黔东平秋金矿含金石英脉包裹体地球化学

本文主要通过包裹体岩相学特征、测温及成分分析等几个方面,对锦屏县平秋金矿含金石英脉的包裹体进行研究。结果显示成矿流体主要表现为具岩浆热液性质的中低温、低盐度、低密度的热液。     

陕西石泉将军河地区石英脉期次及包裹体地球化学研究

陕西石泉北部将军河地区石英脉发育, 具有多期特征。目前, 发现了大石板沟、叶家坡、青泥涧等多处金矿化点, 金矿化与石英脉关系较密切。划分石英脉的形成期次, 对比研究各期石英脉包裹体地球化学特征, 对工作区找金矿具有重要指导意义。研究显示将军河地区第一期石英脉(顺S1面理产出)包裹体为中低温(170~220℃)和较高盐度;第二期石英脉(顺S2面理产出)包裹体为中高温(270~370℃)和较高盐度;第三期石英脉(顺S3面理产出)包裹体为中低温(170~220℃)和较低盐度;区域上金矿分布主要与第二期石英脉展布方向一致, 长沟、羊坪湾金矿床中含金石英脉包裹体为中低温和较低盐度。通过采样分析, 发现将军河地区第二期石英脉形成温度和盐度较高,金矿化较贫, 今后找金矿应该重视中低温和较低盐度的石英脉包裹体地段。     

Mineral Paragenesis, Fluid Inclusions and Sulfur Isotope Systematics of the Lepanto Far Southeast Porphyry Cu-Au Deposit, Mankayan, Philippines

Abstract: The Lepanto Far Southeast porphyry Cu‐Au deposit is located beneath and to the southeast of the Lepanto enargite‐luzonite Cu–Au deposit in Mankayan, Benguet Province, Philippines. The principal orebody consists of potassic alteration subjected to partial retrograde chlorite alteration that rims stock‐work of quartz‐anhydrite veinlets. Fluid inclusions found in stockwork quartz and anhydrite in the biotitized orebody center are dominated by polyphase inclusions that homogenize at temperatures of >500C. Sulfur isotopic thermometry applied to the sulfides‐anhydrite pairs suggests around 500C. The principal ore minerals associated with quartz‐anhydrite stockworks are chalcopyrite and pyrite with minor bornite and Bi–Te–bearing tennantite, with trace of native gold. Rounded pyrite grains appear fractured and corroded and are interpreted as remnants of primary intermediate solid solution + pyrite assemblage. A breccia pipe truncates the deposit. Mineralization in the breccia pipe is brought by quartz‐anhydrite veinlets and infilling in the interstices between clasts. Chalcopyrite‐Au mineralization associated with molybdenite is recognized in the deeper zone in the breccia pipe. Fluid inclusion microthermometry on polyphase inclusions in veinlet quartz as well as sulfur isotope thermometry applied for the pair of anhydrite and sulfides suggests >450C. Fluid inclusions in veinlet quartz and anhydrite in the fringe advanced argillic alteration are chiefly composed of coexisting liquid‐rich inclusions and gas‐rich inclusions, in addition to coexisting polyphase inclusions and gas‐rich inclusions. These inclusions exhibit a wide range of homogenization temperatures, suggesting heterogeneous entrapping in the two‐fluid unmixing region. Sulfur isotopes of aqueous sulfide and sulfate exhibit a general trend from the smallest fractionation pairs (about 11%) in the biotitized orebody center to the largest fractionation (about 25%) pairs in the fringe advanced argillic alteration, suggesting a simple evolution of hydrothermal system. The slopes of arbitrary regression lines in δ³⁴S versus ³⁴S[SO₄ = –H₂S] diagram suggest that the abundance ratio of aqueous sulfate to sulfide in the hydrothermal fluid has been broadly constant at about 1:3 through temperature decrease. The intersection of these two regression lines at the δ³⁴S axis indicates that the bulk δ³⁴S is about +6%. Thus, the Lepanto FSE deposit is a further example which confirms enrichment in ³⁴S in the hydrous intermediate to silicic magmas and associated magmatic hydrothermal deposits in the western Luzon arc.     

