西藏扎西康锌多金属矿床地质特征及银的赋存状态研究   总被引：3，自引：1，他引：2  

林彬  唐菊兴  郑文宝  冷秋锋  王艺云  刘敏院  杨欢欢  丁帅  张立华  杨红章 《矿床地质》2013,32(5):899-914

扎西康锌多金属矿床位于西藏特提斯喜马拉雅板片的"金锑多金属"成矿带东段。研究显示,矿体主要呈脉状、透镜状产于近南北向的张性断裂中。热液成矿作用主要可划分为早、晚2个成矿阶段,7个成矿亚阶段,早期以铅锌矿化为主,晚期以锑(铅)矿化为主。岩矿石镜下鉴定和电子探针分析表明,扎西康矿床矿石种类繁多,矿物组合和成矿元素均呈现明显的分带现象,由深至浅(W→E)为含锡(铁)闪锌矿+铁锰碳酸盐+少量方铅矿+少量黄铜矿(深部)→(铁)闪锌矿+铁锰碳酸盐+少量方铅矿+黄铁矿+毒砂+少量银黝铜矿+少量石英(中深部)→方铅矿+闪锌矿+脆硫锑铅矿+铁锰碳酸盐+硫锑铅矿+少量银黝铜矿+石英(中部)→辉锑矿+方铅矿+少量闪锌矿+石英+少量铁锰碳酸盐(浅部),对应的元素分带为Zn(Pb+Ag+Cu+Sn)→Zn(Pb+Ag)→Zn+Pb(Sb+Ag)→Pb+Sb+Ag+Zn。矿区银矿化主要集中在Ⅴ号矿体ZK2703-ZK2302、ZK1502-ZK1105和ZK806三个区域,与铅锑矿化关系密切。矿石中银主要以类质同象的形式存在,独立银矿物相对较少。其中,类质同象银主要赋存在方铅矿中,少量赋存在硫锑铅矿、脆硫锑铅矿、毒砂、黄铁矿等金属硫化物中;独立银矿物有少量的银黝铜矿、硫锑铅银矿、银(含银)硫铜锑矿。成矿流体中铅、锌、锑、银的运移和富集沉淀是受体系中温度、压力、浓度、pH值等多种因素综合控制的结果。  相似文献   

Evaporites,brines and base metals: Low‐temperature ore emplacement controlled by evaporite diagenesis     

