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1.
地球化学场分解的理论与方法 总被引：3，自引：0，他引：3
由于多期地质地球化学作用的相互叠加，地球化学场通常表现为复杂的叠加场。在叠加场内，元素组合的成因特征、变差函数的多级套合结构和多标度分形谱能有效地反映地质地球化学的多期性。相应地，用Ｒ型因子分析法、单变量因子克立格法和多标度分形谱便能有效地实现地球化学场的分解。 相似文献
2.
赵玉祥 《物探化探计算技术》1988,(3)
文章阐明基岩地球化学场可被分解为地球化学同生场和后生叠加场两部分,并应用地球化学理论和R型因子分析对北京八达岭地区进行了基岩地球化学场的分解,编制了同生场和后生叠加场地球化学图,在叠加场基础上编制了综合异常分区图,收到了良好的效果,使该区地球化学分布规律得出了新的认识。 相似文献
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多标度多形与地球化学场分解 总被引：3，自引：0，他引：3
在地球化学叠加场内，不同时期、不同规模的地质作用形成的地球化学景观具有不同的分形标度区间和分维。利用多标度方法把黑龙江省团结沟金矿外围的叠加地球化学场分解成了分别与北东向和北西构造相对应的地球化学正常场和异常场，并在此基础上讨论了地球化学场的演化。 相似文献
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多标度分形与地球化学场分解 总被引：3，自引：0，他引：3
在地球化学叠加场内，不同时期、不同规模的地质作用形成的地球化学景观具有不同的分形标度区间和分维。利用多标度分形方法把黑龙江省团结沟金矿外围的叠加地球化学场分解成了分别与北东向和北面向构造相对应的地球化学正常场和异常场，并在此基础上，讨论了地球化学场的演化。 相似文献
5.
地球化学模式及成因初探 总被引：4，自引：4，他引：4
如何对已发现的地球化学异常进行解释与评价，一直是困扰勘查地球化学家的难题。针对这一难题，笔者提出了地球化学模式的3种分类方案：规模分类、成因分类和成熟度分类。按照规模大小将地球化学模式分为：局部异常、区域异常、地球化学省、地球化学巨省和地球化学域， 同时将规模达地球化学省以上，并且内部具有套合结构特点的立体地球化学模式称作地球化学块体。地球化学模式依成因可分为原生地球化学模式和次生地球化学模式。成熟度分类是笔者首次提出，地球化学模式的成熟度是指地球化学异常相对于矿的关系而言的。笔者将地球化学模式按成熟度的不同，依次分为原始地球化学模式，中间地球化学模式和终极地球化学模式。提出成熟度分类是试图为科学利用所发现的地球化学模式进行异常解释与评价提供理论依据。 相似文献
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中国金的地球化学省及其成因的微观解释 总被引：3，自引：0，他引：3
利用全国1:20万区域化探扫面600×104km2和东天山、中蒙边界1:100万地球化学填图86×104km2的金分析数据,在全国圈定了15处金的地球化学省集中区,并发现与金矿成矿带或大型矿集区有关的地球化学省都具有多层套合结构特征。这种具有多层套合特征的地球化学省的形成是由高背景岩石、成矿作用和矿床风化产生的次生分散相互叠加的结果。高背景岩石提供了成矿元素的初始物源,成矿过程使得元素的进一步活化和富集,矿床风化产生元素的点源分散进一步形成叠加异常浓集中心,最后形成了具有多层套合的地球化学异常。通过使用微米和纳米观测手段发现地球化学样品中存在大量微米至纳米级金微粒,这种金微粒具有极强的活动性,能被各种营力作长距离搬运,形成了大规模具有多层套合特征的金地球化学省。 相似文献
8.
圈定地球化学异常是勘查地球化学和环境地球化学研究中的一项基础性工作。笔者通过详细分析近30年来与地球科学密切相关的分形和多重分形等现代非线性理论和新方法的迅速发展和应用,特别是以解决地球化学复杂背景与叠加异常分解难题为例,介绍了广义自相似理论与分形滤波技术的发展和应用,相信在资源、环境、灾害的其他应用领域也将发挥重要影响。文中阐明了多重分形是更具普适性的地球化学元素分布模式,"密度-面积"分形模型是刻画地球化学异常的基础模型,并为多个空间开展分形滤波和分解地球化学复杂背景与叠加异常的理论基础。该方法的显著优势在于将地球化学场的各向异性、尺度不变性、广义自相似性等特征集于一体,具有压制变化性背景干扰,突出局部异常的能力,其中C-A和S-A业已广泛应用于矿产勘查靶区圈定和环境污染模式识别,形成了分解地球化学复杂背景和叠加异常的常用技术,在国内外多个成矿区带取得了显著的找矿效果。 相似文献
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地球化学场的叠加与分解一直是地质工作者的重要研究内容之一,按成因可分为地球化学同生场和地球化学叠加场两部分.同生场反映了成岩作用的元素分布,叠加场反映了后期蚀变矿化叠加作用的元素分布.两者代表的是性质和意义截然不同的两种地质过程,应用因子分析方法通过对元素组合的专属性可以推断出地质成因和地球化学作用的过程,借助因子分析模型进行“逆演”实现地球化学场的分解.结合趋势面分析方法再现出局部异常,并形成一套关联的图件,对成矿预测、地质找矿及成矿规律的研究具有实用意义,同时证明分解后的地球化学场找矿意义更明确,找矿效果更好. 相似文献
10.
