西藏北部舍索与拉屋铜矿床硫化物铅同位素特征

本文在系统的野外地质工作基础上,对舍索与拉屋矿床的矿石硫化物铅同位素组成进行综合分析,进而示踪其成矿物质来源。结果显示,舍索矿区矿石硫化物铅的206Pb/204Pb值为18.517~18.776,207Pb/204Pb值为15.671~15.756,208Pb/204Pb值为38.955~39.33;拉屋矿区矿石硫化物铅的206Pb/204Pb值为18.651~18.757,207Pb/204Pb值为15.707~15.823,208Pb/204Pb值为39.183~39.561。研究表明,舍索与拉屋矿床矿石硫化物铅同位素含量比值具有明显的上地壳特征,指示两个矿床成矿物质主要来自上地壳。其中舍索矿床成矿物质富集受燕山期岩浆作用影响,而拉屋矿床部分成矿物质由晚石炭纪地幔物质的喷流沉积作用提供。     

河南栾川脉状铅锌矿床Pb同位素地球化学特征

针对分布于豫西南栾川地区的脉状铅锌矿床,进行铅锌矿、地层和岩浆岩的铅同位素数据对比分析研究显示:该区铅锌矿床的铅同位素组成(赤土店矿床206Pb/204Pb=17.005～17.953,207Pb/204Pb=15.414～15.587,208Pb/204Pb=37.948～39.036;冷水北沟矿床206Pb/204Pb=17.602～17.954,207Pb/204Pb=15.458～15.606,208Pb/204Pb=38.208～38.772;百炉沟矿床206Pb/204Pb=17.552～18.426,207Pb/204Pb=15.451～15.5794,208Pb/204Pb=38.264～39.637)与区内燕山期斑岩和地层的铅同位素组成(燕山期斑岩206Pb/204Pb=17.189～17.894,207Pb/204Pb=15.381～15.569,208Pb/204Pb=37.655～39.01;元古界岩石206Pb/204Pb=17.694～19.249,207Pb/204Pb=15.467～15.585,208Pb/204Pb=38.303～41.104)有一定的相似和差别。铅同位素特征值(μ值、ω值)、Δβ-Δγ、206Pb/204Pb-207Pb/204Pb、Δα-Δβ-Δγ等分析研究,揭示铅锌矿床铅与燕山期斑岩和地层铅的来源关系,综合研究,认为栾川地区脉状铅锌床为与燕山中期斑岩侵入有关的岩浆热液充填-交代型矿床,成矿物质存在燕山期岩浆和围岩地层两种来源。     

安徽青阳峙门口层状硫铁矿矿床地质特征及成因研究

青阳峙门口层状硫铁矿矿床赋存于石炭纪地层中,矿体主要呈似层状、透镜状;尽管经历了热变质与接触变质作用,但矿体中仍残留胶黄铁矿和菱铁矿,矿石中不仅可以见到交代残余结构,还可见到草莓结构和微层理构造.黄铁矿中砷的质量分数和S/Se,Co/Ni比值显示火山热水沉积特征.同位素分析显示,矿石中硫化物的硫同位素组成表现出火山热水沉积和热液改造特征;矿石中铅同位素组成则显示,黄铁矿中铅以上地壳铅为主,混有少量地幔铅.上述研究表明峙门口层状硫铁矿矿床是由石炭纪喷流沉积形成的层状矿床或矿胚层,经燕山期岩浆热液和构造作用改造所形成.     

