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Determining Fluid Compositions in the H_2O-NaCl-CaCl_2 System with Cryogenic Raman Spectroscopy:Application to Natural Fluid Inclusions

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Acta Geologica Sinica(English Edition) 2015年第3期89卷 894-901页

作者： CHU Haixia chi guoxiang Department of Geology University of Regina

Previous cryogenic Raman spectroscopic analysis of H_2O-NaCl-CaCl_2 solutions has identified the Raman peaks of various hydrates of NaCl and CaCl_2,and established a linear relationship between Raman band intensity of the hydrates and the composition of the solution（NaCl/（NaCl＋CaCl_2） molar ratio,or X_（NaC1）） using synthetic fluids,which created the opportunity to quantitatively determine the solute composition of aqueous fluid inclusions with cryogenic Raman *** paper aims to test the feasibility of this newly established method with natural fluid ***-five fluid inclusions in quartz from various occurrences which show a high degree of freezing during the cooling processes were carefully chosen for cryogenic Raman analysis.X_（Na）Cl was calculated using their spectra and an equation established in a previous *** inclusions were then analyzed with the thermal decrepitation-SEM-EDS *** X_（NaCl） values estimated from the two methods show a 1：1 correlation,indicating that the new,non-destructive cryogenic Raman spectroscopic analysis method can indeed be used for fluid inclusion compositional study.

关键词： cryogenic Raman XNaCI fluid inclusion H2O-NaCl-CaCl2

Microstructural analysis of a subhorizontal gold-quartz vein deposit at Donalda,Abitibi greenstone belt,Canada:Implications for hydrodynamic regime and fluid-structural relationship

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Geoscience Frontiers 2011年第4期2卷 529-538页

作者： guoxiang chi Jayanta Guha Department of Geology University of Regina Regina Saskatchewan Canada Sciences de la Terre/Centre d＇Etude sur les Ressources Minerales Universite du Quebec a Chicoutimi Chicoutimi Quebec Canada

The Donalda gold deposit in the southern part of the Archean Abitibi greenstone belt consists mainly of a subhonzontal gold-quartz vein perpendicular to subvertical shear *** 0.3—0.5 m thick vein is characterized by vein-parallel banding structures indicating multiple episodes of fracture opening and mineral *** of the c-axis of primary growth quartz indicates that quartz preferentially grew perpendicular to the fracture,suggesting open space filling and/or extensional nature of the *** of the orientations of microfractures,veinlets and fluid—inclusion planes（FIPs） crosscutting primary growth quartz indicates that the vein minerals were subject to a vertical maximum principal stress（σ_1）,which is inconsistent with the subhorizontalσ_1 inferred from the regional stress field with N—S *** apparent discrepancy is explained by invoking episodic fluid pressure fluctuation between supralithostatic and hydrostatic regimes accompanied by episodic opening and closing of the sub-horizontal *** fluid pressure was higher than the lithostatic value,the fracture was opened and primary growth minerals were precipitated,whereas when fluid pressure decreased toward the hydrostatic value,the hanging wall of the fracture collapsed,causing collision of protruding primary growth minerals from both sides of the fracture and resulting in formation of vein-parallel deformation *** columns where the two facing sides of the fracture collided were subject to higher-than-lithostatic stress due to the bridging effect and reduced support surface area,explaining the development of verticalσ_*** hypothesis is consistent the fault-valve model,and explains the flipping ofσ_1 without having to change the regional stress field.

关键词： Hydrodynamics Fluid-structural relationship Gold deposit Fluid inclusion planes Microstructural Subhorizontal veins

A New Method for Determining Fluid Compositions in the H_2O-NaClCaCl_2 System with Cryogenic Raman Spectroscopy

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Acta Geologica Sinica(English Edition) 2014年第4期88卷 1169-1182页

作者： chi guoxiang CHU Haixia Ryan SCOTT CHOU I-Ming Department of Geology University of Regina Laboratory for Experimental Study Under Deep-sea Extreme Conditions Sanya Institute of Deep-sea Science and EngineeringChinese Academy of Sciences

Raman peaks of various hydrates in the H20-NaCl-CaCl2 system have been previously identified, but a quantitative relationship between the Raman peaks and XNaCl （i.e.,NaCl/ （NaCl＋CaCl2）） has not been established, mainly due to the difficulty to freeze the solutions. This problem was solved by adding alumina powder to the solutions to facilitate nucleation of crystals. Cryogenic （-185℃） Raman spectroscopic studies of alumina-spiced solutions indicate that XNaCl is linearly correlated with the total peak area fraction of hydrohalite. Capsules of solutions made from silica capillary were prepared to simulate fluid inclusions. Most of these artificial fluid inclusions could not be totally frozen even at temperatures as low as -185℃, and the total peak area fraction of hydrohalite is not correlated linearly with XNaCI. However, the degree of deviation （△XNaCl） from the linear correlation established earlier is related to the amount of residual solution, which is reflected by the ratio （r） of the baseline ＂bump＂ area, resulting from the interstitial unfrozen brine near 3435 cm^-1, and the total hydrate peak area between 3350 and 3600 cm^-1. A linear correlation between △XNaCl and r is established to estimate XNaCl from cryogenic Raman spectroscopic analysis for fluid inclusions.

