Hydrogeochemical exploration for Mississippi valley-type deposits, Arkansas, U.S.A.

Three areas located in northern Arkansas, U.S.A., representing differing host rock and mineralization, were selected to investigate the usefulness of hydrogeochemical exploration for Mississippi Valley-type Pb-Zn mineralization. Despite the geologic differences among the areas, there were no great differences in groundwater chemistry and threshold values. Anomalous Pb concentrations, and also anomalous Zn concentrations to a lesser extent, are useful in detecting the Pb-Zn mineralized areas; however, specific deposits could not be located. Because of the low threshold values (about 20 μg/1) for Pb and Zn, spring water must be utilized in order to avoid plumbing contamination.     

川滇黔地区MVT铅锌矿床分布、特征及成因

位于扬子地台西南缘的川滇黔铅锌多金属成矿区是中国重要的铅、锌、银、锗生产基地,目前在该成矿区已经发现大、中、小型铅锌矿床和矿点400多处。经过对比研究,这些矿床的赋矿围岩为震旦系一二叠系碳酸盐岩,矿体明显受控于断裂构造,并伴随有强烈的白云岩化和方解石化,以低温、低盐度为特征,成矿时代可能为中生代,成矿物质主要来自地层本身。它们为受热对流循环流体经过成矿物质萃取、搬运和卸载而成矿,是大陆边缘造山带东侧伸展带中的产物,属于比较典型的密西西比河谷型铅锌矿床。     

超大型矿床成矿背景-过程-勘查三位一体的找矿理念

超大型矿床是某一(或某些)矿种资源的巨大储库.据统计,全球矿产资源70％～85％的勘探储量集中分布于占全球矿床数10％的超大型矿床.由此可见发现超大型矿床对一个国家经济与社会发展的极端重要性.超大型矿床成矿背景是其形成的基础,成矿过程是其成矿的关键,勘查评价是其发现的根本途径.文章试图从成矿背景、成矿过程与勘查评价相互...     

密西西比河谷型(MVT)铅锌矿床:认识与进展

MVT铅锌矿床作为一种重要的沉积型铅锌矿床类型一直受到人们的重视,近年来取得了许多重要进展,主要体现在6个方面:①MVT铅锌矿床研究范围逐渐扩大,在全世界发现了诸多相关矿床,多归为其亚类;②提出该类矿床主要分布在造山带的前陆盆地、逆冲推覆带等构造挤压环境,少数产于陆内伸展环境,改变了MVT矿床与板块构造无关的观点;③放射性同位素测年和古地磁测年技术广泛应用,获得了大量成矿年龄数据,表明MVT矿床主要形成在显生宙石炭纪—早三叠纪和白垩纪—第三纪两个时期,与地球演化史上全球尺度的板块会聚时间密切相关;④流体包裹体研究揭示了成矿流体温度主要为90~150℃,盐度w(NaCleq)为10%~30%,成矿流体具有盆地卤水特征,卤水源自近地表蒸发海水或围岩蒸发盐,同位素资料反映Pb来自地壳岩石,S来自地壳岩石或沉积物中残留的硫酸盐。成矿流体驱动机制包括构造挤压和重力驱动两种;⑤古地磁和生物化学标志物判定,单期热液活动可能持续几千到几万年,而整个矿床形成可能持续几个到十几个百万年;⑥矿质沉淀机制主要有3种:流体混合、硫酸盐还原和还原硫机制,不同成矿环境可能受不同机制控制。     

滇西维西-普洱成矿带之与碳酸盐岩有关铅锌矿床的矿化特征

文章通过对维西-普洱成矿带中主要铅锌矿床的特征进归纳对比,从控矿因素、物质来源、矿化特征、含矿层位等方面探寻成矿规律。结合矿带的地质特征,重点讨论了矿带的成矿地质条件,提出以研究矿带的区域构造以及碳酸盐岩的分布等为思路来指导找矿。     

Fluid inclusions in hydrothermal ore deposits

The principal aim of this paper is to consider some of the special problems involved in the study of fluid inclusions in ore deposits and review the methodologies and tools developed to address these issues. The general properties of fluid inclusions in hydrothermal ore-forming systems are considered and the interpretation of these data in terms of fluid evolution processes is discussed. A summary of fluid inclusion data from a variety of hydrothermal deposit types is presented to illustrate some of the methodologies described and to emphasise the important role which fluid inclusion investigations can play, both with respect to understanding deposit genesis and in mineral exploration. The paper concludes with a look to the future and addresses the question of where fluid inclusion studies of hydrothermal ore deposits may be heading in the new millenium.     

