow, boiling, and discharge along the Witch Creek drainage. The calculated advective flow from the basin is 78 ± 16 L s-1of parent thermal water, corresponding to 68 ± 14 MW, or ˜1% of the estimated thermal flux from Yellowstone. Helium and carbon isotopes reveal minor addition of locally derived crustal, biogenic, and meteoric gases as this fluid boils and degasses, reducing the He isotope ratio (Rc/Ra) from 2.91 to 1.09. The HLGB is one of the few thermal areas at Yellowstone that approaches a closed system, where a series of progressively boiled waters can be sampled along with related steam and noncondensable gas. At other Yellowstone locations, steam and gas are found without associated neutral Cl waters (e.g., Hot Spring Basin) or Cl-rich waters emerge without significant associated steam and gas (Upper Geyser Basin).

  8. High-temperature carbonate minerals in the Stillwater Complex, Montana, USA

    NASA Astrophysics Data System (ADS)

    Aird, Hannah M.; Boudreau, Alan E.

    2013-10-01

    High-temperature carbonate minerals have been observed in association with sulfide minerals below the platiniferous Johns-Manville (J-M) reef of the Stillwater Complex in a stratigraphic section that has been previously shown to be characterized by unusually Cl-rich apatite. The carbonate assemblage consists of dolomite with exsolved calcite in contact with sulfide minerals: chalcopyrite and pyrrhotite in the Peridotite Zone; and pyrrhotite with pentlandite, pyrite and chalcopyrite in Gabbronorite Zone I of the Lower Banded Series. A reaction rim surrounds the carbonate-sulfide assemblages, showing an alteration of the host orthopyroxene to a more calcium-enriched, Fe-depleted pyroxene. The calcite-dolomite geothermometer yields a minimum formation temperature as high as 950 °C for the unmixed assemblages. Iron and manganese concentrations exceed the range seen in carbonatite and mantle xenolith carbonates and are distinctly different from the nearly pure end-member carbonates associated with greenschist-grade (and lower) assemblages (e.g., carbonate veins in serpentinite) that occur locally throughout the complex. The association of high-temperature carbonates with sulfides beneath the J-M reef supports the hydromagmatic theory which involves a late-stage chloride-carbonate fluid percolating upwards, dissolving PGE and sulfides and redepositing them at a higher stratigraphic level. Characterization of the processes which form strategically important metal deposits, such as the J-M reef of the Stillwater Complex and the analogous Merensky reef of the Bushveld Complex in South Africa, could potentially lead to better exploration models and, more broadly, a deeper understanding of the cooling and compositional evolution of large bodies of ultramafic and mafic magma and of carbonatites, on both a local and a regional scale.

  9. Equilibrium Iron Isotope Fractionation Factors of Minerals: Reevaluation from the Data of Nuclear Inelastic Resonant X-ray Scattering and Mossbauer Spectroscopy

    SciTech Connect

    Polyakov, Dr. V. B.; Clayton, R. N.; Horita, Juske; Mineev, S. D.

    2007-01-01

    We have critically reevaluated equilibrium iron isotope fractionation factors for oxide and sulfide minerals using recently acquired data obtained by Moessbauer spectroscopy and inelastic nuclear resonant X-ray scattering (INRXS) synchrotron radiation. Good agreement was observed in the iron {beta}-factors of metallic iron ({alpha}-Fe) and hematite calculated using both Moessbauer- and INRXS-derived data, which supports the validity and reliability of the calculations. Based on this excellent agreement, we suggest the use of the present data on the iron {beta}-factors of hematite as a reference. The previous Moessbauer-derived iron {beta}-factor for magnetite has been modified significantly based on the Fe-sublattice density of states obtained from the INRXS experiments. This resolves the disagreement between naturally observed iron isotope fractionation factors for mineral pairs involving magnetite and those obtained from the calculated {beta}-factors. The correctness of iron {beta}-factor for pyrite has been corroborated by the good agreement with experimental data of sulfur isotope geothermometers of pyrite-galena and pyrite-sphalerite. A good correlation between the potential energy of the cation site, the oxidation state of iron and the iron {beta}-factor value has been established. Specifically, ferric compounds, which have a higher potential energy of iron than ferrous compounds, have higher {beta}-factors. A similar dependence of b-factors on the oxidation state and potential energy could be extended to other transition metals. Extremely low values of INRXS-derived iron {beta}-factors for troilite and Fe{sub 3}S significantly widen the range of iron b-factors for covalently bonded compounds.

  10. Trace and minor elements in sphalerite from metamorphosed sulphide deposits

    NASA Astrophysics Data System (ADS)

    Lockington, Julian A.; Cook, Nigel J.; Ciobanu, Cristiana L.