关中盆地花岗岩石英脉流体包裹体与氦气成藏特征研究

关中盆地位于秦岭造山带和鄂尔多斯盆地的过渡带。基于钻井和地热井的资料,关中盆地具有富氦天然气和水溶氦气的资源,氦气主要来自于壳源气,富铀花岗岩是其主要的源岩。本文样品采自关中盆地南缘花岗岩中石英脉,通过显微激光拉曼光谱对石英裂隙的包裹体成分进行分析,测试结果显示为气液两相包裹体和H2O-NaCl-CO2包裹体,包裹体成分主要为H2O和CO2,还有少量的CH4、H2和H2S。按照类型划分为近原生包裹体,早期次生包裹体和晚期次生包裹体。包裹体均一温度测定结果,近原生包裹体的均一温度大于430℃,早期次生包裹体温度为330~370℃,晚期次生包裹体温度为170~230℃。据包裹体成分分析、包裹体均一温度测定,结合地区埋藏史,确定该区有2期成藏,其中晚期为主要成藏期,对应地质时期为中新世-上新世。     

万宝源斑岩型钼矿流体包裹体及成矿物质来源研究

万宝源斑岩型钼矿位于辽东裂谷内,产于石柱子花岗闪长岩体及其后侵入的石英斑岩内。矿化类型可以分为浸染状、细脉充填状和石英脉状三种。为了解决该钼矿的成矿流体来源及矿床形成机制问题,我们从流体包裹体、REE、S、D-O同位素入手进行了研究。石英中的流体包裹体测试数据揭示:钼矿化可以分为三个阶段,高温阶段、中温阶段和低温阶段,以中温阶段为主。REE分析表明,成矿物质起源于花岗闪长岩体,后经分离结晶作用,最终与花岗闪长岩体表现出不同的REE配分模式;S同位素分析显示,S来源于岩体与地层,是一种混合硫;D-O同位素研究则说明,成矿流体是以岩浆水为主,后期有天水加入的混合流体。最后建立石柱子成矿系统,对石柱子花岗闪长岩内外接触带上的矿床成因进行了探讨。     

四川木里长枪穹隆石英流体包裹体特征及其地质意义

通过木里长枪构造-热穹隆体砂泥质变质岩及分泌石英脉中较系统的石英流体包裹体测试与研究,表明穹隆体中石英流体包裹体主要有NaCL-H2O、纯H2O及CO2-H2O、纯CO2等四类,有三个形成或捕获阶段,分别与穹隆体变形变质阶段吻合,其所限定的穹隆体变质条件及抬升P-T轨迹与变形-变质演化研究结果基本一致.     

湖南渣滓溪锑钨矿床流体包裹体特征及其意义

湘中锑矿带中的渣滓溪锑钨矿床,是我国典型的大型脉状充填型锑矿床,前人对其成矿流体研究较少,该矿的矿石沉淀机制和成矿过程,目前尚不清楚。本次采用红外显微测温和传统显微测温相结合的方法,对渣滓溪矿区的白钨矿、辉锑矿及与其共生的石英中的流体包裹体,进行了系统的岩相学和显微测温研究。研究表明,该区矿物中发育的流体包裹体有四种类型,纯液相包裹体、富液相的气液包裹体、富气相的气液包裹体和纯气相包裹体。该区白钨矿中流体包裹体的均一温度为147～285℃,盐度为2.4%～6.0%NaCleqv,与其共生的石英中流体包裹体的均一温度为147～314℃,盐度为3.1%～6.2%NaCleqv;辉锑矿中流体包裹体的均一温度为124～269℃,盐度为0.4%～4.5%NaCleqv,与其共生的石英中流体包裹体的均一温度为114～298℃,盐度为0.2%～5.9%NaCleqv,成矿流体为一种中温、低盐度,以H2O为主的热水溶液。该区钨矿石中的白钨矿和石英、锑矿石中的辉锑矿和石英分别具有相似的均一温度和盐度。钨矿石和锑矿石具有不同的沉淀机制,前者是由于流体混合作用导致的,而后者则是由于流体沸腾引起的。湘西浅变质...     

