Based on the petrology,isotope geochemistry and fluid inclusions analysis,we established the evolutionary mode of the diagenetic fluid of dawsonite-bearing sandstone in the Jiyang Depression.Dawsonite-bearing sandston...Based on the petrology,isotope geochemistry and fluid inclusions analysis,we established the evolutionary mode of the diagenetic fluid of dawsonite-bearing sandstone in the Jiyang Depression.Dawsonite-bearing sandstone is characterized by double injection of CO_(2)and oil-gas in the Jiyang Depression that have experienced a relatively complex diagenetic fluid evolution process.The diagenetic sequence of secondary minerals involves secondary enlargement of quartz,kaolinite,first-stage calcite,dawsonite,second-stage calcite,ferrocalcite,dolomite and ankerite.Hydrocarbon charging in the dawsonite-bearing sandstone occurred at around 2.6–0 Myr.The CO_(2)charging event occurred during Dongying tectonism,forming the Pingfangwang CO_(2)gas reservoir,which provided an abundant carbon source for dawsonite precipitation.Carbon and oxygen isotopic compositions of dawsonite demonstrate that CO_(2)forming the dawsonite was of an inorganic origin derived from the mantle,and that water mediating the proc-ess during dawsonite precipitation was sequestered brine with a fluid temperature of 82℃.The evolutionary sequence of the diagenetic fluid in the dawsonite-bearing sandstone was:alkaline syngenetic fluids,weak alkaline fluids during organic acid forma-tion,acidic fluids in the early stage of CO_(2)injection,alkaline fluids in the late stage of CO_(2)injection,and weak alkaline fluids during oil and gas charging.The mode indicates an increase in-HCO_(3)because of the CO_(2)injection,and the loss of Ca^(2+)and Mg^(2+)due to the precipitation of carbonate minerals.Therefore,the evolutionary mode of diagenetic fluids is in good agreement with high HCO_(3)^(-),low Ca^(2+)and low Mg^(2+)composition of the present formation water in the dawsonite-bearing sandstone.展开更多
Carbonate-bearing fluids widely exist in different geological settings,and play important roles in transporting some elements such as the rare earth elements.They may be trapped as large or small fluid inclusions(with...Carbonate-bearing fluids widely exist in different geological settings,and play important roles in transporting some elements such as the rare earth elements.They may be trapped as large or small fluid inclusions(with the size down to<1μm sometimes),and record critical physical-chemical signals for the formations of their host minerals.Spectroscopic methods like Raman spectroscopy and infrared spectroscopy have been proposed as effective methods to quantify the carbonate concentrations of these fluid inclusions.Although they have some great technical advantages over the conventional microthermometry method,there are still some technical difficulties to overcome before they can be routinely used to solve relevant geological problems.The typical limitations include their interlaboratory difference and poor performance on micro fluid inclusions.This study prepared standard ion-distilled water and K_(2)CO_(3)aqueous solutions at different molarities(from 0.5 to 5.5 mol/L),measured densities,collected Raman and infrared spectra,and explored correlations between the K_(2)CO_(3)molarity and the spectroscopic features at ambient P-T conditions.The result confirms that the Raman O-H stretching mode can be used as an internal standard to determine the carbonate concentrations despite some significant differences among the correlations,established in different laboratories,between the relative Raman intensity of the C-O symmetric stretching mode and that of the O-H stretching mode.It further reveals that the interlaboratory difference can be readily removed by performing one high-quality calibration experiment,provided that later quantifying analyses are conducted using the same Raman spectrometer with the same analytical conditions.Our infrared absorption data were collected from thin fluid films(thickness less than~2μm)formed by pressing the prepared solutions in a Microcompression Cell with two diamond-II plates.The data show that both the O-H stretching mode and the O-H bending mode can be used as internal standards to determine the carbonate concentrations.Since the IR signals of the C-O antisymmetric stretching vibration of the CO32ion,and the O-H stretching and bending vibrations from our thin films are very strong,their relative IR absorbance intensity,if well calibrated,can be used to investigate the micron-sized carbonate-bearing aqueous fluid inclusions.This study establishes the first calibration of this kind,which may have some applications.Additionally,our spectroscopic data suggest that as the K_(2)CO_(3)concentration increases the aqueous solution forms more large water molecule clusters via more intense hydrogen-bonding.This process may significantly alter the physical and chemical behavior of the fluids.展开更多
