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1.
福建大坪花岗斑岩体位于永定县城南部的大石凹—蓝地火山喷发盆地,具斑状结构,基质呈霏细结构、细-微粒结构。文章运用电子探针(EMPA)和激光剥蚀电感耦合等离子体质谱仪(LA-ICP-MS)等技术,对大坪岩体ZK10001钻孔中不同深度的岩石样品进行了矿物和岩石化学分析。分析结果表明,大坪岩体岩性为黑鳞云母碱长花岗斑岩,属于过铝质钙碱性花岗岩,具有较高的分异演化程度,Nb2O5和Ta2O5含量达到了花岗岩型稀有金属矿床的工业品位。铌钽矿物主要与黄玉、萤石的集合体呈稀疏浸染状、星点状产于基质间隙内,其次以星点状存在于石英和长石斑晶中。矿石矿物赋存特征与宜春钽铌矿床类似,可能具有一定的可选性和经济价值。大坪岩体的铌钽富集特征不同于斑岩型铜、钼矿床,与花岗岩型铌钽矿床也存在较大的差别,铌钽的富集过程经历了深部斑晶阶段和浅部基质阶段两阶段岩浆结晶分异作用,F等挥发分促进了铌钽在结晶残余岩浆中富集,在基质间隙间沉淀。大坪矿化岩体的发现暗示斑岩型铌钽矿床存在的可能性。 相似文献
2.
广西栗木钽铌锡多金属矿床的成矿流体演化及其对成矿过程的制约 总被引：1，自引：0，他引：1
广西栗木钽铌锡多金属矿床既产具明显垂直分带的花岗岩型钽铌锡矿体,又有石英脉型钨锡矿体,是研究岩浆-热液演化过程的典型实例。本次研究对栗木矿区中水溪庙和金竹源两个矿床开展了系统成矿流体研究。研究表明栗木矿区中的包裹体类型主要有盐水溶液包裹体、H2O-CO2-Na Cl包裹体和熔体包裹体三类。自云英岩化钠长石花岗岩→似伟晶岩→长石石英脉型→锂云母萤石脉,盐水溶液包裹体逐渐由定向分布的次生包裹体特征,转变为面状孤立分布的原生包裹体特征,而且均一温度、盐度和密度逐渐降低,具有低均一温度(150~210℃)、低盐度(1.0%~9.0%NaC leqv)和低密度(0.83~1.05g/cm3)的特点。H2O-CO2-NaC l包裹体和熔体包裹体主要产在钠长石花岗岩和似伟晶岩中,H2O-CO2-NaC l包裹体孤立分布,均一温度为260~350℃,盐度为0.8%~8.5%NaC leqv;熔体包裹体的固相初熔温度为560~600℃,完全均一温度为704~853℃,流体相具有与盐水溶液包裹体相近的均一温度和盐度。根据以上资料,本文把栗木矿区的成矿作用分为岩浆阶段的钽铌锡成矿作用和岩浆热液阶段的钨锡成矿作用,估算成岩成矿压力约为270MPa,这有利于栗木矿区的钽铌锡在花岗岩浆阶段发生了相对贫化的富集作用,钽、铌、锡、钨等元素在熔体/流体的分配系数制约了钽铌成矿作用发生在岩浆阶段,而钨锡成矿作用主要发生在热液阶段。 相似文献
3.
