Petrogenetic and Metallogenetic Background of the Dajing Cu–Sn–Ag–Pb–Zn Ore Deposit, Inner Mongolia, and Characteristics of the Mineralizing Fluid

Abstract: The Dajing Cu–Sn–Ag–Pb–Zn ore deposit, Inner Mongolia of China, is a fissure‐filling hydrothermal ore deposit that occurs within the Upper Permian Linxi group. No magmatic pluton and volcanic rocks outcrop on the surface of the deposit. Most of ore veins show clear‐cut boundary with country rocks. Wallrock alterations that include silicification, carbonation, chlori–tization, and sericitization are generally weak and occur in the close vicinity of ore veins. Mineralization is divided into three stages: (1) cassiterite–arsenopyrite–quartz stage, (2) sulfide stage, and (3) Pb–Zn–Ag–carbonate stage. These mineralization stages have distinct ranges of homogenization temperatures, 290–350C for Stage 1, 260–320C for Stage 2, and 150–250C for Stage 3. However, salinities for Stages 1, 2, and 3 overlap and range between 2.2 and 10.4 wt % NaCl equivalent. The dD values relative to V‐SMOW of inclusion water from quartz are lower than –88% and centered at –100 to –130%. The δ³⁴S values relative to CDT of sulfide ore minerals and δ¹³C values relative to PDB of carbonate gangue minerals, vary from –0.3 to +2.6%, and from –7.0 to –2.9%, respectively. Integrated isotopic data point to two major contributions to the mineralizing fluid that include a dominant meteoric‐derived water and the other from hypogene magma for sulfur and carbon species. Analyses of inclusion gas and liquid compositions are performed. The H₂O and CO₂ are the two most abundant gaseous components, whereas SO₄^2‐ and Cl^‐, and Na⁺, Ca²⁺, and K⁺ are the major anions and cations, respectively. A linear trend is shown on the gaseous H₂O versus CO₂ plot. Phase separation is excluded as cause for the trend on the basis of isotope data and fluid inclusion microthermometry. In addition, a weak wallrock alteration does not support fluid‐rock interaction as an efficient mechanism. Hence, the linear H₂O–CO₂ trend is interpreted in terms of absorption or dilution of CO₂–dominant magmatic vapor by meteoric‐derived water. Cooling effects resulting from dilution may have caused precipitation of ore minerals. Major and trace element compositions of regional granites show a high‐K calc–alkaline characteristics and an arc–affinity. Lead isotopic compositions of galena samples from the Dajing deposit exhibit elevated U/Pb and Th/Pb ratios. These characteristics indicate a common source of supra subduction zone mantle wedge for regional granites and metals from the Dajing deposit.     

PREDICTION OF LOCATION OF HIDDEN ORE DEPOSITS IN THE AGED ORE FIELDS:AN EXAMPLE FROM FENGHUANGSHAN ORE FIELD,TONGLING,CHINA

This paper discusses the strategy for successfully predicting the location of potential hidden ore bodies in aged ore field,and presents the result of location prediction of hidden ore bodies in Fenghuangshan ore field,Tongling.Innovative conceptual targeting procedures based on a genetic understanding of mineralization systems,carefully geological investigation and correct deduction,together with new geochemical and geophysical technology and integrating of comprehensive information are all very important for the successful prediction.In the aged Fenghuangshan ore field,through researching by application of the metallogenic theory of polygenetic compound ore deposits and triple-frequency induced polarization method and exploration tectono-geochemical method,we predicted location and quality of hidden ore bodies.According to the prediction,hidden high quality Cu-Au ore bodies of skarn type and porphyry type have been discovered.     