    2014-12-01

    Sphalerite is a common sulphide and is the dominant ore mineral in Zn-Pb sulphide deposits. Precise determination of minor and trace element concentrations in sulphides, including sphalerite, by Laser-Ablation Inductively-Coupled-Plasma Mass-Spectrometry (LA-ICP-MS) is a potentially valuable petrogenetic tool. In this study, LA-ICP-MS is used to analyse 19 sphalerite samples from metamorphosed, sphalerite-bearing volcanic-associated and sedimentary exhalative massive sulphide deposits in Norway and Australia. The distributions of Mn, Fe, Co, Cu, Ga, Se, Ag, Cd, In, Sn, Sb, Hg, Tl, Pb and Bi are addressed with emphasis on how concentrations of these elements vary with metamorphic grade of the deposit and the extent of sulphide recrystallization. Results show that the concentrations of a group of trace elements which are believed to be present in sphalerite as micro- to nano-scale inclusions (Pb, Bi, and to some degree Cu and Ag) diminish with increasing metamorphic grade. This is interpreted as due to release of these elements during sphalerite recrystallization and subsequent remobilization to form discrete minerals elsewhere. The concentrations of lattice-bound elements (Mn, Fe, Cd, In and Hg) show no correlation with metamorphic grade. Primary metal sources, physico-chemical conditions during initial deposition, and element partitioning between sphalerite and co-existing sulphides are dominant in defining the concentrations of these elements and they appear to be readily re-incorporated into recrystallized sphalerite, offering potential insights into ore genesis. Given that sphalerite accommodates a variety of trace elements that can be precisely determined by contemporary microanalytical techniques, the mineral has considerable potential as a geothermometer, providing that element partitioning between sphalerite and coexisting minerals (galena, chalcopyrite etc.) can be quantified in samples for which the crystallization temperature can be independently

  11. Equilibrium thermodynamics of multiply substituted isotopologues of molecular gases

    NASA Astrophysics Data System (ADS)

    Wang, Zhengrong; Schauble, Edwin A.; Eiler, John M.

    2004-12-01

    Isotopologues of molecular gases containing more than one rare isotope (multiply substituted isotopologues) can be analyzed with high precision (1σ <0.1 ‰), despite their low natural abundances (˜ ppm to ppt in air), and can constrain geochemical budgets of natural systems. We derive a method for calculating abundances of all such species in a thermodynamically equilibrated population of isotopologues, and present results of these calculations for O 2, CO, N 2, NO, CO 2, and N 2O between 1000 and 193 to 77 K. In most cases, multiply substituted isotopologues are predicted to be enriched relative to stochastic (random) distributions by ca. 1 to 2 ‰ at earth-surface temperatures. This deviation, defined as Δ i for isotopologue i, generally increases linearly with 1/T at temperatures ≤ 500 K. An exception is N 2O, which shows complex temperature dependences and 10's of per-mill enrichments or depletions of abundances for some isotopologues. These calculations provide a basis for discriminating between fractionations controlled by equilibrium thermodynamics and other sorts of isotopic fractionations in the budgets of atmospheric gases. Moreover, because abundances of multiply substituted isotopologues in thermodynamically equilibrated populations of molecules vary systematically with temperature, they can be used as geothermometers. Such thermometers are unusual in that they involve homogeneous rather than heterogeneous equilibria (e.g., isotopic distribution in gaseous CO 2 alone, rather than difference in isotopic composition between CO 2 and coexisting water). Also, multiple independent thermometers exist for all molecules having more than one multiply substituted isotopologue (e.g., thermometers based on abundances of 18O 13C 16O and 18O 12C 18O are independent); thus, temperatures estimated by this method can be tested for internal consistency.

  12. A geochemical model of the Platanares geothermal system, Honduras

    USGS Publications Warehouse

    Janik, C.J.; Truesdell, A.H.; Goff, F.; Shevenell, L.; Stallard, M.L.; Trujillo, P.E., Jr.; Counce, D.

    1991-01-01

    Results of exploration drilling combined with results of geologic, geophysical, and hydrogeochemical investigations have been used to construct a geochemical model of the Platanares geothermal system, Honduras. Three coreholes were drilled, two of which produced fluids from fractured Miocene andesite and altered Cretaceous to Eocene conglomerate at 450 to 680 m depth. Large volume artesian flows of 160-165??C, predominantly bicarbonate water are chemically similar to, but slightly less saline than widespread boiling hot-spring waters. The chemistry of the produced fluid is dominated by equilibrium reactions in sedimentary rocks at greater depths and higher temperatures than those measured in the wells. Chemical, isotope, and gas geothermometers indicate a deep fluid temperature of 200-245??C and reflect a relatively short residence time in the fractures feeding the wells. Chloride-enthalpy relations as well as isotopic and chemical compositions of well discharges, thermal springs, and local cold waters support a conceptual model of ascending high-temperature (minimum 225??C) parent fluid that has cooled conductively to form the 160-165??C shallow (to 680 m) fluid encountered by the wells. The hot-spring waters are formed by boiling and steam loss from more or less conductively cooled parent fluid. The more dilute boiling spring waters (Cl = ???32 mg/kg) have cooled from > 225??C to about 160??C by conduction and from 160??C to 98??C by boiling. The most concentrated boiling spring waters (Cl = 37 mg/kg) have cooled from > 225??C to about 200??C by conduction and from 200??C to 98??C by boiling. Intermediate concentrations reflect mixed cooling paths. ?? 1991.

  13. Geochemical signatures of metasedimentary rocks of high-pressure granulite facies and their relation with partial melting: Carvalhos Klippe, Southern Brasília Belt, Brazil

    NASA Astrophysics Data System (ADS)

    Cioffi, Caue Rodrigues; Campos Neto, Mario da Costa; da Rocha, Brenda Chung; Moraes, Renato; Henrique-Pinto, Renato

