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1.
内蒙古乌努(奴)格吐山铜铅锌矿整装勘查区位于得尔布干成矿带西南段,是我国北方重要的Cu-Mo-Fe-Au-AgPb-Zn成矿带。近年来随着多接收电感耦合等离子体质谱(MC-ICP-MS)的广泛应用,使Mo、Cu、Fe、Zn等同位素的研究应用于矿床学研究中。本文通过对乌努格吐山斑岩型矿床黄铜矿Cu同位素、辉钼矿Mo同位素组成,绢云母Ar-Ar年龄进行研究,借此探讨该矿床的形成时代、矿床成因。结果显示,矿床成矿早阶段的绢云母坪年龄为181.9 ± 1.1Ma,等时线年龄为181.0±2.3Ma,与辉钼矿Re-Os等时线年龄相一致。而石英+钾长石+辉钼矿+黄铜矿+黄铁矿脉中和石英+黄铜矿+黄铁矿脉中黄铜矿的δ~(65) Cu平均值分别为0.31y‰和0.40‰,显示黄铜矿的δ~(65) Cu值从早到晚逐渐增高,这可能为流体出溶过程中~(63) Cu优先进入富气相流体,残余岩浆流体逐渐富集~(65) Cu的结果。辉钼矿的δ~(98) Mo/δ~(95) Mo介于-0.16‰~0.35‰之间,说明在成矿作用的过程中Mo进入不同的矿物组合中并发生了同位素分馏,可能受到了氧化还原条件、温度等物理化学条件的变化,或者是辉钼矿的多型特征的影响。得尔布干成矿带矿床的形成与蒙古鄂霍次克洋的演化密切相关,结合前人研究成果,将成矿带斑岩型矿床分为240~230Ma、180~200Ma、150~160Ma三期。  相似文献   

2.
新寮岽铜多金属矿床是近年来粤东地区新发现的铜多金属矿床之一,矿区位于东南沿海锡、钨、铜等重要矿产发育地区,成矿地质条件非常好。本文通过对矿体中黄铜矿的铜同位素研究表明,其δ~(65)Cu值(-0.34‰~+1.37‰)与斑岩型矿床的δ~(65)Cu值基本一致,成矿物质Cu主要来源于深部岩浆,成矿流体显示为中高温(250~420℃)岩浆热液特征,Cu的分馏与岩浆热液活动关系密切,矿体的形成与成矿流体出溶有关。铜同位素组成随深度增加有增高趋势,能形成规模矿体。同时,铜同位素可以直接指示热源的位置,在热液流体石英脉出现的区域,铜矿体δ~(65)Cu值都低于0,在热液接触带、特殊的赋矿围岩和构造作用部位铜同位素值较高,预示着主矿体的边缘或前锋,是最为明显的找矿标志。  相似文献   

3.
江西东乡铜矿床成因:铜和硫同位素联合约束   总被引:1,自引:0,他引:1       下载免费PDF全文
东乡铜矿床的赋矿岩石以石炭系砂岩和燕山期花岗斑岩为主。文章对东乡铜矿床同位素地球化学进行了研究,探讨了成矿物质来源及矿床成因。东乡矿区块状矿石和花岗斑岩的黄铁矿δ~(34)S值(0.3‰~1.2‰)非常接近深部地幔硫的值,其δ~(34)S值呈现明显的塔式分布,分布范围较窄,表明矿石中的硫主要来自深源岩浆。δ~(65)Cu值分布范围较窄(-2.10‰~0.17‰),整体接近于零附近,明显不同于块状硫化物矿床(δ~(65)Cu=-0.98‰~3.14‰)、矽卡岩型矿床(δ~(65)Cu=-1.29‰~2.98‰)和热液脉型矿床中δ~(65)Cu值(-3.70‰~0.44‰)的分布范围,其δ~(65)Cu值变化范围大于岩浆矿床的δ~(65)Cu值(-0.62‰~0.40‰),更接近于斑岩型矿床的δ~(65)Cu值(-1.16‰~0.81‰),表明东乡铜矿与岩浆热液作用具有密切的成因联系。因此,推断东乡铜矿为岩浆热液型矿床。  相似文献   