关键词： cryogenic Raman H20-NaCl-CaCl2 XNaCI fluid inclusion

An overview of hydrodynamic studies of mineralization

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Geoscience Frontiers 2011年第3期2卷 423-438页

作者： guoxiang chi Chunji Xue Department of Geology University of Regina Regina SK S4S OA2 Canada State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China

Fluid flow is an integral part of hydrothermal mineralization, and its analysis and characterization constitute an important part of a mineralization model. The hydrodynamic study of mineralization deals with analyzing the driving forces, fluid pressure regimes, fluid flow rate and direction, and their relationships with localization of mineralization. This paper reviews the principles and methods of hydrodynamic studies of mineralization, and discusses their significance and limitations for ore deposit studies and mineral exploration. The driving forces of fluid flow may be related to fluid overpressure, topographic relief, tectonic deformation, and fluid density change due to heating or salinity variation, depending on specific geologic environments and mineralization processes. The study methods may be classified into three types, megascopic （field） observations, microscopic analyses, and numerical modeling. Megascopic features indicative of significantly overpressured （especially lithostatic or supralithostatic） fluid systems include horizontal veins, sand injection dikes, and hydraulic breccias. Microscopic studies, especially microthermometry of fluid inclusions and combined stress analysis and microthermometry of fluid inclusion planes （FIPs） can provide important information about fluid temperature, pressure, and fluid-structural relationships, thus constraining fluid flow models. Numerical modeling can be carried out to solve partial differential equations governing fluid flow, heat transfer, rock deformation and chemical reactions, in order to simulate the distribution of fluid pressure, temperature, fluid flow rate and direction, and mineral precipitation or dissolution in 2D or 3D space and through time. The results of hydrodynamic studies of mineralization can enhance our understanding of the formation nrocesses of hvdrothermal denosits, and can be used directly or indirectly in mineral exnloration.

关键词： Fluid flow Hydrodynamics Mineralization Hydraulic fracturing Numerical modeling Exploration

Determination of Fe^(2+)/Fe^(3+)Ratios of Magnetite using Different Methods:A Case Study from the Qimantag Metallogenic Belt

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Acta Geologica Sinica(English Edition) 2022年第6期96卷 2135-2147页

作者： YI Liwen LI Qiuping LU Anhuai GU Xiangping chi guoxiang School of Geographical Sciences Hunan Normal UniversityChangsha 410081China School of Geosciences and Info-Physics Central South UniversityChangsha 410083China School of Earth and Space Sciences Peking UniversityBeijing 100871China Department of Geology University of ReginaReginaSaskatchewan S4S 0A2Canada

Determination of Fe^(2+)/Fe^(3+) ratios from metallogenic belts to explore controlling physical and chemical conditions of rock formation is of great *** order to explore magnetite Fe^(2+)/Fe^(3+) ratios of the Qimantag metallogenic belt,part of the Eastern Kunlun orogenic belt in the northeastern margin of the Qinghai–Tibetan plateau,western Central Orogenic Belt of china,and overcome the limitation of the traditional electronic probe,five different measurement methods are proposed and their respective advantages and disadvantages evaluated,with the composition data of the magnetite obtained using electron probe microanalysis(EPMA).The direct oxygen measurement method has a significant impact on the determination results of FeO and Fe2O3,but the accuracy and uniformity of the results are *** valence method(Flank method)based on the spectral intensity ratio of Lαto Lβfor iron is also unreliable for FeO and Fe_(2)O^(3) measurements because it is difficult to establish a relationship between Lβ/Lα,the spectral intensity ratio,and the Fe^(2+)/Fe^(3+) content *** comparison,the charge difference method,the surplus-oxygen method and the Mössbauer spectrum method are still the most favorable.Mössbauer spectroscopy,with its isomer movement particularly sensitive to the oxidation state of iron,yields results closer to 0.5,which is relatively *** magnetite deposits are located in intrusions or contact zones and formed by magmatic fluids with high Fe2+/Fe3+ratios,whereas later magnetite deposits are farther away from intrusions and have low Fe^(2+)/Fe^(3+) *** transformation mechanism of hematite and magnetite in the Qimantage metallogenic belt is also *** large volume changes,such as pore filling and shrinkage fracture,were detected in the metallogenic belt,and the transformation mechanism is more similar to a reoxidation and reduction mechanism.