    2012-12-01

    High-grade metasedimentary rocks can preserve geochemical signatures of their sedimentary protolith if significant melt extraction did not occur. Retrograde reaction textures provide the main evidence for trapped melt in the rock fabrics. Carvalhos Klippe rocks in Southern Brasília Orogen, Brazil, present a typical high-pressure granulite assemblage with evidence of mica breakdown partial melting (Ky + Grt + Kfs ± Bt ± Rt). The metamorphic peak temperatures obtained by Zr-in-Rt and ternary feldspar geothermometers are between 850 °C and 900 °C. The GASP baric peak pressure obtained using grossular rich garnet core is 16 kbar. Retrograde reaction textures in which the garnet crystals are partially to totally replaced by Bt + Qtz ± Fsp intergrowths are very common in the Carvalhos Klippe rocks. These reactions are interpreted as a result of interactions between residual phases and trapped melt during the retrograde path. In the present study the geochemical signatures of three groups of Carvalhos Klippe metasedimentary rocks are analysed. Despite the high metamorphic grade these three groups show well-defined geochemical features and their REE patterns are similar to average compositions of post-Archean sedimentary rocks (PAAS, NASC). The high-pressure granulite facies Grt-Bt-Pl gneisses with immature arenite (wacke, arkose or lithic-arenite) geochemical signatures present in the Carvalhos Klippe are compared to similar rocks in amphibolite facies from the same tectonic framework (Andrelândia Nappe System). The similar geochemical signatures between Grt-Bt-Pl gneisses metamorphosed in high-pressure granulite facies and Grt-Bt-Pl-Qtz schists from the Andrelândia and Liberdade Nappes, with minimal to absent melting conditions, are suggestive of low rates of melt extraction in these high-grade rocks. The rocks with pelitic compositions most likely had higher melt extraction and even under such circumstances nevertheless tend to show REE patterns similar to

  14. A systematic evaluation of the Zr-in-rutile thermometer in ultra-high temperature (UHT) rocks

    NASA Astrophysics Data System (ADS)

    Pape, Jonas; Mezger, Klaus; Robyr, Martin

    2016-05-01

    The Zr-in-rutile geothermometer is potentially a widely applicable tool to estimate peak metamorphic temperatures in rocks from diverse geological settings. In order to evaluate its usefulness and reliability to record and preserve high temperatures in granulite facies rocks, rutile from UHT rocks was investigated to assess different mechanisms of Zr (re-)distribution following cooling from high temperature. Granulite facies paragneisses from the lowermost part of the Ivrea Zone, Italy, incorporated as thin sheets into the extensive basaltic body of the Mafic Complex were selected for this study. The results show that Zr-in-rutile thermometry, if properly applied, is well suited to identify and study UHT terranes as it preserves a record of temperatures up to 1190 °C, although the thermometer is susceptible to partial post-peak metamorphic resetting by Zr diffusion. Texturally homogeneous rutile grains preserve Zr concentrations corresponding to temperatures of prograde rutile growth. Diverse rutile textures and relationships between some rutile host grains and included or adjacent Zr-bearing phases bear testimony to varying mechanisms of partial redistribution and resetting of Zr in rutile during cooling and link Zr-in-rutile temperatures to different steps of the metamorphic evolution. Rutile grains that equilibrated their Zr concentrations at temperatures above 1070 °C (i.e. 1.1 wt% Zr) could not retain all Zr in the rutile structure during cooling and exsolved baddeleyite (ZrO2). By subsequent reaction of baddeleyite exsolution lamellae with SiO2, zircon needles formed before the system finally closed at 650-700 °C without significant net loss of Zr from the whole host rutile grain. By reintegration of zircon exsolution needles, peak metamorphic temperatures of up to 1190 °C are derived for the studied rocks, which demonstrates the suitability of this solution thermometer to record UHT conditions and also confirms the extraordinary geological setting of the

  15. Major and trace-element composition and pressure-temperature evolution of rock-buffered fluids in low-grade accretionary-wedge metasediments, Central Alps

    NASA Astrophysics Data System (ADS)

    Miron, George D.; Wagner, Thomas; Wälle, Markus; Heinrich, Christoph A.

    2013-05-01

    The chemical composition of fluid inclusions in quartz crystals from Alpine fissure veins was determined by combination of microthermometry, Raman spectroscopy, and LA-ICPMS analysis. The veins are hosted in carbonate-bearing, organic-rich, low-grade metamorphic metapelites of the Bündnerschiefer of the eastern Central Alps (Switzerland). This strongly deformed tectonic unit is interpreted as a partly subducted accretionary wedge, on the basis of widespread carpholite assemblages that were later overprinted by lower greenschist facies metamorphism. Veins and their host rocks from two locations were studied to compare several indicators for the conditions during metamorphism, including illite crystallinity, graphite thermometry, stability of mineral assemblages, chlorite thermometry, fluid inclusion solute thermometry, and fluid inclusion isochores. Fluid inclusions are aqueous two-phase with 3.7-4.0 wt% equivalent NaCl at Thusis and 1.6-1.7 wt% at Schiers. Reproducible concentrations of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, B, Al, Mn, Cu, Zn, Pb, As, Sb, Cl, Br, and S could be determined for 97 fluid inclusion assemblages. Fluid and mineral geothermometry consistently indicate temperatures of 320 ± 20 °C for the host rocks at Thusis and of 250 ± 30 °C at Schiers. Combining fluid inclusion isochores with independent geothermometers results in pressure estimates of 2.8-3.8 kbar for Thusis, and of 3.3-3.4 kbar for Schiers. Pressure-temperature estimates are confirmed by pseudosection modeling. Fluid compositions and petrological modeling consistently demonstrate that chemical fluid-rock equilibrium was attained during vein formation, indicating that the fluids originated locally by metamorphic dehydration during near-isothermal decompression in a rock-buffered system.