Hydrothermal Quartz Vein Formation, Revealed by Coupled SEM-CL Imaging and Fluid Inclusion Microthermometry: Shuteen Complex, South Gobi, Mongolia

Abstract. Scanning electron microscopy-cathodoluminescence (SEM-CL) imaging of vein quartz in the Cu-mineralised, Shuteen Complex (South Gobi, Mongolia) has revealed a complex history of crystal growth, dissolution and microfracture healing, associated with several hydrothermal events that could not be detected using other observational techniques (e.g. transmitted/reflected light microscopy, back-scattered electron imaging, or secondary electron imaging).
The quartz initially grew as CL-bright/grey crystals in a 345±30C liquid reservoir, as inferred by the analysis of primary liquid fluid inclusions (average Th of 343C; 6.6∼7.7 wt% NaCl_eq). Quartz precipitation occurred at the edge of the crystals as reservoir fluids cooled to 260±25C, as indicated by micron-scale CL-dark/CL-bright quartz growth bands containing abundant fluid inclusions (with an average T_h values of 261C). Pressure fluctuations were the likely cause of dissolution, as SEM-CL imaging reveals the quartz have corroded or rounded crystal edges, and precipitation of later quartz into open space. SEM-CL imaging shows the quartz contains healed microfractures that trapped low salinity fluids (3.9 wt% NaC1_eq) with Th values of 173±15C.
SEM-CL imaging provides a means of deciphering the thermal and chemical evolution of the fossil Shuteen hydrothermal system, and the nature of hydrothermal quartz vein-forming processes, by facilitating the correlation of distinct fluid inclusion populations and their relative chronology, with specific hydrothermal events.     

Near-infrared and Visible Light Microthermometry of Fluid Inclusions in Sphalerite from a Possible Southeast Extension of the Toyoha Polymetallic Deposit, Japan

Abstract. Near-infrared (NIR) and visible light microthermometry was applied to the fluid inclusions in sphalerite from a possible southeast extension of the Toyoha polymetallic deposit. Sphalerite occurs as euhedral-subhedral crystals or collo-form aggregates with a variety of color, which contain a well-developed growth banding. Combined with morphological observations, fluid inclusions in dark-colored sphalerite were examined using a near-infrared light microscopic technique, whereas those in light-colored sphalerite and quartz were examined by a conventional visible light microscopy.
Salinities of fluid inclusions in dark-colored sphalerite have a wide variation (1.0–10.3 wt % NaCl equiv.) compared to that in light-colored sphalerite and quartz (0.0–3.4 wt % NaCl equiv.). These variations suggest that the conventional microthermometric data from light-colored sphalerite and quartz were inadequate to interpret the ore formation process. Dark-colored colloform sphalerite and a dark core of subhedral sphalerite formed from high-salinity fluids (6.5–10.3 wt % NaCl equiv.) under highly supersaturated conditions with respect to sphalerite.
The NIR and visible light microthermometry of fluid inclusions in sphalerite combined with its morphological observations is an invaluable method to infer the formation conditions of sphalerite. The NIR and visible light microthermometry is useful to reveal how the nature of ore fluids changed with time.     

热液硬石膏流体包裹体的显微测温实验研究——石膏子晶的形成对盐度和均一温度测量的影响

硬石膏是海底热液多金属硫化物矿床中常见的少数几种透明矿物之一,是流体包裹体研究的主要对象。对Juan de Fuca洋脊Endeavour段的黑烟囱样品中硬石膏流体包裹体的显微观察发现包裹体内含有石膏子晶。显微测温研究也发现包裹体冷冻到-50℃后,再放置12小时,通常会发育新的石膏子晶。通过反复测定石膏子晶生成前后冰点的变化,发现石膏的生成使得冰点大幅降低,相应地提高残留流体的盐度(上升0.32%~1.6%NaCleq.)。流体包裹体中石膏生成是硬石膏水化和硬石膏溶解造成溶液过饱和沉淀石膏共同作用的结果,其中硬石膏水化起了主要作用,溶液过饱和沉淀石膏为硬石膏水化提供了有利条件。冷冻条件下和/或储藏时间越长,硬石膏水化对盐度的影响越大。加热包裹体到130℃能使石膏分解,释放出所结合的水分子,恢复包裹体的原始盐度。而石膏的生成对均一温度的测量没有影响。     

