There exists abundant thermal water recourses in Guanzhong basin, Shaanxi province (northwestern China). With the deepening of exploitation for thermal aquifer nowadays, the information about the origin and movement o...There exists abundant thermal water recourses in Guanzhong basin, Shaanxi province (northwestern China). With the deepening of exploitation for thermal aquifer nowadays, the information about the origin and movement of thermal water is limited by using traditional methods. This paper applies environmental isotope techniques to offer direct constraints on the recharge and movement of thermal water and improve the geological and hydrogeological data- base in Guanzhong Basin. The research on the environmental isotopes shows that the geothermal water of the area is mainly recharged by meteoric water. The temperature of meteoric water which replenishes geothermal water in the study area is -16 ℃. The estimated age of recharging the geothermal water is 13.3-28.2 ka based on the isotope analysis, belonging to the last glacial period in Late Quaternary. The source of replenishment of the geothermal water is thought to have been derived from glacial snow-melt water with an elevation higher than 1 500 m (ASL) in the north side of Qinling Mountain. The isotopic analysis denotes that the geothermal water in the southern Guanzhong basin is the mixture of net thermal water and normal temperature groundwater. Based on calculating the percentage of the mixture, nearly half of cold groundwater had participated the circulating of the geothermal water. However, in the center part of the basin, some artificial factors such as mismanage of pumping are probably the reason for the mixturing. The temperature range of the geothermal reservoirs in the basin is estimated at about 80-121 ℃ based on calculation of both SiO2 geothermometer and thermal water saturation index, which are basically in accordance with the measured temperature of thermal water. Based on the replenishment time and mixture extent with cold water, the thermal water in the studied area can be classified into three parts: mixed thermal water replenished by modern meteoric water; mixed thermal water replenished by both modern and ancient meteoric water, and deep circulating thermal water replenished by ancient meteoric water without mixture.展开更多
Formation and evolution of sedimentary basin is the clue for oil-and-gas generation zones of sedimentary cover that makes the problem of sedimentary basins geodynamics of great importance one. Geodynamics of relief is...Formation and evolution of sedimentary basin is the clue for oil-and-gas generation zones of sedimentary cover that makes the problem of sedimentary basins geodynamics of great importance one. Geodynamics of relief is defined by deep mantle movements. Mechanical-mathematical model of the lithosphere dynamics gives possibility to link the basin parameters with mantle diaper upwelling. Analysis of geophysical fields gives opportunity to evaluate the astenosphere upwelling, and the elaborated self-conjugated thermo-gravimetric model makes this evaluation reliable and trustworthy one.展开更多
Based on the observed data, the average value of surface heatflow in the Yinggehai Basin is calculated and it turns out to be 84.1 mW/m2. The thermal evolution of the basin since the Cenozoic era has been attempted by...Based on the observed data, the average value of surface heatflow in the Yinggehai Basin is calculated and it turns out to be 84.1 mW/m2. The thermal evolution of the basin since the Cenozoic era has been attempted by tectono-thermal modeling. Three-phase extension made the basin become hotter and hotter, reaching its climax in paleo-temperature history since 5.2 Ma. And nowadays, the basin is in the heat flow decreasing period. During the Cenozoic era, the basement heat flow remained at 50-70 mW/m2 all the time. This is related to the degree of each extension phase, stretching rate mode and also the limited basin scale. Modeling results also show that, the surface heat flow is controlled mainly by the basement heat flow, and less than 20% comes from radiogenic heat production in the sediments of the basin.展开更多
The Permian Lucaogou Formation is an important hydrocarbon source rock in the Junggar, Turpan, and Santanghu basins in Xinjiang, NW China. For the first time, dolostones associated with mantle-originated exhalative hy...The Permian Lucaogou Formation is an important hydrocarbon source rock in the Junggar, Turpan, and Santanghu basins in Xinjiang, NW China. For the first time, dolostones associated with mantle-originated exhalative hydrothermal fluid flows are discovered in Yuejingou section in the Santanghu Basin area. They include dolomicrite, doloarenite, and a small amount of dolorudite, and are finely (0.05-0.15 cm thick) interlaminated with lime micrite and dolomicritic analcime laminites. Alkali feldspar and analcime grains are common in doloarenite and are interpreted as having been derived from analcime phonolites and peralkaline magmatic rocks. These magmatic fragments were brought up from subsurface by hydrothermal fluid flow and had experienced exhalative brecciation, transport, and deposition on the lake floor. The matrix consists dominantly of dolomite and ankerite smaller than 0.01 mm. The dolostones can be subdivided into four types on the basis of mineral composition and content. The detrital analcime and alkaline feldspar grains and tuff lithics are interpreted as intraclasts, which were deposited in an under-filled starved lake basin. The δ18OPDB values of dolostones are -5‰ to -21.1‰, and -11.9‰ on average; the 87Sr/86Sr ratios of dolostones are 0.70457 to 