西藏甲玛铜多金属矿床成因研究——来自流体包裹体的证据 总被引：1，自引：0，他引：1
甲玛铜多金属矿床位于西藏冈底斯斑岩铜矿带东段,是近年来勘探发现的超大型斑岩-矽卡岩型铜多金属矿床。通过冷热台显微观察与测温、扫描电镜、激光拉曼探针测试,对甲玛矿床各成矿阶段典型矿物的流体包裹体研究表明,成矿流体富含挥发分,临界相均一的流体来自岩浆超临界流体出溶,主成矿阶段具有沸腾包裹体组合特征,有机质包裹体荧光效应显著。显微测温结果显示,岩浆-热液阶段斑岩中石英斑晶的流体包裹体均一温度范围为250～540℃,含石盐子晶高盐度包裹体盐度范围为35～61(wt%)NaCl.eq,中等盐度的临界均一的气液包裹体盐度范围为3～29(wt%)NaCl.eq,岩浆期后热液阶段斑岩、角岩中石英脉的流体包裹体均一温度范围为210～410℃,盐度范围为33～41(wt%)NaCl.eq,与其不混溶共生的中低盐度气液两相流体包裹体盐度范围为5～25(wt%)NaCl.eq。矽卡岩阶段矿物均一温度范围为130～360℃,盐度范围为3～41(wt%)NaCl.eq,从岩浆热液过渡阶段到石英-硫化物阶段均一温度与盐度呈阶梯式降低趋势。斑岩体石英的流体包裹体中含有较多黄铜矿子矿物,岩浆结晶分异过程中已经具成矿元素的富集。激光拉曼探针测试结果显示,成矿早期至主成矿期矿物流体包裹体气相成分主要为CO2、CH4和N2,各阶段矿物流体包裹体气相成分具有继承性。成矿流体为高温度高盐度,富含CO2、CH4的流体。成矿流体主要源于岩浆,后期混有大气降水。当岩浆热液上升时因压力的突然释放造成高温含矿热流体发生减压沸腾,CO2和CH4等气体大量逃逸,导致成矿物质快速沉淀。矿床在成因上与岩浆-热液成矿作用密切相关。 相似文献
4.
铌钽矿研究进展和攀西地区铌钽矿成因初探 总被引：12，自引：3，他引：9
铌钽矿主要产出类型包括伟晶岩型、富Li-F花岗岩型、碱性侵入岩型、碳酸岩型及冲积砂矿型。前2种类型以钽为主,后3种则以铌占主导。铌和钽大多以铌钽独立矿物(铌铁矿、钽铁矿、细晶石、烧绿石等)呈浸染状分布于含矿岩石中,也有部分以类质同象的形式分布于云母、榍石、霓石、钛铁矿等矿物中。关于铌钽矿的富集机制,一些学者认为可由富F-Na和稀有金属(铌、钽等)的花岗质熔体经结晶分异作用形成;另一些学者则根据铌钽矿化与岩石的钠长石化、锂云母化等紧密共生的特点,认为铌钽的富集是岩浆期后流体交代早期形成的花岗岩所致。攀西(攀枝花-西昌)地区的铌钽矿床(化)基本上都是沿着断裂带分布,矿体赋存于印支期碱性岩脉(碱性正长伟晶岩)中,有少数存在于碱性花岗岩中,与区域上邻近的正长岩体及花岗岩体关系密切。其矿石矿物主要为烧绿石、褐钇铌矿等。初步推断,攀西地区的铌钽矿与二叠纪地幔柱活动有关。碱性的正长岩体及花岗岩体与广泛分布的峨眉山玄武岩、辉长岩均是地幔柱岩浆活动的产物,长英质岩体(包括正长岩体和花岗岩体)是富铌钽岩石的母岩体。碱性伟晶岩脉(如炉库和白草地区)是碱性岩浆逐步演化的产物,含矿的碱性花岗岩是花岗质岩浆分异演化的结果。此外,在该地区的铌钽矿床中,铌钽矿物几乎都富集在钠长石化发育的地段,说明后期的热液交代对铌钽的富集也起到了一定作用。因此,攀西地区铌钽的富集是岩浆结晶分异和岩浆期后热液交代共同作用的结果。 相似文献
5.
滇西北衙金矿蚀变斑岩中的流体包裹体研究 总被引：6，自引：0，他引：6
位于爆破角砾岩筒边缘的接触带矿化斑岩中早期流体包裹体以CO2-H2O包裹体为主,而岩体内无或弱矿化斑岩中对应的流体包裹体以高盐度H2O-NaCl包裹体为主,反映来源于富碱岩浆的流体在它的早期阶段即分异出富碳相和盐水相,富碳相位于流体的外层,成矿元素主要在富碳相中迁移。因此,外接触带及其附近的围岩是成矿的有利部位。岩体内部蚀变岩石样品石英斑晶中的次生流体包裹体可大致划分为4个阶段。根据显微测温结果、形成温度和压力的估算及均一温度-盐度关系,结合H2O-NaCl体系P-T投影图,包裹体的4个阶段反映了环境条件的变化过程及相关的地质过程。 相似文献
6.