4.
为查明朱砂红矿床成矿流体来源及矿床蚀变-矿化流体演化过程,在已厘定的朱砂红矿床脉体类型基础之上,选取了不同蚀变阶段的蚀变矿物,进行了系统的H_O同位素测试。研究发现:早期A脉[无矿团块状石英脉(A1脉)、石英-钾长石脉(A3脉)]石英中包裹体δ18O值介于+6.0‰~+11.2‰,δD值介于-90‰~-101‰之间,在δ18O-δD图解中,A脉样品的H_O值组成整体位于去气作用后的残余岩浆水范围,表明引起早期钾硅酸盐化的流体性质为一套高温、高盐度岩浆热液;绿帘石-石英脉(B1脉)的δ18O值和δD值(+6.6‰和-101‰)显示青磐岩化蚀变形成与高温岩浆流体相分离后的低密度气相流体有关;而斑岩中的石英-黄铁矿-黄铜矿(B3脉)形成时,流体δ18O值(+4.1‰~+6.0‰)开始朝雨水线方向发生轻微的氧漂移,表明开始有少量大气降水的加入;晚期D脉形成时的成矿流体δ18O值(+2.8‰~+4.9‰)具有明显朝雨水线发生漂移的趋势,表明引起石英-绢云母化及泥化蚀变的成矿热液为岩浆热液和大气降水的混合流体。总之,朱砂红矿床钾硅酸盐化、青磐岩化蚀变,以及该蚀变阶段形成的A脉和早期B脉,均由岩浆热液作用引起,大气降水在钾硅酸盐化向长石分解蚀变转变的阶段开始进入蚀变-矿化系统,而长石分解蚀变为大气降水与岩浆热液共同作用的产物。  相似文献   

5.
西秦岭温泉斑岩钼矿床岩浆-热液演化   总被引:5,自引:3,他引:2  
邱昆峰  宋开瑞  宋耀辉 《岩石学报》2015,31(11):3391-3404
西秦岭北缘广泛出露印支期中酸性侵入岩和相关的斑岩-矽卡岩矿床。温泉矿床位于该矿带东段,是其内已探明规模最大的斑岩钼矿床。温泉矿床发育多阶段热液脉体,黄铁矿作为其中的贯通性金属硫化物,其化学组成蕴含着岩浆-热液演化及金属沉淀过程等诸多信息,对于斑岩系统模型的厘定具有重要意义。温泉矿床热液脉体时序为:钾长石-黑云母-石英脉(A脉)、石英-黄铜矿脉、石英-辉钼矿脉(B脉)和石英-绢云母-黄铁矿脉(D脉)。A脉是斑岩系统岩浆-热液演化的最早期脉体,主要矿物组合为钾长石+黑云母+石英+黄铁矿±磁铁矿±磷灰石±黄铜矿,代表了引起早期基性岩浆矿物被蚀变为黑云母的流体通道;B脉与钾长石化蚀变关系密切,围岩中斜长石斑晶大量被蚀变为钾长石;石英-辉钼矿脉切割所有早期黑云母化-钾化蚀变阶段的石英-硫化物网脉,并形成于所有斑岩侵位之后,少量黄铁矿和黄铜矿共生于辉钼矿裂隙及边部;D脉是斑岩系统岩浆-热液成矿作用的最晚期事件,其主要被黄铁矿和石英及少量黄铜矿填充,发育晚期的绢英岩化和泥化蚀变,长石多发生破坏性蚀变。四个阶段石英网脉中黄铁矿电子探针分析显示,A脉的黄铁矿中Cu、Mo和Au含量均较低,有少量的金属硫化物(黄铁矿+黄铜矿)沉淀,但通常不能形成规模矿体;石英-黄铜矿脉的黄铁矿中Cu含量明显较高,且多与高品位Cu矿体的空间产出位置相一致,可能是斑岩系统伴随钾化蚀变作用主要的铜沉淀阶段;B脉的黄铁矿中Mo含量明显较高,与高品位钼矿体空间产出关系密切,可能代表了斑岩系统钼成矿作用的主要阶段;D脉的黄铁矿中Au含量明显升高,可能代表了金在斑岩系统岩浆-热液成矿作用的最晚期事件中的沉淀。  相似文献   

