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Jian Chen - One of the best experts on this subject based on the ideXlab platform.
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iodine 129 chronological study of brines from an ordovician paleokarst reservoir in the lunnan oilfield tarim basin
Applied Geochemistry, 2016Co-Authors: Jian Chen, Pingan Peng, Hou Xiaolin, Zhang Baoshou, Dayong Liu, Chen Ning, Xiao ZhongyaoAbstract:Abstract Previous studies have shown that brines in an Ordovician paleokarst reservoir of the Lunnan oilfield in the Tarim Basin, China, are the product of mixing of paleo-evaporated seaWater in the east with paleoMeteoric Waters in the west. In order to put time constraints on the brine and related hydrocarbons in this field, 10 brine samples were collected, for which the iodine concentrations and 129 I/I ratios were measured and discussed. The iodine concentration (3.70–31.2 mg/L) and the 129 I/I ratio (189–897 × 10 −15 ) show that the iodine in the paleoseaWater and Meteoric Water (MW) had different origins and 129 I characteristics. The paleoseaWater has a high iodine content (∼31 mg/L), indicating that iodine was introduced into the reservoir along with thermally generated hydrocarbons, possibly in the Cretaceous, from the Caohu Sag in the eastern area. Based on consideration of all possible origins of iodine and 129 I in the brines, it is suggested that the Meteoric Water maintained its initial iodine content (0.01 mg/L) and 129 I/I ratio (1500 × 10 −15 ), whereas the iodine-enriched paloseaWater (IPSW) exhibited a secular 129 I equilibrium (N sq = 39 atom/μL) as a result of fissiogenic 129 I input in the reservoir over a long period of time. The model of brine evolution developed on that basis confirmed that Meteoric Water entered the reservoir in the Miocene at about 10 Ma, and partially mixed with the iodine-enriched paleoseaWater. The movement of Meteoric Water was facilitated by faults created during the Himalayan orogeny, then became more dense after dissolving Paleogene halite and infiltrated into the reservoir at high pressure. The iodine and 129 I concentration in the brine contains information about the path and history of the fluid in the reservoir. This may be useful in oil exploration, since the movement of Water was, to some extent, related to hydrocarbon migration.
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the sources and formation processes of brines from the lunnan ordovician paleokarst reservoir tarim basin northwest china
Geofluids, 2013Co-Authors: Jian Chen, Dehan Liu, Pingan Peng, Baoshou Zhang, Zhongyao XiaoAbstract:The most important petroleum exploration target in the Tarim Basin, northwest China, is the paleokarst reservoir. To understand the source and evolution of brine in this type of reservoir, a total of 37 formation-Water samples were collected from the Middle-Lower Ordovician paleokarst reservoir in the Lunnan oilfield. The δD-δ18O correlation and Cl/Br ratios reflect the mixture of two fluids: Meteoric Water and evaporated seaWater. The different degree of mixture divided samples into two groups. Group 1 samples, from deep strata (5150–6667 m.b.s.l.) in the east of the field, with elevated δD (−53.5 to −38.0‰), δ18O values (0.66–5.99‰), and lower Cl/Br ratios (336–478 for Cl/Br, except LN634-1 and LN631-1) were formed by evaporation of seaWater plus a small contribution from Meteoric Water. Group 2 samples, from shallow strata (5038–6067 m.b.s.l.), in the west of the field, have contrasting features (−59.6 to −48.5‰ for δD, −0.47 to 2.17‰ for δ18O, and 501 to 871 for Cl/Br), which reflect a mixture of evaporated seaWater with a high proportion of Meteoric Water. Both of the fluid types exchanged oxygen isotope with minerals. The investigation into cation composition reveals that, before entering into the current reservoir, Waters suffered albitization of plagioclase; moreover, Meteoric Water dissolved evaporites and seaWater experienced dolomitization. A mixing trend showed by strontium isotopes (0.709801–0.711628) gave further evidence for the mixture of two fluid types. Based on the correlation of geological history with our data, two infiltration models of Meteoric Waters can be constructed. According to the chemical and isotopic compositions of the Waters, an east fluid regime (Group 1) and a west fluid regime (Group 2) have thus been defined. Better understanding of the subsurface fluid movement patterns may be helpful for the local exploration.
