变差函数在赣杭构造带火山岩型铀矿田(床)评价中的应用

在简要介绍变差函数的原理、算法和研究区地质情况的基础上,将变差函数引入火山岩型铀成矿作用与地形相关性研究中。详细描述了赣杭构造带中不同成矿规模矿田(床)区地形高程变差统计的过程,初步分析了变差统计结果的地质意义。研究结果表明,地形高程值变差函数的长轴方向可以反映研究区的主要构造方向,变差函数的长短轴半径与铀矿床的成矿规模在一定程度上具有对应关系。     

Gold mineralizations in the Arabian shield: statistical control on mining potential

Saudi Arabia possesses numerous low-grade gold deposits and many occurrences are located in the Arabian Shield. Currently, there are five operating gold mines and major plans are underway to develop three gold mining regions in various parts of the shield. Because of the presence of numerous deposits and a significant amount of investments earmarked for the development of these deposits by the Saudi Government during the last few years, Saudi Arabia is expected to become one of the leading gold producers in the world. This paper starts with an introduction of gold mineralization and mining activities in the Arabian Shield in a historical perspective. This is followed by a brief review of geology and the geological importance of the Arabian Shield as a host for various types of gold deposits. The latter part of the paper discusses the statistical distribution of gold grades and its impact on cutoff grade variations on the gold reserves and their mining potentials. Finally, considering the lognormal distribution of gold grades and reduction in cutoff grades, it is demonstrated how some of the previously classified uneconomic resources can be gradually converted into mineable reserves with increasing proportions.     

加拿大拉布拉多地区主要金属矿床地质特征及其时空分布

拉布拉多是加拿大大西洋成矿域中具地质多样性的最大的成矿省,区域成矿地质条件优越,产有Superior型含铁建造、岩浆硫化物、铂族元素、火山成因块状硫化物、铀、稀有稀土等多种金属矿床。文章介绍了拉布拉多铁、铀、稀有稀土、镍多金属等优势金属矿床的成矿背景、成矿特征、矿床(点)分布、典型矿床地质特征及最新勘探成果,分析了区域地质演化作用与区域内主要金属矿床的时空分布。     

刚果(金)马诺诺地区稀有金属矿床成矿地质特征与成矿规律

刚果(金)马诺诺地区地处基巴拉稀有金属成矿带,成矿地质条件优越。本文通过对该区稀有金属矿床成矿地质背景、典型矿床特征分析,总结了该区的成矿规律。结果表明,区域性断裂控制了该区的构造格局及矿产分布,具有明显的带状分布特征;岩浆活动强烈,其中尤以G4期岩浆侵入活动与稀有金属成矿关系密切;地层中的云母片岩类岩石提供良好的封闭条件,此3种要素的耦合有利于促使该区形成稀有金属矿床。     

Application of discriminant analysis to evaluate compositional controls of stratiform massive sulfide deposits in Canada

Multiple discriminant analysis is used to identify systematic variations of Cu, Pb, Zn, Ag, and Au grade values in the Canadian massive sulfide deposits with the three geological parameters of age, environment, and composition of volcanic lithology. The deposits have been separated into three groups on each of the three parameter scales and discriminant functions that separated the three groups on the basis of metal grades were then obtained. The results of the analysis indicated that Pb and Cu are the most significant in indicating specific trends along the three geological parameter scales. Pb grade increases in younger deposits with an increase in the sedimentary character of their environments, or with a more felsic nature to their volcanic rocks. On the other hand, Cu grade increases in deposits that occur in volcanic environments and with a more mafic nature to the volcanic host rocks. The results could have useful applications in mineral exploration.     

Nonparametric estimation of multivariate joint and conditional spatial distributions

To estimate the recoverable reserves of deposits containing more than one metal, linear combinations of sample grades based on the economic importance of each metal have been employed. These linear combinations, called equivalent grades, have inherent problems at least one of which is that the contribution of an individual metal is confounded with all others. As an alternative to equivalent grades, multivariable joint and conditional spatial distributions may be estimated using indicator variable methods. These spatial distributions may then be used to determine the joint or conditional amounts of the metals in the estimated recoverable reserve.This paper was presented at MGUS 87 Conference, Redwood City, California, 14 April 1987.     

变异函数在马关都龙曼家寨锡锌多金属矿床中的应用

变异函数是地质统计学的核心内容和基本工具,它既能描述区域化变量的空间结构性变化,又能描述其随机性变化.本文在阐述了变异函数理论研究的基础上,依据都龙锡锌矿体的地质特征,运用变异函数,对该矿床Sn、Zn品位进行了变异函数的模拟和结构分析,为该矿床的储量计算和生产勘探提供了科学依据.     

