This paper presents a biotite-calcic hornblende geothermometer which was empirically calibrated based on the garnet-biotite geothermometer and the garnet-plagioclase-hornblende-quartz geobarometer, in the ranges of 56...This paper presents a biotite-calcic hornblende geothermometer which was empirically calibrated based on the garnet-biotite geothermometer and the garnet-plagioclase-hornblende-quartz geobarometer, in the ranges of 560 800°C (T) and 0.26?1.4 Gpa (P) using the data of metadolerite, amphibolite, metagabbro, and metapelite collected from the literature. Biotite was treated as symmetric Fe-Mg-AlVI-Ti quaternary solid solution, and calcic hornblende was simplified as symmetric Fe-Mg binary solid solution. The resulting thermometer may rebuild the input garnet-biotite temperatures well within an uncertainty of 50°C. Errors of 0.2 Gpa for input pressure, along with analytical errors of 5% for the relevant mineral compositions, may lead to a random error of 16°C for this thermometer, so that the thermometer is almost independent of pressure estimates. The thermometer may clearly discriminate different rocks of lower amphibolite, upper amphibolite and granulite facies on a high confidence level. It is assumed that there is a ferric iron content of 11.6% in biotite, and that the iron content in calcic hornblende may be calculated according to the method of Dale et al. (2000). This thermometer can be used for medium- to high-grade metabasites and metapelites.展开更多
This paper elaborates the chemical constituent change principles of deep geothermal fluid during the process of upward movement. It summarizes research methods of hydrochemistry, isotope and numerical modelling techni...This paper elaborates the chemical constituent change principles of deep geothermal fluid during the process of upward movement. It summarizes research methods of hydrochemistry, isotope and numerical modelling technique for the physiochemical processes such as decreasing temperature, shallow groundwater infusion, and degassing. The multi-component chemical geothermometry methods including gas geochemical method are discussed. High-temperature geothermal fields in China are mostly located in the southwest with frequent new tectonic movements, especially in Tibet high-temperature geothermal areas. Therefore the paper also focuses the status of high-temperature geothermal fluid research. At last, it's pointed out in the paper that in the future we can start from typical high-temperature geothermal zones and geothermal fields to explore optimization of the multi-component geothermometry method and use it in the reconstruction and analogue of the formation mechanism and internal relevancy of regional geothermal systems.展开更多
Experiments for oxygen isotope exchange between ferberite and water were carried out and the followingequation on oxygen isotope fractionation between ferberite and water against temperature was obtained:Combining thi...Experiments for oxygen isotope exchange between ferberite and water were carried out and the followingequation on oxygen isotope fractionation between ferberite and water against temperature was obtained:Combining this equation with the equation of Clayton et al. (1972) on oxygen isotope fractionation be-tween quartz and water, an equation on oxygen isotope fractionation between quartz and ferberite was ob-tained:The Bigeleison-Mayer function method was used to calculate the oxygen isotope fractionation betweenquartz and ferberite. The theoretical curve obtained agrees with the experimental calibration results quite wellin the temperature range of study.The above calibrated equation has been used in 5 world famous tungsten deposits to determine their tem-peratures of formation. The results show that the temperature range for an idividual deposit determined by thisgeothermometer agrees with those obtained from fluid inclusion determination and other isotopegeothermometers.展开更多
The calibration of the olivine-spinel geothermometer by Fabries(1979) is commonly adopted by a number of petrologists.But the temperatures calculated in this way for ultramafic focks are significantly lower than those...The calibration of the olivine-spinel geothermometer by Fabries(1979) is commonly adopted by a number of petrologists.But the temperatures calculated in this way for ultramafic focks are significantly lower than those obtained by the pyroxene geothermometers.These O1-Sp temperatures are also lower than those measured experi-mentally in the natural system (four-phase lherzolite).Different rates of cation diffusion cannot fully account for these differences.The temperature deviation is actually related to the inconsistencies between natural and experimental data which support the calibration .A re-evaluation of the calibration is proposed on the basis of a set of new experimental data.展开更多
A new experimental calibration was undertaken in this study to get a more reliable sphalerite-galenasulfur isotope geothermometer. The experimental conditions selected in study were very similar to those of naturalhyd...A new experimental calibration was undertaken in this study to get a more reliable sphalerite-galenasulfur isotope geothermometer. The experimental conditions selected in study were very similar to those of naturalhydrothermal solution. The high-precision SF6 method was used in sulfur isotope analyses. The obtained calibrationcurve for sulfur isotope fractionation between sphalerite and galena can be expressed with the equation 1000lnαSp-Gn=0.74×106T-2+0.08.展开更多