河南卢氏—栾川地区铅锌矿成矿多样性分析及成矿预测

河南省卢氏-栾川地区位于华北陆块南缘与秦岭造山带的衔接部位,是中国重要的钼、钨、铅、锌多金属成矿区。通过控矿地质条件与成矿环境多样性分析,将研究区铅锌矿划分为3种成因类型:岩浆热液交代型铅锌矿床、MVT型铅锌矿床和SEDEX型铅锌矿床。在此基础上,利用“成矿专属性”和“成矿多样性”相结合的找矿思路,对矿区不同类型矿床成矿进行远景评价,指出具有良好的找矿前景。     

湖南省主要金属矿产的时空分布规律

湖南地处扬子与华夏陆块结合部,构造、岩浆活动强烈,矿产资源丰富,有着“金属矿产之乡”的美誉。除铬、镁、铂族元素、锶等少数几种矿产没有查明的资源储量外,其他金属矿产均有发现和查明的资源储量,钨、锡、锑、铋、锰等更是位居全国前列,“世界金属博物馆”柿竹园,“世界锑都”锡矿山等一批矿床名闻遐迩,引无数矿床学者“竞折腰”。     

扬子板块周缘MVT型铅锌矿床闪锌矿微量元素组成特征与指示意义:LA-ICPMS研究

扬子板块周缘铅锌多金属成矿带内分布着数以百计的沉积岩容矿型铅锌矿床,它们不仅是我国主要的铅锌矿产地,同时也是重要的稀散元素(Ge、Ga等)生产基地。本次研究采用LA-ICPMS技术分别测定了扬子板块西南缘的会泽铅锌矿床、金沙厂铅锌矿床、大梁子铅锌矿床,扬子板块北缘的马元铅锌矿床以及扬子板块东南缘的凤凰茶田锌(铅)汞矿床中闪锌矿的微量元素组成,以揭示闪锌矿中微量元素(稀散元素)的富集规律和赋存状态,并为矿床成因类型的厘定及稀散元素矿产资源综合利用提供更多依据。LA-ICPMS微量元素测定结果显示闪锌矿中不同微量元素(稀散元素)分布不均匀,但这些矿床中闪锌矿总体以富集稀散元素Ge、Ga、Cd,贫In、Se、Tl、Te为特征,其Fe、Mn含量要明显低于与岩浆热液有关的高温闪锌矿,指示了扬子板块周缘铅锌矿床可能形成于中-低温成矿流体,而与岩浆热液无直接的成因联系,此外这些矿床中闪锌矿富Ge贫In的特征与其他的密西西比河谷型铅锌矿床(MVT)一致。同时,本次研究综合分析了闪锌矿中不同微量元素(稀散元素)之间的相关关系,并与闪锌矿微量元素LA-ICPMS时间分辨率特征相结合,研究表明:这些铅锌矿床中稀散元素Ge可能主要通过3Zn2+?Ge4++2(Cu+,Ag+)和2Zn2+?Ge4++□(晶体空位)的替代方式进入闪锌矿,Ga在闪锌矿中富集机理主要为2Zn2+?(Cu,Ag)++(Ga,As,Sb)3+。此外,为进一步揭示不同成因类型铅锌矿床中稀散元素的富集规律,本文还系统对比了全球范围内不同类型铅锌矿床闪锌矿的稀散元素(均为LA-ICPMS数据)组成特征,并初步探讨了造成不同成因闪锌矿中稀散元素(Ge、Ga和In)差异性富集的主要控制因素,研究表明:(1) Ge在中低温盆地卤水成矿系统(MVT和SEDEX矿床)和岩浆-火山热液成矿系统(浅成脉状铅锌矿床和VMS矿床)形成的闪锌矿中均可能富集成矿,但中低温浅成脉状矿床中Ge的富集程度要明显高于高温脉状矿床,指示了成矿温度是控制闪锌矿中Ge富集的一个重要因素。(2)铅锌矿床闪锌矿中In主要为岩浆来源,In倾向于在成矿温度较高的岩浆及火山热液成因铅锌矿床中富集成矿,而壳源的MVT和SEDEX型铅锌矿床中闪锌矿均贫In。可见除形成温度外,成矿物质来源是决定闪锌矿是否富In的关键因素。(3)除矽卡岩型铅锌矿床外,其他不同成因类型、不同形成温度的铅锌矿床中闪锌矿均可能富Ga。矽卡岩型铅锌矿床闪锌矿具有明显的贫Ga、Ge的特征,这可能是由于矽卡岩化过程中稀散元素Ga、Ge大量进入早期矽卡岩矿物,进而导致了成矿流体以及随后形成的闪锌矿中Ga、Ge的贫化。综上所述,闪锌矿中稀散元素富集与否和富集程度受成矿物质来源、成矿流体性质以及流体演化过程等多因素的综合控制。(4)扬子板块周缘铅锌矿床闪锌矿的微量元素(稀散元素)组成特征指示了它们形成于中低温成矿环境,稀散元素的富集规律与其它MVT型铅锌矿床类似。     

