枪马金矿金品位统计分布特征及其地质意义

地质变量的变化与地质体的特征密切相关,通过地质变量的研究可以揭示地质体某一特征的规律性。多次地质事件的数理统计特征表现为多个总体叠加的混合分布,因此通过研究混合分布和单一分布的特征,对矿床的矿化成因、矿化过程和矿化特征认识有指导意义。研究发现,枪马金矿的金品位主要由2个对数正态分布总体叠加而成,并对应于本区2次主要的成矿事件。对金的特征参数垂直空间上的研究表明,金矿化强度向深部逐渐增高,深部找矿远景很大。     

峪耳崖金矿床元素地球化学地质统计分析

峪耳崖金矿床为大型－特大中温热液型金矿床，形成于燕山中晚期，金矿脉包括两种自然类型，即脉型和细脉网脉浸染型，通过对金的统计分布特征和空间分布特征的研究，认为金矿化为一个矿化期两个矿化阶段，金品位由对应于矿化阶段的两个对数正态分布总体混合而成，在垂向空间上各空间段的金品位都是由两个对数正态总体控一定比例叠加而成；三个矿化带在垂向空间依次向下分布，矿化强度随标高减小而增高，综合考虑相关分析，聚类分析，模糊聚类分析的结果，提炼出与金矿化密切相关的最佳地球化学标志组合，运用回归分析，模型出原生金矿化元素地球化学模型，利用变异指数法确定了矿体原生晕垂向分带。     

高龙金矿金品位统计分布特征及其对深部矿化信息的指示

通过对高龙金矿鸡公岩矿段各中段金品位数据进行的初步数理统计研究，发现矿化标志X1和t1随着矿体深度的加深而逐渐变小，说明金矿化强度自上而下有逐渐减弱的趋势；变异系数V则随深度的加大逐渐变大，表明向深部金的矿化愈来愈不稳定。这三项参数的变化特征表明，矿化向深部渐弱，最后可能逐渐消失。     

甘肃合作早子沟金矿床品位变化规律及特征探讨

早子沟金矿床是近年来在西秦岭地区发现的又一特大型金矿床。文章通过对该矿区矿体的矿化强度指数、品位变化规律的统计计算,建立了矿体金品位变异函数模型,分析研究了矿体金品位分形分布特征及矿体金金属量-平均品位特征。金品位变化规律及特征的研究表明,金矿体在深部向北东侧伏,金矿体品位呈波状变化,矿体金品位的对数转换分布基本服从正态分布,变异函数模型显示具有各向异性,北东55°方向为矿化最连续方向;金品位分形结构特征研究表明,对矿区资源储量贡献最大的矿石类型是石英细脉-网脉脉岩型矿石,脉岩与地层的内、外接触带及部分含矿小岩脉应是今后勘查的重点,沿倾向金品位具有明显的等间距变化特征,向北东方向每隔140~260 m将会出现富矿段。基于以上认识,结合矿体产出的空间位置、控矿构造条件,探讨了矿床深部找矿方向,总结了今后的勘查重点部位及重要的岩性组合。     

墨江金厂金矿床金元素空间富集规律研究

运用数理统计和地质统计学方法,从矿区地层岩性、构造、岩浆岩、矿体的空间分布等方面研究了墨江金厂金矿床金元素的空间富集规律。结果表明,金元素空间分布总体上遵循左偏对数正态分布,为两个正态分布的混合,金品位平均值分布区构成了矿化区的主体;金矿体较集中分布于三叠系底板起伏较大的地段,富集方向主要呈北西、北西西向,矿体厚度、品位变化大;北西向断层组较北北西向断层组易于金元素的矿化富集,形成大矿体;矿体金品位一般有远离岩体升高、靠近岩体降低的趋势。     

山东寺庄金品位参数统计和分形特征及其对矿化信息的指示

采集寺庄金矿区82个钻孔的金品位数据4597个,按照100m的标度分析其在垂向上的均值、标准差、变异系数和大于工业品位的矿石所占比例等统计参数,对比其在垂向上的分形分维值特征,发现如下规律：寺庄金矿区深部矿体明显优于浅部矿体,以-700- -800m区间为矿化中心,垂直分布至少500m以上;通过围岩蚀变分带特征、矿石组合特征、井下脉体相互穿插关系和金品位分形分维值研究,说明该区金成矿时间上至少经历了3次地质成矿作用的叠加,其中显著成矿作用发生在后2次,在空间上深部（-1000m以下）具有较大的找矿潜力;金品位分形分维特征能较好地划分成矿阶段,在同一个成矿阶段,分维值越小,矿化作用越好,在同一个成矿区间,分维值越大,成矿作用越好。     