  16. 3-Dimensional Geologic Modeling Applied to the Structural Characterization of Geothermal Systems: Astor Pass, Nevada, USA

    SciTech Connect

    Siler, Drew L; Faulds, James E; Mayhew, Brett

    2013-04-16

    Geothermal systems in the Great Basin, USA, are controlled by a variety of fault intersection and fault interaction areas. Understanding the specific geometry of the structures most conducive to broad-scale geothermal circulation is crucial to both the mitigation of the costs of geothermal exploration (especially drilling) and to the identification of geothermal systems that have no surface expression (blind systems). 3-dimensional geologic modeling is a tool that can elucidate the specific stratigraphic intervals and structural geometries that host geothermal reservoirs. Astor Pass, NV USA lies just beyond the northern extent of the dextral Pyramid Lake fault zone near the boundary between two distinct structural domains, the Walker Lane and the Basin and Range, and exhibits characteristics of each setting. Both northwest-striking, left-stepping dextral faults of the Walker Lane and kinematically linked northerly striking normal faults associated with the Basin and Range are present. Previous studies at Astor Pass identified a blind geothermal system controlled by the intersection of west-northwest and north-northwest striking dextral-normal faults. Wells drilled into the southwestern quadrant of the fault intersection yielded 94°C fluids, with geothermometers suggesting a maximum reservoir temperature of 130°C. A 3-dimensional model was constructed based on detailed geologic maps and cross-sections, 2-dimensional seismic data, and petrologic analysis of the cuttings from three wells in order to further constrain the structural setting. The model reveals the specific geometry of the fault interaction area at a level of detail beyond what geologic maps and cross-sections can provide.

  17. Hydrogeochemistry of the Simav geothermal field, western Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Gemici, Ünsal; Tarcan, Gültekin

    2002-08-01

    Thermal waters hosted by Menderes metamorphic rocks emerge along fault lineaments in the Simav geothermal area. Thermal springs and drilled wells are located in the Eynal, Çitgöl and Naşa locations, which are part of the Simav geothermal field. Studies were carried out to obtain the main chemical and physical characteristics of thermal waters. These waters are used for heating of residences and greenhouses and for balneological purposes. Bottom temperatures of the drilled wells reach 163°C with total dissolved solids around 2225 mg/kg. Surface temperatures of thermal springs vary between 51°C and 90°C. All the thermal waters belong to Na-HCO 3-SO 4 facies. The cold groundwaters are Ca-Mg-HCO 3 type. Dissolution of host rock and ion-exchange reactions in the reservoir of the geothermal system shift the Ca-Mg-HCO 3 type cold groundwaters to the Na-HCO 3-SO 4 type thermal waters. Thermal waters are oversaturated at discharge temperatures for aragonite, calcite, quartz, chalcedony, magnesite and dolomite minerals giving rise to a carbonate-rich scale. Gypsum and anhydrite minerals are undersaturated with all of the thermal waters. Boiling during ascent of the thermal fluids produces steam and liquid waters resulting in an increase of the concentrations of the constituents in discharge waters. Steam fraction, y, of the thermal waters of which temperatures are above 100°C is between 0.075 and 0.119. Reservoir pH is much lower than pH measured in the liquid phase separated at atmospheric conditions, since the latter experienced heavy loss of acid gases, mainly CO 2. Assessment of the various empirical chemical geothermometers and geochemical modelling suggest that reservoir temperatures vary between 175°C and 200°C.

  18. Temperatures of Thermal and Slightly Thermal Springs on Mount Hood, Oregon, Apparently Unperturbed by the Magnitude-4.5 Earthquake on June 29, 2002

    NASA Astrophysics Data System (ADS)

    Nathenson, M.; Mariner, R. H.

    2002-12-01

    On the basis of water chemistry, three distinct hydrothermal systems have been identified on Mount Hood. Swim Warm Springs has a series of vents with temperatures ranging from 9° to 25°C with temperatures determined by mixing of thermal and nonthermal water. The hottest feature was 25.6° to 26.2°C in 1976-78, 25°C in 1997, and 24.7°C in 2001. The hot-water component is interpreted to have a source water that boiled from 187°C, re-equilibrated at 96°C, and then mixed with nonthermal water to produce the range of compositions found in various springs. The Meadows Spring is a slightly thermal spring with measured temperatures of 4.8°, 6.1°, 6.6°C in 1997, 1999, and 2001 related to mixing of thermal and nonthermal water. The hot-water component is interpreted to have a source water that boiled from 223°C, re-equilibrated at 94°C, and then mixed with nonthermal water to produce the range of compositions found in the spring over several years. Both systems contain water from precipitation at high elevation. The summit fumaroles have gas-geothermometer temperatures generally over 300°C, indicating that they are not the steam discharge from the Swim and Meadows hydrothermal systems. Field measurements in July-August, 2002, after the magnitude-4.5 earthquake of June 29, 2002, showed that the highest-temperature vent at Swim Warm Springs was 25.7°C, similar to values found in other years. Measurements on a hot afternoon and a cool morning yielded temperatures of 25.7° and 25.2°C, indicating that this low-flow feature is subject to some solar heating. The Meadows Spring was 6.3°C, consistent with its previous behavior of mixing. The lower temperature indicates that there is a variability associated with unknown hydrologic factors rather than confirming an apparent trend of continuously increasing temperatures for the 1997-2001 period. The Crater Rock fumarole was 89°C, similar to previous measurements. Post-earthquake measurements of spring temperatures

  19. Synkinematic Temperature Estimates and Complex, 3d Strain Patterns in a Partially Molten Crust, ARAÇUAÍ Belt (se Brazil)

    NASA Astrophysics Data System (ADS)

    Cavalcante, G.; Vauchez, A. R.; Egydio-Silva, M.