Reservoir temperature estimation is vitally important for assessing the exploitation potential of a geothermal field.In this study,the concentrations of major chemical constituents in geothermal water sampled from boi...Reservoir temperature estimation is vitally important for assessing the exploitation potential of a geothermal field.In this study,the concentrations of major chemical constituents in geothermal water sampled from boiling and hot springs in the Tengchong hydrothermal area were measured,and quartz and cationic solutes geothermometers were used to calculate subsurface temperatures.Log(Q/K) diagrams and Na-K-Mg triangular diagrams were applied to evaluating the equilibrium status of geothermal water samples with regard to reservoir minerals,and results were used to select suitable geothermometers.The results show that samples RH01,RH03,RH04,RH05,and LL16 were in or very close to full equilibrium with the selected minerals,and therefore a NaK geothermometer is appropriate.A K/Mg geothermometer,however,is applicable to LP08 and PZH18 whose chemical compositions adjusted to the shallow reservoir temperatures during their re-equilibrium processes.In contrast,cationic solute geothermometers are unsuitable for SQ20 and RH07,which are categorized as immature water in the Na-K-Mg diagram;a quartz geothermometer was adopted to evaluate the corresponding subsurface temperatures of these samples.According to the reservoir temperature estimation made in this study,there is at least one high-temperature reservoir below Rehai with a possible temperature range of 210-270 ℃.展开更多
This paper briefly introduces twenty one versions of garnet biotite Fe Mg exchange geothermometry, points out the sources of systematic errors inherent in geothermometry. The sources lie in that: (1) ideal Fe Mg mixin...This paper briefly introduces twenty one versions of garnet biotite Fe Mg exchange geothermometry, points out the sources of systematic errors inherent in geothermometry. The sources lie in that: (1) ideal Fe Mg mixing in garnet and biotite is assumed; (2) non ideal properties of both garnet and biotite are not considered completely; (3) minor elements—Mn, Ca in garnet, and Al Ⅵ, Ti, Mn in biotite are almost neglected; (4) effects of pressure on equilibrium, although little, are almost not taken into consideration, and experiments were conducted at one fixed pressure; (5) the data used for regression analysis is too scarce in quantity; (6) internal consistency of the data used for empirical calibration is not fully guaranteed; (7) the authors take energy parameters W’s (Margule’s parameters) independent of pressure and temperature, though the former are actually the functions of the latter items; and (8) the most important composition activity relationship is not consistent with the mineral compositions used for calibration. Furthermore, it is believed that empirical calibrations cannot avoid the following problems: (1) effect of retrograde metamorphism; (2) inconsistent data set; (3) effect of pressure on temperature estimation; and (4) effect of Fe 3+ calculation. Exact experimental work should be done in order to accurately calibrate the geothermometer in which the Margule’s parameters should be treated as the functions of pressure, temperature, and mineral compositions.展开更多
The Ain El Bey abandoned mine, in North-West Tunisia, fits into the geodynamic context of the European and African plate boundary. Ore deposit corresponds to veins and breccia of multiphase Cu–Fe-rich mineralization ...The Ain El Bey abandoned mine, in North-West Tunisia, fits into the geodynamic context of the European and African plate boundary. Ore deposit corresponds to veins and breccia of multiphase Cu–Fe-rich mineralization related to various hydrothermal fluid circulations. Petromineralogical studies indicate a rich mineral paragenesis with a minimum of seven mineralization phases and, at least, six pyrite generations. As is also the case for galena and native silver, native gold is observed for the first time as inclusion in quartz which opens up, thus, new perspectives for prospecting and evaluating the potential for noble metals associated with the mineralization. Scanning Electron Microscope--Energy Dispersive Spectroscopy and Transmission electron microscopy analyses show, in addition, a large incorporation of trace elements, including Ag and Au, in mineral structures such as fahlores(tetrahedrite-tennantite) and chalcopyrite ones. The mineral/mineral associations, used as geothermometers, gave estimated temperatures for the mineralizing fluids varying from 254 to 330 ℃ for phase Ⅲ, from 254 to 350 ℃ for phase Ⅳ, and from 200 to 300 ℃ for phases Ⅴ and Ⅵ. The seventh and last identified mineralization phase, marked by a deposit of native gold, reflects a drop in the mineralizing fluid’s temperature(< 200 ℃) compatible with boiling conditions. Such results open up perspectives for the development of precious metal research and the revaluation of the Cu–Fe ore deposit at the Ain El Bey abandoned mine, as well as at the surrounding areas fitting in the geodynamic framework of the Africa-Europe plate boundary.展开更多
基金the China National Natural Science Foundation(grants40002017 , 40074022) wasalso under the auspices of the National Key Project for Basic Research +1 种基金 CAS Project for the Tibetan Research Project(KZ.-951-A1-204 , KZ95T-06) a China Geological Survey grant(J2.1.4).