Hydrothermal Alteration and Fluid Geochemistry of the Tongonan Geothermal Field, Philippines

Abstract: The alteration mineralogy, the present-day fluid chemistry, and some fluid inclusion data are used to make inferences on the chemical changes that have occurred in the fluids during the history of the Tongonan Geothermal Field. Thermal activity in the Tongonan area began in the Miocene when emplacement of many plutons forming a batholith contact metamorphosed the overlying volcanics to hornblende hornfels assemblages. In the early Pliocene, when tectonic uplift occurred along the Philippine Fault, about 2 mole % of mainly carbon dioxide and sulfur gas was released to a geothermal fluid and condensed in groundwater with geothermal steam. The condensate intensely altered the reservoir rock and formed an acid mineral assemblage, which was overprinted by a later, lower temperature, neutral-pH assemblage. Some chlorite, epidote and illite in the reservoir rock formed at temperatures up to 100°C lower than present-day temperatures possibly during the Plio-Pleistocene uplift period, i.e., the system was heating up. The assemblage garnet-anhydrite formed in fractures from a condensate after the gas had nearly completely separated from the deep, CO₂-rich fluid during vigorous boiling possibly during hydrothermal eruptions. The output of gas to the geothermal fluid decreased, while the salinity (10,000 mg/kg or - 2 wt% NaCl) and the temperature of the geothermal fluid remained nearly constant throughout the Quaternary. When this neutral-pH, alkali chloride fluid boiled, it initially precipitated albite or epidote on the rims then anhydrite at the center of fractures at high temperatures (-250–300°C). At lower temperatures (-150–250°C), adularia or wairakite and later calcite were deposited as the proportion of gas in the steam condensate increased. The origin of solutes is also discussed.     

流体包裹体成分分析研究

笔者在日本研修期间学习和了解了先进的流体包裹体成分分的方法,其中包括分析群体包裹体液相成分的ＩＣＰ－ＭＳ和ＰＩＸＥ分析方法;分析单个包裹体液相成分的ＬＡ－ＩＣＰ－ＭＳ方法,ＬＲＭ,ＦＴ－ＩＲ单个包裹体气相成分分析方法等。这些方法极大地提高了包裹体成分分析的水平,促进了包裹体研究的发展,本文简要介绍这几种流体包裹体成分分析方法和其它包裹体研究方法及笔者的一些研究成果,以供国内同行借鉴和共同探讨。     

Geochemical Evolution of Hydrothermal Fluids at the Daejang Cu–Zn–Pb Vein Deposit, Korea