滇东南白牛厂多金属矿床铅同位素组成及铅来源新认识

白牛厂矿床位于滇东南锡多金属成矿带中部,是一个Ag、Pb、Zn、Sn等共生的多金属矿床,但成因争议较大.前人引用早期矿床矿石矿物铅同位素数据得出矿石铅主要来源于基底岩石淋滤,矿床经历了热水沉积+岩浆热液叠加两个成矿阶段的结论.本文采用最新铅同位素数据系统研究了白牛厂矿床的铅同位素组成,其中,白牛厂矿床矿石矿物的铅同位素组成206Pb/204Pb、207Pb/204Pb和208Pb/204Pb分别为17.264～18.537、14.843～15.862和38.481～39.424;薄竹山花岗岩长石铅同位素组成206Pb/204Pb、207Pb/204Pb和208Pb/204Pb分别为18.301～18.387、15.611～15.670和38.677～38.904;薄竹山岩体接触带型矿床(点)矿石矿物铅同位素组成206Pb/204Pb、207Pb/204Pb和208Pb/204Pb分别为18.302～18.417、15.603～15.692和38.596～38.868;区域地层及矿区地层钻孔样品铅同位素组成206Pb/204Pb、207Pb/204Pb和208Pb/204Pb分别为18.307～19.206、15.622～15.809和38.436～39.932.对比四者铅同位素组成特征,白牛厂矿床矿石矿物、薄竹山花岗岩长石、薄竹山岩体接触带型矿床(点)矿石矿物具有一致的铅同位素组成,与地层铅同位素组成相差甚远,表明白牛厂矿床铅主要来自岩浆作用,在侵入的过程中可能受到了地层的轻度混染.矿床地质特征及近期地球化学和年代学研究成果表明,白牛厂矿床的形成主要受岩浆作用影响,沉积成矿作用在白牛厂矿床很可能是不存在的.     

浙江淳安银山银铅锌多金属矿床硫铅同位素地球化学特征

银山银铅锌多金属矿是近几年来在该区域发现的中型以上的银铅锌多金属矿床,为地层-构造-岩浆综合控制型矿床。运用矿区的黄铁矿矿石S、Pb同位素示踪的方法探讨了矿床成矿物质来源。矿区黄铁矿和方铅矿的硫同位素组成δ34S值为-1.5‰~27.9‰,且硫同位素分布直方图中显示3种来源特征,指示成矿物质来源可能为海水、地层或岩浆。Pb同位素组成μ(~(238)U/~(204)Pb)值特征、Zartman构造模式、Δγ-Δβ成因分类研究表明,矿区矿石铅为幔-壳混源,指示物源主要来自于中生代岩浆热液,而非海底热液沉积物。综合表明银山银铅锌多金属矿床是中生代岩浆热液型矿床。     

大兴安岭南段白音查干Sn多金属矿床成因：矿床地质特征及Sr-Nd、S、Pb同位素证据

白音查干矿床是大兴安岭南段新发现的一处大型Sn多金属矿床。为查明该矿床Sn成矿作用与Ag-Pb-Zn成矿作用的关系,本文开展了矿床地质、萤石和石英斑岩Sr-Nd同位素、硫化物S-Pb同位素和原位S同位素地球化学特征研究。SrNd同位素分析结果显示,所有萤石样品均具有相近的(~(87)Sr/~(86) Sr)_i、(~(143)Nd/~(144)Nd)_i和ε_(Nd)(t)值范围,而且与石英斑岩的Sr-Nd同位素组成基本一致,说明矿床各成矿阶段的萤石具有相同的成因,与石英斑岩岩浆作用关系密切。单矿物和原位S同位素数据显示,Ⅰ区Ag-Pb-Zn矿石中的硫化物δ~(34)S值范围(-13.9‰～-4.8‰)与Ⅲ Sn矿石硫化物的δ~(34)S值范围(-12.5‰～-5.3‰)基本一致;而且,Ⅰ区闪锌矿原位δ~(34)S值变化范围较小且较为均一(-12.4‰～-7.3‰,平均为-9.2‰),与石英斑岩"Zn-F-B集合体"中闪锌矿原位δ~(34)S值变化范围(-10.6‰～-9.0‰,平均为-9.7‰)基本一致,说明S可能主要来源于石英斑岩岩浆。Pb同位素特征显示,Ⅰ区Ag-Pb-Zn矿石中的硫化物Pb同位素组成(~(206) Pb/~(204) Pb=18.177～18.200、~(207)Pb/~(204)Pb=15.519～15.531、~(208) Pb/~(204)Pb=37.985～38.053)与石英斑岩Pb同位素组成(~(206)Pb/~(204)Pb=18.206～18.235、~(207)Pb/~(204)Pb=15.529～15.530、~(208)Pb/~(204)Pb=38.025～38.036)基本一致,说明Ag-Pb-Zn成矿作用的Pb可能主要来源于石英斑岩岩浆。结合矿床地质特征、Sr-Nd、S、Pb同位素数据可知,白音查干矿床Sn成矿作用与Ag-Pb-Zn成矿作用具有密切的成因联系,矿床成矿流体和成矿物质可能主要来源于石英斑岩岩浆。     