    2013-12-01

    The Araçuaí belt was formed during the amalgamation of West Gondwana by the collision between the São Francisco and Congo cratons. Its eastern region is characterized by the presence of migmatites, leucogranites, granulites and migmatitic kinzigites that probably represent the record of a widespread partial melting of the middle to lower crust. Synkinematic temperatures obtained from the TitaniQ geothermometer suggest that the minimum temperatures for the crystallization of quartz grains are ~750°C. This temperature value combined with bulk rock composition of isolated leucosome of migmatites indicates that the viscosity of the anatectic rocks dropped to at least 1014 Pa s. Such low viscosity value suggests that approximately 30% melt volume was produced during orogeny. Detailed mineralogy investigation suggests a dominantly paramagnetic behavior for the migmatites and ferromagnetic for the granulites. Crystallographic preferred orientation (CPO) measurements using the EBSD (Electron Backscatter Diffraction) technique reveal that the magnetic foliation results from the preferred orientation of the biotite [001] axis oriented normal to the flow plane. Correspondence between [001] of feldspars and k1 (magnetic lineation) is due to the CPO of small inclusions of ilmenite that mimic the CPO of their host minerals. Correlation between k1 of the Anisotropy of Anhysteretic Remanent Magnetization (AARM) and k1 of the AMS demonstrates that, at the specimen scale, the magnetic lineation has a contribution of the anisotropy of the ferromagnetic minerals. Therefore, it is interpreted that the origin of the magnetic lineation is related to the CPO of biotite and feldspars, and less so, to the preferred alignment of ferromagnetic grains. AMS measurements performed to recover the mineral fabric and investigate the migmatitic flow field revealed a complex strain pattern in which it is possible to characterize three structural sectors. The north region (structural sector 1

  20. Geochemical assessment of hydrocarbon migration phenomena: Case studies from the south-western margin of the Dead Sea Basin

    NASA Astrophysics Data System (ADS)

    Sokol, Ella; Kozmenko, Olga; Smirnov, Sergey; Sokol, Ivan; Novikova, Sofya; Tomilenko, Anatoliy; Kokh, Svetlana; Ryazanova, Tatyana; Reutsky, Vadim; Bul'bak, Taras; Vapnik, Yevgeny; Deyak, Michail

    2014-10-01

    Calcite veins with fluid and solid bitumen inclusions have been discovered in the south-western shoulder of the Dead Sea rift within the Masada-Zohar block, where hydrocarbons exist in small commercial gas fields and non-commercial fields of heavy and light oils. The gas-liquid inclusions in calcite are dominated either by methane or CO2, and aqueous inclusions sometimes bear minor dissolved hydrocarbons. The enclosed flake-like solid bitumen matter is a residue of degraded oil, which may be interpreted as “dead carbon”. About 2/3 of this matter is soot-like amorphous carbon and 1/3 consists of n-C8sbnd C18 carboxylic acids and traces of n-alkanes, light dicarboxylic acids, and higher molecular weight (>C20) branched and/or cyclic carboxylic acids. Both bitumen and the host calcites show genetic relationship with mature Maastrichtian chalky source rocks (MCSRs) evident in isotopic compositions (δ13C, δ34S, and δ18O) and in REE + Y patterns. The bitumen precursor may have been heavy sulfur-rich oil which was generated during the burial compaction of the MCSR strata within the subsided blocks of the Dead Sea graben. The δ18O and δ13C values and REE + Y signatures in calcites indicate mixing of deep buried fluids equilibrated with post-mature sediments and meteoric waters. The temperatures of fluid generation according to Mg-Li-geothermometer data range from 55 °С to 90 °С corresponding to the 2.5-4.0 km depths, and largely overlap with the oil window range (60-90 °С) in the Dead Sea rift (Hunt, 1996; Gvirtzman and Stanislavsky, 2000; Buryakovsky et al., 2005). The bitumen-rich vein calcites originated in the course of Late Cenozoic rifting and related deformation, when tectonic stress triggers damaged small hydrocarbon reservoirs in the area, produced pathways, and caused hydrocarbon-bearing fluids to rise to the subsurface; the fluids filled open fractures and crystallized to calcite with entrapped bitumen. The reported results are in good agreement

  1. Potential Temperatures of Sources of MORB, OIB and LIPs Based on AL Partitioning Between Olivine and Spinel

    NASA Astrophysics Data System (ADS)

    Sobolev, A. V.; Batanova, V. G.; Krasheninnikov, S.; Borisov, A.; Arndt, N.; Kuzmin, D.; Krivolutskaya, N.; Sushevskaya, N.

    2013-12-01

    Knowledge of potential temperatures of convecting mantle is required for the understanding the global processes on the Earth [1]. The common way to estimate these is the reconstruction of primary melt compositions and liquidus temperatures based on the Fe-Mg partitioning between olivine and melt. This approach requires knowledge of the compositions of primitive melts in equilibrium with olivine alone as well as composition of olivine equilibrium with primary melts. This information is in most cases unavailable or of questionable quality. Here we report a new approach to obtain crystallization temperatures of primary melts based on the olivine-spinel Al-Cr geothermometer [2]. The advantages of this approach are: (1) low rate of diffusion of Al in the olivine, which promises to preserve high magmatic temperatures and (2) common presence of spinel in assemblage with high-Mg olivine. In order to decipher influence of elevated Ti concentrations in spinel we have run several experiments at high temperatures (1400-1200 degree C), atmospheric pressure and controled oxygen fugacity. We also analysed over two thousand spinel inclusions and high-Mg host olivines from different MORB, OIB, LIP and Archean komatiites on the JXA-8230 EPMA at ISTerre, Grenoble, France. Concentrations of Al, Ti, Na, P, Zn, Cr, Mn, Ca, Co, Ni were determined with a precision of 10 ppm (2 standard errors) using a newly developed protocol [3]. When available, we also analysed matrix glass and glass inclusions in olivine and found that temperature estimations from olivine-spinel (Al-Cr) and olivine-melt (Fe-Mg) [4] equilibrium match within (+/-30 degree C). The results show contrasting crystallization temperatures of Mg-rich olivine of the same Fo content from different types of mantle-derived magmas, from the lowest (down to 1220 degree C) for MORB to the highest (up to 1550 degree C) for komatiites and Siberian meimechites. These results match predictions from Fe-Mg olivine-melt equilibrium and

  2. Problems in Trace Element EPMA: Modeling Secondary Fluorescence with PENEPMA

    NASA Astrophysics Data System (ADS)

    Fournelle, J.

