Characteristics of fine fluid inclusions in quartz and symplectitic minerals from UHP jadeite quartzite, Dabieshan China
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Homogenization
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Well-known Jiaojia-type gold depozed are characterized by fractured altered rock-type gold mineralization. However, big gold-bearing quartz veins have also been found there. The fluid inclusions in this kind of gold-bearing quartz vein are mainly two-phase liquid-vapor inclusions with subordinate LCO2 inclusions. The main and minor homogenization temperature peaks are about 200 and 290℃ respectively. The salinities range mainly from 2 to 10 wt% NaCl. The pressures estimated by LCO2 inclusions range from 20 to 38 MPa. The dominant component of the vapor phase of the inclusions in quartz is H2O, and next comes CO2. The ion composition of the inclusions in pyrite generally shows Na+K+Ca2+ and SO42-Cl-F- and the ion composition of the inclusions in quartz generally shows K+Na+Ca2+(Na+K+Ca2+ in deformed quartz)and SO42-Cl-F-. All the above features of the gold-bearing quartz veins in Jiaojia-type gold deposits are similar to those of the gold-bearing quartz veins in Linglong-type gold deposits but somewhat different from those of the fractured altered rock-type gold mineralization in the same Jiaojia-type gold deposits. This difference may be due to the following: gold-bearing quartz veins are formed by filling, fractured altered rocks-type gold mineralization results from emplacement.
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There are three types of fluid inclusions in the quartz of quartz-vein ores,Baiganhu-Jialesai W-Sn mineralization belts,Qimantage: Liquid-rich two-phase inclusions,CO2 and CH4-rich three-phase inclusions and water inclusions,of which the first two types are primary inclusions and are closely related with W-Sn mineralization.The peak homogenized temperatures and salinity of liquid-rich two-phase inclusions in quartz,with liquid component of H2O and gas component of CO2 and CH4,range from 220℃ to 260℃ and from 0.88% to 20.82% NaCleqv respectively,the total density of fliuds range from 0.72 to 1.06g·cm-3.The peak homogenized temperatures and salinity of CO2 and CH4-rich three-phase inclusions in quartz range from 260℃ to 280℃ and from 6.63% to 15.212% NaCleqv respectively,the total density of fliud range from 0.60 to 0.91g·cm-3.The gas components of CO2 and CH4-rich three-phase inclusions are mainly CO2,CH4 and less H2S,N2,H2,while the liquid components are mainly H2O and less CO2,CH4,H2S.The value of δ18OH2O and δD of quartz-vein ores range from 4.02‰ to 6.32‰ and -75.5‰ to -42.8‰ respectively,both of which indicate that the fluid is significantly magmatic water.In all,the initial fluid of quartz-vein ores is from magmatic hydrothermal fluid,which belongs to NaCl-H2O-CO2 system with middle-high temperature (220~280℃),middle salinity (10%~14% NaCleqv) and lower density.The W-Sn mineralization is closely related with the Caledonian magmatism,and the uneven fluids are captured when the quartz-vein ores formed.The significant factors of forming of quartz-vein ores are immiscibility of ore-forming fluids,and changes of temperature,pressure and value of pH,Eh,fO2 and fS2.