锡铁山SEDEX铅锌矿床成矿物质来源研究——铅同位素地球化学证据

青海锡铁山超大型铅锌矿床产于柴达木盆地北缘早古生代造山带中,发育一套完整的喷流沉积系统,包括管道相、近喷口相与远喷口相以及喷流沉积岩等。对不同对象中硫化物系统的铅同位素测定研究表明,锡铁山矿床铅同位素组成总体较集中,可细分为两组,均呈线性分布:大部分的样品,包括非层状矿、网脉状石英钠长岩、代表供给系统的脉体、基性岩等,以及绝大部分的层状矿体,组成一组,线性回归方程为(207Pb/204Pb)=1.254(206Pb/204Pb)-7.296,相关系数0.997。分布于铅锌矿体及大理岩上盘的含浸染状黄铁矿化的炭质片岩、一个层状矿体样品组成一组,线性回归方程为(207Pb/204Pb)=0.123(206Pb/204Pb)+13.347,相关系数0.902。两条直线交点的同位素组成为206Pb/204Pb=18.253,207Pb/204Pb=15.590,208Pb/204Pb=38.370。结合成矿模型的研究认为,矿床的铅同位素具有造山带与上地壳混合来源的特点,显示喷流成矿过程中铅及成矿金属物质主要由喷流卤水提供,少量物质来自海水;在喷流系统的远端或喷流活动的间歇期,前寒武纪变质岩也可能提供了少量物质。而层状矿体与非层状矿体经历了相同的演化历史,均形成于喷流沉积过程中,非层状矿体属未喷出海底的热液矿体,而不是后期改造的结果。断层沟地区的矿化是后期改造重新定位的,铅同位素组成在改造过程中得到进一步的均一化。     

安徽峙门口铜—铁—金—硫矿床地球化学特征

峙门口铜—铁—金—硫矿床发育上部层状矿体和下部脉状矿体。上部层状矿石重晶石的δ~(34)S值为+14.10‰～+18.90‰。上部层状矿石黄铁矿和方铅矿的δ~(34)S值为+3.50‰～+5.84‰,下部脉状矿石黄铁矿的δ~(34)S值为+4.80‰～+6.80‰。下部脉状矿石中脉石英的δ~(18)O值为+14.3‰～+1 8.5‰,δ~(30)Si值为-0.3%0～-0.2‰。下部脉状矿石黄铁矿Re/Os比值为78.342～175.540,上(顶)部层状矿石中黄铁矿Re/Os比值为62.298～169.545。从下部脉状矿石到上部层状矿石,δ~(34)S值、Re/Os比值和流体包裹体温度249 ℃→97 ℃逐渐降低,~(206)Pb/~(204)Pb、~(207)Pb/~(204)Pb、~(208)Pb/~(204)Pb平均值和Os_总、Re、~(187)Re等含量逐渐增高。矿石黄铁矿Re-Os同位素等时线年龄303±33 Ma。地质地球化学特征反映峙门口铜—铁—金—硫矿床为海底热水喷流沉积成因。     