    2007-12-01

    In EPMA the incident electron beam scatters, producing the "electron interaction volume". However, X-rays produced within that volume may spread tens to hundreds of microns and produce secondary fluorescence in other materials. This can be ignored in many/most cases where major element compositions are being measured. However, when minor or especially trace elements are being measured by EPMA, secondary fluorescence needs to be considered. In some cases it can be eliminated by separating the materials and mounting them by themselves, or by reducing the kV to minimize fluorescence. However, in many cases these efforts are not possible. In those cases, modeling the EPMA experience by Monte Carlo simulation is useful. PENEPMA is a Fortran program based upon the PENELOPE radiation transport model of Salvat et al (2006). It differs from other MC electron interaction programs in that it follows each electron and photon and records all interactions at each point in the "particle's path". It also permits complicated geometries with many materials. Both continuum and characteristic secondary fluorescence can be tracked, and at the end of a run, compared to x-rays produced only from primary electrons. This has important applications in geology and petrology. Llovet and Galan (2003) used it to correct calculations for olivine-cpx thermobarometry. Recent attention has been given to Ti in zircon as a geothermometer. PENEPMA has now been used to model 2 different situations: (1) rutiles present on or near zircon, (2) ilmenite present near zircon. In the first case, several geometries are modeled: a 30 micron diameter zircon (Ti-free) is surrounded by Ti-bearing silicate glass (yielding an apparent 452 ppm Ti in zircon core); with five 30 um surrounding rutiles at 15 micron distance (yielding an apparent 948 ppm Ti in zircon core); if the silicate glass were replaced by epoxy, the apparent Ti would increase to 1179 ppm. In a second case, the effect of zircon with nearby ilmenite

  3. Tectonic Evolution of the Cretaceous Sava-Klepa Massif, Former Yugoslav Republic of Macedonia, based on field observations and microstructural analysis - Towards a new geodynamic Model

    NASA Astrophysics Data System (ADS)

    Altmeyer, Tobias; Peternell, Mark; Prelević, Dejan; Köpping, Jonas

    2016-04-01

    the deformation history, i.e. the switch from compressive to extensional, rift forming, regime. REFERENCES Ferrill, D.A. et al. (2004). Calcite twin morphology: a low-temperature deformation geothermometer. Journal of Structural Geology 26: 1521-1529. Peternell, M. et al. (2010). Evaluating quartz crystallographic preferred orientations and the role of deformation partitioning using EBSD and fabric analyser techniques. Journal of Structural Geology 32: 803-817. Robertson, A.H.F. & Karamata, S. (1994). The role of subduction-accretion processes in the tectonic evolution of the Mesozoic Tethys in Serbia. Tectonophysics, 234:73-94. Schmid, S.M. et al. (2008). The Alpine-Carpathian-Dinaridic orogenic system: correlation and evolution of tectonic units. Swiss Journal of Geoscience, 101:139-183.

  4. The origin of a zoned ignimbrite: insights into the Campanian Ignimbrite magma chamber (Campi Flegrei, Italy)

    NASA Astrophysics Data System (ADS)

    Forni, Francesca; Bachmann, Olivier; Mollo, Silvio; De Astis, Gianfilippo

    2016-04-01

    The Campanian Ignimbrite (CI; Campi Flegrei, Italy), dated at 39 ka, is a widespread pyroclastic sequence emplaced during a cataclysmic caldera-forming eruption fed by trachytic to phonolitic magmas. The CI pyroclastic sequence is famous for its remarkable geochemical gradients,attributed to the presence of a vertically zoned magma chamber. Combining bulk-rock data with detailed phenocrysts and matrix glass analyses from well characterized stratigraphic units, we investigate the relatioships between such chemical zoning and the crystallinity variations observed along the CI pyroclastic sequence. Using geothermometers and hygrometers specifically calibrated for alkaline magmas, we reconstruct the reservoir storage conditions, revealing the presence of gradients in temperature and magma water content. In particular, we observe an increase in crystallinity and temperature and a decrease in magma evolution and water content from the bottom to the top of the sequence. We interpret these features as the result of protracted fractional crystallization leading to the formation of a cumulate crystal mush at the base of the eruptible reservoir, from which highly evolved, crystal-poor, water-rich and relatively cold melts were separated. The extracted melts, forming a buoyant, easily eruptible cap at the top of the magma chamber, fed the initial phases of the eruption, until caldera collapse and eruption of the deeper, more crystalline part of the system. This late-erupted, crystal-rich material, represents remobilized portions of the cumulate crystal mush, rejuvenated after mafic recharge. Our interpretation is supported by: 1) the bulk-rock positive Eu anomalies and the high Ba and Sr contents observed in the crystal-rich units, implying feldspar accumulation; 2) the positive Eu anomalies in the matrix glass of the crystal-rich units, testifying to the presence of liquid derived from partial melting of low temperature mineral phases within the crystal mush (feldspars and

  5. Chemical indicators of subsurface temperature applied to hot spring waters of Yellowstone National Park, Wyoming, U.S.A.