J. K. Warren 《Australian Journal of Earth Sciences》2013,60(2):179-208

Salt beds and salt allochthons are transient features in most sedimentary basins, which through their dissolution can carry, focus and fix base metals. The mineralisation can be subsalt, intrasalt or suprasalt, and the salt body or its breccia can be bedded or halokinetic. In all these evaporite‐associated low‐temperature diagenetic ore deposits there are four common factors that can be used to recognise suitably prepared ground for mineralisation: (i) a dissolving evaporite bed acts either as a supplier of chloride‐rich basinal brines capable of leaching metals, or as a supplier of sulfur and organics that can fix metals; (ii) where the dissolving bed is acting as a supplier of chloride‐rich brines, there is a suitable nearby source of metals that can be leached by these basinal brines (redbeds, thick shales, volcaniclastics, basalts); (iii) there is a stable redox interface where these metalliferous chloride‐rich waters mix with anoxic waters within a pore‐fluid environment that is rich in organics and sulfate/sulfide/H₂S; and (iv) there is a salt‐induced focusing mechanism that allows for a stable, long‐term maintenance of the redox front, e.g. the underbelly of the salt bed or allochthon (subsalt deposits), dissolution or halokinetically maintained fault activity in the overburden (suprasalt deposits), or a stratabound intrabed evaporite dissolution front (intrasalt deposits). The diagenetic evaporite ‐ base‐metal association includes world‐class Cu deposits, such as the Kupferschiefer‐style Lubin deposits of Poland and the large accumulations in the Dzhezkazgan region of Kazakhstan. The Lubin deposits are subsalt and occur where long‐term dissolution of salt, in conjunction with upwelling metalliferous basin brines, created a stable redox front, now indicated by the facies of the Rote Faule. The Dzhezkazgan deposits (as well as smaller scale Lisbon Valley style deposits) are suprasalt halokinetic features and formed where a dissolving halite‐dominated salt dome maintained a structural focus to a regional redox interface. Halokinesis and dissolution of the salt bed also drove the subsalt circulation system whereby metalliferous saline brines convectively leached underlying sediments. In both scenarios, the resulting redox‐precipitated sulfides are zoned and arranged in the order Cu, Pb, Zn as one moves away from the zone of salt‐solution supplied brines. This redox zonation can be used as a regional pointer to both mineralisation and, more academically, to the position of a former salt bed. In the fault‐fed suprasalt accumulations the feeder faults were typically created and maintained by the jiggling of brittle overburden blocks atop a moving and dissolving salt unit. A similar mechanism localises many of the caprock replacement haloes seen in the diapiric provinces of the Gulf of Mexico and Northern Africa. Evaporite‐associated Pb–Zn deposits, like Cu deposits, are focused by brine flows associated with both bedded and halokinetic salt units or their residues. Stratabound deposits, such as Gays River and Cadjebut, have formed immediately adjacent to or within the bedded salt body, with the bedded sulfate acting as a sulfur source. In allochthon/diapir deposits the Pb–Zn mineralisation can occur both within a caprock or adjacent to the salt structure as replacements of peridiapiric organic‐rich pyritic sediments. In the latter case the conditions of bottom anoxia that allowed the preservation of pyrite were created by the presence of brine springs and seeps fed from the dissolution of nearby salt sheets and diapirs. The deposits in the peridiapiric group tend to be widespread, but individual deposits tend to be relatively small and many are subeconomic. However, their occurrence indicates an active metal‐cycling mechanism in the basin. Given the right association of salt allochthon, tectonics, source substrate and brine ponding, the system can form much less common but world‐class deposits where base‐metal sulfides replaced pyritic laminites at burial depths ranging from centimetres to kilometres. This set of diagenetic brine‐focusing mechanisms are active today beneath the floor of the Atlantis II Deep and are thought to have their ancient counterparts in some Proterozoic sedex deposits. The position of the allochthon, its lateral continuity, and the type of sediment it overlies controls the size of the accumulation and whether it is Cu or Pb–Zn dominated.  相似文献   

根际环境锌镉镍的形态变化与植物有效性   总被引：1，自引：1，他引：1  

孙丽娜李玉双  李昕馨孙铁珩 《岩矿测试》2007,26(4):257-263

以抚顺西露天采场60平盘5种修复植物根际与非根际土为研究对象，运用顺序提取实验和数理统计分析方法研究了根际与非根际土中Zn、Cd、Ni的形态分布与植物有效性。结果表明，Zn、Ni在根际与非根际土中主要以硫化物态存在；而Cd在非根际土中以硫化物态为主，在根际土中以可交换态和松、紧有机态为主。与Ni相比，非根际土中Zn的紧有机态、氧化物态和Cd的紧有机态、氧化物态、可交换态比例明显偏大；与非根际土相比，根际土中Zn的铁锰氧化物态和硫化物态含量增加，碳酸盐态含量降低，松有机态、紧有机态和可交换态Zn在不同植物根际变化不同。Cd的硫化物态降低，可交换态、松有机态、碳酸盐态、氧化物态和紧有机态含量在不同植物根际变化不同。Ni的紧有机态显著增加，可交换态、碳酸盐态和硫化物态明显降低，松有机态在不同植物根际变化不同；根际Cd的碳酸盐态增加和氧化物态降低有利于植物Cd的吸收；碳酸盐态Zn的减少可促进植物Zn的增高。  相似文献   

铜精矿中铅锌的连续测定   总被引：2，自引：0，他引：2  

王建琴  王劲榕 《岩矿测试》2000,19(4):295-297

利用铜铁试剂分离Ｃｕ、Ｆｅ等干扰元素,同时铜铁试剂与Ｐｂ和Ｚｎ产生络合物吸附波,可连续测定铜精矿中的Ｐｂ和Ｚｎ。体系中铅峰在－０．５４Ｖ,锌峰在－０．９９Ｖ,线性范围Ｐｂ为８０～１６００μｇ／ＬＺｎ为１２０～１２００μｇ／Ｌ,检出限Ｐｂ为４０μｇ／Ｌ,Ｚｎ为８０μｇ／Ｌ,测定结果与参考值相符,ＲＳＤ（ｎ＝３）Ｐｂ（ｎ＝３）Ｐｂ〈６％,Ｚｎ〈１０％。  相似文献   