藏东玉龙斑岩铜矿床多期流体演化与成矿的流体包裹体证据 总被引：6，自引：9，他引：6
通过对王龙斑岩铜矿石英斑晶、辉钼矿石英脉中流体包裹体岩相学、包裹体显微测温分析、包裹体成分的激光拉曼探针分析及包裹体中子矿物的扫描电镜/能谱分析,发现矿化斑岩石英斑晶中发育多期流体包裹体。斑晶中除流体包裹体外尚可见少量熔体包裹体,与斑岩期矿化有关的成矿流体以中高温(200～537℃)、高盐度(29.6～44.7 wt%NaCleq)为特征,与粘土化蚀变有关的流体包裹体以低温、富 Ca 为特征,不同气相充填度的气液两相包裹体与高盐度含子矿物多相包裹体共存,且具有相似的均一温度,显示不混溶流体包裹体特征。温度、压力降低引起的流体不混溶是造成斑岩型矿化矿质沉淀的主要因素,斑岩期流体与浅成低温热液期流体形成于统一的流体系统,为同源演化结果。 相似文献
7.
黑龙江乌拉嘎金矿的次火山岩浆-热液成矿:熔体-流体包裹体证据 总被引：4，自引：1，他引：3
黑龙江乌拉嘎金矿是我国陆相火山岩区的重要金矿之一。构造位置处于古亚洲构造域与滨太平洋构造域交接复合部位的东北缘,矿体主要分布于团结沟斜长花岗斑岩接触带部位的隐爆角砾岩带和黑龙江群变质岩的层间裂隙中。斜长花岗斑岩的石英斑晶中发育3类包裹体:熔体包裹体、原生的L-V包裹体(及少量的L-V-S包裹体)和次生的L-V包裹体。玻璃质熔体包裹体相当于酸性殘浆的成分(SiO2达69.5%～73.8%),其捕获温度大于800℃。石英斑晶中次生L-V包裹体均一温度集中在210～350℃、盐度5%～7%NaCleqv,代表了次火山岩浆热液的特征,与黄铁矿-早期白色玉髓状石英阶段中Q1的包裹体均一温度范围很接近,而盐度略高于白色玉髓状石英Q1的。乌拉嘎金矿的金成矿可划分3个成矿阶段,发育盐水溶液包裹体:(1)黄铁矿-早期白色玉髓状石英阶段,包裹体均一温度为154～355℃,集中在190～330℃,盐度为1.3%～8.2%NaCleqv,密度为0.53～0.88g/cm3。(2)烟灰色玉髓状石英-多金属硫化物阶段,石英中包裹体均一温度为159～196℃,集中在170～190℃,盐度为2.2%～3.2%NaCleqv,密度0.79～0.92g/cm3。(3)碳酸盐-石英阶段,方解石中包裹体均一温度集中在170～270℃;盐度0.5%～2.9%NaCleqv。成矿流体以中低温、低盐度、贫CO2的盐水体系为特征,与国内外陆相火山-次火山热液矿床十分相似。石英斑晶中熔体、流体包裹体及其共存反映了次火山岩浆活动晚期,由硅酸盐熔体通过不混溶产生含矿的盐水溶液的可能,说明了金成矿与斑岩的成因联系,乌拉嘎金矿应该属于陆相火山-次火山活动有关的中低温浅成热液金矿床。 相似文献
8.