6.
随着同位素测试技术的发展,高温下重同位素分馏逐渐运用到地球化学领域.为了探索岩浆演化过程中是否会发生Cu同位素分馏,文章对西藏驱龙斑岩铜矿床同来源、不同演化阶段的两套岩浆岩(闪长岩包体和花岗闪长岩)进行了Cu同位素测试.测试结果显示,闪长岩包体的δ65Cu值集中在+0.08‰-+0.35‰之间,平均值为+0.25‰,花岗闪长岩的δ65Cu值为+0.42‰~+0.87‰,平均值为+0.60‰.△65Cu花岗闪长岩-闪长岩包体≈+0.4‰,并且δ65Cu值与样品w(SiO)变化存在一定的正相关性.结合地质学及同位素方面考虑,花岗闪长岩和闪长岩包体的Cu同位素组成差异可能是岩浆演化过程中发生了Cu同位素分馏所致.在驱龙矿区中新世岩浆演化过程中,随着岩浆去气作用,63Cu随HS-、Cl-等挥发分优先进入气相,导致残留岩浆熔体相对富集65Cu.此外,两者的Cu同位素组成差异也可能与岩浆演化过程中斜长石、角闪石、黑云母等矿物的不断结晶分离有关,矿物结晶分离时,基性矿物富集63Cu,而残余熔体则富集65Cu.  相似文献   

7.
胡文峰  张烨恺  刘金华  郭亮  周炼 《地球科学》2019,44(6):1923-1934
选取西藏冈底斯成矿带的驱龙、达布斑岩型铜钼矿及鸡公村石英脉型钼矿为研究对象, 分别挑选含矿斑岩和石英脉中的黄铜矿、辉钼矿进行Cu、Mo同位素测定.结果表明, 西藏冈底斯斑岩型黄铜矿的δ65/63Cu介于0.01‰~0.98‰, 辉钼矿的δ97/95Mo介于-0.34‰~-0.15‰, 热液脉型矿床中辉钼矿的δ97/95Mo介于-0.35‰~-0.23‰.形成于陆-陆碰撞造山后的冈底斯斑岩型铜钼矿床的Cu同位素与俯冲带产出的斑岩型矿床中的Cu同位素组成具有一定的相似性, 均表现为单峰分布的特征.驱龙斑岩型矿床中热液脉与含矿斑岩中的δ65/63Cu具有一致性, 可能反映了二者在来源上具有一致性.在冈底斯斑岩型铜钼矿床中, 不同蚀变带具有不同的Cu、Mo同位素组成, 自蚀变中心向外, δ65/63Cu与δ97/95Mo表现出负相关趋势, 可能与成矿流体的性质密切相关.冈底斯石英脉型钼矿较斑岩型铜钼矿δ97/95Mo相对偏负, 结合两类矿床的成矿年代, 可能暗示两类矿床的成矿物质是同一源区连续演化的结果.   相似文献   

8.
西藏甲玛铜多金属矿硫同位素地球化学研究   总被引:1,自引:0,他引:1  
西藏墨竹工卡县甲玛铜多金属矿床位于冈底斯成矿带东段,Cu、Mo、Pb+Zn、Au、Ag均达大型规模,并伴生Co、Bi、W、Ni等多金属矿化。黄铜矿、斑铜矿、辉钼矿、方铅矿、闪锌矿、黝铜矿、辉铜矿等硫化物为主要的矿石矿物,硫酸盐矿物以硬石膏为主,含矿岩浆岩以花岗斑岩、二长花岗斑岩和花岗闪长斑岩为主。通过对甲玛矿区主要硫化物和硬石膏的硫同位素分析,并结合前人研究,甲玛矿区硫化物的硫同位素δ34S值变化于13.6‰~+12.5‰,平均值1.33‰(样品数86)、硬石膏δ34S值+0.5‰~+1.8‰,平均值+1.13‰(样品数3)、岩浆岩δ34S值0.7‰~0.2‰,平均值0.5‰(样品数3),与岩浆硫δ34S值0±3‰一致。闪锌矿-方铅矿-黄铜矿矿物对的硫同位素地质温度计,显示成矿温度为408~433℃,说明其形成时硫同位素处于平衡状态。冈底斯成矿带上的驱龙等斑岩型矿床中硫化物和岩浆岩硫同位素,均具有δ34S值变化范围小,平均值接近0值,与岩浆硫特征一致的特点,反映了甲玛铜多金属矿床具有矽卡岩-斑岩型矿床硫同位素地球化学特征,硫以岩浆来源为主。  相似文献   