富镉锌矿成矿流体地球化学研究:以贵州都匀牛角塘富镉锌矿为例   总被引：15，自引：1，他引：14  

叶霖  刘铁庚  邵树勋 《地球化学》2000,29(6):597-603

通过对贵州都匀牛角塘富镉锌矿包裹体的研究,发现有一定数量的有机包裹体。该矿床与密西西比河谷型（ＭＶＴ）矿床相似,均属于Ｎａ＾＋－Ｃａ＾２＋－Ｋ＾＋－Ｍｇ＾２＋－Ｃｌ＾－体系,同时,两者在成矿流体温度、盐度和密度方面也有一定差别。该矿床成矿流体组分与油田卤水相似,仅Ｃａ＾２＋和Ｍｇ＾２＋含量偏高,这可能与晚阶段的碳酸盐有关。笔者认为,成矿流体可能与麻江古油藏的油田卤水有关,正是由于油田卤水携带了Ｃｄ  相似文献   

Zinc speciation in the Northeastern Atlantic Ocean     

Michael J. Ellwood  Constant M. G. Van den Berg 《Marine Chemistry》2000,68(4)

Measurements of zinc and zinc complexation by natural organic ligands in the northeastern part of the Atlantic Ocean were made using cathodic stripping voltammetry with ligand competition. Total zinc concentrations ranged from 0.3 nM in surface waters to 2 nM at 2000 m for open-ocean waters, whilst nearer the English coast, zinc concentrations reached 1.5 nM in the upper water column. In open-ocean waters zinc speciation was dominated by complexation to a natural organic ligand with conditional stability constant (log K_ZnL′) ranging between 10.0 and 10.5 and with ligand concentrations ranging between 0.4 and 2.5 nM. The ligand was found to be uniformly distributed throughout the water column even though zinc concentrations increased with depth. Organic ligand concentrations measured in this study are similar to those published for the North Pacific. However the log K_ZnL′ values for the North Atlantic are almost and order of magnitude lower than those reported by Bruland [Bruland, K.W., 1989. Complexation of zinc by natural organic-ligands in the central North Pacific. Limnol. Oceanogr., 34, 269–285.] using anodic stripping voltammetry for the North Pacific. Free zinc ion concentrations were low in open-ocean waters (6–20 pM) but are not low enough to limit growth of a typical oceanic species of phytoplankton.  相似文献   

锡铁山铅锌矿床的找矿潜力与找矿方向   总被引：3，自引：1，他引：2  

祝新友  邓吉牛  王京彬  林龙军  樊俊昌 《地质与勘探》2006,42(3):18-23

锡铁山大型铅锌矿床发育有完整的海相喷流沉积系统,包括喷流管道相、近喷口相和沉积相.其中,网脉状蚀变角砾岩带长＞2km、宽＞200m,代表喷流管通相;容矿大理岩长＞3km,宽＞1km,最大厚度＞200m,分布于网脉状蚀变岩的外侧,为喷流沉积岩;穿插于厚层块状大理岩中的非层状铅锌矿体是未喷出海底的含矿热液充填、交代的产物,条带状结构的层状铅锌矿体属喷流沉积相.锡铁山矿床喷流管道系统规模巨大,其大规模的物质供给系统为国内外现已发现的SEDEX铅锌矿床中罕见.现已揭露的锡铁山矿床主体属于喷流沉积系统的中心和近喷口相部分,锡铁山地区还存在巨大规模的层状铅锌矿体(床)尚待发现,同时,在矿床东南方向深部的侧伏延深部位,还具有一定规模的赋存于厚层大理岩中的非层状铅锌矿体.这些大规模层状铅锌矿体的找矿标志层可能不再是大理岩,主要围岩可能是富含炭质、钙质的沉积岩,如深灰-灰黑色的含炭方解石片岩、炭质片岩、方解石绢云片岩等.锡铁山东南部地区的滩涧山群相应赋存层位是大规模层状铅锌矿的主攻找矿方向.  相似文献   