基于地质异常单元金矿找矿有利地段圈定与评价

许多大型,超大型内生金属矿床通常位于壳昨杂的区域,如不同类型岩石圈板块的边界等,从而形成一些诸如环太平洋金属成矿带等全球规模的成矿域,对一些内生热液金属矿床就位的地质条件的统计分析表明：几乎所有被调查的主要工业矿床的矿田地质结构与其周围地区相比都是具有显著差异,而表现异常的特征。     

Robust Resampling Confidence Intervals for Empirical Variograms

The variogram function is an important measure of the spatial dependencies of a geostatistical or other spatial dataset. It plays a central role in kriging, designing spatial studies, and in understanding the spatial properties of geological and environmental phenomena. It is therefore important to understand the variability attached to estimates of the variogram. Existing methods for constructing confidence intervals around the empirical variogram either rely on strong assumptions, such as normality or known variogram function, or are based on resampling blocks and subject to edge effect biases. This paper proposes two new procedures for addressing these concerns: a quasi-block-bootstrap and a quasi-block-jackknife. The new methods are based on transforming the data to decorrelate it based on a fitted variogram model, resampling blocks from the decorrelated data, and then recorrelating. The coverage properties of the new confidence intervals are compared by simulation to a number of existing resampling-based intervals. The proposed quasi-block-jackknife confidence interval is found to have the best properties of all of the methods considered across a range of scenarios, including normally and lognormally distributed data and misspecification of the variogram function used to decorrelate the data.     

密西西比型（MVT）铅锌矿床研究进展

密西西比型(MVT)铅锌矿床是全球重要的铅锌矿床类型之一,其铅锌资源量占全球铅锌资源量的20%左右.近几十年来,通过不断的探索,人们在矿床的地质特征、地球化学特征、成矿物质来源、成矿流体运移和沉淀机制、年代厘定以及矿床形成的地球动力学背景等方面取得了重要进展.文章在综合前人工作成果的基础上,就MVT矿床的分布规律、特征、地质背景、矿床地质特征、地球化学特征、成矿模型、控矿因素等方面进行了介绍,并分析了目前成矿模型研究中的各种流体运移机制、金属卸载机制之间的优缺点,探讨了成矿模型研究所面临的问题.同时,将中国典型的MVT矿床纳入到全球MVT矿床的背景之中,进行了相关的讨论.最后,总结对比了主要控矿因素和勘查阶段中物化探方法在找矿过程中的作用.     

大别山北麓上天梯-皇城山一带中生代火山岩成矿系列研究

以往对赋存于大别山北坡中生代火山岩中的上天梯非金属矿带和皇城山银矿带分割开来进行地质评价和研究,且厘定出各自的火山岩地层层序。据近年研究成果,上天梯-皇城山一带的火山碎屑岩为同源二次熔结凝灰岩喷发产物,形成于火山柱体喷发塌落机制,乃是相应喷发的不同产物。因而,由火山岩浆活动所形成的金属矿床与非金属矿床不仅与岩相、构造有密切联系,而且与岩浆热液活动机理亦密切相关。本文便是从火山岩喷发相入手,结合火山矿床特征,把与上天梯-皇城山一带中生代火山岩相有关的已知金属、非金属矿床划分为与母山潜火山侵入活动有关、与皇城山浅成火山热液活动有关、和与杨家湾侵出活动有关的三个成矿系列,并对各成矿系列的典型矿床特征进行了详细论述。     

非参数地质统计学进展

地质统计学从解决固体矿产资源评价起源,应用领域迅速扩展。文章简要介绍了地质统计学的理论研究现状和应用现状。为了减轻人为因素在创建模型中的作用,非参数的地质统计学得到发展,文章重点介绍了非参数地质统计学的4种变异函数模型。此外,文章阐述了多点地质统计学的概念,这是一种用训练映像代替变异函数的地质统计学方法,使得地质现象的解释更直观。     

云南兰坪-维西地区铜矿床成矿地质条件研究

兰坪-维西地区属西南“三江”重要的有色金属成矿区(带),该区地质构造作用十分强烈且多期发生,基础地质与矿床研究相对薄弱。文章通过对该区地质勘查与科研成果的总结,讨论了铜矿床成矿地质条件。研究认为,脆性剪切变形作用与铜矿化关系密切,断裂活动有利于成矿作用的发生,成矿物质具有多源性。     

Mononodal indicator variography—Part II: Application to a computer-simulated deposit

The theory of mononodal variography developed in the preceeding paper is checked against a simulated deposit consisting of 60,500 grade values, called Stanford II. In the case of this deposit at least, assumptions underlying the concept of mononodal variography are borne out accurately. In particular, a linear relationship does exist indeed between indicator and grade variogram values of Stanford II at corresponding lags. Furthermore, such grade-indicator plots, and the information deduced from them, are robust under reduction of data at the mononodal cutoff. The method thus has predictive potential for grade variograms of highly variant deposits. Forecasting a grade variogram from the associated mononodal indicator variogram and grade-indicator plot is illustrated. Agreement with the experimental variogram is shown to be excellent.     