广西栗木钨锡铌钽矿区流体包裹体及氢氧同位素研究 总被引：2，自引：0，他引：2
本文通过对广西栗木矿区金竹源矿床和水溪庙矿床的流体包裹体研究,得出该矿区流体包裹体主要有两相H_2O-NaCl和H_2O-NaCl-CO_2两种类型。显微测温结果表明:两相H_2O-NaCl型流体包裹体均一温度主要集中于181.9~258.8℃,盐度w(Na Cleq)主要集中于4.01%~6.87%,密度0.690~0.988 g/cm3;H_2O-NaCl-CO_2型流体包裹体均一温度为178.5~331.1℃,主要集中在两个温度段,分别为高-中温段(265.3~315.5℃)和中-低温段(202.3~264.1℃),盐度w(NaCleq)主要集中在0.21%~5.05%,密度为0.678~0.886 g/cm3。栗木矿区成矿流体有两个温度集中段,且具有低盐度、低密度的特征。氢氧同位素研究结果表明:金竹源矿床钨锡铌钽矿化花岗岩石英δD值为-73.6‰~-62.8‰,δ~(18)OV-SMOW值为7.5‰~8.9‰,计算得δ~(18)OH2O值为6.00‰~7.40‰;水溪庙矿床钨锡铌钽矿化花岗岩石英δD值为-73.8‰~-58.3‰,δ~(18)OV-SMOW值为11.0‰~13.2‰,计算得δ~(18)OH2O值为9.50‰~11.70‰,水溪庙矿床含钨锡石英脉石英δD值为-75.3‰~-56.6‰,δ~(18)OV-SMOW值为11.8‰~14.1‰,计算得δ~(18)OH2O值为2.20‰~4.50‰。栗木矿区钨锡铌钽矿化花岗岩成矿流体来源于岩浆水,含钨锡石英脉成矿流体来源于岩浆水和大气降水的混合流体。 相似文献
9.
滇西北衙斑岩型金多金属矿床成矿流体特征及其演化 总被引：2，自引：2，他引：0
北衙超大型金多金属矿床位于扬子陆块西缘与三江特提斯造山带的结合部位。本文通过对北衙矿区内的斑岩体石英斑晶、斑岩型矿化、矽卡岩矿化中的矽卡岩及外围似层状热液型铅锌银矿化的岩(矿)石中发育的流体包裹体进行了系统研究,发现北衙矿区内主要发育CO2、富CO2、含CO2、含子矿物三相、富气相水溶液及气液两相水溶液包裹体六类流体包裹体;与斑岩型矿化有关的成矿流体为中-高温Na Cl-H2O-CO2体系热液,矽卡岩矿化相关成矿流体为一种高温的Na Cl-H2O及Na Cl-H2O-CO2体系热液,而外围似层状铅锌银矿化相关的成矿流体则为中温的Na Cl-H2O-CO2体系热液。对比分析表明,矽卡岩矿化中的矽卡岩矿物(以绿帘石类矿物为主)形成较早,其中发育富气相的流体包裹体,可以推断岩浆侵位后先分异出富水蒸气的流体,此后CO2才从成矿流体中大量分异。斑岩型矿化及外围地层中似层状铅锌银矿化脉体中发育的流体包裹体与斑岩体石英斑晶内发育的流体包裹体组合类型基本一致,表明成矿流体主要来自斑岩体结晶分异出的岩浆热液。流体包裹体研究表明,北衙金多金属矿区内的矽卡岩型(金铜铁)、斑岩型(铜金钼)及外围碳酸盐岩等地层中的似层状热液型(铅锌银)矿床系列为与富碱斑岩体侵位活动有关的,由岩浆分异热液并逐渐演化形成的斑岩型金-铁铜-铅锌(银)多金属成矿系统。 相似文献
10.
甘肃天祝干沙鄂博稀土矿床产于霓辉正长岩和霓辉正长斑岩中,矿体形态呈不规则脉状、透镜状和板状。成矿过程可分为岩浆期、岩浆-热液期、热液期和表生期,其中岩浆-热液期为主要成矿期。本矿床中的包裹体有熔体包裹体、流体-熔体包裹体、H_2O包裹体、CO_2包裹体、CO_2-H_2O包裹体、含子矿物H_2O包裹体和含子矿物CO_2-H_2O包裹体7类,并以富含流体-熔体包裹体、CO_2-H_2O包裹体为显著特征。包裹体组合从熔体包裹体→流体-熔体包裹体、H_2O包裹体、CO_2包裹体和CO_2-H_2O包裹体→H_2O包裹体的变化,反映本矿床的形成经历了从岩浆→岩浆+热液→热液的演化过程。岩浆期熔体包裹体均一温度为780℃;岩浆-热液期均一温度为191~700℃,盐度为5.26%~22.24%,属中低盐度,成矿压力为68~95 MPa,相应的成矿深度为2.6~3.6 km;热液期均一温度为129~225℃,盐度为0.35%~7.73%,为低盐度。从岩浆期到岩浆-热液期再到热液期,温度逐渐降低,矿化作用主要发生在岩浆-热液期,属中高温、中深成岩浆-热液过渡型矿床。 相似文献
11.