Interaction of trace metals with natural particle surfaces: Comparison between adsorption experiments and field measurements     

Beat Müller  Laura Sigg 《Aquatic Sciences - Research Across Boundaries》1990,52(1):75-92

The distribution of the metal ions Zn and Pb between particulate and dissolved phase in river Glatt was studied by field measurements and compared with calculated simulations, using parameters obtained by adsorption experiments with natural suspended particulate material. Differences in distribution coefficients obtained from field data are observed in function of the sampling locations and of the composition of the particulate matter.Experiments in which metal ion solutions are titrated with a suspension of natural particles and analyzed by anodic stripping voltammetry, are interpreted in terms of binding capacities and conditional stability constants of Zn and Pb with the surface sites. Binding constants of a particular metal ion varied very little for all samples. We obtained mean values for the conditional average complex formation constants at pH 8 of: log^cond K _Pb = 9.44 ± 0.18 and log^cond K _Zn = 8.17 ± 0.20. At this pH, binding capacities of 5 10^–3 – 1.7 10^–2 mol/kg of particles were obtained for samples collected at different locations and times; organic material, iron and manganese oxides are considered to be the main components that control the adsorption to the particles.Distribution coefficients are calculated from the experimentally obtained binding capacities and conditional stability constants. Calculated distribution coefficients for Zn agree with those obtained from the field data and are not very sensitive to changes in the composition of the solution. Good agreement was obtained for lead as well; for some samples it was important to take two types of sites with different affinity into consideration.  相似文献   

Reactive flow models of the Anarraaq Zn–Pb–Ag deposit,Red Dog district,Alaska     

Christian Schardt  Grant Garven  Karen D. Kelley  David L. Leach 《Mineralium Deposita》2008,43(7):735-757

The Red Dog ore deposit district in the Brooks Range of northern Alaska is host to several high-grade, shale-hosted Zn + Pb deposits. Due to the complex history and deformation of these ore deposits, the geological and hydrological conditions at the time of formation are poorly understood. Using geological observations and fluid inclusion data as constraints, numerical heat and fluid flow simulations of the Anarraaq ore deposit environment and coupled reactive flow simulations of a section of the ore body were conducted to gain more insight into the conditions of ore body formation. Results suggest that the ore body and associated base metal zonation may have formed by the mixing of oxidized, saline, metal-bearing hydrothermal fluids (<200°C) with reducing, HS-rich pore fluids within radiolarite-rich host rocks. Sphalerite and galena concentrations and base metal sulfide distribution are primarily controlled by the nature of the pore fluids, i.e., the extent and duration of the HS⁻ source. Forward modeling results also predict the distribution of pyrite and quartz in agreement with field observations and indicate a reaction front moving from the initial mixing interface into the radiolarite rocks. Heuristic mass calculations suggest that ore grades and base metal accumulation comparable to those found in the field (18% Zn, 5% Pb) are predicted to be reached after about 0.3 My for initial conditions (30 ppm Zn, 3 ppm Pb; 20% deposition efficiency).  相似文献   

Post-mine metal transport and attenuation in the Keno Hill mining district, central Yukon, Canada   总被引：6，自引：0，他引：6  

Y. T. J. Kwong  C. F. Roots  P. Roach  W. Kettley 《Environmental Geology》1997,30(1-2):98-107

 The Keno Hill mining district in central Yukon was the second largest silver producer in Canada with mines operating from 1913 to 1989 on more than 65 vein silver deposits. The seven and a half decades of mining activities have generated large volumes of mine waste disposed on the land surface, resulting in elevated metal contents in numerous small drainages. To assess the extent of metal mobilization, old mine workings and the associated mine waste were examined and the water courses draining to a major river valley sampled. The results of field observations and an array of water and sediment analyses led to three major conclusions. 1. Acid mine drainage is not widespread because of galvanic protection of pyrite from oxidative dissolution and neutralization by carbonates in the country rock. 2. Mechanisms operative to limit aqueous metal transport in small streams in the district include cryogenic precipitation, coprecipitation and sorption. 3. The near-surface concentration of metals limits the options of waste disposal in future mining developments due to potential metal-leaching problems. Received: 12 December 1995 · Accepted: 26 March 1996  相似文献