地球化学场及其在隐伏矿体三维预测中的作用 总被引：1，自引：1，他引：0
本文从物理学"场论"的角度介绍了地球化学场的概念,并从场源、场作用及地球化学指标分布三个基本要素出发阐述了地球化学场的扩散、对流-扩散的动力学机制。首先,按照采样介质,将地球化学场分为原生的岩石地球化学场,以及次生的土壤、水系沉积物、水文和气体地球化学场,描述了组成各类地球化学场的要素。其次,将地球化学场的分析方法概括为静态的空间结构分析和动态的时空结构分析两种,提出要以场的动力学机制为基础,利用地球物理学中的正、反演理论来研究四维时空中地球化学场的发展和演化。最后,探讨了地球化学场时空结构分析与三维地学模拟两者之间彼此补充和相互验证的关系,三维地学模拟构建的场源及空间介质模型,为地球化学场的正、反演提供了初始条件,地球化学场反演的结果又可用来修正三维地质模型;探讨了地球化学场与大数据分析技术间的关系,即采用大数据的"数据驱动"的思路来挖掘其与多元地学数据之间的隐性联系,探索其与成矿过程的关联性。地球化学场与三维地学模拟、大数据分析技术的结合将为隐伏矿体三维预测中地下成矿物质的分布和演化提供依据。 相似文献
11.
Estimating Variogram Uncertainty 总被引：10，自引：0，他引：10
The variogram is central to any geostatistical survey, but the precision of a variogram estimated from sample data by the method of moments is unknown. It is important to be able to quantify variogram uncertainty to ensure that the variogram estimate is sufficiently accurate for kriging. In previous studies theoretical expressions have been derived to approximate uncertainty in both estimates of the experimental variogram and fitted variogram models. These expressions rely upon various statistical assumptions about the data and are largely untested. They express variogram uncertainty as functions of the sampling positions and the underlying variogram. Thus the expressions can be used to design efficient sampling schemes for estimating a particular variogram. Extensive simulation tests show that for a Gaussian variable with a known variogram, the expression for the uncertainty of the experimental variogram estimate is accurate. In practice however, the variogram of the variable is unknown and the fitted variogram model must be used instead. For sampling schemes of 100 points or more this has only a small effect on the accuracy of the uncertainty estimate. The theoretical expressions for the uncertainty of fitted variogram models generally overestimate the precision of fitted parameters. The uncertainty of the fitted parameters can be determined more accurately by simulating multiple experimental variograms and fitting variogram models to these. The tests emphasize the importance of distinguishing between the variogram of the field being surveyed and the variogram of the random process which generated the field. These variograms are not necessarily identical. Most studies of variogram uncertainty describe the uncertainty associated with the variogram of the random process. Generally however, it is the variogram of the field being surveyed which is of interest. For intensive sampling schemes, estimates of the field variogram are significantly more precise than estimates of the random process variogram. It is important, when designing efficient sampling schemes or fitting variogram models, that the appropriate expression for variogram uncertainty is applied. 相似文献
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The variogram matrix function is an important measure for the dependence of a vector random field with second-order increments, and is a useful tool for linear predication or cokriging. This paper proposes an efficient approach to construct variogram matrix functions, based on three ingredients: a univariate variogram, a conditionally negative definite matrix, and a Bernstein function, and derives three classes of variogram matrix functions for vector elliptically contoured random fields. Moreover, various dependence structures among components can be derived through appropriate mixture procedures demonstrated in this paper. We also obtain covariance matrix functions for second-order vector random fields through the Schoenberg–Lévy kernels. 相似文献
14.
