Types of endogenous geochemical fields and their significance for prospecting

When prospecting ore deposits in Trans-Baikal region the endogenous geochemical fields (EGF) are taken as the main search element, as was proposed by L.V. Tauson (1983). Such fields are classified into: geochemical fields of dispersion (GFD), concentration (GFC) and removal (GFR). With regard to their formation conditions they are subdivided into magmatic (associated with magmatic chambers), intratelluric (associated with activity of intratelluric emanations), hydrothermal-metamorphic (vadose-thermal solutions), metamorphogenic, and sedimentary-metamorphogenic ones. Magmatic EGFs are divided into three groups: magmatic, pneumatolytic, and hydrothermal stages. This study identified their polygenetic origin and association with ore-magmatic systems. The geochemical fields of ore zones, fields, and deposits result from the late and post-magmatic processes; they also include the EGF of host rocks and those which altered at pre-ore stage of the natural system development.At ore deposits the EGFs are responsible for supply and redistribution of elements through the entire ore formation process. The fields were divided into EGF of poor concentration (contrast coefficient CC normalized after background to 10), mean (CC >10–100), and intense (CC >> 100). The EGF intensity progressively increases at the hierarchy stage: “host rock—pre-ore metasomatite—syn-ore hydrothermalite—ore body—ore pillar”.To summarize, the fields, ore districts, zones, and deposits are characterized by diverse patterns of dispersion, concentration, and removal.The specific features of composition, structure, and zonal distribution of elements in geochemical fields are exemplified by some gold-bearing zones of the Trans-Baikal region. The paper reports new approaches to investigating these natural formations. The authors promote transition from the generally accepted evaluation of a halo separation to the volumetric survey of endogenous geochemical fields (GFD, GFC, and GFR included) of ore deposits and ore-magmatic systems, in general. The acquired evidence supports the assumption that endogenous geochemical fields should be regarded as a complete system differentiated in space and time preserving specifics and pattern of the internal structure.     

东天山红云滩铁矿床矿物学、矿物化学特征及矿床成因探讨

东天山红云滩铁矿赋存于下石炭统雅满苏组火山碎屑岩地层中.矿体主要呈层状、似层状、透镜状.矿石矿物以大量磁铁矿为主,含少量的磁赤铁矿、镜铁矿、黄铁矿和极少量的黄铜矿等.脉石矿物主要有石榴石、透辉石、阳起石、绿帘石、绿泥石、黑云母、钠长石、石英等.矿石构造以块状构造和浸染状构造为主,局部为条带状构造、脉状构造;矿石结构包括半自形-他形粒状结构、交代结构.围岩蚀变对称分带明显,从矿(化)体到两侧围岩,蚀变呈现从深色到浅色的变化现象.根据矿物共生组合、矿石组构的观察,本次工作识别出矽卡岩期和热液期两个成矿期,进一步细分为4个成矿阶段:矽卡岩阶段、退化蚀变阶段(主成矿期)、热液早期阶段及石英-硫化物阶段.电子探针分析表明石榴石端员组分以钙铁榴石-钙铝榴石系列为主,辉石端员组分以透辉石-钙铁辉石为主,角闪石端员组分主要为阳起石和透闪石,这些特点表明矿区矽卡岩为热液交代钙矽卡岩.磁铁矿的主、微量元素特征表明其形成与矽卡岩密切相关.结合成矿地质特征,认为矽卡岩是由富铁岩浆热液流体沿断裂构造运移、交代下石炭统雅满苏组富钙火山碎屑岩地层而形成的,磁铁矿的形成与矽卡岩的退化变质作用有关.     

智利铁氧化物-铜-金矿床区域定位构造-矿田构造类型与特征

智利铁氧化物铜金矿床形成于安第斯型活动大陆边缘中生代岩浆弧及弧后盆地,区域构造特征主要为岩浆侵入构造岩相带和阿塔卡玛断裂系统(AFZ),岩浆侵入构造及岩相分带控制矿田形成,AFZ断裂系统控制了矿化带和大型矿体产出.矿田构造主要有五种类型:火山构造;岩浆侵入构造+复式背斜;NS向平行韧性断裂带+岩浆侵入构造;走滑断裂弯曲...     

On the chemical composition of the ore breccia at Luossavaara,northern Sweden

An important argument for a magmatic affiliation of the Kiruna type of ore is the presence of ore breccia which accompany the main ore bodies. According to Parák (1975a and b) the main ore bodies are not of the same origin as the breccias. This is based on data from the Luossavaara deposit in northern Sweden: the main ore and the breccia have different chemical compositions. Microprobe analyses made in the present study, however, clearly demonstrate similarity in chemical composition, strengthening the hypothesis of a common origin for both formations.     