Jiang Wang - One of the best experts on this subject based on the ideXlab platform.
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mineral paragenesis and hydrothermal evolution of the dabaiyang tellurium gold deposit hebei province china constraints from fluid inclusions h o he ar isotopes and physicochemical conditions
Ore Geology Reviews, 2020Co-Authors: Dazhao Wang, Shimin Zhen, Jiajun Liu, Emmanuel John M Carranza, Jiang WangAbstract:Abstract The Dabaiyang deposit is a typical Te-Au deposit hosted in Archean metamorphic rock in the Zhangjiakou district, northern margin of the North China Craton. It is located close to the famous Dongping Te-Au deposit; however, few researches have performed on the Archean metamorphic rock hosted Te-Au deposits, which precludes the studies on enrichment processes and mechanisms of Te-Au deposits in the Zhangjiakou district. In this contribution, four mineralization stages have been recognized in the Dabaiyang deposit: (1) K-feldspar−quartz veins; (2) quartz-pyrite veins; (3) polymetallic sulfide-quartz veins; and (4) calcite and quartz veins. Metallic minerals in this deposit include pyrite, chalcopyrite, galena, sphalerite, bornite, altaite, hessite, petzite, tetradymite, tellurobismuthite, native gold and electrum, and most of them were precipitated in stage III. Petrography, fluid inclusion microthermometry, and laser Raman spectroscopy revealed that the ore-forming fluid was a medium temperature H2O-NaCl hydrothermal system. Fluid temperatures evolved from 264–337℃ to 233–323℃ to 209–268℃ to 130–245℃, and salinities varied from 1.2–10.3 wt% to 1.2–8.8 wt% to 4.3–10.5 wt% to 3.8–8.3 wt% NaCl equivalent. Ore-forming fluids yield H and O isotope compositions of −2.4‰ to 4.9‰ and −101.2‰ to −75.5‰, respectively, and 3He/4He and 40Ar/36Ar ratios of 1.31–1.58 and 3489.0–21824.1, respectively. The hydrothermal fluids were derived initially from magmatic Water (stage I), but more mixture of magmatic and Meteoric Water or heated Meteoric Water was added to the system (stages II and III), and significant Water-rock exchange with the Sanggan metamorphic rock happened during evolution. Calculated physicochemical conditions of ore mineral formation shows that pH decreased, logfO2 and logfS2 did not change significantly from the early to the late stage; logfTe2 and logαAu+(aq)/αAg+(aq) values of stage III are -10.7 to -9.8 and -6.8, respectively. Ore-forming fluid did not suffer boiling during evolution, but mixing with low-temperature Meteoric Water and Water-rock reaction were the dominant mechanisms that led to the precipitation of sulfides, tellurides and Au−Ag minerals in the deposit. The Dabaiyang Te-Au deposit is an epithermal gold deposit and its various hydrothermal fluid sources compared with intrusion hosted Te-Au deposits led to their differences in Te and Au contents, hydrothermal systems and mineral deposition mechanisms.
Xiao Zhongyao - One of the best experts on this subject based on the ideXlab platform.