Simultaneous determination of sulfide, polysulfides and thiosulfate as an aid to ore exploration

The interaction of water and sulfide minerals yields dissolved species which can be utilized to trace back the presence of sulfide minerals and associated minerals. Computer modeling and laboratory and field results show that the most characteristic dissolved species are hydrogen sulfide (H₂S, HS⁻), polysulfide ions (S_n²⁻) and thiosulfate (S₂O₃²⁻), derived from the hydrolysis of sulfide minerals. Typical concentration ranges are: 10⁻⁵ – 10⁻⁷ mole/l for hydrogen sulfide, 10⁻⁶ – 10⁻⁹ mole/l for polysulfides and 10⁻⁵ – 10⁻⁸ mole/l for thiosulfate. The chemical reactivity of these species at contact with air makes them difficult to assess unless determined immediately after sampling.These sulfur species can be determined rapidly and accurately in field conditions by simultaneous titration with mercuric chloride employing an Ag/Ag₂S electrode for the determination of the end points.The application to ore exploration is exemplified by the results of the research on roll-type uranium deposits in the southwest of France.     

Discriminant analysis for evaluating the use of lithogeochemistry along the Tetsusekiei Horizon as an exploration tool in search for Kuroko type ore deposits

Tetsusekiei (literally, iron quartz) is in the form of thin, discontinuous beds that occur in the hanging wall of the Kuroko-type massive sulphide ores and at some distance beyond ore, along the uppermost part of the ore horizon tuff. The presence of tetsusekiei within a volcano-sedimentary sequence marks a horizon of fossil hydrothermal activity. Tetsusekiei shows elevated concentrations in trace elements of exhalative input relative to normal pelagic sediments and consists of two components; a clastic and a chemical component. Discriminant analysis applied to the following three groups: chemical component of tetsusekiei, clastic component of tetsusekiei and the upper part of the ore horizon tuff which is stratigraphically equivalent to tetsusekiei, has aided in providing the exploration geologist with a number of statistically significant major and trace elements that may be useful to exploration. The lateral distribution of the statistically significant major elements, expressed in the alteration index $$\operatorname{R} \% = \frac{{\left( {K_2 O + MgO} \right) \times 100}}{{K_2 O + Na_2 O + MgO + CaO}}$$ (Ishikawa et al. 1976) for the clastic component of tetsusekiei along the same stratigraphic horizon, shows an increase from about 50% to 90% approaching the Fukazawa mine from the northwest. The trace elements which are of exhalative origin show a relatively erratic distribution. In addition, the accommodation of barium, which is of exhalative origin, in the sericite constituent of the clastic component, combined with its higher concentration in the clastic relative to that in the chemical component, may indicate the presence of sulphide and/or barite ore lower in the stratigraphy.     