关键词： iron magnetite direct oxygen measurement flank-charge difference-surplus-oxygen methods Mössbauer spectra Qimantage

Effects of hydrocarbon generation on fluid flow in the Ordos Basin and its relationship to uranium mineralization

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Geoscience Frontiers 2011年第3期2卷 439-447页

作者： Chunji Xue guoxiang chi Wei Xue State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China School of the Earth Sciences and Resources China University of Geosciences Beijing 100083 China Department of Geology University of Regina Regina Saskatchewan Canada

The Ordos Basin of North china is not only an important uranium mineralization province, but also a major producer of oil, gas and coal in china. The genetic relationship between uranium mineralization and hydrocarbons has been recognized by a number of previous studies, but it has not been well understood in terms of the hydrodynamics of basin fluid flow. We have demonstrated in a previous study that the preferential localization of Cretaceous uranium mineralization in the upper part of the Ordos Jurassic section may have been related to the interface between an upward flowing, reducing fluid and a downward flowing, oxidizing fluid. This interface may have been controlled by the interplay between fluid overpressure related to disequilibrium sediment compaction and which drove the upward flow, and topographic relief, which drove the downward flow. In this study, we carried out numerical modeling for the contribution of oil and gas generation to the development of fluid overpressure, in addition to sedi- ment compaction and heating. Our results indicate that when hydrocarbon generation is taken into account, fluid overpressure during the Cretaceous was more than doubled in comparison with the simu- lation when hydrocarbon generation was not considered. Furthermore, fluid overpressure dissipation at the end of sedimentation slowed down relative to the no-hydrocarbon generation case. These results suggest that hydrocarbon generation may have played an important role in uranium mineralization, not only in providing reducing agents required for the mineralization, but also in contributing to the driving force to maintain the upward flow.

关键词： Ordos Basin Uranium deposits Hydrodynamics Hydrocarbon generation Fluid overpressure Fluid flow Numerical modeling

Zinc, copper, and strontium isotopic variability in the Baiyangping Cu–Pb–Zn–Ag polymetallic ore field, Lanping Basin, Southwest china

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Acta Geochimica 2021年第4期40卷 557-574页

作者： Caixia Feng Shen Liu guoxiang chi Xianwu Bi Ruizhong Hu Ian MCoulson State Key Laboratory of Continental Dynamics Department of GeologyNorthwest University229 Taibai RoadXi’an 710069China Departments of Geology University of Regina3737 Wascana ParkwayReginaSK S4S 0A2Canada Institute of Geochemistry Chinese Academy of Sciences99 Lincheng RoadGuiyang 550002China

The Baiyangping Cu-Ag polymetallic ore district is located in the northern part of the Lanping-Simao foreland fold belt,between the Jinshajiang-Ailaoshan and Lancangjiang faults,and the deposit can be divided into eastern and western ore *** upon microscope observation of ore minerals and analysis of zinc,copper,and strontium isotope composition,we conclude that:(1)the zinc isotopic compositions of sphalerite from the eastern and western ore belt of the Baiyangping polymetallic ore deposits are enriched in both the heavy(-0.09‰ to+0.15‰) and light(-0.19‰ to-0.01‰)zinc *** fractionation is likely the additional factor controlling the observed temporal and spatial variations in zinc isotopes in the two studied ore *** zinc isotopic composition in the Baiyangping polymetallic Pb-Zn deposits may have the same fractionation as that of magmatic-hydrothermal,VHMS,SEDEX,and MVT deposits,as demonstrated by geological and other geochemical evidence;(2) the range of δ^(65)Cu in massive tetrahedrite is from-0.06‰ to+0.12 ‰ that relates to the early stages of ore-formation,which are higher than that of venial chalcopyrite(from-0.72‰ to-0.07‰)formed at a late ore-forming stage in the western ore *** ore-forming stages and alteration or leaching processes are likely the main factors controlling the observed variations in copper isotopes in the western ore zone;(3) the ^(87)Sr/^(86)Sr value of hydrothermal calcite in eastern(0.7080-0.7093) and western(0.7085-0.7113) ore belt suggested that mineralization of early calcite,with^(87)Sr/^(86)Sr values much higher than in ancient Late Triassic seawater,may be related to recrystallization from a radiogenic Sr-rich or silicifying fluid,either from the strata that the ore-forming fluid flows through or from other fluids.