Abstract: The Daejang mine is located within the Cretaceous Gyeongsang basin. Mineral paragenesis can be divided into four stages (stages I, II, III and IV) by major tectonic fracturing. Stages I, III and IV are economically barren. Stage II, at which the precipitation of major ore minerals occurred, is further divided into three substages with paragenetic time based on minor fractures and discernible mineral assemblages: substage IIa, marked by deposition of quartz and Fe–sulfides; substage IIb, by introduction of base-metal sulfides within carbonates and some quartz; substage IIc, by quartz and carbonates with various sulfosalts. Fluid inclusion data indicate a complex geochemical evolution of hydrothermal fluids. Both CO₂–rich and H₂O–rich fluids were trapped in fluid inclusions at stage I and substage IIa. It is suggested that a compositionally heterogeneous fluid was formed by fluid boiling and CO₂ immiscibility at temperatures of about 400° to 300°C. Composite lodes of base-metal sul–fides, carbonates and quartz at substage IIb were deposited in open spaces created by fracturing. The fracturing event prompted rapid decreases in pressure and temperature of residual fluids and resulted in retrograde fluid boiling at about 200 bars and 300°–250°C during substage IIb. The progressive loss of CO₂ by CO₂ effervescence and retrograde boiling from substage IIa and IIb fluids resulted in pH increase and related increase in carbonate activity, causing deposition of abundant carbonates. The change in pH also caused the decrease of stability of hydrogen sulfide with Cu, Zn and Pb chloride complexes (as main transporting agents at Daejang) and resulted in the pricipitation of base-metal minerals. Deposition of Ag– and Sb-bearing sul–fides and sulfosalts of substage IIc occurred at temperatures of about 250° to 150°C from a dominantly aqueous fluid with low salinity (down to 3. 0 equiv. wt % NaCl). At this substage, aqueous fluid formed by mixing with cooler and less saline meteoric groundwater. There is a systematic decrease in caculated δ¹⁸O_water values with the mineralization stage (and decreasing temperature) in the Daejang hydrothermal system, from values of about 11% for stage I, through about 4% for stages II and III, to about –3 per mil for stage IV. The result of stable isotope and fluid inclusion studies are interpreted to indicate progressive less evolved and/or unexchanged meteoric water influx of an early hydrothermal system formed by highly evolved meteoric waters.     

铜陵狮子山矿田大团山铜（钼） 矿床流体包裹体研究

大团山铜（钼） 矿床是安徽铜陵狮子山矿田内较为典型的岩浆热液叠加型铜钼矿床,其成因与早白垩世大团山石英 二长闪长岩有密切关系。系统采集硫化物阶段的矿化石英脉并经岩相学显微观察发现,石英中捕获有大量的流体包裹体, 主要分为三种类型,即富气相（Ⅰ型）、富液相（Ⅱ型） 的两相水溶液包裹体和含子晶的三相水溶液包裹体（Ⅲ型）。显微 测温研究表明,流体包裹体的均一温度统计峰值分别出现在375~405°C和285~315°C之间,流体盐度的统计峰值出现在5.0 wt.%~10.0 wt.% NaCl eq.之间。激光拉曼探针分析表明,流体包裹体的气相成分以水蒸汽为主,含有少量CO2和CH4。流体 氢、氧同位素组成呈岩浆流体特征。研究表明,大团山铜（钼） 矿床的成矿流体主要来源于岩浆流体,在成矿过程中经历 了相态变化,沸腾的流体体系受到了不均匀捕获。结合前人研究成果,狮子山矿田内早白垩世叠加改造型流体表现出同源 特征,在物理化学演化方面具有一定规律性,流体的多次沸腾作用很可能对成矿元素的分配、迁移与沉淀起到了重要作用。     

Fluid Inclusion and Stable Isotope Studies at Don Sixto,a Precious Metal Low Sulfidation Deposit in Mendoza Province,Argentina

The Don Sixto mining area in Mendoza province, central‐western Argentina, contains an epithermal low sulfidation Au–Ag deposit. It is a small deposit (～4 km²), with a gold resource of 36 t. In Don Sixto, ore minerals are disseminated in the hydrothermal quartz veins and hydrothermally altered volcanic‐pyroclastic rock units of Permian–Triassic age. On the basis of the texture, ore mineral paragenesis and cross cutting relationship of gangue minerals, seven stages of mineralization were recognized and described. The first six stages are characterized by quartz veins with minor amounts of base metal minerals and the last stage is represented by fluorite veins with minimal quantities of base metal minerals; the precious metal mineralization is mainly related to the fourth stage. The hydrothermal veins exhibit mainly massive, crustiform and comb infilling textures; the presence of bladed quartz replacement textures and quartz veins with adularia crystals are indicative of boiling processes in the system. Fluid inclusion and complementary stable isotope studies were performed in quartz, fluorite, and pyrite samples from the vein systems. The microthermometric data were obtained from primary, biphasic (liquid‐vapor) fluid inclusion assemblages in quartz and fluorite. The maximum values for salinity and homogenization temperature (T_h) came from the stage IV where quartz with petrographic evidence of boiling has average values of 4.96 wt% NaCl_equiv. and 286.9°C respectively. The lower values are related to the last stage of mineralization, where the fluid inclusions in fluorite have average salinities of 1.05 wt% NaCl_equiv. and average homogenization temperatures of 173.1°C. The oxygen and sulfur isotopic fractionation was analyzed in quartz and pyrite. The calculated isotopic fractionation for oxygen in the hydrothermal fluid is in the range of δ¹⁸O_H2O = ?6.92 up to ?3.08‰, which indicates dominance of a meteoric source for the water, while sulfur reaches δ³⁴S_H2S = 1.09‰, which could be reflecting a possible magmatic, or even a mixed source.     