安徽水竹岭铜-铁-金-硫矿床同位素地球化学特征

水竹岭铜-铁-金-硫矿床发育上部层状矿体和下部脉状矿体。上部层状矿石重晶石δ34S值为+19.9‰。上部层状矿石黄铁矿δ34S值为+0.9～+5.8‰,下部脉状矿石黄铁矿δ34S值为+3.2～+6.4‰。下部脉状矿体中方解石的δ18O值为+13.3‰,δ13C值为1.2‰,上部层状矿石白云石的δ18O值为+14.1‰,δ13C值为2.2‰。下部脉状矿石和矿化岩石中黄铁矿的206Pb/204Pb、207Pb/204Pb、208Pb/204Pb平均值分别为18.2241、15.5245和38.2289;上部层状矿石中黄铁矿的206Pb/204Pb、207Pb/204Pb、208Pb/204Pb平均值分别为18.0692、15.5020和38.1232。从下部脉状矿石到上部层状矿石,黄铁矿的δ34S值、206Pb/204Pb、207Pb/204Pb、208Pb/204Pb平均值逐渐降低,δ18O值和δ13C值等逐渐增高。地质和同位素地球化学特征反映水竹岭铜-铁-金-硫矿床为海底热水喷流沉积成因,揭示了块状硫化物矿床的二元结构性。     

青海德令哈蓄集银铅矿床地质与S-Pb同位素组成及其成矿学意义

蓄集矿床是宗务隆构造带内发现的重要银铅矿床。蓄集银铅矿床赋存于石炭-二叠系宗务隆群果可山组灰岩夹千枚岩地层中,矿体呈脉状、透镜状、似层状,明显受近东西走向的断裂构造控制,矿体围岩蚀变主要为硅化和绢云母化,矿石矿物主要为方铅矿和银黝铜矿,脉石矿物主要为石英,矿石具有斑杂状和网脉状构造。对该矿床开展了S-Pb同位素组成分析。硫同位素分析结果表明矿石中硫化物矿物δ~(34)S值变化于5.0‰～8.4‰之间,显示硫主要为岩浆来源,有少量地层的贡献;铅同位素分析结果表明,矿石~(206)Pb/~(204) Pb=17.896～17.922,~(207)Pb/~(204) Pb=15.589～15.617,~(208) Pb/~(204) Pb=38.072～38.166,与围岩铅同位素组成(~(206) Pb/~(204) Pb=17.94～18.976,~(207)Pb/~(204) Pb=15.600～15.696,~(208) Pb/~(204) Pb=38.106～40.943)较为相似,而与蓄集峡口闪长岩铅同位素组成(~(206) Pb/~(204) Pb=18.144～18.589,~(207)Pb/~(204) Pb=15.623～15.636,~(208)Pb/~(204) Pb=38.790～39.033)相差较大,反映成矿物质主要来自围岩地层宗务隆群果可山组。综合分析认为,蓄集银铅矿床与宗务隆构造带晚二叠世岩浆活动关系密切,应属岩浆热液为主的热液充填-交代成因类型。     

Lead isotopes of the carbonate-hosted Kabwe, Tsumeb, and Kipushi Pb-Zn-Cu sulphide deposits in relation to Pan African orogenesis in the Damaran-Lufilian Fold Belt of Central Africa