关键词： Zn-Cu-Sr isotopic variation Cu-Pb-Zn-Ag poly-metallic ore deposit Baiyangping Lanping Basin

Geochemical Characteristics and Sources of Ore-forming Fluids of the Mayuan Pb-Zn Deposit,Nanzheng,Shaanxi,china

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Acta Geologica Sinica(English Edition) 2015年第3期89卷 783-793页

作者： LIU Shuwen LI Ronxi chi guoxiang ZENG Rong LIU Lingfang SHI Shun Chang'an University Key Laboratory for the study of Focused Magmatism and Giant Ore Deposits MLR University of Regina Geophysical and Geochemical Exploration Corporation of Northwest Geological Exploration and Mining Bureau for Nonferrous Metals

The Mayuan stratabound Pb-Zn deposit in Nanzheng,Shaanxi Province,is located in the northern margin of the Yangtze Plate,in the southern margin of the Beiba *** orebodies are stratiform and hosted in breciated dolostone of the Sinian Dengying *** ore minerals are primarily sphalerite and galena,and the gangue minerals comprise of dolomite,quartz,barite,calcite and solid *** inclusions from ore-stage quartz and calcite have homogenization tempreatures from 98 to 337℃ and salinities from 7.7 wt%to 22.2 wt%（NaCl equiv.）.The vapor phase of the inclusions is mainly composed of CH_4 with minor CO_2 and H_*** δD_（fluid） values of fluid inclusions in quartz and calcite display a range from-68‰ to-113‰（SMOW）,and the δ^（18）O_（fluid）values calculated from δ^（18）O_（quartz） and δ^（18）O_（calcite） values range from 4.5‰ to 16.7‰（SMOW）.These data suggest that the ore-forming fluids may have been derived from evaporitic sea water that had reacted with organic *** δ^（13）C_（CH4） values of CH_4 in fluid inclusions range from-37.2‰ to-21.0‰（PDB）,suggesting that the CH_4 in the ore-forming fluids was mainly derived from organic ***,together with the abundance of solid bitumen in the ores,suggest that organic matter played an important role in mineralization,and that the thermochemical sulfate reduction（TSR） was the main mechanism of sulfide *** Mayuan Pb-Zn deposit is a carbonate-hosted epigenetic deposit that may be classified as a Mississippi Valley type（MVT） deposit.

关键词： fluid inclusion ore-forming fluids organic matter Mayuan Pb-Zn deposit Shaanxi

Multiple and prolonged porphyry Cue Au mineralization and alteration events in the Halasu deposit, chinese Altai, Xinjiang,northwestern china

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Geoscience Frontiers 2016年第5期7卷 799-809页

作者： Chunji Xue guoxiang chi Xiaobo Zhao Ganguo Wu Zhanfeng Zhao Lianhui Dong State Key Laboratory of Geological Processes and Mineral Resources Faculty of Earth Sciences and Resources China University of Geosciences Beijing 100083 China Department of Geology University of Regina Regina Saskatchewan 545 OA2 Canada Xinjiang Bureau of Geology and Mineral Resource Urumqi Xinjiang 830000 China

The Halasu area is located in the southeastern margin of the chinese Altai in Xinjiang, china. It is part of the Altaid orogenic collage where a number of porphyry-type Cue Moe Au deposits have been discovered in recent years. Geological mapping and drilling indicate the presence of various mineralized porphyritic intrusions in the Halasu Cue Au deposit, which is currently under exploration. Ue Pb dating of zircon crystals from four different mineralized porphyries reveals three significantly different ages of magmatic intrusion, i.e., ca. 372e382 Ma granodioritic porphyry and porphyritic granite, ca. 266 Ma quartz monzonitic porphyry, and ca. 216 Ma quartz dioritic porphyry. Ree Os dating of molybdenite from veinletdissemination ores in the granodioritic porphyry yields an age of mineralization of ca. 377 Ma, and Ar e Ar dating of K-feldspar from K-feldsparequartzechalcopyrite veins produces ages of ca. 269 and ca.198 Ma. The mineralization（and alteration） ages correspond broadly to the three episodes of magmatic intrusion, suggesting three overprinting porphyry mineralization events that are significantly separated in time. The first episode of porphyry intrusion and mineralization may be related to the magmatic arc being above a plate subduction zone, and the second was formed in a late-collisional environment during the closing of the Junggar Ocean, whereas the third episode of mineralization took place in the postcollisional stage. This case study suggests that in orogens where major porphyry deposits have been found in magmatic arc environments, the potential of discovering late- to post-collisional porphyry deposits cannot be neglected; conversely, in orogens where most porphyry deposits have late- to postcollisional ages, more attention should be paid to porphyries that were formed earlier in magmatic arc environments.

关键词： Porphyry copper deposit Multiple mineralization and alterations U-Pb dating Re-Os dating Ar-Ar dating Xinjiang Halasu