中国新疆矿床成矿系列类型

研究认为在不同时代、不同地质构造单元中重复出现的矿床成矿系列，可称为矿床成矿系列类型。新疆主要矿床成矿系列类型带有鲜明的古生代造山带成矿作用特点，它们联系于新疆各造山带古生代地壳发展的拉张型过渡壳－洋壳－汇聚型过渡壳－古生代新陆壳的各特定阶段，与各阶段地质构造作用密不可分。矿床成矿系列类型本身也随着地壳发展、地壳成熟度的提高而有规律地演化     

Rational combination of mathematical methods for predicting ore deposits

Summary This study emphasizes the important role of a flexible, multipurpose data base, including both qualitative and quantitative information, for metallogenic investigations and prospect assessment. Information stored in such a data base allows processing by various methods for different purposes and obtaining efficient and comparable results.     

Hydrothermal mixing,carbonate dissolution and sulfide precipitation in Mississippi Valley-type deposits

A large number of Mississippi Valley-Type (MVT) deposits are located within dissolution zones in carbonate host rocks. Some genetic models propose the existence of cavities generated by an earlier event such as a shallow karstification, that were subsequently filled with hydrothermal minerals. Alternative models propose carbonate dissolution caused by the simultaneous precipitation of sulfides. These models fail to explain either the deep geological setting of the cavities, or the observational features which suggest that the dissolution of carbonates and the precipitation of minerals filling the cavities are not strictly coeval. We present a genetic model inspired by the textural characteristics of MVT deposits that accounts for both the dissolution of carbonate and precipitation of sulfides and later carbonates in variable volumes. The model is based on the mixing of two hydrothermal fluids with a different chemistry. Depending on the proportion of the end members, the mixture dissolves and precipitates carbonates even though the two mixing solutions are both independently saturated in carbonates. We perform reactive transport simulations of mixing of a regional groundwater and brine ascending through a fracture, both saturated in calcite, but with different overall chemistries (Ca and carbonate concentrations, pH, etc). As a result of the intrinsic effects of chemical mixing, a carbonate dissolution zone, which is enhanced by acid brines, appears above the fracture, and another zone of calcite precipitation builds up between the cavity and the surrounding rock. Sulfide forms near the fracture and occupies a volume smaller than the cavity. A decline of the fluid flux in the fracture would cause the precipitation of calcite within the previously formed cavities. Therefore, dissolution of carbonate host rock, sulfide precipitation within the forming cavity, and later filling by carbonates may be part of the same overall process of mixing of fluids in the carbonate host rock.Editorial handling: C. Everett     

大功率激电和CSAMT在隐伏矿产勘查中的应用

隐伏矿产勘查是我国现今的主要任务,近几年在内蒙古锡盟地区做了大量的电法测量工作,主要应用大功率激电和可控源音频大地电磁测深方法组合进行找矿,取得了很好的找矿效果。在内蒙古某深部隐伏铅锌矿的勘查中,将大功率激电法用于快速发现和圈定矿区矿化范围及构造展布情况,用可控源音频大地电磁测深法反演电阻率断面图推测地下岩性电性特征、地质结构、构造产状、规模和矿(化)体的赋存空间,为钻探工程提供依据。     

澜沧江铁矿带惠民式-疆峰式铁矿床特征与含铁建造

通过对惠民式和疆峰式铁矿的研究,认为它们都是受变质中基性火山岩建造控制的海相火山-沉积型铁矿床,前者兼有条带状含铁建造(BIF)和粒状含铁建造(GIF)的特征,而后者则为条带状含铁建造.它们均具备元古代条带状铁硅建造铁矿的特征,满足形成前寒武纪大型条带状含铁建造的“大型海洋热液供应系统、作为沉积仓储的大陆架体貌及有能力...     