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iodine 129 chronological study of brines from an ordovician paleokarst reservoir in the lunnan oilfield tarim basin
Applied Geochemistry, 2016Co-Authors: Jian Chen, Pingan Peng, Hou Xiaolin, Zhang Baoshou, Dayong Liu, Chen Ning, Xiao ZhongyaoAbstract:Abstract Previous studies have shown that brines in an Ordovician paleokarst reservoir of the Lunnan oilfield in the Tarim Basin, China, are the product of mixing of paleo-evaporated seaWater in the east with paleoMeteoric Waters in the west. In order to put time constraints on the brine and related hydrocarbons in this field, 10 brine samples were collected, for which the iodine concentrations and 129 I/I ratios were measured and discussed. The iodine concentration (3.70–31.2 mg/L) and the 129 I/I ratio (189–897 × 10 −15 ) show that the iodine in the paleoseaWater and Meteoric Water (MW) had different origins and 129 I characteristics. The paleoseaWater has a high iodine content (∼31 mg/L), indicating that iodine was introduced into the reservoir along with thermally generated hydrocarbons, possibly in the Cretaceous, from the Caohu Sag in the eastern area. Based on consideration of all possible origins of iodine and 129 I in the brines, it is suggested that the Meteoric Water maintained its initial iodine content (0.01 mg/L) and 129 I/I ratio (1500 × 10 −15 ), whereas the iodine-enriched paloseaWater (IPSW) exhibited a secular 129 I equilibrium (N sq = 39 atom/μL) as a result of fissiogenic 129 I input in the reservoir over a long period of time. The model of brine evolution developed on that basis confirmed that Meteoric Water entered the reservoir in the Miocene at about 10 Ma, and partially mixed with the iodine-enriched paleoseaWater. The movement of Meteoric Water was facilitated by faults created during the Himalayan orogeny, then became more dense after dissolving Paleogene halite and infiltrated into the reservoir at high pressure. The iodine and 129 I concentration in the brine contains information about the path and history of the fluid in the reservoir. This may be useful in oil exploration, since the movement of Water was, to some extent, related to hydrocarbon migration.
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Iodine-129 chronological study of brines from an Ordovician paleokarst reservoir in the Lunnan oilfield, Tarim Basin
'Elsevier BV', 2016Co-Authors: Chen Jian, Liu Dayong, Peng Ping'an, Ning Chen, Hou Xiaolin, Zhang Baoshou, Xiao ZhongyaoAbstract:Previous studies have shown that brines in an Ordovician paleokarst reservoir of the Lunnan oilfield in the Tarim Basin, China, are the product of mixing of paleo-evaporated seaWater in the east with paleo-Meteoric Waters in the west. In order to put time constraints on the brine and related hydrocarbons in this field, 10 brine samples were collected, for which the iodine concentrations and I-129/I ratios were measured and discussed. The iodine concentration (3.70-31.2 mg/L) and the I-129/I ratio (189 -897 x 10(-15)) show that the iodine in the paleoseaWater and Meteoric Water (MW) had different origins and I-129 characteristics. The paleoseaWater has a high iodine content (similar to 31 mg/L), indicating that iodine was introduced into the reservoir along with thermally generated hydrocarbons, possibly in the Cretaceous, from the Caohu Sag in the eastern area. Based on consideration of all possible origins of iodine and I-129 in the brines, it is suggested that the Meteoric Water maintained its initial iodine content (0.01 mg/L) and I-129/I ratio (1500 x 10(-15)), whereas the iodine-enriched paloseaWater (IPSW) exhibited a secular I-129 equilibrium (N-sq = 39 atom/mu L) as a result of fissiogenic I-129 input in the reservoir over a long period of time. The model of brine evolution developed on that basis confirmed that Meteoric Water entered the reservoir in the Miocene at about 10 Ma, and partially mixed with the iodine-enriched paleoseaWater. The movement of Meteoric Water was facilitated by faults created during the Himalayan orogeny, then became more dense after dissolving Paleogene halite and infiltrated into the reservoir at high pressure. The iodine and I-129 concentration in the brine contains information about the path and history of the fluid in the reservoir. This may be useful in oil exploration, since the movement of Water was, to some extent, related to hydrocarbon migration. (C) 2015 Elsevier Ltd. All rights reserved
Kezhang Qin - One of the best experts on this subject based on the ideXlab platform.