Lead isotope ratios of galena from the carbonate-hosted massive sulphide deposits of Kabwe (Pb-Zn) and Tsumeb (Pb-Zn-Cu) in Zambia and Namibia, respectively, have been measured and found to be homogeneous and characteristic of upper crustal source rocks. Kabwe galena has average isotope ratios of ^206/204Pb = 17.997 ± 0.007, ^207/204Pb = 15.713 ± 0.010 and ^208/204Pb = 38.410 ± 0.033. Tsumeb galena has slightly higher ^206/204Pb (18.112 ± 0.035) and slightly lower ^207/204Pb (15.674 ± 0.016) and ^208/204Pb (38.276 ± 0.073) ratios than Kabwe galena. The isotopic differences are attributed to local differences in the age and composition of the respective source rocks for Kabwe and Tsumeb. The homogeneity of the ore lead in the two epigenetic deposits suggests lead sources of uniform isotopic composition or, alternatively, thorough mixing of lead derived from sources with relatively similar isotopic compositions. Both deposits have relatively high ²³⁸U/²⁰⁴Pb ratios of 10.31 and 10.09 for Kabwe and Tsumeb galenas, respectively. These isotope ratios are considered to be typical of the upper continental crust in the Damaran-Lufilian orogenic belt, as also indicated by basement rocks and Cu-Co sulphides in stratiform Katangan metasediments which have a mean μ-value of 10.25 ± 0.12 in the Copperbelt region of Zambia and the Democratic Republic of Congo (formerly Zaire). The ²³²Th/²⁰⁴Pb isotope ratios of 43.08 and 40.42 for Kabwe and Tsumeb suggest Th-enriched source regions with ²³²Th/²³⁵U (κ-values) of 4.18 and 4.01, respectively. Model isotopic ages determined for the Kabwe (680 Ma) and Tsumeb (530 Ma) deposits indicate that the timing of the mineralisation was probably related to phases of orogenic activity associated with the Pan-African Lufilian and Damaran orogenies, respectively. Galena from the carbonate-hosted Kipushi Cu-Pb-Zn massive sulphide deposit in the Congo also has homogeneous lead isotope ratios, but its isotopic composition is comparable to that of the average global lead evolution curve for conformable massive sulphide deposits. The μ (9.84) and κ (3.69) values indicate a significant mantle component, and the isotopic age of the Kipushi deposit (456 Ma) suggests that the emplacement of the mineralisation was related to a post-tectonic phase of igneous activity in the Lufilian belt. The isotope ratios (^206/204Pb, ^207/204Pb, ^208/204Pb) of the three deposits are markedly different from the heterogeneous lead ratios of the Katangan Cu-Co stratiform mineralisation of the Copperbelt as well as those of the volcanogenic Nampundwe massive pyrite deposit in the Zambezi belt which typically define radiogenic linear trends on lead-lead plots. The host-rock dolomite of the Kabwe deposit also has homogeneous lead isotope ratios identical to the ore galena. This observation indicates contamination of the Kabwe Dolomite Formation with ore lead during mineralisation. Received: 8 September 1997 / Accepted: 21 August 1998     

黔西北筲箕湾铅锌矿床成矿物质来源:Pb同位素证据

筲箕湾铅锌矿床位于扬子地块西南缘川滇黔相邻铅锌矿集区黔西北铅锌成矿区垭都―蟒硐断裂带,是贵州省有色金属及核工业地质勘探局近年发现的中型矿床。对该矿床原生矿体中主要矿石矿物黄铁矿、方铅矿和闪锌矿进行了Pb同位素组成分析,结果表明矿床Pb同位素组成变化不大,其中206Pb/204Pb、207Pb/204Pb和208 Pb/204 Pb的分布范围分别在18.616～18.686、15.682～15.728和39.067～39.181之间,在206 Pb/204 Pb-207 Pb/204 Pb和206 Pb/204 Pb-208 Pb/204 Pb图中,样品投影在上地壳铅平均演化线附近的狭小区域和区域基底岩石的Pb同位素组成范围之内,靠近不同时代碳酸盐地层以及川滇黔相邻矿集区滇东北成矿区会泽超大型铅锌矿床和黔西北成矿区天桥铅锌矿床,与震旦纪灯影组白云岩和峨眉山玄武岩分布范围存在明显差异。推测矿床成矿物质来源以基底岩石为主,区域上不同时代碳酸盐地层可能提供了部分成矿物质。     

Differences in lead isotope composition in the stratiform McArthur zinc-lead-silver deposit