9.
宁镇地区成矿斑岩与铁镁质包体铜同位素研究   总被引:1,自引:0,他引:1  
长江中下游地区成矿斑岩的成因及铜矿中铜的来源一直受到争议。寻找斑岩铜矿中铜的来源归根结底是限定其寄主岩的成因。本文拟通过测定宁镇地区一系列中生代岩体的成矿斑岩及其铁镁质包体的Cu同位素组成,来探究成矿斑岩中Cu的来源。测定结果显示,安基山闪长斑岩δ65Cu值为-0.13‰~+0.36‰;其辉长岩包体δ65Cu的值为+0.14‰~+0.19‰。铜山成矿斑岩δ65Cu值为+0.03‰~+0.36‰;其辉长岩包体δ65Cu的值为+0.10‰~+0.20‰。象山花岗闪长岩δ65Cu为+0.20‰±0.06‰;其辉长岩包体δ65Cu为+0.16‰±0.06‰。三个岩体成矿斑岩δ65Cu值为-0.13‰~+0.36‰,变化范围较大;而辉长岩包体δ65Cu值均在+0.1‰~+0.2‰之间,平均δ65Cu为+0.15‰±0.05‰,与地幔δ65Cu值(+0.07‰±0.10‰)吻合。结合前人对研究区成矿斑岩高Mg O、Mg#值,低放射性成因Pb同位素组成,以及古老下地壳来源的岩石具有较大的Cu同位素组成变化的认识,我们认为宁镇地区成矿斑岩及成矿物质主要为幔源岩浆和古老下地壳部分熔融岩浆混合成因。  相似文献   

10.
雪鸡坪斑岩铜矿位于西南三江构造火成岩带义敦岛弧带,其成矿斑岩为印支期石英闪长玢岩和石英二长斑岩。研究对该矿区安山岩、矿化斑岩和矿石矿物系统进行S,Pb同位素分析结果表明:金属硫化物的δ34S值为-3.1‰~ 0.7‰,平均值为-1.1‰,与矿化斑岩的硫同位素组成(-1.4‰和-1.5‰)一致,均落入幔源硫范围,表明硫主要来自岩浆;δ34S黄铁矿(-1.8‰~ 0.7‰,平均-0.5‰)>δ34S黄铜矿(-2.2‰~0.0‰,平均-1.2‰)>δ34S方铅矿(-3.1‰~-1.3‰,平均-2.4‰),硫同位素分馏基本达到平衡。矿石矿物(208Pb/204Pb=37.917~38.230,平均值38.075;207Pb/204Pb=15.528~15.614,平均值15.571;206Pb/204Pb=17.929~18.082,平均值17.981)与矿化斑岩(208Pb/204Pb=37.832、37.883,207Pb/204Pb=15.529、15.538,206Pb/204Pb=17.906、17.910)以及安山岩(208Pb/204Pb=37.816~37.884,207Pb/204Pb=15.549~15.562,206Pb/204Pb=17.845~17.919)的初始铅组成基本一致,变化范围较小,表明三者具有相同的来源;在铅构造模式图上,所有样品铅同位素均位于造山带演化线上或附近,在铅同位素源区判别图中,均落入造山带和下地壳区域,这表明Pb主要来源于壳幔混合。雪鸡坪铜矿S,Pb同位素组成共同指示成矿物质主要来自于深部岩浆,这种岩浆可能主要起源于俯冲洋壳板片的部分熔融并受到少量地壳物质的混染。  相似文献   