吐哈盆地早二叠世玄武岩原始岩浆性质:来自熔融包裹体成分的制约 总被引：3，自引：3，他引：0
东天山地区的二叠纪玄武岩沿着区域的北东东向断裂呈脉状分布,吐哈盆地玄武岩的40Ar-39Ar坪年龄为298.2±3.8Ma,为早二叠世,与前人的玄武岩年龄结果在误差范围内一致。可能与东天山地区二叠纪岩浆铜镍矿床镁铁-超镁铁岩有密切的成因联系。吐哈玄武岩的主微量成分显示其为岛弧拉斑、大陆弧玄武岩,轻稀土富集和Nb、Ta负异常,指示源区可能经历过俯冲作用的改造。吐哈盆地二叠纪玄武岩含有新鲜的橄榄石和长石斑晶,橄榄石斑晶中熔融包裹体较发育。熔融包裹体为玻璃质、气相和玻璃质、气相、固相两种类型。包裹体中不透明矿物主要为磁铁矿,说明捕获包裹体时岩浆的氧逸度和Fe含量较高。熔融包裹体分为高MgO和低MgO含量两种。高MgO含量的包体同时具有低SiO_2、低微量和稀土元素含量的特征,可能为地幔高部分熔融的产物,且经历过深部演化程度较弱。该高MgO熔体的微量元素显示Nb、Ta亏损的特征,具有N-MORB特征的微量和稀土元素分配模式,预示该熔体为受到俯冲交代的地幔熔融形成。熔融包裹体相对玄武岩具有低的Th和Ta含量、相对弱的Nb和Ta的负异常的特征,指示熔融包裹体的成分经受改造程度低于玄武岩,暗示可能为经历过较少后期作用改造的相对原始的熔体。熔体中Cu含量(12.4×10~(-6)~299×10~(-6))在正常玄武质岩浆含量范围内,而Ni含量(236×10~(-6)~697×10~(-6))高于高镁溢流科马提岩和洋中脊玄武岩。该Cu、Ni含量略显解耦的熔体可能代表了经历过深部少量的硫化物熔离,带走小部分Cu和Ni等成矿元素之后所捕获的岩浆。如果将该熔体视为东天山地区二叠纪岩浆铜镍硫化物矿床的母岩浆,该母岩浆中Ni含量相对较高可能是岩浆铜镍硫化物矿床中矿石的Ni/Cu比值大多大于1.0的主要因素。 相似文献
12.
Bo XIAO Kezhang QIN Guangming LI Jinxiang LI Daixiang XIA Lei CHEN Junxing ZHAO 《Resource Geology》2012,62(1):4-18
The Miocene Qulong porphyry Cu‐Mo deposit, which is located at the Gangdese orogenic belt of Southern Tibet, is the largest porphyry‐type deposit in China, with confirmed Cu ～10 Mt and Mo ～0.5 Mt. It is spatially and temporally associated with multiphase granitic intrusions, which is accompanied by large‐scale hydrothermal alteration and mineralization zones, including abundant hydrothermal anhydrite. In addition to hydrothermal anhydrite, magmatic anhydrite is present as inclusions in plagioclase, interstitial minerals between plagioclase and quartz, and phenocrysts in unaltered granodiorite porphyry, usually in association with clusters of sulfur‐rich apatite in the Qulong deposit. These observations indicate that the Qulong magma‐hydrothermal system was highly oxidized and sulfur‐rich. Three main types of fluid inclusions are observed in the quartz phenocrysts and veins in the porphyry: (i) liquid‐rich; (ii) polyphase high‐salinity; and (iii) vapor‐rich inclusions. Homogenization temperatures and salinities of all type inclusions decrease from the quartz phenocrysts in the porphyry to hydrothermal veins (A, B, D veins). Microthermometric study suggests copper‐bearing sulfides precipitated at about 320–400°C in A and B veins. Fluid boiling is assumed for the early stage of mineralization, and these fluids may have been trapped at about 35–60 Mpa at 460–510°C and 28–42 Mpa at 400–450°C, corresponding to trapping depths of 1.4–2.4 km and 1.1–1.7 km, respectively. 相似文献
13.