Lead isotopic composition and uranium and lead concentrations have been determined for galena, sphalerite, pyrite and acetic acid soluble material from the McArthur area in order to test the hypothesis of a dual sulphur source suggested by the sulphur isotope data of Smith and Croxford (Sulphur isotope ratios in the McArthur lead-zinc-silver deposit, Nature Phys. Sci. 245, 10–12 (1973)). Galena, sphalerite and the acetic acid washes from the McArthur deposit have uniform isotopic ratios (²⁰⁶Pb/²⁰⁴Pb, 16.07–16.15; ²⁰⁷Pb/²⁰⁴Pb, 15.37–15.47; ²⁰⁸Pb/²⁰⁴Pb, 35.57–35.89) consistent with other conformable ore deposits, whereas the ratios for pyrite are variable and quite radiogenic (²⁰⁶Pb/²⁰⁴Pb, 16.24–16.49; ²⁰⁷Pb/²⁰⁴Pb, 15.42–15.58; ²⁰⁸Pb/²⁰⁴Pb, 35.82–36.98). Acid washes where dolomite is a major dissolved phase are also radiogenic. The lead in the pyrite appears to have been derived from at least two sources: the less radiogenic lead coming from an exhalative source as for galena and sphalerite and the more radiogenic lead probably being leached from the country rocks. It is proposed that analysis of pyrite for isotopic composition and concentration of lead could be used as an indicator for similar types of deposits in this area.     

黑龙江省东宁县五道沟金矿成矿流体特征及矿床成因

五道沟金矿位于太平岭金-铜多金属成矿带,矿体呈脉状赋存于下二叠统双桥子组碳质板岩中,并严格受NE向断裂控制。根据野外观察和岩相学研究,将五道沟金矿成矿划分为早期石英阶段、石英-黄铁矿阶段、石英-碳酸盐阶段3个阶段,其中石英-黄铁矿阶段为主要成矿阶段。石英流体包裹体显微测温和拉曼光谱分析表明,金成矿期流体为中低温、低盐度的含CO₂流体。氢氧同位素分析表明,成矿流体是岩浆水和大气降水的混合流体。黄铁矿微量元素特征表明矿区内黄铁矿为岩浆热液成因;矿石硫同位素数据显示其具有岩浆硫和地层硫的混合特征。铅同位素组成图上,矿石铅、围岩铅和岩浆岩铅三者呈线性关系,具有同源特征,矿石中²⁰⁷Pb/²⁰⁴Pb和²⁰⁸Pb/²⁰⁴Pb值明显高于围岩的相应值,暗示了矿石铅为围岩铅淋滤产物。矿石同位素特征表明双桥子组碳质板岩应为金矿矿源层。综合矿床地质特征、流体包裹体和H-O-S-Pb同位素分析,认为五道沟金矿为造山型金矿。     

http://www.sciencedirect.com/science/article/pii/S1674987113000790

The Heilangou gold deposit is located in the northern QixiaePenglai gold belt, which is one amongst the three large gold belts in the eastern Shandong Province （Jiaodong Peninsula）. The ore body has formed within the Guojialing granite. In this study, we report the mineral chemistry of pyrite, as well as the S, Pb, and HeO isotope data of the Heilangou gold deposit. The chemical composition of pyrite in the Heilangou gold deposit indicates that the associated gold deposit is a typical magmatic hydrothermal one. The geochemical signatures and crystal structure of pyrite show that the ore-forming materials have been derived from the crust. The S isotope data of the pyrites from Heilangou show an overall range from 5.5 to 7.8＆amp;and an average of 6.7＆amp;. The S isotope data in this deposit are similar to those from the deposits in the Jiaodong gold belt. The Pb and S isotope variations are small in the Heilangou gold deposit. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios are 17.4653e17.5958, 15.5105e15.5746 and 38.0749e38.4361, respec-tively. These data plot between the lower crust and the orogenic belt. The Pb isotope data in the Heilangou gold deposit are similar to those in the Linglong gold deposit. From the Qixia gold area （the Liukou and Majiayao gold deposits） to the MupingeRushan gold belt （Rushan gold deposit） to the ZhaoeYe gold belt （the Linglong, Sanshandao and Jiaojia gold deposits）, the 206Pb/204Pb ratios progressively increase. The DeO isotope data obtained from quartz separates suggest that the ore-forming fluid was similar to a mixture of magmatic and meteoric waters. These results suggest that the ore-forming elements were primarily from source fluids derived from the lower crust.     