从地洼学说谈浙江地区锡的找矿方向

在大地构造上,浙江地区锡矿(化)主要形成于中、新生代以来的地洼阶段。以江山-绍兴深断裂为界,可以划分为浙东洼陷和浙西洼隆。从地质条件、矿床成因、岩石类型和物质组分等特征,将浙江锡矿(化)划分为斑岩型、矽卡岩型、云英岩型、锡石-石英脉型,锡石-石硫化物型和砂矿型六种类型。亲石型锡矿建造主要分布于陈蔡—龙泉地穹内;亲铁型和亲硫型锡矿建造主要分布于富阳—开化地洼陷带。从锡矿(化)受控于构造、沉积建造的特点,结合锡的赋存状态,提出乌岙—洋滨一带是浙江找锡最有利的部位。     

铜陵天马山硫金矿床地质特征及成因探讨

天马山硫金矿床的矿体分为层状矿体、接触带矿体和穿层矿体。层状矿体和穿层矿体受石炭系黄龙组、船山组地层层位和层间断裂控制。接触带矿体受接触带控制 ,具矽卡岩型矿体典型特征。矿床的形成受地层、构造及岩浆岩控制 ,矿床成因为层控矽卡岩型硫金矿床     

糜棱岩型金矿床地质特征

当糜棱岩中金元素的含量足以满足工业利用,即在糜棱岩中可圈出独立的金矿体时,这种金矿床便可称为糜棱岩型金矿床.糜棱岩型金矿床是"中国金矿床工业类型"中的重要类型之一.此类金矿床多分布在古老地块周边长期活动的构造带之中.介绍了糜棱岩型金矿床的赋矿岩系、控矿构造、矿床、矿体、矿石以及含金矿物等地质特征.同时,对金成矿地质环境及矿床成因等作了探讨     

地球化学方法在吉家洼金矿区外围找矿中的应用

吉家洼金矿是华北陆块南缘熊耳山金矿田的一个小型矿床, 金矿体赋存于含矿断裂带内, 并严格受其控制, 矿体的形态、产状与含矿断裂基本一致。通过对矿区外围F1、F7断裂带开展系统的岩石地球化学测量, 圈定了多个受断裂控制的高强度Au异常, 经钻探施工, 见矿情况良好。进一步对钻孔进行了岩石原生晕采样化验和统计分析, 结果显示矿体向下有一定的延深, 经钻探施工, 在断裂深部发现工业矿体, 矿床规模扩大至中型。吉家洼矿区外围含矿断裂带数量多、矿化强度高, 而地表Au前缘元素非常发育, 向深部矿体头部元素及矿体元素发育并伴有前缘指示元素, 矿尾元素不发育, 已发现的矿体深部不封闭, 说明矿体沿倾向具有长距离延深, 深部找矿前景好。      

山东莱芜接触交代—热液铁矿矿体形态研究

在对莱芜接触交代铁矿地质特征研究中发现以往地质报告在矿体连接上存在混乱,使矿体形态失真。为便于今后矿体对比和成矿规律的认识,提出了矿体形态分类原则,并以三分法对矿体形态进行分类。指出矿体产状变化是矿体膨胀收缩、分支复合和尖灭再现的结果。根据矿体形态分类指出了找矿方向。不同的矿体形态反映不同的控矿构造,反映不同的矿体规模,反映不同的成矿岩体形态产状。单斜缓倾矿体的成矿岩体是岩床,控矿较小;陡倾矿体和背向斜矿体的成矿岩体是岩盖,控矿较大。     

四川冕宁县马头金矿成矿特征与找矿潜力分析

冕宁马头金矿床位于上扬子陆块与羌塘—三江造山系的交界部位,金矿成矿与喜马拉雅期马头山—司依诺走滑断裂活动关系密切,矿体产于断裂旁侧的构造蚀变带内。金矿成矿受NNE向次级构造蚀变带、灰岩与辉绿岩脉以及二者的岩性转换界面控制。通过对矿床成矿条件、矿石特征、金的赋存状态等研究认为,马头金矿属于幔源岩浆中低温热液型金矿床。通过与相邻金矿区的对比、土壤异常成果分析、矿体延伸展布趋势分析,认为矿区地表及深部还有较好的找矿潜力。     

Geology and ore genesis of the manganese ore deposits of the Postmasburg manganese-field,South Africa

The Postmasburg Mn/Fe-ores occur exclusively in dolomitic Precambrian sinkhole structures with siliceous breccias and shales as hostrocks. The main manganese minerals are braunite and bixbyite, apart from secondary alteration products of the psilomelane-manganomelane family. Various generations of ore minerals could be identified. The ore mineralization is subdivided into three different genetic types. They are classified either as pure karst deposits or as combined formations of karst origin and shallow marine sedimentation due to the transgression of the Banded Iron Formation (BIF) sea. Post-sedimentary metamorphism is identified as very low grade. The development of the different ore types is illustrated schematically.     