11.
The study presents copper (Cu) isotope data of mineral separates of chalcopyrite from four drill core samples in the Miocene Dabu porphyry Cu-Mo deposit formed in a post-collisional setting in the Gangdese porphyry copper belt, southern Tibet. Copper isotope values in hypogene chalcopyrite range from –1.48‰ to +1.12‰, displaying a large variation of up to 2.60‰, which demonstrates Cu isotope fractionation at high-temperature during hydrothermal evolution. The majority of measured chalcopyrite isotopic compositions show a gradual increasing trend from –1.48‰ to +1.12‰ with the increase of drilling depth from 130m to 483m, as the alteration assemblages change from potassic to phyllic. Similarly, the other δ65Cu values (δ65Cu = ((65Cu/63Cu)sample/(65Cu/63Cu)standard  1) × 1000) of the chalcopyrite show a gradual increasing trend from −1.48‰ to +0.59‰ with the decrease of drilling depth from 130 m to 57 m, as the alteration assemblages change from potassic, phyllic, through argillic to relatively fresh. These observations suggest a genetic link between Cu isotope variation and silicate alteration assemblages formed at different temperatures, indicative of a Rayleigh precipitation process resulting in the large variation of δ65Cu values at Dabu. In general, samples closest to the center of hydrothermal system dominated by high-temperature potassic alteration are isotopically lighter, whereas samples dominated by low-temperature phyllic alteration peripheral to the center are isotopically heavier. The predicted flow pathways of hydrothermal fluids are from No. 0 to No. 3 exploration line, and the lightest δ65Cu values are the most proximal to the hydrothermal source. Finally, we propose that the northwest side of the No. 0 exploration line has high potential for hosting undiscovered orebodies. The pattern of Cu isotope variation in conjunction with the features of silicate alteration in porphyry system can be used to trace the hydrothermal flow direction and to guide mineral exploration.  相似文献   

12.
目前冈底斯成矿带报道的斑岩型矿床主要集中在东段,而鲁尔玛斑岩型铜(金)矿为冈底斯成矿带西段新发现的铜矿,具有钾硅酸盐化、绢英岩化、青磐岩等明显的斑岩型矿床蚀变特征.其热液脉体从早到晚化分为:钾硅酸盐化脉(A脉)、石英-金属硫化物脉(B脉)以及石英-绿帘石-碳酸盐化脉(D脉).对各阶段热液脉体的的流体包裹体进行了岩相学、显微测温、显微激光拉曼和H-O-C同位素等分析.发现A脉石英中流体包裹体的形成温度集中在390~460℃,盐度介于4.5%~21.6% NaCleqv和43.6%~59.6% NaCleqv两个区间;B脉石英中流体包裹体的形成温度集中在310~380℃,盐度介于3.6%~19.8% NaCleqv和6.0%~16.0% NaCleqv两个区间;D脉石英和方解石中流体包裹体的形成温度集中在200~320℃,盐度集中在0.4%~14.7% NaCleqv.拉曼分析表明,鲁尔玛铜(金)矿的流体包裹体含CO2、N2、CH4等气体及石盐子晶和多种金属硫化物和金属氧化物子晶.各热液脉体石英中流体包裹体的δDH2O,V-SMOW值的变化范围为-128‰~-110‰,δ18OH2O,V-SMOW值的变化范围为-9.09‰~-1.45‰,方解石的δ13CCal,V-PDB值的变化范围为-20.8‰~-19.8‰,δ18OCal,V-SMOW值的变化范围为-5.9‰~-4.9‰,展现出岩浆热液的特征,晚期还有大气降水的加入.研究结果显示,成矿流体属高温、高盐度、含CO2、N2、CH4等气体和Cu、Fe、Mo等金属元素的Ca+-Na+-Cl-H2O体系流体,具有典型的斑岩型铜矿床成矿流体的特征.成矿流体从深部封闭体系运移到浅部的开放体系,温压环境突变导致金属硫化物沉淀,形成A脉和B脉型矿化.随着成矿物质的大量析出,同时伴随着大气降水等因素的影响,流体温度、盐度迅速降低,产生D脉型矿化.   相似文献   

13.
Transition metal isotopes are sensitive geochemical tracers of ore genesis. Here we present MC-ICP-MS analytical data of Cu isotope compositions from the Hongshan-Hongniu Cu deposit in Yunnan province. The δ65Cu values (δ65Cu = [(65Cu/63Cu)sample/(65Cu/63Cu)NIST976  1] × 1000) of seven whole-rock quartz monzonite porphyries and twenty-two chalcopyrite samples from the skarn ore-bodies display relatively narrow ranges from −0.15‰ to 0.38‰ and from −0.02‰ to 0.77‰, respectively. The overlap of δ65Cu values indicates a genetic relationship between the quartz monzonite porphyry and skarn ore-bodies. We also evaluate the spatial and temporal variations of Cu isotope compositions in the skarn ore-bodies by comparison with some well-documented porphyry deposits in the world. The quartz monzonite porphyry shows compositional zoning with the inner domain enriched in heavy Cu isotope and the skarn related to the porphyry depleted in heavy Cu isotope. The chalcopyrites that formed during the late stage of mineralization tend to be enriched in heavy Cu isotope, and this feature is analogous to porphyry deposits. The δ65Cu values of the quartz monzonite porphyry show typical features of hypogene mineralization, suggesting a potential scope for deep exploration and development in this deposit.  相似文献   