The carbon isotopic composition of CO_(2)inclusions trapped in minerals reflects the origin and evolution of CO_(2)-bearing fluids and melts,and records the multiple-stages carbon geodynamic cycle,as CO_(2)took part i...The carbon isotopic composition of CO_(2)inclusions trapped in minerals reflects the origin and evolution of CO_(2)-bearing fluids and melts,and records the multiple-stages carbon geodynamic cycle,as CO_(2)took part in various geological processes widely.However,the practical method for determination isotope composition of individual CO_(2)inclusion is still lacking.Developing a microanalytical technique with spatial resolution in micrometers to precisely determinate theδ^(13)C value of individual CO_(2)inclusion,will make it possible to analyze a tiny portion of a zoning mineral crystal,distinguish the differences in micro-scale,and possible to find many useful information that could not be obtained with the bulk extraction and analysis techniques.In this study,we systematically collected Raman spectra of CO_(2)standards with different d13C values(34.9‰to 3.58‰)at 32.0℃and from 7.0 MPa to 120.0 MPa,and developed a new procedure to precisely determinate theδ^(13)C value of individual CO_(2)inclusion.We investigated the relationship among the Raman peak intensity ratio,d13C value,and CO_(2)density,and established a calibration model with high accuracy(0.5‰1.5‰),sufficient for geological application to distinguish different source of CO_(2)with varyingδ^(13)CO_(2).As a demonstration,we measured theδ^(13)C values and the density of CO_(2)inclusions in the growth zones of alkali basalt-hosted corundum megacrysts from Changle,Shandong Province.We found the significant differences of density and d13C between the CO_(2)inclusions in the core of corundum and those inclusions in the outer growth zones,the d13C value decreases from core to rim with decreasing density:δ^(13)C values are from7.5‰to9.2‰for the inclusions in the core,indicating the corundum core was crystallized from mantle-derived magmas;from13.5‰to18.5‰for CO_(2)inclusions in zone 1 and from16.5‰to–22.0‰for inclusions in zone 2,indicating the outer zones of corundum grew in a lowδ^(13)C value environment,resulted from an infilling of low d13C value fluid and/or degassing of the ascending basaltic magma.展开更多
In this paper some new advances in the study of fluid inclusions of the Yinshan deposit in Jiangxi Province, China, are presented. The fluid inclusions of the deposit can be divided into four types: 1) gas rich inclus...In this paper some new advances in the study of fluid inclusions of the Yinshan deposit in Jiangxi Province, China, are presented. The fluid inclusions of the deposit can be divided into four types: 1) gas rich inclusions; 2) liquid rich inclusions; 3) salt saturated H 2O inclusions; and 4) single phase or multiphase CO 2 rich inclusions. Homogenization temperatures of the fluid inclusions range from 100 to 520℃, mainly in the range 120-400℃. The daughter crystal bearing multiphase inclusions present in quartz porphyries (including Nos. 13 and 4 dikes) have been observed. In ore veins, some daughter crystal bearing multiphase inclusions have been observed, too. On the basis of the results of fluid inclusion research, the authors suggest that the ore forming fluid must have a close genetic relation to magmatic hydrothermal solution. The ore forming fluid was dominantly originated from the depth and the mixing of magmatic solution with meteoric water was enhanced during ascending of the fluid, accompanying immiscibility and boiling of fluid. There may be a concealed igneous body at the depth of the Yinshan deposit, which furnishes the scientific basis for metallogenic prognosis at the depth of the Yinshan deposit.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42072130,41872152).
文摘Based on the petrology,isotope geochemistry and fluid inclusions analysis,we established the evolutionary mode of the diagenetic fluid of dawsonite-bearing sandstone in the Jiyang Depression.Dawsonite-bearing sandstone is characterized by double injection of CO_(2)and oil-gas in the Jiyang Depression that have experienced a relatively complex diagenetic fluid evolution process.The diagenetic sequence of secondary minerals involves secondary enlargement of quartz,kaolinite,first-stage calcite,dawsonite,second-stage calcite,ferrocalcite,dolomite and ankerite.Hydrocarbon charging in the dawsonite-bearing sandstone occurred at around 2.6–0 Myr.The CO_(2)charging event occurred during Dongying tectonism,forming the Pingfangwang CO_(2)gas reservoir,which provided an abundant carbon source for dawsonite precipitation.Carbon and oxygen isotopic compositions of dawsonite demonstrate that CO_(2)forming the dawsonite was of an inorganic origin derived from the mantle,and that water mediating the proc-ess during dawsonite precipitation was sequestered brine with a fluid temperature of 82℃.The evolutionary sequence of the diagenetic fluid in the dawsonite-bearing sandstone was:alkaline syngenetic fluids,weak alkaline fluids during organic acid forma-tion,acidic fluids in the early stage of CO_(2)injection,alkaline fluids in the late stage of CO_(2)injection,and weak alkaline fluids during oil and gas charging.The mode indicates an increase in-HCO_(3)because of the CO_(2)injection,and the loss of Ca^(2+)and Mg^(2+)due to the precipitation of carbonate minerals.Therefore,the evolutionary mode of diagenetic fluids is in good agreement with high HCO_(3)^(-),low Ca^(2+)and low Mg^(2+)composition of the present formation water in the dawsonite-bearing sandstone.
基金the DREAM project of MOST,China(Grant No.2016YFC0600408)the Strategic Priority Research Program(B)of Chinese Academy of Sciences(Grant No.XDB18000000)the Program of the National Mineral Rock and Fossil Specimens Resource Center from MOST,China.