XIE Yuling WANG Bogong LI Yingxu LI Guangming DONG Suiliang GUO Xiang WANG Lei 《《地质学报》英文版》2015,89(3):811-821
The Zhaxikang Pb-Zn-Sb polymetallic deposit is one of the most important deposits in the newly recognized southern Tibet antimony-gold metallogenic belt.Compared to the porphyry deposits in the Gangdese belt,much less researches have addressed these deposits,and the genesis of the Zhaxikang deposit is still controversial.Based on field investigation,petrographic,microthermometric,Laser Raman Microprobe（LRM） and SEM/EDS analyses of fluid,melt-fluid,melt and solid inclusions in quartz and beryl from pegmatite,this paper documents the characteristics and the evolution of primary magmatic fluid which was genetically related to greisenization,pegmatitization,and silification in the area.The results show that the primary magmatic fluids were derived from unmixing between melt and fluid and underwent a phase separation process soon after the exsolution.The primary magmatic fluids are of low salinity,high temperature,and can be approximated by the H2O-NaCl-CO2 system.The presence of Mn-Fe carbonate in melt-fluid inclusions and a Zn-bearing mineral（gahnite） trapped in beryl and in inclusions from pegmatite indicates high Mn,Fe,and Zn concentrations in the parent magma and magmatic fluids,and implies a genetic link between pegmatite and Pb-Zn-Sb mineralization.High B and F concentrations in the parent magma largely lower the solidus of the magma and lead to late fluid exsolution,thus the primary magmatic fluids related to pegmatite have much lower temperature than those in most porphyry systems.Boiling of the primary magmatic fluids leads to high-salinity and high-temperature fluids which have high capacity to transport Pb,Zn and Sb.The decrease in temperature and mixing with fluids from other sources may have caused the precipitation of Pb-Zn-Sn（Au） minerals in the distal fault systems surrounding the causative intrusion. 相似文献
14.
Akira IMAI 《Resource Geology》2000,50(1):1-23
Abstract: The Mamut deposit of Sabah, East Malaysia, is a porphyry type Cu‐Au deposit genetically related to a quartz monzonite (“adamellite”) porphyry stock associated with upper Miocene Mount Kinabalu plutonism. The genesis of the Mamut deposit is discussed based on petrology of the intrusives in the Mount Kinabalu area combined with ore– and alteration–petrography, fluid inclusion and sulfur isotope studies. Groundmass of the adamellite porphyry at Mamut is rich in K which suggests vapor transport of alkaline elements during the mineralizing magmatic process, while the groundmass of the post‐ore “granodiorite” porphyry at Mamut contains small amounts of normative corundum suggesting depletion in alkaline elements at the root zone of the magma column. Sub‐dendritic tremolitic amphibole rims on hornblende phenocrysts in the Mamut adamellite porphyry suggest interaction between the mineralizing magma and the exsolved fluids. Occurrences of clinopyroxene microphenocrysts and pseudomor‐phic aggregates of shredded biotite and clinopyroxene after hornblende phenocrysts in the barren intrusives imply lower water fugacity and decreasing in water fugacity, respectively. Compositional gap between the core of hornblende phenocrysts and the tremolitic amphibole rims and those in the groundmass of the Mamut adamellite porphyry suggests a decrease in pressure. Higher XMg (=Mg/(Mg+Fe) atomic ratio) in the tremolitic amphibole rims in the Mamut adamellite porphyry compared to those of the barren intrusions suggests high oxygen fugacity. High halogen contents of igneous hydrous minerals such as amphiboles, biotite and apatite in the Mamut adamellite porphyry suggest the existence of highly saline fluids during the intrusion and solidification of the mineralizing magma. Fluid inclusions found in quartz veinlet stockworks are characterized by abundant hypersaline polyphase inclusions associated with subordinate amounts of immiscible gaseous vapor. Both Cu and Au are dispersed in disseminated and quartz stockwork ores. Chalcopyrite and pyrrhotite as well as magnetite are the principal ore minerals in the biotitized disseminated ores. Primary assemblage of intermediate solid solution (iss) and pyrrhotite converted to the present assemblage of chalcopyrite and pyrrhotite during cooling. Subsequent to biotitization, quartz veinlet stockworks formed associated with retrograde chlorite alteration. The Cu‐Fe sul–fides associated with stockwork quartz veinlet are chalcopyrite and pyrite. Overlapping Pb and Zn and subsequent Sb mineralizations were spatially controlled by NNE‐trending fractures accompanying the phyllic and advanced argillic alteration envelope. Sulfur isotopic composition of ore sulfides are homogeneous (about +2%) throughout the mineralization stages. These are identical to those of the magmatic sulfides of Mount Kinabalu adamellitic rocks. 相似文献
15.