文摘This paper presents a biotite-calcic hornblende geothermometer which was empirically calibrated based on the garnet-biotite geothermometer and the garnet-plagioclase-hornblende-quartz geobarometer, in the ranges of 560 800°C (T) and 0.26?1.4 Gpa (P) using the data of metadolerite, amphibolite, metagabbro, and metapelite collected from the literature. Biotite was treated as symmetric Fe-Mg-AlVI-Ti quaternary solid solution, and calcic hornblende was simplified as symmetric Fe-Mg binary solid solution. The resulting thermometer may rebuild the input garnet-biotite temperatures well within an uncertainty of 50°C. Errors of 0.2 Gpa for input pressure, along with analytical errors of 5% for the relevant mineral compositions, may lead to a random error of 16°C for this thermometer, so that the thermometer is almost independent of pressure estimates. The thermometer may clearly discriminate different rocks of lower amphibolite, upper amphibolite and granulite facies on a high confidence level. It is assumed that there is a ferric iron content of 11.6% in biotite, and that the iron content in calcic hornblende may be calculated according to the method of Dale et al. (2000). This thermometer can be used for medium- to high-grade metabasites and metapelites.
基金supported by the Chinese Academy of Geological Sciences Fund (No.YK201611)the Chinese Academy of Geological Sciences Hydrogeological Environment Geology Institute Fund (No. SK201408)
文摘This paper elaborates the chemical constituent change principles of deep geothermal fluid during the process of upward movement. It summarizes research methods of hydrochemistry, isotope and numerical modelling technique for the physiochemical processes such as decreasing temperature, shallow groundwater infusion, and degassing. The multi-component chemical geothermometry methods including gas geochemical method are discussed. High-temperature geothermal fields in China are mostly located in the southwest with frequent new tectonic movements, especially in Tibet high-temperature geothermal areas. Therefore the paper also focuses the status of high-temperature geothermal fluid research. At last, it's pointed out in the paper that in the future we can start from typical high-temperature geothermal zones and geothermal fields to explore optimization of the multi-component geothermometry method and use it in the reconstruction and analogue of the formation mechanism and internal relevancy of regional geothermal systems.
文摘Experiments for oxygen isotope exchange between ferberite and water were carried out and the followingequation on oxygen isotope fractionation between ferberite and water against temperature was obtained:Combining this equation with the equation of Clayton et al. (1972) on oxygen isotope fractionation be-tween quartz and water, an equation on oxygen isotope fractionation between quartz and ferberite was ob-tained:The Bigeleison-Mayer function method was used to calculate the oxygen isotope fractionation betweenquartz and ferberite. The theoretical curve obtained agrees with the experimental calibration results quite wellin the temperature range of study.The above calibrated equation has been used in 5 world famous tungsten deposits to determine their tem-peratures of formation. The results show that the temperature range for an idividual deposit determined by thisgeothermometer agrees with those obtained from fluid inclusion determination and other isotopegeothermometers.
文摘The calibration of the olivine-spinel geothermometer by Fabries(1979) is commonly adopted by a number of petrologists.But the temperatures calculated in this way for ultramafic focks are significantly lower than those obtained by the pyroxene geothermometers.These O1-Sp temperatures are also lower than those measured experi-mentally in the natural system (four-phase lherzolite).Different rates of cation diffusion cannot fully account for these differences.The temperature deviation is actually related to the inconsistencies between natural and experimental data which support the calibration .A re-evaluation of the calibration is proposed on the basis of a set of new experimental data.
文摘A new experimental calibration was undertaken in this study to get a more reliable sphalerite-galenasulfur isotope geothermometer. The experimental conditions selected in study were very similar to those of naturalhydrothermal solution. The high-precision SF6 method was used in sulfur isotope analyses. The obtained calibrationcurve for sulfur isotope fractionation between sphalerite and galena can be expressed with the equation 1000lnαSp-Gn=0.74×106T-2+0.08.