云南富宁者桑金矿床硫铅同位素地球化学特征与成矿物质来源

者桑金矿床赋存于上二叠统吴家坪组沉积碎屑岩中,矿体受构造破碎带控制,呈似层状、透镜状产出,是滇东南金成矿带上一个典型的卡林型金矿床。硫铅同位素地球化学研究显示,沉积黄铁矿和热液硫化物(黄铁矿和毒砂)的δ34S值均为正值,变化范围较窄(8.4‰～11.3‰),与二叠纪沉积时期海水硫酸盐δ34S值一致,具有地层硫的特征。矿石中的硫主要通过地层中有机质与海水硫酸盐的热还原作用(TSR)提供。铅同位素组成中,206Pb/204Pb变化范围较宽,207Pb/204Pb和208 Pb/204 Pb较为稳定,计算获得的模式年龄变化范围大(-62～389Ma),甚至出现"负年龄",表明除正常铅外,还有较多的放射性成因铅的混入。铅主要来自于上地壳,有少量岩浆物质的混入。矿石与围岩的硫铅同位素具有一定的继承性,成矿物质主要来自地层。     

Pb同位素对努日铜钼钨多金属矿床成矿物源的制约

西藏努日铜钼钨矿是冈底斯成矿带规模最大的首例含白钨矿多金属矿床，对于矿床的成矿物质来源还存在较大的争议.为厘定努日铜钼钨矿的成矿物质来源，对矿区的侵入岩和各类硫化物进行了Pb同位素研究，研究结果表明，矿区各类辉钼矿、黄铁矿具有较为一致的Pb同位素组成:206Pb/204Pb比值为17.525~18.581；207Pb/204Pb比值为15.621~15.661；208Pb/204Pb比值为37.524~38.929.黄铜矿的206Pb/204Pb比值为18.414~18.578；207Pb/204Pb比值为15.619~15.642；208Pb/204Pb比值为38.617~38.863，且黄铜矿存在明显的分组特征.S-Pb同位素特征表明:努日铜钼钨矿的成矿物质主要来源于地幔，矿床的辉钼矿Re-Os同位素特征也暗示其成矿物质主要来源于地幔.该矿床可能是在印度板块向欧亚板块俯冲-碰撞-伸展构造环境下，印度陆块下地壳部分熔融形成的熔体在其向上运移过程中与俯冲洋壳释放出的富含Fe3+的流体发生混合后，与雅鲁藏布江MORB亏损地幔橄榄岩发生交代作用，Fe3+氧化地幔中赋存的各类硫化物后，使得成矿物质Cu、Mo等被释放进入岩浆系统；并在上升过程中萃取了部分加厚下地壳部分熔融形成黑云母花岗岩中的Cu等，最终在浅部与围岩发生接触交代形成努日铜钼钨多金属矿床.      