0.706194, and 0.705005 on average. These values, in combination with evidence of multi-episodes of peralkaline extrusion, suggest a mantle origin of the hydrothermal fluids, which may have promoted primary dolomite formation. The fluid from the upper mantle caused serpentinization of ultramafic rocks that intruded into the lower crust to obtain Mg2+ and Fe2+, and injected the ions into the lake water as the Mg and Fe sources for dolomite and ankerite. Hydro- thermal fluids associated with peralkaline magmatic rocks also provided Ca2+, Mg2+, Fe2+, and CO32-. Explosive breccias formed and dolostones were convoluted near the vent of hydrothermal fluid exhalation, whereas laminated dolostones formed farther away from the vent. The dolostones are primary dolomite deposition in an intracontinental rift basin and associated with mantle-originated hydrothermal fluids. They provide an insight into the origin of dolomite formation in the geologic history and clues to understand the sedimentary environments and tectonic conditions in northern Xinjiang during the late Paleozoic.展开更多
The Sichuan Basin is a superimposition basin composed of terrestrial and marine sediments that is well known for its abundant petroleum resources. Thermal history reconstruction using paleogeothermal indicators, inclu...The Sichuan Basin is a superimposition basin composed of terrestrial and marine sediments that is well known for its abundant petroleum resources. Thermal history reconstruction using paleogeothermal indicators, including vitrinite reflectahoe and thermochronological data, shows that different structural subsections of the Sichuan Basin have experienced various paleogeothermal episodes since the Paleozoic. The lower structural subsection comprising the Lower Paleozoic to Middle Permian （Pz-P2） successions experienced a high paleogeothermal gradient （23.0-42.6℃/km） at the end of the Middle Permian （P2）, whereas the upper structural subsection comprising Late Permian to Mesozoic strata underwent a relatively lower paleogeothermal gradient （13.2-26.9℃/km） at the beginning of the denudation （Late Cretaceous or Paleocene in the different regions）. During the denudation period, the Sichuan Basin experienced a successive cooling episode. The high paleogeothermal gradient resulted from an intensive thermal event correlated to the Emeishan mantle plume. The heat flow value reached 124.0 mW/m2 in the southwestern basin near the center of the Emeishan large igneous province. The low geothermal gradient episode with heat flow ranging from 31.2 to 70.0 mW/m2 may be related to the foreland basin evolution. The cooling event is a result of the continuous uplift and denudation of the basin.展开更多
Based on the GC-MS analytical data of aromatic fractions of over forty highly mature coal-bearing source rock samples collected from the Upper Triassic Xujiahe Formation in the northern Sichuan Basin, the thermal evol...Based on the GC-MS analytical data of aromatic fractions of over forty highly mature coal-bearing source rock samples collected from the Upper Triassic Xujiahe Formation in the northern Sichuan Basin, the thermal evolution of aromatic hydrocarbons during late-mature to over-mature stage （R0=1.13%-2.85%） was characterized, and aromatic indicators suitable for recognizing the organic source and sedimentary environment of high maturity source rocks were discussed. The results indicated that the concentrations of low carbon-cycle naphthalene as well phenanthrene series reduce gradually with increasing Ro at the highly mature levels. However, some high-cyclic components such as chrysene, benzofluoranthene, and benzo[e]pyrene are relatively enriched, in companying an enhancement of parent aromatic compounds. The variations are attributed to thermal cracking and polymerization reactions due to continuous dehydrogenation under enhanced burial temperature. As thermal maturity rises, MPI1 （Methylphenanthrene Index） values display a two-modal varying trend, namely, increasing when Ro is below 1.80% and decreasing above 1.8% Ro. The relationships between Ro and MPI1 are Ro=0.98MPI1＋0.37 for R0〈1.80% and R0=-0.90MPI1＋3.02 at R0〉1.8%, being different from the previous research. The amount of dibenzofurans declines sharply at Ro higher than 1.1%, leading to a significant change of relative composition among dibenzothiophenes, dibenzofurans and fluorenes （referred as three-fluorenes series composition）. Thus, this parameter appears to be unsuitable for identifying the sedimentary environment of the highly matured source rocks. 4-/1-MDBT （methyldibenzothiophene） ratio could be served as an effective indicator for organic facies, and can distinguish coals from mudstones at over-maturity in this case. The ratios of 2,6-/2,10-DMP （dimethylphenanthrene） and 1,7-/1,9-DMP and relative abundance of triaromatic steroids in these highly mature rocks could be considered as biological source parameters for relative input of terrigenous versus aquatic organic matter.展开更多
基金Project 2005003 supported by the Natural Science Foundation of Shaanxi Province