Magmatic water
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Donghai rocked quartz deposit is located in the Su-Lu Ultra-high pressure (UHP) metamorphic zone, Jiangsu province. Its genesis and its relationship with UHP metamorphism remain unclear. Petrographic, microthermometric, and the Laser Raman investigations recognized that there are three types fluid inclusions in rocked quartz, i. e. pure liquid H2O, liquid-vapor H2O and CO2-H2O fluid inclusions, the liquid-vapor H2O fluid inclusions are dominated, it size are range from 5 to 50μm, but that of liquid-vapor H2 O fluid inclusions in rutile-bearing rocked quartz are more than 300μm. In additional to H2 O and CO2, there are minor N2, CH4, H2S and C2H6 also are detected in the fluid inclusions. In different decrepitation temperature, the fluid inclusions release different gases, for example, in low temperature, H2 Oand CO2 were released with minor H2 S、CH4 and C2 H6, whereas in high temperature, H2O、CH4、C2H6 and CO2 were released with minor N2 and H2S. The homogenization temperature and salinity of fluid inclusions in rocked quartz are divided into three sections respectively, i. e. 100℃- 120℃, 160℃-220℃and 240℃-260℃and 0 -2 wt%NaCl, 4 - 12wt%NaCl, 14 - 16wt%NaCl, which reflect multi-stage fluids overprinted in rocked quartz. Theδ18O andδ34Si in quartz range from -5. 6 - +4. 6‰and -0. 2 - +0. 2‰, respectively, but those in rutile-bearing quartz, are in the range from 10. 5 - 14. 9 and -0. 2 - +0. 1‰, respectively. Contrasted with chlinochlore related to rocked quartz, the scale-biotite is more rich in Nb、Cr、Fe、V、W、Ti and Zr. This paper indicates that rocked quartz deposit in Donghai is related to quartz-bearing eclogite overprinted by different fluids after the exhumation, the rutile-bearing quartz is overprinted by fluids rich in Nb and Ta.
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Mesothermal
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Abstract The Siljan structure represents a deep erosion level of an astrobleme. Post-impact formation of minerals as various types of vein fillings is common. Non-shocked milky quartz from a large vein revealed fluid inclusions of three types:(1) one-phase, regularly shaped inclusions, < 1 to 10 μm in size, (2) two-phase, regularly to irregularly shaped inclusions, 2 to 7 μm, (3) larger irregular two-phase inclusions, 8–20 μm. The one-phase inclusions dominate; density of inclusion occurrence is estimated at 46 × 104 inclusions per cm2. Melting temperatures indicate a total salinity of 1.0 eq. wt. % NaCl. Homogenization temperatures range between 165 and 309°C. The fluid inclusion data imply a complex origin of the quartz. It consists in part of breccia fragments formed after the impact. The quartz vein was cemented by deep circulating meteoric waters at successively lowered temperatures initially over 300°C. Key Words: Astroblemebrecciaquartzfluid inclusionsmicrothermometrySiljan Ring structurePaleozoicBodacentral Dalarnacentral SwedenN6085 N6104 E1515 E1507
Breccia
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Melt inclusions
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There are two types of gold deposits in Linglong mine area: one is altered rock type gold deposit,and the other is quartz vein type gold deposit.In this paper,characteristics of fluid inclusions in quartz vein type gold deposit has been studied mainly.Altered rock type gold deposits distributes in Linglong brush structures.There are more than 300 quartz-bearing veins whichi were controlled by brsuh structrual faults and joints.As showed by microscopic observation of fluid inclusions,fresh granite and potassic granite inclusions in Linglong quartz vein type gold deposit contained H 2O inclusions mainly,and followed by a small amount of H2O-CO2 inclusions;while pyrite phyllic usually contained more coarse-grained quartz aggregates phyllic quartz with rich H2O,especially H2O-CO2 inclusions.Gold ore bodies(gold bearing quartz veins) contained a significant number of H2O-CO2 inclusions,especially in the presence of a larger three-phase H2O-CO2 inclusions.Size,shape,contents and abundance of H2O and H2O-CO2 inclusions in quartz in different periods(generations) were very different.
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Native Au from two mining levels of a "Central" quartz vein from the Muruntau deposit has been investigated using scanning electron microscopy and cathodoluminescence microscopy. Fluid inclusions in the surrounding quartz have been studied using microthermometry and laser Raman spectroscopy. Two types of native Au inclusions can be distinguished in the investigated samples. Primary Au (Au I) is characterized by euhedral crystals which occur isolated inside of moderately deformed quartz grains. Probable remobilized Au (Au II) mostly occurs as groups of irregularly formed aggregates that are located at grain boundaries between partly recrystallized quartz grains. The probably remobilized Au is lower in Ag contents than the primary Au. Fluid inclusion investigations suggest the presence of a probable heterogeneous CO2-bearing fluid during recrystallization of quartz and precipitation of Au II.
Cathodoluminescence
Recrystallization (geology)
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