蚕庄金矿上庄矿区控矿构造特征及构造模拟

上庄矿区的主要控矿断裂具有多期活动的特点，主断裂、次级断裂及节理的多种组合方式控制了矿体的产出。运用断裂面波形模拟方法得出了控矿主断裂在成矿期的断裂面波形图，并以此对上庄矿区的深部矿体进行了预测。     

Chemical compositions of tourmaline in the Yindongzi-Tongmugou Pb-Zn deposits,Qinling, China: Implications for hydrothermal ore-forming processes

A microprobe study has been carried out on the chemical composition of tourmaline from the Yindongzi and Tongmugou stratabound Pb-Zn ore deposits, eastern Qinling, China. Tourmaline was analysed from a variety of rock types representative of its various occurrences associated with the ore bodies. All the tourmalines studied here belong to the schorl-dravite series. Most are of hydrothermal origin with Mg > Fe and Na > Ca. Some detrital cores of tourmaline have been recognized from their geometry and chemistry, with Fe > Mg. The chemical trends from core to rim in zoned grains suggest a multi-stage model for the growth of tourmaline and genesis of the ore bodies. The first stage was represented by a more Mg-rich hydrothermal fluid in the submarine hydrothermal system, producing Mg-rich tourmalines by selective replacement of clay-rich sediments close to the sediment-water interface. The second stage was dominated by Fe-rich hydrothermal fluid and resulted in overgrowth of Fe-rich tourmaline rims. This stage also led to the nucleation and growth of new tourmaline crystals and was responsible for the formation of the main massive sulphide orebodies. Finally, a further period of hydrothermal activity or a metamorphic event led to the formation of an additional rim of Mg-rich tourmaline.     

青海东昆仑成矿带综合选区研究

笔者通过改进先前提出的基于专家证据权重法的成矿远景区划与评价方法的不足之处,重新对青海东昆仑地区Au、Cu和Co3矿种进行成矿远景区划与评价,将各矿种的远景区按成矿潜力大小划分为A、B、C三级。在此基础上,提出了将多个单矿种远景区合成综合成矿远景区的评价方法和手段,最终圈定出青海东昆仑的综合远景区25个,并对它们也按成矿潜力大小划分为A、B、C三级。从青海东昆仑地区已知Au、Cu、Co矿床(点)在各综合远景区内的数量和规模分布情况来看,结果令人满意。青海东昆仑地区的综合选区研究成果可望为该区进一步找矿工作部署提供部分科学依据。     

对西藏岗巴上白垩统的新认识

在前人研究的基础上对岗巴地区上白垩统的划分做了厘定 ,进一步建立了晚白垩世的 1 2个浮游有孔虫化石带。根据岩性特征及化石带的研究 ,上白垩统被划分为赛诺曼期至土仑早期的冷青热组 ;土仑中期至三冬期的岗巴村口组和康潘期至马斯特里赫特期的宗山组。该区赛诺曼期与土仑期的界线位于冷青热组上部 ,以 H elvetoglobotruncana praehelvetica的初现为标志。     

中国主要镍矿类型及其与古板块构造的关系

新中国成立后,开展了大规模持续的地质找矿工作,发现了一系列镍矿床。这些矿床的探明,充分证实我国是一个镍矿资源十分丰富的国家。本文在归纳划分了镍矿类型之后,试图对在古板块构造作用下镍矿区域成矿问题作些探讨。主要依据现代海洋资料建立起来的板块构造学说,生动而又精辟地阐述了晚近地质时期某些地质构造规律和成矿作用。但是,对于古板块构造作用和受古板块制约的古成矿作用来     

伊宁吐拉苏火山盆地构造与金矿成矿关系

伊宁吐拉苏火山盆地发育在前寒武纪和加里东基底上,盖层主要由早石炭世陆相火山岩组成。基底与盖层中的断裂、褶皱构造特征有显著差异。火山构造单元划有火山喷发带、火山构造带、火山机体三级。构造演化经历了基底和火山盆地形成及剥蚀三个阶段。金矿产于大哈拉军山组。认为三级控矿构造与三级火山构造相对应,分别控制着金矿带、金矿田、金矿床（点）的展布和产出。     

Analysis of sedimentary facies and depositional environments of Paleogene sequence of Cambay basin,India