14.
内蒙古霍各乞铜多金属矿床的含矿建造及矿床成因分析   总被引:8,自引:4,他引:8  
内蒙古霍各乞矿床是狼山地区著名的大型铜多金属矿床,含矿建造层序依次为中元古界陆缘裂谷拉斑玄武岩系→矿化热水沉积岩系→陆源碎屑岩系。拉斑玄武岩及基性侵入岩大部分变质为绿泥石片岩,但局部残留基性火山岩和辉长岩类变余结构构造,局部达到斜长角闪岩相,且w(Na2O)>w(K2O)。变余辉长岩的稀土总量较低,且轻、重稀土基本没有分异,黑云绿泥片岩的稀土总量较高,其配分曲线呈轻稀土富集、重稀土亏损型。黑云绿泥片岩中B、F、K、Ti、Zn、Rb、Sn、Nb、Ag、Ba、Pb、U相对富集,Cu、Pb、Zn富集系数高于变余辉长岩,表明绿泥石片岩具有热液蚀变的特征。含矿岩段条带状石英岩、透辉透闪石岩的稀土总量偏低,轻、重稀土有明显分异,并表现为特征的正Eu异常。除矿化富集外,微量元素Be、B、F、Rb、Ag、Ba、Th、U也有明显富集,表现了热水富集成因的特征。矿床矿化受岩性层控制的特征明显,并且在一定的构造部位富集,具有热液叠加改造的特征。硫同位素变化范围大,多表现为正值,硫化物δ34S值的大小排序为黄铁矿>磁黄铁矿>黄铜矿>方铅矿、闪锌矿。矿床成因分析表明霍各乞多金属矿床为热水沉积块状硫化物矿化叠加变质热液改造富集而形成的矿床。  相似文献   

15.
The Tonglushan Cu–Fe deposit (1.12 Mt at 1.61% Cu, 5.68 Mt at 41% Fe) is located in the westernmost district of the Middle–Lower Yangtze River metallogenic belt. As a typical polymetal skarn metallogenic region, it consists of 13 skarn orebodies, mainly hosted in the contact zone between the Tonglushan quartz-diorite pluton (140 Ma) and Lower Triassic marine carbonate rocks of the Daye Formation. Four stages of mineralization and alterations can be identified: i.e. prograde skarn formation, retrograde hydrothermal alteration, quartz-sulphide followed by carbonate vein formation. Electron microprobe analysis (EMPA) indicates garnets vary from grossular (Ad20.2–41.6Gr49.7–74.1) to pure andradite (Ad47.4–70.7Gr23.9–45.9) in composition, and pyroxenes are represented by diopsides. Fluid inclusions identify three major types of fluids involved during formation of the deposit within the H2O–NaCl system, i.e. liquid-rich inclusions (Type I), halite-bearing inclusions (Type II), and vapour-rich inclusions (Type III). Measurements of fluid inclusions reveal that the prograde skarn minerals formed at high temperatures (>550°C) in equilibrium with high-saline fluids (>66.57 wt.% NaCl equivalent). Oxygen and hydrogen stable isotopes of fluid inclusions from garnets and pyroxenes indicate that ore-formation fluids are mainly of magmatic-hydrothermal origin (δ18O = 6.68‰ to 9.67‰, δD = –67‰ to –92‰), whereas some meteoric water was incorporated into fluids of the retrograde alteration stage judging from compositions of epidote (δ18O = 2.26‰ to 3.74‰, δD= –31‰ to –73‰). Continuing depressurization and cooling to 405–567°C may have resulted in both a decrease in salinity (to 48.43–55.36 wt.% NaCl equivalent) and the deposition of abundant magnetite. During the quartz-sulphide stage, boiling produced sulphide assemblage precipitated from primary magmatic-hydrothermal fluids (δ18O = 4.98‰, δD = –66‰, δ34S values of sulphides: 0.71–3.8‰) with an extensive range of salinities (4.96–50.75 wt.% NaCl equivalent), temperatures (240–350°C), and pressures (11.6–22.2 MPa). Carbonate veins formed at relatively low temperatures (174–284°C) from fluids of low salinity (1.57–4.03 wt.% NaCl equivalent), possibly reflecting the mixing of early magmatic fluids with abundant meteoric water. Boiling and fluid mixing played important roles for Cu precipitation in the Tonglushan deposit.  相似文献   