西藏驱龙超大型斑岩铜矿的成因：流体包裹体及H O同位素证据

与多数产于岩浆弧环境中的斑岩铜矿不同,西藏冈底斯带斑岩铜矿形成于碰撞造山环境,查明其形成过程有助于理解非岩浆弧环境中斑岩铜矿床的成因.为此,选择冈底斯带最大的斑岩铜矿--驱龙斑岩铜矿进行解剖,通过对矿床岩浆-热液过程形成的各类脉体详细的流体包裹体研究,以及不同蚀变阶段蚀变矿物的H-O同位素研究发现:引起矿床早期蚀变(钾硅酸盐化)与矿化的流体并非通常认为的高盐度岩浆热液,而是直接从岩浆房出溶的中等盐度(约9% NaCl)、近临界密度的高温(550～650℃)气相;气相近临界密度的特征表明,早期蚀变与矿化形成于较高的压力(105±15～90±20 MPa)条件下,用静岩压力估算,对应的古深度在4.2±0.6～3.6±0.8 km之间,成矿后(约16 Ma)矿区发生了至少3～3.5 km的剥蚀;与高盐度流体相比,中等盐度气相与熔体密度差较大,很难在斑岩体顶部聚集并集中释放,而连续释放则直接导致矿床含矿斑岩体与Cu、Mo矿体时空关系的解耦,并造就了矿床早期蚀变范围大、但强度弱,矿化范围大、但品位低的矿床地质特征;成矿物质的沉淀并非温度降低的结果,而是因压力降低及气相中S大量减少所致.总之,驱龙斑岩铜矿是一类成矿与低密度气相有关的斑岩铜矿类型,其蚀变-矿化特征及成矿过程与高盐度流体引发的斑岩矿床类型有所不同,意识到斑岩矿床蚀变及矿化特征与矿床成因的密切关系,对矿床勘查将具有重要的现实意义.     

The δ18O of UST Quartz in Two Porphyry Deposits,China

The unidirectional solidification textures (UST) quartz is generally thought to form from fluids exsolved from shallow intrusions and/or magma chambers, but such an idea is still poorly constrained from the evidence of stable isotopes. In this study, we report for the first time the δ¹⁸O of quartz that shows UST from the Qulong Cu–Mo and the Yechangping Mo porphyry deposits in China. The analysis results show that the UST quartz samples from the Qulong deposit have δ¹⁸O values ranging from +6.2 ‰ to +7.6 ‰, which are similar to that of quartz phenocrysts (+6.7 ‰ to +7.8 ‰). In contrast, the UST quartz samples from the Yechangping porphyry Mo deposit yield a high δ¹⁸O value (+10.0 ‰). The δ¹⁸O_water value of Yechangping UST quartz (+8.5 ‰) is also higher than that of Qulong (+4.6 ‰ to +5.8 ‰). Hydrothermal biotite from potassic alteration and sericite from early phyllic alteration at Qulong have similar δ¹⁸O values to UST quartz, suggesting the involvement of magmatic fluids during this stage of deposit evolution.     