广西巴里—龙头山100号锡多金属矿床成矿物理化学环境研究——氧逸度(f_(o_2))、CO_2逸度(f_(co_2))、硫逸度(f_(s_2))、mΣs

根据已知的 10 0号矿体的成矿温度及成矿压力 ,并结合矿体的矿物组合推算出10 0号矿体是在相对低硫、氧和二氧化碳逸度 ,溶液为酸性至弱碱性的物理化学环境下形成的。     

祁东留书塘铅锌矿地质特征及资源远景预测

矿床赋存于中泥盆统棋子桥组碳酸盐岩中，受总体呈近SN走向的F1挤压破碎带控制。矿体呈脉状、透镜状，走向长4 500 m，宽1～5 m，平均品位（×10－2）：Zn 5.91、Pb 0.22、Ag 126.95 g/t，富矿体Pb＋Zn最高达24.83×10－2、Ag 506.02 g/t。围岩蚀变有硅化、重晶石化等，铁帽可视为直接找矿标志。资源量预测表明，经过进一步勘查，可望找到一个Pb＋Zn达 n×102 万t、Ag n×103 t的铅锌多金属脉状充填矿床。     

东安牛头寨地区锑矿床控制因素及成因探讨

锑矿床严格受构造控制，表现出逐级控矿特征：区域性F1断裂、牛头寨复式背斜及北北东、北北西、北西向次级断裂，分别控制着锑矿带、锑矿床的空间展布及锑矿脉的形态、产状与规模。地层岩石建造对成矿的控制，主要表现在赋矿地层中的白云岩、硅质岩等易碎裂，为矿液的运移提供了有利的通道。部分含矿地层的Sb高丰度，还可能成为矿提供了矿源。已有的研究表明，锑矿床的硫同位素组成具有岩浆硫特征，并混入了部分围岩沉积硫。石英的氢氧同位素组成反映出岩浆流体与变质水混入溶液特征。矿物包裹体的爆裂温度平均为157℃。石英的包裹体成分测试结果，揭示了矿液为K－Na-Ca-Cl型富硅的弱碱性溶液。矿床成因厘定为岩浆期后中低温热液脉状充填矿床。     

航空遥感影像中道路的半自动提取

为了达到各种信息融合的目的，针对不同的情况，提出了多种信息约束下的道路提取方法。为了对提出的方法进行检验，给出了航空影像中不同类型的道路提取的例子     

地震CT在寻找隐伏铜镍矿中的应用

用透射地震ＣＴ方法在金川龙首矿进行了隐伏铜镍矿体的探测试验．试验是在地下５００ｍ的１２８０平面上进行的，覆盖面积３００ｍ×３００ｍ．使用ＥＳ－２４０１Ｘ型４８道高分辨数字地震仪．铜镍矿体为高波速值的超基性侵入岩，采用纵波速度作为层析物理量是敏感的．研究区划分成８１×６４个单元，单元体大小为４ｍ×４ｍ．有效地震射线７６１９条，使用联合迭代重建法（ＳＩＲＴ）求解慢度走时方程．速度图像及地质解释表明测区中西部有一个高波速异常体，推断与含铜镍矿体或花岗体有关；此外还发现一条近东西向的低波速带，推断为断裂．     

几种有效的测井找气方法

已建立的几种有效测井找气方法,在我国天然气勘探开发中应用,发现了许多气层.本文综述这几种有效的测井找气方法,并给出了实例.     

四川冕西稀土成矿区的地质特征及其远景探讨

笔者从区域地质条件、矿床地质特征、冕西岩体性质、稀土模式、主要稀土矿物特征以及矿石的工艺性质进行了考查,并作了区域性对比。初步认为,在冕西地区以碱长花岗体为主体,形成了面积近800km~2的稀土成矿区。霓石碱性花岗岩-构造破碎带-碱性(伟晶)岩脉是区内稀土成矿的基本要素,也是最直接的找矿标志,围绕冕西岩体出露的卫星式霓石碱性花岗岩有着不同于A型碱长花岗岩的稀土模式,是稀土成矿矿源体。不同产地的稀土矿物特征、矿石矿物组合和矿石类型均有很好的可比性,属易采易选优品级稀土矿石。在该区有必要进一步开展矿产普查工作。     

江西永平铜矿田构造地球化学

本文在对永平铜矿田构造调查研究的基础上,初步探讨了矿田主要控岩控矿构造——F_1断裂构造地球化学和候家—嵩山倒转背斜褶皱构造地球化学,以及构造应力对矿液和成矿物质的运移与富集的影响——成矿构造地球化学。最后还提出了永平铜矿田构造地球化学成矿模式。