16.
The Tiegelongnan Cu (Au) deposit is the largest copper deposit newly discovered in the Bangong–Nujiang metallogenic belt. The deposit has a clear alteration zoning consisting of, from core to margin, potassic to propylitic, superimposed by phyllic and advanced argillic alteration. The shallow part of the deposit consists of a high sulphidation‐state overprint, mainly comprising disseminated pyrite and Cu–S minerals such as bornite, covellite, digenite, and enargite. At depth porphyry‐type mineralization mainly comprises disseminated chalcopyrite, bornite, pyrite, and a minor vein molybdenite. Mineralization is disseminated and associated with veins contained within the porphyry intrusions and their surrounding rocks. The zircon U–Pb ages of the mineralized diorite porphyry and granodiorite porphyry are 123.1 ± 1.7 Ma (2σ) and 121.5 ± 1.5 Ma (2σ), respectively. The molybdenite Re–Os age is 121.2 ± 1.2 Ma, suggesting that mineralization was closely associated with magmatism. Andesite lava (zircon U–Pb age of 111.7 ± 1.6 Ma, 2σ) overlies the ore‐bodies and is the product of post‐mineralization volcanic activity that played a critical role in preserving the ore‐bodies. Values of ?4.6 ‰ to + 0.8 ‰ δ34S for the metal sulfides (mean ? 1.55 ‰) suggest that S mainly has a deep magmatic source. The H and O isotopic composition is (δD = ?87 ‰ to ?64 ‰; δ18OH2O = 5.5 ‰ to 9.0 ‰), indicating that the ore‐forming fluids are mostly magmatic‐hydrothermal, possibly mixed with a small amount of meteoric water. The zircon εHf(t) of the diorite porphyry is 3.7 to 8.3, and the granodiorite porphyry is 1.8 to 7.5. Molybdenite has a high Re from 382.2 × 10?6 to 1600 × 10?6. Re and Hf isotope composition show that Tiegelongnan has some mantle source, maybe the juvenile lower crust from crust–mantle mixed source. Metallogenesis of the Tiegelongnan giant porphyry system was associated with intermediate to acidic magma in the Early Cretaceous (~120 Ma). The magma provenance of the Tiegelongnan deposit has some mantle‐derived composition, possibly mixed with the crust‐derived materials.  相似文献   

17.
卢琦园  郑义  王成明  王岳军 《地球科学》2018,43(9):3141-3153
新疆乌拉斯沟铜矿床位于阿尔泰造山带南缘克兰盆地内,为近年来新发现的矿床,受NW向断裂控制的脉状矿体产于泥盆系康布铁堡组变质火山岩系中,目前其成矿流体和成矿物质来源尚不明确.在细致的矿床地质研究基础上,通过开展S-Pb-Sr-Nd-C-H-O同位素分析,根据野外和显微镜下观察,可将乌拉斯沟铜矿床的形成划分为黄铁矿-磁铁矿-石英、黄铜矿-绿泥石-绿帘石-石英及石英-碳酸盐阶段.同位素分析结果显示:乌拉斯沟铜矿硫化物样品δ34S值为0.1‰~3.2‰,平均为1.6‰,落入未矿化围岩δ34S值范围(-4.7‰~18.68‰),矿石硫可能源自康布铁堡组.成矿晚阶段的方解石样品δ13CV-PDB‰=-1.1‰,δ18OV-PDB‰=-20.3‰,海相碳酸盐地层和有机碳是可能的碳质来源.8件黄铁矿的Pb同位素为206Pb/204Pb=17.939~18.508(平均18.255),207Pb/204Pb=15.519~15.674(平均15.578),208Pb/204Pb=37.881~38.653(平均38.209),与康布铁堡组围岩类似.初始ISr(220 Ma)为0.710 4~0.711 7,平均值为0.711 1,初始143Nd/144Nd值为0.512 002~0.512 240(平均0.512 103).矿石Sr-Nd-Pb同位素组成均指示乌拉斯沟铜矿成矿物质可能主要源自围岩康布铁堡组,并可能有外来成矿物质的加入.流体的δDV-SMOW变化于-103.8‰~-92‰(平均值为-99.2‰),石英和方解石矿物的δ18OV-SMOW值集中在9.4‰~11.5‰(平均值为10.4‰),δ18OH2O值为2.1‰~4.2‰(平均值为3.1‰),结合流体包裹体物理化学特征,成矿热液可能来源于变质水,但可能受到大气降水的影响而偏移.因此,乌拉斯沟铜矿成矿物质主要来源于赋矿围岩的变质脱挥发分作用,这与造山型矿床的成矿机制吻合.   相似文献   