贵州锦丰（烂泥沟）金矿床含砷黄铁矿和脉石英及其包裹体的微量元素特征

贵州锦丰（烂泥沟）金矿是滇黔桂“金三角”目前已探明最大的卡林型金矿床。含砷黄铁矿是该矿床最主要的载金矿物,硅化及石英脉是最显著的热液蚀变类型。本文采用高精度电感耦合等离子质谱（ICP-MS）对含砷黄铁矿和脉石英及其包裹体的微量元素进行了测试,结果表明含砷黄铁矿富亲硫元素,并相对于围岩和上部地壳均强烈富集;亏损V,Sr 及高场强元素。同生黄铁矿也具有类似的特征。脉石英除亲石元素含量高以外,还表现为亲硫元素以及Mo,Bi 含量较高。但与上部地壳相比,绝大部分元素贫化。相应包裹体的微量元素含量普遍低于单矿物,但变化特征一致。结合矿物和包裹体的稀土元素分析,发现脉石英和含砷黄铁矿及其包裹体均表现为HFSE明显亏损,Th/La,Nb/La 比值小于1,说明成矿流体为富Cl 的流体。含砷黄铁矿及其包裹体中Co/Ni 比值远小于1,反映成矿温度较低,推测成矿流体主要来源于以沉积建造水为主的盆地流体。     

富钙长石-橄榄石型包体与典型富Ca,Al包体的矿物岩石学特征对比研究

本文研究了2个富钙长石-橄榄石型包体和2个富黄长石-尖晶石型和富尖晶石-辉石型包体（分别来自宁强和南极格罗夫山碳质球粒陨石）的矿物岩石学特征,并对它们进行了对比。富钙长石-橄榄石型包体的矿物模式组成具有富橄榄石和缺失黄长石的特征,其可能是球粒和典型难熔包体之间的中间产物,是认识它们之间相互关系的钥匙。矿物岩石学特征表明富黄长石-尖晶石型和富尖晶石-辉石型包体可能是星云直接凝聚的产物,而富钙长石-橄榄石型包体经历过熔融结晶过程。富钙长石-橄榄石型包体的初始物质可能是富Al的球粒或含难熔组分的蠕虫状橄榄石集合体。矿物化学组成对比研究发现,GRV 022459-RI6中的尖晶石具有最富FeO的特征,表明包体的蚀变可能发生在高氧逸度的星云环境。     

青海省都兰县果洛龙洼金矿成矿流体

果洛龙洼金矿是青海东昆仑地区最典型、最具规模的金矿床之一。在前人资料基础上,将果洛龙洼金矿热液成矿期划分为4个成矿阶段：贫矿化石英阶段、石英-多金属硫化物阶段（主要成矿阶段）、石英-贫硫化物阶段（次要成矿阶段）和石英-碳酸盐阶段。随后对主要和次要成矿阶段石英脉开展流体包裹体显微测温和H-O同位素研究。结果表明：原生流体包裹体主要包括气液两相、富CO₂三相、纯CO₂两相共3类;成矿流体总体以CO₂-NaCl-H₂O体系为主,均一温度为130.0~357.3 ℃,盐度（w(NaCl)）为1.83%~20.11%。石英-多金属硫化物阶段石英δ¹⁸O_V-SMOW值为14.8‰~17.2‰,据此计算流体的δ¹⁸O_H2O值为5.5‰~8.5‰,流体的δD_V-SMOW值为-61‰~-96‰;而石英-贫硫化物阶段石英δ¹⁸O_V-SMOW值为15.7‰~16.9‰,据此计算流体的δ¹⁸O_H2O值为4.1‰~5.3‰,流体的δD_V-SMOW值为-84‰~-101‰。由此认为：主要成矿阶段成矿流体可能为高温低盐度富CO₂变质热液和低温中高盐度岩浆热液两个端元组成的混合流体;次要成矿阶段成矿流体主要为混合后更均匀的中低温中低盐度热液,但后期明显有大气降水混入。总之,成矿流体的来源、性质及其演化等方面的研究结果进一步证明果洛龙洼金矿为造山型金矿。