    USGS Publications Warehouse

    Fournier, R.O.; Truesdell, A.H.

    1970-01-01

    Under favorable conditions the chemistry of hot springs may give reliable indications of subsurface temperatures and circulation patterns. These chemical indicators can be classified by the type of process involved: {A table is presented}. All these indicators have certain limitations. The silica geothermometer gives results independent of the local mineral suite and gas partial pressures, but may be affected by dilution. Alkali ratios are strongly affected by the local mineral suite and the formation of complex ions. Carbonate-chloride ratios are strongly affected by subsurface PCO2. The relative concentration of volatiles can be very misleading in high-pressure liquid systems. In Yellowstone National Park most thermal waters issue from hot, shallow aquifers with pressures in excess of hydrostatic by 2 to 6 bars and with large flows (the flow of hot spring water from the Park is greater than 4000 liters per second). These conditions should be ideal for the use of chemical indicators to estimate aquifer temperatures. In five drill holes aquifer temperatures were within 2??C of that predicted from the silica content of nearby hot springs; the temperature level off at a lower value than predicted in only one hole, and in four other holes drilling was terminated before the predicted aquifer temperature was reached. The temperature-Na/K ratio relationship does not follow any published experimental or empirical curve for water-feldspar or water-clay reactions. We suspect that ion exchange reactions involving zeolites in the Yellowstone rocks result in higher Na/K ratios at given temperatures than result from feldspar or clay reactions. Comparison of SiO2 and Cl/(HCO3 + CO3) suggest that because of higher subsurface PCO2 in Upper Geyser Basin a given Cl/(HCO3 + CO3) ratio there means a higher temperature than in Lower Geyser Basin. No correlation was found in Yellowstone Park between the subsurface regions of highest temperature and the relative concentration of volatile

  6. The Blacktail Creek Tuff: an analytical and experimental study of rhyolites from the Heise volcanic field, Yellowstone hotspot system

    NASA Astrophysics Data System (ADS)

    Bolte, Torsten; Holtz, Francois; Almeev, Renat; Nash, Barbara

    2015-02-01

    The magma storage conditions of the 6.62 Ma Blacktail Creek Tuff eruption, belonging to the Heise volcanic field (6.62-4.45 Ma old) of the Yellowstone hotspot system, have been investigated by combining thermobarometric and experimental approaches. The results from different geothermometers (e.g., Fe-Ti oxides, feldspar pairs, apatite and zircon solubility, and Ti in quartz) indicate a pre-eruptive temperature in the range 825-875 °C. The temperature estimated using two-pyroxene pairs varies in a range of 810-950 °C, but the pyroxenes are probably not in equilibrium with each other, and the analytical results of melt inclusion in pyroxenes indicate a complex history for clinopyroxene, which hosts two compositionally different inclusion types. One natural Blacktail Creek Tuff rock sample has been used to determine experimentally the equilibrium phase assemblages in the pressure range 100-500 MPa and a water activity range 0.1-1.0. The experiments have been performed at fluid-present conditions, with a fluid phase composed of H2O and CO2, as well as at fluid-absent conditions. The stability of the quartzo-feldspathic phases is similar in both types of experiments, but the presence of mafic minerals such as biotite and clinopyroxene is strongly dependent on the experimental approach. Possible explanations are given for this discrepancy which may have strong impacts on the choice of appropriate experimental approaches for the determination of magma storage conditions. The comparison of the composition of natural phases and of experimentally synthesized phases confirms magma storage temperatures of 845-875 °C. Melt water contents of 1.5-2.5 wt% H2O are required to reproduce the natural Blacktail Creek Tuff mineral assemblage at these temperatures. Using the Ti-in-quartz barometer and the Qz-Ab-Or proportions of natural matrix glasses, coexisting with quartz, plagioclase and sanidine, the depth of magma storage is estimated to be in a pressure range between 130 and

  7. Spinel + quartz assemblage in granulites from the Achankovil Shear Zone, southern India: Implications for ultrahigh-temperature metamorphism

    NASA Astrophysics Data System (ADS)

    Shimizu, Hisako; Tsunogae, Toshiaki; Santosh, M.

    2009-09-01

    We report the finding of equilibrium spinel + quartz assemblage enclosed within garnet in garnet-orthopyroxene-cordierite granulites from Pakkandom within the Achankovil Shear Zone, a region which is considered as the trace of an accretionary suture in recent tectonic models on southern India. The spinel + quartz bearing granulites are composed of poikiloblastic garnet and subidioblastic orthopyroxene in the matrix of quartz, plagioclase, biotite, cordierite, and Fe-Ti oxides. Garnet contains numerous inclusions of sillimanite and biotite as well as spinel and quartz. The spinel in direct contact with quartz has moderate XMg (= Mg/(Fe 2+ + Mg) = 0.44-0.47), and is Zn and Fe 3+ poor ( XZn = Zn/(Fe 2+ + Mg + Zn) = 0.027-0.036, Fe 3+/(Fe 2+ + Fe 3+) = 0.12-0.17). Spinel is also present in the matrix surrounded by magnetite, but the matrix spinel contains more Zn( XZn = 0.067-0.072) and does not show any contact relationship with quartz. Such Zn- and Fe 3+-poor spinel in direct contact with quartz has been regarded as a diagnostic evidence of ultrahigh-temperature (UHT) metamorphism. The high-temperature stability of the spinel + quartz is also supported by the results of geothermobarometric calculation of garnet-orthopyroxene assemblages that provides robust evidence for peak UHT metamorphism at 920-980 °C and 8-10 kbar, which was further confirmed by Al-in-Opx and magnetite-ilmenite geothermometers (900-950 °C and ˜1000 °C, respectively). The peak UHT event was followed by decompression down to 4.0-4.2 kbar and 640-670 °C toward the stability of cordierite along a clockwise P-T path. Similar spinel + quartz assemblage enclosed in poikiloblastic garnet has also been reported from the Palghat-Cauvery Shear Zone system, the trace of a major suture zone within the Gondwana amalgam with evidence for prograde high-pressure ( P up to 20 kbar) metamorphism followed by UHT event. The fine-grained spinel + quartz may thus indicate decompression from higher pressure