A study on the sedimentary facies characterization and depositional environment interpretations for the K#Field (K-Oil Field) in Cambay petroleum basin of western onshore, India was conducted based on the sub-surface data from drilled wells, including well logs, borehole images, cores and the regional knowledge of the basin. In this work, an effort is made to integrate the current data from seismics and well logging, to study and analyze its depositional environments and establish the petroleum systems. The study regions for the present work are K45 and K48 blocks. The target strata includes 2 oil-bearing formations of Paleogene, which is about 3600 ft; they are M#Fm (M-Formation) of the Eocene and N#Fm (N-Formation) of Oligocene, subdivided into 11 zones. The sediment fill is mostly of Tertiary. The research attempts to decipher the oil - depositional source correlation problems of the basin. Sedimentary models were established referring to the core analysis, core photographs and well logs. Reservoir and heterogeneity study included reservoir lithology features, physical properties and pore structure features.Well facies analysis of oil well WELL-0297 and WELL-0129 was done and the results were analyzed for further drilling of new wells for oil and gas exploration. The study found that the Eocene, Oligocene, Miocene and Paleogene are fluviatile facies sand and mud interbed sediment with the thickness 2000-4000 ft, which are main oil-bearing formations in these areas. Studies concluded that the fluvial reservoirs of the K#Field are characterized by large variations from laterally extensive bodies with good interconnectedness and high net-to-gross ratios, multi-storey ribbon bodies with poor interconnections and low net-to-gross ratios.     

辽东白云-小佟家堡子矿集区控矿构造及成矿有利区预测

白云-小佟家堡子矿集区是辽东青城子矿集区的重要组成部分之一,包括位于北部的白云（二道沟、三道沟）、荒甸子等大中型金矿床及位于南部的林家三道沟、小佟家堡子、杨树、桃源等大型或中小型金矿床,高家堡子、凤银大地、姜家沟等大中型银矿床.前人对该区成岩成矿时代及金-多金属成矿作用开展了大量的研究工作,但控矿构造研究相对薄弱.研究结果表明,北部白云-荒甸子矿区容（含）矿构造为近东-西走向,向南倾,倾角30°左右逆冲断裂带,沿走向延伸近8 km.该逆冲断裂带由主逆冲断层及与其近于平行的若干条逆冲断层组成,宽度可达200 m.主断层面下部地层产状陡,上部缓,明显切层;而上部逆冲断层则以顺层为主.断层面一般呈舒缓波状,缓倾部位为矿体富集区域.南部林家三道沟-小佟家堡子矿区容矿构造为总体向北倾的缓倾逆冲断层,延伸稳定,在盖县组碎屑岩与大石桥组上部大理岩硅-钙面上部碎屑岩中形成金矿体,而硅-钙面下部大理岩中则形成铅锌银矿体,不同矿区赋矿层位近于一致.NW走向的尖山子断裂是本区规模最大的陡倾断裂,长度超过13 km,并具有多期活动特征.该断裂早期以右行走滑为主,晚期为正断层,在成矿后还有明显活动,可能将白云-荒甸子矿区近东-西向容矿逆冲断裂带向南错移至扈家堡子-马隈子北-毛甸子一带,最大错断距离达6 km.根据对白云-小佟家堡子矿集区控矿构造及赋矿层位的综合分析,结合成矿后断裂活动的改造,提出了白云-荒甸子矿区以南和小佟家堡子金矿-风银大地银矿2个深部成矿有利区及扈家堡子-马隈子北-毛甸子和桃源村以南2个外围成矿有利区.      

新疆琼河坝地区铁矿床类型及其成矿特征

新疆琼河坝位于准噶尔成矿带东段,是一个潜在的以铁、铜、金为主的矿集区。区内铁矿床(点)众多,以往的找矿和研究工作大多聚焦于矽卡岩型富铁矿,对其他类型的铁矿床缺乏足够的重视。为了拓宽琼河坝地区铁矿床勘查思路,需要对区内铁矿床的类型和成矿特征进行系统归纳。文章在野外调查和室内测试分析的基础上,依据矿床(点)的产出地质环境、矿体及矿石矿物成分特征,结合铁矿石主要矿物的主量、微量及稀土元素特征,将琼河坝地区铁矿床划分为矽卡岩型、火山岩型、岩浆分异型、火山间歇期沉积型和湖相沉积型5种类型。矽卡岩型、火山岩型、岩浆分异型和火山间歇期沉积型铁矿赋存在晚古生代泥盆纪—石炭纪火山岩中,湖相沉积型铁矿床赋存于中侏罗统湖沼相含煤碎屑沉积岩中。火山间歇期沉积型铁矿床是在琼河坝地区首次发现的新类型,矿体赋存部位、矿石颗粒磨圆度及胶结成分特征均显示了该类铁矿成矿作用的特殊性。从找矿角度分析,目前主攻方向为矽卡岩型铁矿,而火山岩型铁矿是下一步找矿研究的重点。