文摘There exists abundant thermal water recourses in Guanzhong basin, Shaanxi province (northwestern China). With the deepening of exploitation for thermal aquifer nowadays, the information about the origin and movement of thermal water is limited by using traditional methods. This paper applies environmental isotope techniques to offer direct constraints on the recharge and movement of thermal water and improve the geological and hydrogeological data- base in Guanzhong Basin. The research on the environmental isotopes shows that the geothermal water of the area is mainly recharged by meteoric water. The temperature of meteoric water which replenishes geothermal water in the study area is -16 ℃. The estimated age of recharging the geothermal water is 13.3-28.2 ka based on the isotope analysis, belonging to the last glacial period in Late Quaternary. The source of replenishment of the geothermal water is thought to have been derived from glacial snow-melt water with an elevation higher than 1 500 m (ASL) in the north side of Qinling Mountain. The isotopic analysis denotes that the geothermal water in the southern Guanzhong basin is the mixture of net thermal water and normal temperature groundwater. Based on calculating the percentage of the mixture, nearly half of cold groundwater had participated the circulating of the geothermal water. However, in the center part of the basin, some artificial factors such as mismanage of pumping are probably the reason for the mixturing. The temperature range of the geothermal reservoirs in the basin is estimated at about 80-121 ℃ based on calculation of both SiO2 geothermometer and thermal water saturation index, which are basically in accordance with the measured temperature of thermal water. Based on the replenishment time and mixture extent with cold water, the thermal water in the studied area can be classified into three parts: mixed thermal water replenished by modern meteoric water; mixed thermal water replenished by both modern and ancient meteoric water, and deep circulating thermal water replenished by ancient meteoric water without mixture.
文摘Formation and evolution of sedimentary basin is the clue for oil-and-gas generation zones of sedimentary cover that makes the problem of sedimentary basins geodynamics of great importance one. Geodynamics of relief is defined by deep mantle movements. Mechanical-mathematical model of the lithosphere dynamics gives possibility to link the basin parameters with mantle diaper upwelling. Analysis of geophysical fields gives opportunity to evaluate the astenosphere upwelling, and the elaborated self-conjugated thermo-gravimetric model makes this evaluation reliable and trustworthy one.
基金the National Natural Science Foundation of China (Grant Nos. 49732005 49804004) and Key-Project (KZ951-A1-401) of Chinese Academy of Sciences.
文摘Based on the observed data, the average value of surface heatflow in the Yinggehai Basin is calculated and it turns out to be 84.1 mW/m2. The thermal evolution of the basin since the Cenozoic era has been attempted by tectono-thermal modeling. Three-phase extension made the basin become hotter and hotter, reaching its climax in paleo-temperature history since 5.2 Ma. And nowadays, the basin is in the heat flow decreasing period. During the Cenozoic era, the basement heat flow remained at 50-70 mW/m2 all the time. This is related to the degree of each extension phase, stretching rate mode and also the limited basin scale. Modeling results also show that, the surface heat flow is controlled mainly by the basement heat flow, and less than 20% comes from radiogenic heat production in the sediments of the basin.
基金supported by National Natural Science Fundation of China (Grant No. 40802024)Sinopec Project "Study and Map Compilation for Structure, Lithofacies, and Paleogeography in Northwestern China (Grant No. YPH08103)"State Key Laboratory of Continental Dynamics (Grant No. BJ091358)
文摘The Permian Lucaogou Formation is an important hydrocarbon source rock in the Junggar, Turpan, and Santanghu basins in Xinjiang, NW China. For the first time, dolostones associated with mantle-originated exhalative hydrothermal fluid flows are discovered in Yuejingou section in the Santanghu Basin area. They include dolomicrite, doloarenite, and a small amount of dolorudite, and are finely (0.05-0.15 cm thick) interlaminated with lime micrite and dolomicritic analcime laminites. Alkali feldspar and analcime grains are common in doloarenite and are interpreted as having been derived from analcime phonolites and peralkaline magmatic rocks. These magmatic fragments were brought up from subsurface by hydrothermal fluid flow and had experienced exhalative brecciation, transport, and deposition on the lake floor. The matrix consists dominantly of dolomite and ankerite smaller than 0.01 mm. The dolostones can be subdivided into four types on the basis of mineral composition and content. The detrital analcime and alkaline feldspar grains and tuff lithics are interpreted as intraclasts, which were deposited in an under-filled starved lake basin. The δ18OPDB values of dolostones are -5‰ to -21.1‰, and -11.9‰ on average; the 87Sr/86Sr ratios of dolostones are 0.70457 to 0.706194, and 0.705005 on average. These values, in combination with evidence of multi-episodes of peralkaline extrusion, suggest a mantle origin of the hydrothermal fluids, which may have promoted primary dolomite formation. The fluid from the upper mantle caused serpentinization of ultramafic rocks that intruded into the lower crust to obtain Mg2+ and Fe2+, and injected the ions into the lake water as the Mg and Fe sources for dolomite and ankerite. Hydro- thermal fluids associated with peralkaline magmatic rocks also provided Ca2+, Mg2+, Fe2+, and CO32-. Explosive breccias formed and dolostones were convoluted near the vent of hydrothermal fluid exhalation, whereas laminated dolostones formed farther away from the vent. The dolostones are primary dolomite deposition in an intracontinental rift basin and associated with mantle-originated hydrothermal fluids. They provide an insight into the origin of dolomite formation in the geologic history and clues to understand the sedimentary environments and tectonic conditions in northern Xinjiang during the late Paleozoic.