GONG Xiaodong YAN Guangsheng YE Tianzhu ZHU Xinyou LI Yongsheng ZHANG Zhihui JIA Wenbin YAO Xiaofeng 《《地质学报》英文版》2015,89(3):822-835
The Dahutang tungsten polymetallic ore field is located north of the Nanling W-Sn polymetallic metallogenic belt and south of the Middle—Lower Yangtze River Valley Cu-Mo-Au-Fe porphyry-skarn belt.It is a newly discovered ore field,and probably represents the largest tungsten mineralization district in the world.The Shimensi deposit is one of the mineral deposits in the Dahutang ore field,and is associated with Yanshanian granites intruding into a Neoproterozoic granodiorite batholith.On the basis of geologic studies,this paper presents new petrographic,microthermometric,laser Raman spectroscopic and hydrogen and oxygen isotopic studies of fluid inclusions from the Shimensi deposit.The results show that there are three types of fluid inclusions in quartz from various mineralization stages:liquid-rich two-phase fluid inclusions,vapor-rich two-phase fluid inclusions,and three-phase fluid inclusions containing a solid crystal,with the vast majority being liquid-rich two-phase fluid inclusions.In addition,melt and melt-fluid inclusions were also found in quartz from pegmatoid bodies in the margin of the Yanshanian intrusion.The homogenization temperatures of liquid-rich two-phase fluid inclusions in quartz range from 162 to 363℃ and salinities are 0.5wt%-9.5wt%NaCI equivalent.From the early to late mineralization stages,with the decreasing of the homogenization temperature,the salinity also shows a decreasing trend.The ore-forming fluids can be approximated by a NaCl-H_2O fluid system,with small amounts of volatile components including CO_2,CH_4 and N_2,as suggested by Laser Raman spectroscopic analyses.The hydrogen and oxygen isotope data show that δ5D_(V-smow) values of bulk fluid inclusions in quartz from various mineralization stages vary from-63.8‰ to-108.4‰,and the δ~(18)O_(H2O) values calculated from the δ~(18)O_(V-)smow values of quartz vary from-2.28‰ to 7.21‰.These H-O isotopic data are interpreted to indicate that the ore-forming fluids are mainly composed of magmatic water in the early stage,and meteoric water was added and participated in mineralization in the late stage.Integrating the geological characteristics and analytical data,we propose that the ore-forming fluids of the Shimensi deposit were mainly derived from Yanshanian granitic magma,the evolution of which resulted in highly differentiated melt,as recorded by melt and melt-fluid inclusions in pegmatoid quartz,and high concentrations of metals in the fluids.Cooling of the ore-forming fluids and mixing with meteoric water may be the key factors that led to mineralization in the Dahutang tungsten polymetallic ore field. 相似文献
16.
本文从江西德兴斑岩铜矿铜厂矿床的流体包裹体研究出发,讨论了矿床成矿物质来源与矿床成因。矿床中流体包裹体分为6类,即富液包裹体、富气包裹体、含石盐多相包裹体、含CO2多相包裹体以及熔体包裹体和熔体-流体包裹体。富气包裹体、含石盐多相包裹体和熔体与熔体-流体包裹体代表了成矿早期岩浆热液的特征。在这些包裹体中发现黄铜矿等金属矿物,表明成矿金属主要源自岩浆。含石盐多相包裹体和富气包裹体与矿体关系不甚密切,但其中所含有的金属矿物特别是黄铜矿,暗示早期来自岩浆的热液流体金属含量较高,形成于大气降水与岩浆热液混合之前。成矿中晚期大气降水流体在冷却和稀释岩浆流体方面对于矿床的形成作出了一定贡献,但是来自围岩的大气降水可能并没有向成矿体系提供大量金属。 相似文献
17.