山东龙口大磨曲家金矿床302 脉深部成矿预测

大磨曲家金矿床位于玲珑金矿田北端。区内共产出大小金矿脉23 条,其中302 脉为主要的开采矿脉,含3 个工业矿体。矿体主要产于主断裂面下盘,由黄铁绢英岩化碎裂岩组成,呈似层状或透镜体状。通过对302 脉矿体厚度、金品位及矿脉米克吨值等分析,矿脉在深部自南向北有较好的金矿化显示,是深部隐伏矿体的找矿标志。矿体厚度在垂向变化上显示由74 线到98 线逐渐降低。根据这些找矿标志,在302 脉深部预测5 处找矿靶区。     

山东平邑卓家庄金矿金品位的分形结构特征及意义

卓家庄金矿为隐爆角砾岩型金矿床,主要矿石类型可分为４种：矿浆胶结隐爆角砾岩矿石、热液胶结隐爆角砾岩矿石、熔浆胶结隐爆角砾岩矿石、凝灰质胶结隐爆角砾岩矿石。金品位分形结构研究表明,该矿床具有多次分形结构及规律性变化特点,反映了多次矿化叠加的特点,并预示了深部矿化的存在。     

胶东地区岩浆热液型金矿成矿流体演化与成矿预测

胶东地区岩浆热液型金矿的成矿作用不是一次完成的，成矿作用的多阶段活动不仅表现在矿石结构构造上，包裹体观测表明，在同一包体片中，甚至在同一石英颗粒上经常见有不同类型的原生包裹体。这表明成矿作用过程中深部上升的富含CO2热液与断裂内原地水频繁发生混合作用，即成矿流体是多次脉动式注入的。脉动式叠加矿化的找矿意义是成矿场的垂向迁移。即早期金矿化倾向于分布在浅部，随着时间的推移，成矿温度下降，在矿场向深部迁移，矿化深度增加。因此剖面上存在多个矿化富集段，富集段与贫化段相同分布。     

浅谈峪耳崖金矿花岗岩的成矿作用

简述了峪耳崖金矿地质特征。认为二拨子东沟金矿与峪耳崖金矿属同一类型，以此为例提出了上部白色花岗仅为成矿提供容矿构造，深部晚期侵入的富碱红色花岗岩是金矿物质的直接提供者。根据这种观点预测含矿花岗岩深部应有富硅富碱花岗岩体和隐伏矿体存在，对含金花岗岩体深部探矿和采矿提出了建议。     

使用“对数正态分布”时易犯的错误

本文对对数正态分布的数学含义及其与原始分布之间的关系作了重新说明，纠正了目前化探中使用对数正态分布假设时常犯的一个错误。     

Reality of the relation between geological objects and mathematical models

Mathematical models and their targets are considered. The results provide an explanation why the shape of the density distribution function is dependent upon both size of the geological object and number of observations. These results have importance both for preparative and interpretative phases of prospecting.     

Models of breakage and selection for particle size distributions

It is generally agreed that particle size distributions of sediments tend ideally to approximate the form of the lognormal probability law, but there is no single widely accepted explanation of how sedimentary processes generate the form of this law. Conceptually, and in its simplest form, sediment genesis involves the transformation of a parent rock mass into a particulate end product by processes that include size reduction and selection during weathering, transportation, and deposition. The many variables that operate simultaneously during this transformation can be shown to produce a distribution of particle sizes that approaches asymptotically the lognormal form when the effect of the variables is multiplicative. This was first shown by Kolmogorov (1941). Currently available models combine breakage and selection in differing degrees, but are similar in treating the processes as having multiplicative effects on particle sizes. The present paper, based on careful specification of the initial state, the nth breakage rule and the nth selection rule, leads to two stochastic models for particle breakage, and for both models the probability distributions of particle sizes are obtained. No attempt is made to apply these models to real world sedimentary processes, although this topic is touched upon in the closing remarks.     