基金the National Natural Science Foundation of China(Grant No.41102152)the PetroChina Innovation Foundation(Grant No.2013D-5006-0102)+1 种基金the National Basic Research Program of China(Grant No.2012CB214703)the Science Foundation of China University of Petroleum,Beijing(Grant No.YJRC2013-002)
文摘The Sichuan Basin is a superimposition basin composed of terrestrial and marine sediments that is well known for its abundant petroleum resources. Thermal history reconstruction using paleogeothermal indicators, including vitrinite reflectahoe and thermochronological data, shows that different structural subsections of the Sichuan Basin have experienced various paleogeothermal episodes since the Paleozoic. The lower structural subsection comprising the Lower Paleozoic to Middle Permian （Pz-P2） successions experienced a high paleogeothermal gradient （23.0-42.6℃/km） at the end of the Middle Permian （P2）, whereas the upper structural subsection comprising Late Permian to Mesozoic strata underwent a relatively lower paleogeothermal gradient （13.2-26.9℃/km） at the beginning of the denudation （Late Cretaceous or Paleocene in the different regions）. During the denudation period, the Sichuan Basin experienced a successive cooling episode. The high paleogeothermal gradient resulted from an intensive thermal event correlated to the Emeishan mantle plume. The heat flow value reached 124.0 mW/m2 in the southwestern basin near the center of the Emeishan large igneous province. The low geothermal gradient episode with heat flow ranging from 31.2 to 70.0 mW/m2 may be related to the foreland basin evolution. The cooling event is a result of the continuous uplift and denudation of the basin.
基金supported by the Key State Science and Technology Project(Grant No.2011ZX05005-03-009HZ)the Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20130101110051)
文摘Based on the GC-MS analytical data of aromatic fractions of over forty highly mature coal-bearing source rock samples collected from the Upper Triassic Xujiahe Formation in the northern Sichuan Basin, the thermal evolution of aromatic hydrocarbons during late-mature to over-mature stage （R0=1.13%-2.85%） was characterized, and aromatic indicators suitable for recognizing the organic source and sedimentary environment of high maturity source rocks were discussed. The results indicated that the concentrations of low carbon-cycle naphthalene as well phenanthrene series reduce gradually with increasing Ro at the highly mature levels. However, some high-cyclic components such as chrysene, benzofluoranthene, and benzo[e]pyrene are relatively enriched, in companying an enhancement of parent aromatic compounds. The variations are attributed to thermal cracking and polymerization reactions due to continuous dehydrogenation under enhanced burial temperature. As thermal maturity rises, MPI1 （Methylphenanthrene Index） values display a two-modal varying trend, namely, increasing when Ro is below 1.80% and decreasing above 1.8% Ro. The relationships between Ro and MPI1 are Ro=0.98MPI1＋0.37 for R0〈1.80% and R0=-0.90MPI1＋3.02 at R0〉1.8%, being different from the previous research. The amount of dibenzofurans declines sharply at Ro higher than 1.1%, leading to a significant change of relative composition among dibenzothiophenes, dibenzofurans and fluorenes （referred as three-fluorenes series composition）. Thus, this parameter appears to be unsuitable for identifying the sedimentary environment of the highly matured source rocks. 4-/1-MDBT （methyldibenzothiophene） ratio could be served as an effective indicator for organic facies, and can distinguish coals from mudstones at over-maturity in this case. The ratios of 2,6-/2,10-DMP （dimethylphenanthrene） and 1,7-/1,9-DMP and relative abundance of triaromatic steroids in these highly mature rocks could be considered as biological source parameters for relative input of terrigenous versus aquatic organic matter.