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porphyry mo and epithermal au ag pb zn mineralization in the zhilingtou polymetallic deposit south china
Mineralium Deposita, 2020Co-Authors: Yongbin Wang, Qingdong Zeng, Jianming Liu, Kezhang QinAbstract:The Zhilingtou polymetallic deposit, South China, provides an excellent opportunity to investigate the magmatic-hydrothermal evolution of the porphyry Mo to epithermal Au–Ag–Pb–Zn ore spectrum. New zircon U–Pb, sphalerite 40Ar/39Ar, and pyrite Rb–Sr ages, together with previous molybdenite Re–Os ages, indicate that the granitic magmatism and Mo–Au–Ag–Pb–Zn mineralization were coeval and cogenetic in the Early Cretaceous (~ 113 Ma). Fluid inclusions and H–O isotope results have established the evolution from an early high-temperature H2O–NaCl magmatic fluid system (Mo mineralization), to a medium-temperature mixed fluid system of magmatic and Meteoric Water (Au–Ag mineralization), to a peripheral late-stage low-temperature H2O–NaCl Meteoric Water fluid system (epithermal Au–Ag–Pb–Zn mineralization). Moreover, the sulfur isotopic compositions (δ34S = 2.1–7.8‰) of the sulfide minerals confirm a genetic link to the granitic magma. Lead isotope data from pyrite and the granite–rhyolite porphyries are similar, indicating that they share a common Pb source. The geochronological, geochemical, and isotopic lines of evidences consistently suggest that the porphyry Mo and epithermal Au–Ag–Pb–Zn mineralization formed in one magmatic–hydrothermal system. The porphyry-epithermal mineralization model for Zhilingtou has significant importance for prospecting work in South China, where Mo and associated Pb–Zn–Ag resources are abundant.
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incursion of Meteoric Water triggers molybdenite precipitation in porphyry mo deposits a case study of the chalukou giant mo deposit
Ore Geology Reviews, 2019Co-Authors: Kezhang Qin, Luying Jin, Guoxue Song, Ri HanAbstract:There has been a long-term debate about the timing of the incursion of Meteoric Water into porphyry systems and whether it plays an important role in ore precipitation. To evaluate the role of Meteoric Water in the mineralization in porphyry Mo deposits, typical hydrothermal veins of different stages from the Chalukou giant porphyry Mo deposit are selected for combined scanning electron microscope cathodoluminescence (SEM-CL), fluid inclusion microthermometry and high-resolution secondary ion mass spectroscopy (SIMS) oxygen isotope analyses. Multiple generations of quartz are identified in almost all of the veins. The barren quartz veins and quartz-magnetite veins of the early Mo mineralization stage are dominated by granular CL-bright quartz (EMQ1), which usually shows dissolution and re-deposition textures and are overprinted by CL-dark quartz (EMQ2)-filled healed fractures. The molybdenite precipitation in the quartz-molybdenite veins of the main Mo mineralization stage is synchronous with small volumes ( 85%) of CL-bright quartz (MMQ1). Similar to the quartz-molybdenite veins, the precipitation of pyrite in the quartz-pyrite veins during the transitional stage and sphalerite in the quartz-sphalerite-pyrite veins during the Zn-Pb mineralization stage are also directly associated with CL-dark quartz (TSQ2, ZPQ2). The SIMS oxygen isotopic values of EMQ1 and MMQ1 fall into the range of 5.42-9.79%o with calculated equilibrium fluid compositions of 2.07-6.45%0, indicating a magma-dominated fluid composition, whereas MMQ2, TSQ2 and ZPQ2 have very low oxygen isotopic values from -4.68 to -4.29 parts per thousand with corresponding fluid compositions of -13.64 to -5.94 parts per thousand, implying that the fluid formed by the mixing of magmatic Water and a large proportion of Meteoric Water. The contrasting SEM-CL features and oxygen isotopic compositions of the two generations of quartz in the quartz-molybdenite veins demonstrate that the incursion of Meteoric Water into the hydrothermal system occurred earlier than the molybdenite precipitation. Based on these results and the crosscutting relationships and spatial distribution of the veins, we reconstructed the quartz evolutionary sequence during the vein development process. After the early precipitation of barren quartz, the reduction in fluid pressure from lithostatic to hydrostatic conditions allowed the incursion of convecting cool Meteoric Water into the relatively hot hydrothermal system, and the temperature of the evolved Mo-rich fluid decreased rapidly from > 500 degrees C to < 400 degrees C, leading to concentrated molybdenite precipitation with small volumes of quartz. Fluid cooling resulting from the incursion of Meteoric Water may have played a greater role in the metal precipitation in the Chalukou Mo deposit than wallrock interactions and fluid boiling. Moreover, this process may have also occurred in other porphyry Mo deposits.
Pingan Peng - One of the best experts on this subject based on the ideXlab platform.