镇旬矿田泥盆系和志留系铅锌矿的成矿地质条件分析

对镇（安）旬（阳）矿田泥盆系、志留系铅锌矿的成矿地质条件分析表明，本区泥盆系、志留系铅锌矿总体属层控矿床类型。铅锌矿赋存于下志留统悔子垭组、中志留统双河镇组及中泥盆统大枫沟组、上泥盆统南羊山组；控矿构造为断裂、褶皱，容矿构造为顺层断裂带、剪切带，含矿岩石为含碳砂岩、千枚岩及灰岩、生物灰岩、白云岩；沉积环境为浅水陆棚相、台地边缘及泻湖、潮坪、台地浅海。以旬阳泗人沟为代表的志留系铅锌矿属细碎屑岩沉积强改造型铅锌矿床；以旬阳大岭、赵家庄为代表的泥盆系铅锌矿属碳酸盐岩沉积弱改造型铅锌矿床；以镇安锡铜沟、月西为代表的泥盆系铅锌矿属碳酸盐岩沉积强改造型铅锌矿床。     

湘西北铅锌矿床的地质特征及找矿标志

湘西北铅锌矿床是中国著名的层控型金属矿床,其地质特征和规模类似于美国的密西西比铅锌矿床。湘西北地跨上扬子地块和江南地块(北西缘)2个二级大地构造单元。按矿床所处的不同大地构造位置及其地质-地球化学特征,将湘西北铅锌矿床划分为洛塔、花垣、保靖铅锌矿田和凤凰铅锌汞矿田。其中控矿层位有3个:下寒武统清虚洞组下段藻灰岩、中寒武统敖溪组上段粉晶云岩和下奥陶统南津关组生物碎屑灰岩。较全面地论述了湘西北铅锌矿床的地质特征,并对找矿标志进行了探讨。     

矽卡岩矿床的汇流扩容空间控矿机制及其对深部找矿的意义:以铜陵—安庆地区为例

本文以铜陵-安庆地区凤凰山铜矿和安庆铜矿为例,通过野外地质分析和计算模拟实验探讨了浅成岩体冷却过程中接触带上汇流扩容空间对矽卡岩矿体的控制.在风凰山矿田和安庆矿田,围绕新屋里岩体和月山岩体的接触带上矿体的分布极不均匀,形成大规模矽卡岩矿体的位置既与接触带本身的特征有关,也与构造变形有关.矿体的边界特征以及与矿体密切相关的角砾岩的特征表明水压致裂在赋矿扩容空间的形成过程中可能起重要的作用.矿体的围岩蚀变特征以及流体包裹体地球化学特征显示来自岩体和囤岩的流体的混合以及高压流体的减压沸腾可能是矿石沉淀的主要机制.新屋里岩体和月山岩体的同构造冷却过程力学变形-传热-流体流动耦合动力学计算模拟结果显示:所有矿体都位于汇流扩容空间内,且主矿体位于最大最强的汇流扩容带内,这表明力-热-流耦合作用形成的汇流扩客空间不仅控制了矿体的位置,也控制了矿体的规模.在铜陵-安庆地区开展深部找矿勘查,应该将重点放在大规模高强度的汇流扩容区,特别是还没有发现大规模矿体的汇流扩容区,凤凰山和安庆铜矿深部找矿已取得的成果证明了汇流扩容空间控矿模式对这一地区深部找矿勘查具有重要意义.     

金属矿地震勘探方法技术研究综述

系统地总结了国内外金属矿地震勘探技术及其研究与应用现状,其中包括反射波法、折射波法、散射波法等,并就多项实验研究中采用的方法技术及取得的良好地质效果进行了概括总结,认为反射波地震方法在振测沉积层控矿床和控矿构造方面效果较好,而散射波地震方法不但可探测与矿体有关的地下局部不均匀体,而且,结合其它物探资料还可确定隐伏矿体的...