18.
The Dexing deposit is located in a NE‐trending magmatic belt along the southeastern margin of the Yangtze Craton. It is the largest porphyry copper deposit in China, consisting of three porphyry copper orebodies of Zhushahong, Tongchang and Fujiawu from northwest to southeast. It contains 1168 Mt of ores with 0.5% Cu and 0.01% Mo. The Dexing deposit is hosted by Middle Jurassic granodiorite porphyries and pelitic schist of Proterozoic age. The Tongchang granodiorite porphyry has a medium K cal‐alkaline series, with medium K2O content (1.94–2.07 wt%), and low K2O/(Na2O + K2O) (0.33–0.84) ratios. They have high large‐ion lithophile elements, high light rare‐earth elements, and low high‐field‐strength elements. The hydrothermal alteration at Tongchang is divided into four alteration mineral assemblages and related vein systems. They are early K‐feldspar alteration and A vein; transitional (chlorite + illite) alteration and B vein; late phyllic (quartz + muscovite) alteration and D vein; and latest carbonate, sulfate and oxide alteration and hematite veins. Primary fluid inclusions in quartz from phyllic alteration assemblage include liquid‐rich (type 1), vapor‐rich (type 2) and halite‐bearing ones (type 3). These provide trapping pressures of 20–400 ´ 105 Pa of fluids responsible for the formation of D veins. Igneous biotite from least altered granochiorite porphyry and hydrothermal muscovite in mineralized granodiorite porphyry possess δ18O and δD values of 4.6‰ and ?87‰ for biotite and 7.1–8.9‰, ?71 to ?73‰ for muscovite. Stable isotopic composition of the hydrothermal water suggests a magmatic origin. The carbon and oxygen isotope for hydrothermal calcite are ?4.8 to ?6.2‰ and 6.8–18.8‰, respectively. The δ34S of pyrite in quartz vein ranges from ?0.1 to 3‰, whereas δ34S for chalcopyrite in calcite veins ranges from 4 to 5‰. These are similar to the results of previous studies, and suggest a magmatic origin for sulfur. Results from alteration assemblages and vein system observation, as well as geochemical, fluid inclusion, stable isotope studies indicate that the involvement of hydrothermal fluids exsolved from a crystallizing melt are responsible for the formation of Tongchang porphyry Cu‐Mo orebodies in Dexing porphyry deposit.  相似文献   

19.
松辽盆地庆深气田异常氢同位素组成成因研究   总被引:2,自引:0,他引:2  
对松辽盆地徐家围子断陷庆深气田天然气组分、碳氢同位素和稀有气体同位素的分析表明,天然气以烷烃气为主,烷烃气碳同位素组成随着碳数增加呈变轻趋势,且δ13C1>-30‰, R/Ra一般大于1.0,δ13CCO2值介于-16.5‰~-5.1‰之间;氢同位素组成δD1=-205‰~-197‰,平均值为-203‰,δD2=-247‰~-160‰,平均值为-195‰,δD3=-237‰~-126‰,平均值为-163‰,且存在氢同位素组成倒转现象,即δD1>δD2<δD3。根据对庆深气田天然气不同地球化学特征分析,认为该气田烷烃气中重烃主要为有机成因,而 CH4有相当无机成因混入。庆深气田烷烃气氢同位素组成具有 CH4变化小,而重烃(δD2,δD3)变化大的特点。根据与朝阳沟地区天然气烷烃气氢同位素组成对比分析,认为 CH4主要表现为无机成因,而重烃气(δD2,δD3)主要为有机成因,且无机成因CH4氢同位素组成重于有机成因CH4。  相似文献   

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