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iodine 129 chronological study of brines from an ordovician paleokarst reservoir in the lunnan oilfield tarim basin
Applied Geochemistry, 2016Co-Authors: Jian Chen, Pingan Peng, Hou Xiaolin, Zhang Baoshou, Dayong Liu, Chen Ning, Xiao ZhongyaoAbstract:Abstract Previous studies have shown that brines in an Ordovician paleokarst reservoir of the Lunnan oilfield in the Tarim Basin, China, are the product of mixing of paleo-evaporated seaWater in the east with paleoMeteoric Waters in the west. In order to put time constraints on the brine and related hydrocarbons in this field, 10 brine samples were collected, for which the iodine concentrations and 129 I/I ratios were measured and discussed. The iodine concentration (3.70–31.2 mg/L) and the 129 I/I ratio (189–897 × 10 −15 ) show that the iodine in the paleoseaWater and Meteoric Water (MW) had different origins and 129 I characteristics. The paleoseaWater has a high iodine content (∼31 mg/L), indicating that iodine was introduced into the reservoir along with thermally generated hydrocarbons, possibly in the Cretaceous, from the Caohu Sag in the eastern area. Based on consideration of all possible origins of iodine and 129 I in the brines, it is suggested that the Meteoric Water maintained its initial iodine content (0.01 mg/L) and 129 I/I ratio (1500 × 10 −15 ), whereas the iodine-enriched paloseaWater (IPSW) exhibited a secular 129 I equilibrium (N sq = 39 atom/μL) as a result of fissiogenic 129 I input in the reservoir over a long period of time. The model of brine evolution developed on that basis confirmed that Meteoric Water entered the reservoir in the Miocene at about 10 Ma, and partially mixed with the iodine-enriched paleoseaWater. The movement of Meteoric Water was facilitated by faults created during the Himalayan orogeny, then became more dense after dissolving Paleogene halite and infiltrated into the reservoir at high pressure. The iodine and 129 I concentration in the brine contains information about the path and history of the fluid in the reservoir. This may be useful in oil exploration, since the movement of Water was, to some extent, related to hydrocarbon migration.
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the sources and formation processes of brines from the lunnan ordovician paleokarst reservoir tarim basin northwest china
Geofluids, 2013Co-Authors: Jian Chen, Dehan Liu, Pingan Peng, Baoshou Zhang, Zhongyao XiaoAbstract:The most important petroleum exploration target in the Tarim Basin, northwest China, is the paleokarst reservoir. To understand the source and evolution of brine in this type of reservoir, a total of 37 formation-Water samples were collected from the Middle-Lower Ordovician paleokarst reservoir in the Lunnan oilfield. The δD-δ18O correlation and Cl/Br ratios reflect the mixture of two fluids: Meteoric Water and evaporated seaWater. The different degree of mixture divided samples into two groups. Group 1 samples, from deep strata (5150–6667 m.b.s.l.) in the east of the field, with elevated δD (−53.5 to −38.0‰), δ18O values (0.66–5.99‰), and lower Cl/Br ratios (336–478 for Cl/Br, except LN634-1 and LN631-1) were formed by evaporation of seaWater plus a small contribution from Meteoric Water. Group 2 samples, from shallow strata (5038–6067 m.b.s.l.), in the west of the field, have contrasting features (−59.6 to −48.5‰ for δD, −0.47 to 2.17‰ for δ18O, and 501 to 871 for Cl/Br), which reflect a mixture of evaporated seaWater with a high proportion of Meteoric Water. Both of the fluid types exchanged oxygen isotope with minerals. The investigation into cation composition reveals that, before entering into the current reservoir, Waters suffered albitization of plagioclase; moreover, Meteoric Water dissolved evaporites and seaWater experienced dolomitization. A mixing trend showed by strontium isotopes (0.709801–0.711628) gave further evidence for the mixture of two fluid types. Based on the correlation of geological history with our data, two infiltration models of Meteoric Waters can be constructed. According to the chemical and isotopic compositions of the Waters, an east fluid regime (Group 1) and a west fluid regime (Group 2) have thus been defined. Better understanding of the subsurface fluid movement patterns may be helpful for the local exploration.