文摘Carbonate-bearing fluids widely exist in different geological settings,and play important roles in transporting some elements such as the rare earth elements.They may be trapped as large or small fluid inclusions(with the size down to<1μm sometimes),and record critical physical-chemical signals for the formations of their host minerals.Spectroscopic methods like Raman spectroscopy and infrared spectroscopy have been proposed as effective methods to quantify the carbonate concentrations of these fluid inclusions.Although they have some great technical advantages over the conventional microthermometry method,there are still some technical difficulties to overcome before they can be routinely used to solve relevant geological problems.The typical limitations include their interlaboratory difference and poor performance on micro fluid inclusions.This study prepared standard ion-distilled water and K_(2)CO_(3)aqueous solutions at different molarities(from 0.5 to 5.5 mol/L),measured densities,collected Raman and infrared spectra,and explored correlations between the K_(2)CO_(3)molarity and the spectroscopic features at ambient P-T conditions.The result confirms that the Raman O-H stretching mode can be used as an internal standard to determine the carbonate concentrations despite some significant differences among the correlations,established in different laboratories,between the relative Raman intensity of the C-O symmetric stretching mode and that of the O-H stretching mode.It further reveals that the interlaboratory difference can be readily removed by performing one high-quality calibration experiment,provided that later quantifying analyses are conducted using the same Raman spectrometer with the same analytical conditions.Our infrared absorption data were collected from thin fluid films(thickness less than~2μm)formed by pressing the prepared solutions in a Microcompression Cell with two diamond-II plates.The data show that both the O-H stretching mode and the O-H bending mode can be used as internal standards to determine the carbonate concentrations.Since the IR signals of the C-O antisymmetric stretching vibration of the CO32ion,and the O-H stretching and bending vibrations from our thin films are very strong,their relative IR absorbance intensity,if well calibrated,can be used to investigate the micron-sized carbonate-bearing aqueous fluid inclusions.This study establishes the first calibration of this kind,which may have some applications.Additionally,our spectroscopic data suggest that as the K_(2)CO_(3)concentration increases the aqueous solution forms more large water molecule clusters via more intense hydrogen-bonding.This process may significantly alter the physical and chemical behavior of the fluids.
基金supported by National Nature Science Foundation of China(92058208)the National Key Research and Development Program of China(2018YFC0310006-04).
文摘The carbon isotopic composition of CO_(2)inclusions trapped in minerals reflects the origin and evolution of CO_(2)-bearing fluids and melts,and records the multiple-stages carbon geodynamic cycle,as CO_(2)took part in various geological processes widely.However,the practical method for determination isotope composition of individual CO_(2)inclusion is still lacking.Developing a microanalytical technique with spatial resolution in micrometers to precisely determinate theδ^(13)C value of individual CO_(2)inclusion,will make it possible to analyze a tiny portion of a zoning mineral crystal,distinguish the differences in micro-scale,and possible to find many useful information that could not be obtained with the bulk extraction and analysis techniques.In this study,we systematically collected Raman spectra of CO_(2)standards with different d13C values(34.9‰to 3.58‰)at 32.0℃and from 7.0 MPa to 120.0 MPa,and developed a new procedure to precisely determinate theδ^(13)C value of individual CO_(2)inclusion.We investigated the relationship among the Raman peak intensity ratio,d13C value,and CO_(2)density,and established a calibration model with high accuracy(0.5‰1.5‰),sufficient for geological application to distinguish different source of CO_(2)with varyingδ^(13)CO_(2).As a demonstration,we measured theδ^(13)C values and the density of CO_(2)inclusions in the growth zones of alkali basalt-hosted corundum megacrysts from Changle,Shandong Province.We found the significant differences of density and d13C between the CO_(2)inclusions in the core of corundum and those inclusions in the outer growth zones,the d13C value decreases from core to rim with decreasing density:δ^(13)C values are from7.5‰to9.2‰for the inclusions in the core,indicating the corundum core was crystallized from mantle-derived magmas;from13.5‰to18.5‰for CO_(2)inclusions in zone 1 and from16.5‰to–22.0‰for inclusions in zone 2,indicating the outer zones of corundum grew in a lowδ^(13)C value environment,resulted from an infilling of low d13C value fluid and/or degassing of the ascending basaltic magma.
文摘In this paper some new advances in the study of fluid inclusions of the Yinshan deposit in Jiangxi Province, China, are presented. The fluid inclusions of the deposit can be divided into four types: 1) gas rich inclusions; 2) liquid rich inclusions; 3) salt saturated H 2O inclusions; and 4) single phase or multiphase CO 2 rich inclusions. Homogenization temperatures of the fluid inclusions range from 100 to 520℃, mainly in the range 120-400℃. The daughter crystal bearing multiphase inclusions present in quartz porphyries (including Nos. 13 and 4 dikes) have been observed. In ore veins, some daughter crystal bearing multiphase inclusions have been observed, too. On the basis of the results of fluid inclusion research, the authors suggest that the ore forming fluid must have a close genetic relation to magmatic hydrothermal solution. The ore forming fluid was dominantly originated from the depth and the mixing of magmatic solution with meteoric water was enhanced during ascending of the fluid, accompanying immiscibility and boiling of fluid. There may be a concealed igneous body at the depth of the Yinshan deposit, which furnishes the scientific basis for metallogenic prognosis at the depth of the Yinshan deposit.