  8. Incompatible Trace Elements in Olivine: Using Sc, Y and V as Temperature and Redox Monitors in Basaltic Magmas

    NASA Astrophysics Data System (ADS)

    Mallmann, G.; O'Neill, H. S.

    2012-12-01

    principle, less disturbed by these late and post-eruptive processes and, therefore, may better represent the high-temperature (pre-eruptive) conditions of the magma. We will present a calibration of an empirical oxybarometer (with typical 1σ precision of ±0.25 log units) based on the sensitivity of the partition of vanadium between olivine and silicate melt to oxygen fugacity, and a geothermometer (with typical 1σ precision of ±15°C) based on the exchange partitioning of Sc and Y between olivine and melt. Application of these methods reveals interesting redox relationships between the different types of terrestrial basalts.

  9. Reassessment of the garnet-clinopyroxene Fe-Mg exchange thermometer: I. Evaluation of the Pattison and Newton (1989) experiments

    NASA Astrophysics Data System (ADS)

    Aranovich, L. Y.; Pattison, D. R. M.

    1995-02-01

    This is Part I of a two-part study on the garnet(Grt)-clinopyroxene(Cpx) Fe-Mg exchange equilibrium widely used in geothermometry of amphibolites, granulites and eclogites. The experimental data set previously published by Pattison and Newton (PN) on this equilibrium comprises potentially the largest source of data used for extraction of thermody- namic properties for Grt and Cpx and for formulation of a new thermometer expression (Part 2 of this study). However, the experiments suggested unusual Grt and Cpx solution properties and resulted in a geothermometer expression that generally returns low temperatures for granulites. To verify the reliability of the experiments, and to test the experimental technique of Grt buffering used in the PN study, 69 of the 125 PN runs were reanalysed using wavelength dispersive spectroscopic analysis guided by backscattered electron images. Special attention was given to analysis of compositional changes in Grt in addition to Cpx. With minor exceptions, the reanalysis supports the analytical results of the original PN study. The mechanism of equilibration in the runs was a multicomponent solution-precipitation process involving dissolution of metastable Grt and Cpx starting materials and precipitation of newly formed Cpx and Grt, the latter assumed to represent equilibrium compositions. The experiments cannot be regarded either as reversed or as strictly bracketing. Nevertheless, Cpx compositional parameters, including Mg?, Na, Ca and Al, show the same smooth variations with temperature, pressure and composition as found by PN, suggestive of a close approach to equilibrium. Grt in run products retained the moderate heterogeneity of the starting Grt, although there are subtle compositional trends indicating small changes in Grt Mg? consistent with mass balance constraints. These results uphold the essential validity of the technique of Grt buffering used in the experiments. Nevertheless, it is possible that the final Grt

  10. Igneous phenocrystic origin of K-feldspar megacrysts in granitic rocks from the Sierra Nevada batholith

    USGS Publications Warehouse

    Moore, J.G.; Sisson, T.W.

    2008-01-01

    Study of four K-feldspar megacrystic granitic plutons and related dikes in the Sierra Nevada composite batholith indicates that the megacrysts are phenocrysts that grew in contact with granitic melt. Growth to megacrystic sizes was due to repeated replenishment of the magma bodies by fresh granitic melt that maintained temperatures above the solidus for extended time periods and that provided components necessary for K-feldspar growth. These intrusions cooled 89-83 Ma, are the youngest in the range, and represent the culminating magmatic phase of the Sierra Nevada batholith. They are the granodiorite of Topaz Lake, the Cathedral Peak Granodiorite, the Mono Creek Granite, the Whitney Granodiorite, the Johnson Granite Porphyry, and the Golden Bear Dike. Megacrysts in these igneous bodies attain 4-10 cm in length. All have sawtooth oscillatory zoning marked by varying concentration of BaO ranging generally from 3.5 to 0.5 wt%. Some of the more pronounced zones begin with resorption and channeling of the underlying zone. Layers of mineral inclusions, principally plagioclase, but also biotite, quartz, hornblende, titanite, and accessory minerals, are parallel to the BaO-delineated zones, are sorted by size along the boundaries, and have their long axes preferentially aligned parallel to the boundaries. These features indicate that the K-feldspar megacrysts grew while surrounded by melt, allowing the inclusion minerals to periodically attach themselves to the faces of the growing crystals. The temperature of growth of titanite included within the K-feldspar megacrysts is estimated by use of a Zr-in-titanite geothermometer. Megacryst-hosted titanite grains all yield temperatures typical of felsic magmas, mainly 735-760 ??C. Titanite grains in the granodiorite hosts marginal to the megacrysts range to lower growth temperatures, in some instances into the subsolidus. The limited range and igneous values of growth temperatures for megacryst-hosted titanite grains support the