Disjunctive kriging revisited: Part II

In order to find distributions other than infinitely divisible distributions which are suitable for disjunctive kriging, infinitesimal generators are used. In addition to distributions developed in Part I, this leads to development of suitable models for the beta (), hypergeometric, and binomial distributions.     

On the character of distribution of chemical elements in nature

Distribution of chemical elements in nature is controlled by the general physical-chemical state of natural processes, a result of the effort to reach thermodynamic equilibrium. Natural processes, forming geologic objects (e.g., rocks, ores) usually do not reach total chemical equilibrium. This is reflected in distributions of chemical elements in nature. We recognize symmetric as well as asymmetric distributions. The question arises, what distribution in nature is most commonly followed? Evidently, this should be a distribution of chemical elements in thermodynamic equilibrium throughout the system, thus with maximum entropy. This paper notes that Gauss's normal distribution may be derived from statistic explanation of entropy as a function of contnt of chemical elements in a system with application of Einstein's formula.     

Disjunctive kriging revisited: Part I

Difficulties in applying disjunctive kriging (D.K.) with an anamorphosis to a normal distribution have led to an interest in D.K. based on other distributions. After reviewing Gaussian D.K., this paper reviews other types of D.K. based on other infinitely divisible distributions (gamma, Poisson, and negative binomial).     

Use of the truncated shifted Pareto distribution in assessing size distribution of oil and gas fields

The truncated shifted Pareto (TSP) distribution, a variant of the two-parameter Pareto distribution, in which one parameter is added to shift the distribution right and left and the right-hand side is truncated, is used to model size distributions of oil and gas fields for resource assessment. Assumptions about limits to the left-hand and right-hand side reduce the number of parameters to two. The TSP distribution has advantages over the more customary lognormal distribution because it has a simple analytic expression, allowing exact computation of several statistics of interest, has a J-shape, and has more flexibility in the thickness of the right-hand tail. Oil field sizes from the Minnelusa play in the Powder River Basin, Wyoming and Montana, are used as a case study. Probability plotting procedures allow easy visualization of the fit and help the assessment.This paper was presented at Emerging Concepts, MGUS-87 Conference, Redwood City, California, 13–15 April 1987.     

Substitution Random Fields with Gaussian and Gamma Distributions: Theory and Application to a Pollution Data Set

This paper presents random field models with Gaussian or gamma univariate distributions and isofactorial bivariate distributions, constructed by composing two independent random fields: a directing function with stationary Gaussian increments and a stationary coding process with bivariate Gaussian or gamma distributions. Two variations are proposed, by considering a multivariate directing function and a coding process with a separable covariance, or by including drift components in the directing function. Iterative algorithms based on the Gibbs sampler allow one to condition the realizations of the substitution random fields to a set of data, while the inference of the model parameters relies on simple tools such as indicator variograms and variograms of different orders. A case study in polluted soil management is presented, for which a gamma model is used to quantify the risk that pollutant concentrations over remediation units exceed a given toxicity level. Unlike the multivariate Gaussian model, the proposed gamma model accounts for an asymmetry in the spatial correlation of the indicator functions around the median and for a spatial clustering of high pollutant concentrations.     

地震作用下边坡动力响应的数值模拟研究

汶川地震中在硬岩、次硬岩区域出现的一些大规模斜坡破坏现象超出了以往对地震作用下边坡稳定性问题的认识。本文使用FEPG有限元程序分析了水平和垂直2种不同加载方式作用下,经过不同的震动持续时间,不含裂隙岩质坡体内部的应力场和位移场的变化规律。得出的结论认为,在输入震动振幅为0.1m的加载作用下,岩质边坡内部的应力和位移均出现极值:在边坡的顶部及坡面上最大拉伸应力值大于100MPa,超过了花岗岩、灰岩等硬岩、次硬岩的抗拉强度,可能使岩体产生破裂发生崩塌、滑坡灾害。研究结果还表明,与水平方向振动加载相比,垂直方向振动加载产生的响应结果要大,边坡顶端一点的在垂直方向位移的峰值达到0.43m,远远超过了输入的震动振幅,垂直方向的震动是引起边坡的不稳定的主要因素。此外,震动持续时间越长,造成的变形和破坏就越大。