The Zaldívar porphyry copper deposit, Northern Chile, consists of two major intrusions, the 290 Ma Zaldívar, and the more recent Miocene (38.7 Ma) Llamo porphyry. Five types of inclusions have been identified in quartz phenocrysts from Llamo porphyry, including melt inclusions (M), and four types of fluid inclusions, called MS (multi solids), B (brines), G (vapor-rich) and W (aqueous), respectively.Melt remnants, well preserved as M-inclusions, homogenize around 1000 °C. They show a rhyolitic composition, comparable to the most evolved acidic rhyolitic end member found elsewhere in the regional magmatism and to worldwide volcanic rhyolitic glass. High silica content in some inclusions can, however, be due to partial remelting of the quartz host during the heating run. Copper content in the same inclusions ranges between 0.03 and 0.57 wt.%, with an average concentration of 0.10 wt.%, suggesting a major magmatic source for the copper (orthomagmatic model).MS inclusions, which contain a number of solids at room temperature, mostly H2O-bearing phases (system NaCl–KCl–((Fe, Mg, Cu)Cl)–H2O, average salinity 70 wt.% NaCl equiv.), homogenize at magmatic temperatures (around 1000 °C). They represent the first fluids to have exsolved from the magma at depth, at a pressure of about 2 kbar. Their high homogenization temperature, comparable to values measured for melt inclusions (1000 to 1050 °C), may indicate trapping of MS and M inclusions in host phenocrysts from an immiscible mixture of silicate melt and highly saline fluids expelled from the magma during the early stage of quartz crystallization.The data indicate a magmatic origin for copper, as well as extremely high melt temperatures. These features are interpreted by magmatic differentiation of mantle-derived primitive melts, corresponding to major changes in the tectonic regime of the Andean margin, which occurred in Miocene times. 相似文献
18.
南岭早侏罗世稀有金属成矿作用研究——以闽西南大坪花岗斑岩为例 总被引：1，自引：1，他引：0
华南地区是我国重要的稀有金属矿产区,绝大部分具经济规模的稀有金属矿床均与高演化的富Li-F花岗岩有成因联系。大坪花岗斑岩位于南岭构造带最东缘福建省永定地区,与区内Nb-Ta矿床形成有关。该岩体SIMS和LA-ICP-MS锆石U-Pb定年结果分别为186.7±1.2Ma和190.7±1.1Ma,是华南少见的早侏罗世(200~180Ma)侵入的花岗岩侵入体,也是华南最早报道的早侏罗世稀有金属成矿事件。大坪花岗斑岩具高钾低镁、准铝质到弱过铝质的特征,属于高钾钙碱性花岗岩,并显示A型花岗岩的地球化学特征,如富硅(72.81%~76.44%)、高10000×Ga/Al比值、高FeO^T/MgO和高的Zr+Nb+Ce+Y含量、亏损高场强元素和Eu负异常明显等。全岩体系低的Zr/Hf、Nb/Ta比值,指示岩浆具有较高的分异演化程度,Nb 2 O 5和Ta 2 O 5均含量达到了花岗岩型稀有金属矿床的工业品位。花岗斑岩中锆石Hf-O同位素分析结果显示,其具有比较亏损的Hf同位素与比较均一的O同为素组成(εHf(t)=-2.4~3.4,δ^18 O=6.0‰~6.6‰)。结合微量元素地球化学特征,大坪花岗斑岩源区主要来源于软流圈地幔,并有约20%~30%壳源岩浆的加入,在成岩过程中发生了显著的分离结晶。晚期富氟的流体出熔并向上迁移可能对于Nb和Ta的再次富集与分异具有重要作用。大坪花岗斑岩与闽西南地区同时期的火山岩,如藩坑组双峰式火山岩,在空间上可与前人提出的“南岭山脉早侏罗世发育的东西向裂谷岩浆岩带(OIB型玄武岩、辉长岩和A型花岗岩组合)”相对应,是该裂谷带向东的延伸。 相似文献