浙江安吉港口多金属矿床铅物质来源初探——铅同位素证据

位于浙西北安吉港口的铅锌银(钼)多金属矿床,是新近在钦杭成矿带东北缘发现的一个产于大陆环境且具较好前景的矿床.文章通过对矿区坞山关杂岩体三套岩性单元、细粒花岗岩和方铅矿铅同位素的全面对比研究,探讨了矿床的铅物源岩浆岩.矿区中的方铅矿为含较高放射性成因铅的J-型铅,在铅同位素的V1-V2和△γ-Δβ图解中,本次研究的样品分别落入华南和岩浆作用上地壳混合地幔铅范围,显示出方铅矿与华南地球化学省壳幔混合岩浆作用的密切关系.矿区铅锌矿体的方铅矿铅同位素比值显示其具有共同的物质来源,并基本保持了细粒花岗岩206Pb/204Pb值的特征,而207Pb/204Pb值具有坞山关杂岩体和细粒花岗岩混合的特征,208Pb/204Pb和208Pb/206Pb值则仅显示出与细粒花岗岩最相近.方铅矿铅同位素比值特征和比值等值线分布形式显示,铅主要来源于细粒花岗岩,杂岩体对铅成矿贡献了少量的206Pb和207Pb,矿区地层对铅成矿贡献了一定的208Pb.安吉矿区进一步针对铅的找矿工作围绕细粒花岗岩展开,取得成果的可能性更大.     

西藏浦桑果铜铅锌多金属矿床S、Pb同位素组成及对成矿物质来源的示踪

西藏浦桑果铜铅锌多金属矿床位于南冈底斯成矿带火山岩浆弧内,矿区矽卡岩型铜铅锌矿体主要呈透镜状和似层状近东西向赋存于白垩系塔克那组第四岩性段矽卡岩化大理岩中。基于野外地质调查和成矿地质条件,对矿床主要金属硫化物闪锌矿、方铅矿、黄铜矿等的S、Pb同位素特征进行研究,并结合前人数据,综合探讨矿床的成矿物质来源。结果表明,浦桑果矿床矿石金属硫化物的δ34S值介于-24‰~10‰之间,平均值为-040‰,硫同位素频率直方图具明显的塔式分布特征,指示硫可能与岩浆作用有关,硫同位素具岩浆硫特征,主要与闪长玢岩有关。矿石硫化物中206Pb/204Pb变化于18344~18625之间,平均值为18555; 207Pb/204Pb变化于15549~15794之间,平均值为15716; 208Pb/204Pb变化于3812~3934之间,平均值为39044;矿石铅同位素组成稳定,为正常普通铅。结合铅同位素μ值特征(937～982)及铅同位素构造环境演化图投图结果,综合表明浦桑果矿床的矿石铅主要来源于上地壳物质且伴有地幔物质的混染,铅同位素具壳幔混源的特征。     

He-Ar-S-Pb Isotopic Compositions of Pyrite: Constraints on the Source of Ore-forming Materials of the Chengchao Skarn Iron Deposit, SE Hubei Province, Eastern China

The Chengchao iron deposit,the largest high-grade skarn iron deposit in southeastern Hubei Province,contains considerable amounts of magnetite and by-product anhydrite.To obtain better understanding of the ore-formation process,this study carried out He-Ar-S-Pb multi-isotopic analyses on the pyrites formed during two stages of mineralization.The results indicate that the δ~(34)S values(ranging from 14.0‰ to 17.6‰) of pyrites formed from the two stages have no obvious differences,suggesting that they were not derived from a single magmatic sulfur source.The δ~(34)S values of anhydrite mostly range from 21.9‰ to 28.4‰,similar to that of the Middle Triassic sedimentary anhydrite in the Middle-Lower Yangtze River metallogenic belt(MLYRB).The Pb isotopic compositions of the pyrites of both stages are homogeneous,with values of ~(208)Pb/~(204)Pb,~(207)Pb/~(204)Pb,and~(206)Pb/~(204)Pb being 38.006-38.257,15.523-15.556,and 17.806-18.052,respectively,indicating a mixed crust-mantle source.The He-Ar results exhibit different compositions of the two stages:the ~3He/~4He(R/Ra) and ~(40)Ar/~(36)Ar values for the early-stage pyrite are 0.46-0.63 and 311-322,respectively,whereas the values for late-stage pyrite are 0.23-0.34 and 305-361,respectively.Both stages of pyrites indicate the multiple sources of the ore-forming fluids,with decreasing amount of magmatic water and increasing amount of modified meteoric water(MASW) during fluid evolution.The Triassic evaporites played an important role in the mineralization process.