散射波地震方法在蔡家营多金属矿区的试验研究

地震方法技术应用在金属矿勘查中是一个难度很大的课题,由于金属矿所涉及到的地震地质条件十分复杂,常规的应用于层状介质的反射波地震勘探技术受到了挑战.利用散射波地震技术寻找深部隐伏金属矿是一种大胆的尝试.笔者结合在蔡家营多金属矿区的试验研究,试图从数据采集、数据处理和资料综合解释等方面探讨该方法技术的有效性.     

目标地质体的研究确定与找矿实践

基于以往多年的金属矿床勘查评价研究经验,系统总结20世纪80年代以来具有代表性的地质成矿理论和找矿方法。通过国内外金、镍、钼、铜、铅锌等找矿靶区优选、深边部找矿预测,以及勘查验证实例,阐述勘查找矿过程中的理论、实践及方法。提出对金属矿化分布规律的研究可以明晰矿床成因规律,对矿床成因规律的研究可以开拓找矿思路,明确金属矿化的分布规律。强调对金属矿化与地质体之间分布规律关系的研究,进而阐明了勘查找矿者要紧紧抓住矿带、矿床、矿体定位构造的主要因素、控矿的主要条件,来研究确定目标地质体,优化传统的和现代的最佳找矿方法和手段,以快速评价矿产资源。明确提出勘查找矿目标地质体是个纲,纲举目张促进矿产资源评价。     

大兴安岭成矿带北段区域地球化学背景与成矿带划分

大兴安岭成矿带是中国最重要的有色金属成矿带之一,资源潜力巨大,其北段是中国除新疆以外唯一存在地质空白的地区,矿产勘查与研究程度低。笔者通过对其区域地球化学场特征、大中型内生金属矿床分布规律、区域控矿地质条件的研究,初步认为本区优势内生金属矿产是钼矿、银铅锌矿,其次是金矿和铜矿,潜力矿种是铀矿;以德尔布干、鄂伦春-伊尔施两条深断裂为界,其两侧地球化学背景、成矿环境、矿种及成矿类型差异很大,并将大兴安岭成矿带北段划分为：德尔布干Ⅲ1、大兴安岭西坡Ⅲ2、嫩江Ⅲ3等3个Ⅲ级成矿亚带10个Ⅳ级成矿区。     

蒙-甘-新相邻(北山)地区两种新类型贵重金属矿床的发现及其意义

蒙甘新相邻(北山)地区地处塔里木、哈萨克斯坦-北山和西伯利亚板块交汇处,区内深大断裂纵横交错,各类岩浆岩分布广泛,金属矿床(点)星罗棋布,是我国北方最重要的金属矿化集中区之一.近几年来,随着该区矿产地质调查工作的全面开展,本区金属矿床理论研究和找矿勘查均获重要进展,特别是白山铼(钼)矿床和流沙山金(钼)矿床的发现与厘定,致使本区再度成为国内外矿床地质学家关注的"热点”.认真研究和分析上述2种新类型矿床的产出环境和地质特征,不仅有助于贵重金属矿床形成过程的了解,而且对在北山海西期岩浆岩发育区进一步寻找新类型贵重金属矿床具有重要指导意义.     

Effects of intrusions on grades and contents of gold and other metals in volcanogenic massive sulfide deposits

The reason some VMS deposits contain more gold or other metals than others might be due to the influence of intrusions. A new approach examining this possibility is based on examining the information about many VMS deposits to test statistically if those with associated intrusions have significantly different grades or amounts of metals. A set of 632 VMS deposits with reported grades, tonnages, and information about the observed presence or absence of subvolcanic or plutonic intrusive bodies emplaced at or after VMS mineralization is statistically analyzed.Deposits with syn-mineralization or post-mineralization intrusions nearby have higher tonnages than deposits without reported intrusions, but the differences are not statistically significant. When both kinds of intrusions are reported, VMS deposit sizes are significantly higher than in the deposits without any intrusions. Gold, silver, zinc, lead, and copper average grades are not significantly different in the VMS deposits with nearby intrusions compared to deposits without regardless of relative age of intrusive. Only zinc and copper contents are significantly higher in VMS deposits with both kinds of intrusive reported. These differences in overall metal content are due to significantly larger deposit sizes of VMS deposits where both intrusive kinds are observed and reported, rather than any difference in metal grades.