基金supported by the National Natural Science Foundation of China(No.41120124003)the Ministry of Education of China(111 Project,No.B08030)+1 种基金the Research fund of Bureau of Science and Technology of Qinghai Province(No.2013-G-Q08A)the Fundamental Research Fund for National Universities,China University of Geosciences(Wuhan) (Nos.CUG120505 and CUG120113)
文摘Reservoir temperature estimation is vitally important for assessing the exploitation potential of a geothermal field.In this study,the concentrations of major chemical constituents in geothermal water sampled from boiling and hot springs in the Tengchong hydrothermal area were measured,and quartz and cationic solutes geothermometers were used to calculate subsurface temperatures.Log(Q/K) diagrams and Na-K-Mg triangular diagrams were applied to evaluating the equilibrium status of geothermal water samples with regard to reservoir minerals,and results were used to select suitable geothermometers.The results show that samples RH01,RH03,RH04,RH05,and LL16 were in or very close to full equilibrium with the selected minerals,and therefore a NaK geothermometer is appropriate.A K/Mg geothermometer,however,is applicable to LP08 and PZH18 whose chemical compositions adjusted to the shallow reservoir temperatures during their re-equilibrium processes.In contrast,cationic solute geothermometers are unsuitable for SQ20 and RH07,which are categorized as immature water in the Na-K-Mg diagram;a quartz geothermometer was adopted to evaluate the corresponding subsurface temperatures of these samples.According to the reservoir temperature estimation made in this study,there is at least one high-temperature reservoir below Rehai with a possible temperature range of 210-270 ℃.
文摘This paper briefly introduces twenty one versions of garnet biotite Fe Mg exchange geothermometry, points out the sources of systematic errors inherent in geothermometry. The sources lie in that: (1) ideal Fe Mg mixing in garnet and biotite is assumed; (2) non ideal properties of both garnet and biotite are not considered completely; (3) minor elements—Mn, Ca in garnet, and Al Ⅵ, Ti, Mn in biotite are almost neglected; (4) effects of pressure on equilibrium, although little, are almost not taken into consideration, and experiments were conducted at one fixed pressure; (5) the data used for regression analysis is too scarce in quantity; (6) internal consistency of the data used for empirical calibration is not fully guaranteed; (7) the authors take energy parameters W’s (Margule’s parameters) independent of pressure and temperature, though the former are actually the functions of the latter items; and (8) the most important composition activity relationship is not consistent with the mineral compositions used for calibration. Furthermore, it is believed that empirical calibrations cannot avoid the following problems: (1) effect of retrograde metamorphism; (2) inconsistent data set; (3) effect of pressure on temperature estimation; and (4) effect of Fe 3+ calculation. Exact experimental work should be done in order to accurately calibrate the geothermometer in which the Margule’s parameters should be treated as the functions of pressure, temperature, and mineral compositions.
基金funded by the “Laboratoire de Recherche Ressources, Matériaux et Ecosystémes”, University of Carthage 7021 Zarzouna, Bizerte, Tunisia
文摘The Ain El Bey abandoned mine, in North-West Tunisia, fits into the geodynamic context of the European and African plate boundary. Ore deposit corresponds to veins and breccia of multiphase Cu–Fe-rich mineralization related to various hydrothermal fluid circulations. Petromineralogical studies indicate a rich mineral paragenesis with a minimum of seven mineralization phases and, at least, six pyrite generations. As is also the case for galena and native silver, native gold is observed for the first time as inclusion in quartz which opens up, thus, new perspectives for prospecting and evaluating the potential for noble metals associated with the mineralization. Scanning Electron Microscope--Energy Dispersive Spectroscopy and Transmission electron microscopy analyses show, in addition, a large incorporation of trace elements, including Ag and Au, in mineral structures such as fahlores(tetrahedrite-tennantite) and chalcopyrite ones. The mineral/mineral associations, used as geothermometers, gave estimated temperatures for the mineralizing fluids varying from 254 to 330 ℃ for phase Ⅲ, from 254 to 350 ℃ for phase Ⅳ, and from 200 to 300 ℃ for phases Ⅴ and Ⅵ. The seventh and last identified mineralization phase, marked by a deposit of native gold, reflects a drop in the mineralizing fluid’s temperature(< 200 ℃) compatible with boiling conditions. Such results open up perspectives for the development of precious metal research and the revaluation of the Cu–Fe ore deposit at the Ain El Bey abandoned mine, as well as at the surrounding areas fitting in the geodynamic framework of the Africa-Europe plate boundary.