Spatial Connectivity: From Variograms to Multiple-Point Measures 总被引：3，自引：0，他引：3
Anisotropy and curvilinearity are common characteristics of geological structures. Traditional measures of connectivity such as the variogram are rectilinear in that they do not take into account the curvilinearity of these structures. Recent developments in geostatistics have demonstrated and simulated the effect of curvilinearity and multiple-point (mp) connectivity on the output of transfer functions such as flow simulators. A set of curvilinear channels and set of elliptical lenses may share the same variogram and rectilinear connectivity but would yield different flow responses because of their different curvilinearity. A measure of curvilinearity generalizing the variogram measure is therefore proposed. The proposed measure is directional with a tolerance cone and depends on distance with a tolerance, as with an experimental variogram. 相似文献
15.
Automatic Variogram Modeling by Iterative Least Squares: Univariate and Multivariate Cases 总被引：2，自引：1，他引：1
In this paper, we propose a new methodology to automatically find a model that fits on an experimental variogram. Starting with a linear combination of some basic authorized structures (for instance, spherical and exponential), a numerical algorithm is used to compute the parameters, which minimize a distance between the model and the experimental variogram. The initial values are automatically chosen and the algorithm is iterative. After this first step, parameters with a negligible influence are discarded from the model and the more parsimonious model is estimated by using the numerical algorithm again. This process is iterated until no more parameters can be discarded. A procedure based on a profiled cost function is also developed in order to use the numerical algorithm for multivariate data sets (possibly with a lot of variables) modeled in the scope of a linear model of coregionalization. The efficiency of the method is illustrated on several examples (including variogram maps) and on two multivariate cases. 相似文献
16.
以多重分形理论为基础,对中天山乌拉斯台地区铜多金属元素的岩屑测量数据,采用C-A法获得铜多金属的异常下限值,将其作为阈值进行指示克里格插值,绘制研究区的铜多金属地球化学异常图。研究显示,基于该方法获得的Cu矿化异常高值区主要集中在华力西早期第三侵入次的石英闪长岩和花岗闪长岩岩体中,受北西向和次级北东向断裂构造控制明显,该异常区可以作为寻找热液型铜多金属矿产的重要远景区。该方法对于地球化学数据空间变异性强烈的地区,较之普通克里格插值法具有更好的地球化学异常识别能力和高值信息重建能力,所得结果的最高累计频率值范围与已知矿化点的空间位置吻合度更高,在地球化学异常信息提取工作中具有推广意义。 相似文献
17.
Four variogram models for regional groundwater geochemical data are presented. These models were developed from an empirical study of the sample variograms for more than 10 elements in groundwaters from two geologic regions in the Plainview quandrangle, Texas. A procedure is given for the estimation of the variogram in the isotropic and anisotropic case. The variograms were found useful for quantifying the differences in spatial variability for elements within a geologic unit and for elements in different geologic units. Additionally, the variogram analysis enables assessment of the assumption of statistical independence of regional samples which is commonly used in many statistical procedures. The estimated variograms are used in computation of kriged estimates for the Plainview quadrangle data. The results indicate that an inverse distance weighting model was superior for prediction than simple kriging with the particular variograms used. 相似文献
18.
Assessment of the sampling variance of the experimental variogram is an important topic in geostatistics as it gives the uncertainty of the variogram estimates. This assessment, however, is repeatedly overlooked in most applications mainly, perhaps, because a general approach has not been implemented in the most commonly used software packages for variogram analysis. In this paper the authors propose a solution that can be implemented easily in a computer program, and which, subject to certain assumptions, is exact. These assumptions are not very restrictive: second-order stationarity (the process has a finite variance and the variogram has a sill) and, solely for the purpose of evaluating fourth-order moments, a Gaussian distribution for the random function. The approach described here gives the variance–covariance matrix of the experimental variogram, which takes into account not only the correlation among the experiemental values but also the multiple use of data in the variogram computation. Among other applications, standard errors may be attached to the variogram estimates and the variance–covariance matrix may be used for fitting a theoretical model by weighted, or by generalized, least squares. Confidence regions that hold a given confidence level for all the variogram lag estimates simultaneously have been calculated using the Bonferroni method for rectangular intervals, and using the multivariate Gaussian assumption for K-dimensional elliptical intervals (where K is the number of experimental variogram estimates). A general approach for incorporating the uncertainty of the experimental variogram into the uncertainty of the variogram model parameters is also shown. A case study with rainfall data is used to illustrate the proposed approach. 相似文献
19.
Changik Han Jiyang Wang Mingguo Zheng Ende Wang Jianming Xia GwangSu Li Sunchol Choe 《Earth Science Informatics》2016,9(2):197-213
A critical step for kriging in geostatistics is estimation of the variogram. Traditional variogram modeling comprise of the experimental variogram calculation, appropriate variogram model selection and model parameter determination. Selecting of the variogram model and fitting of model parameters is the most controversial aspect of geostatistics. Shapes of valid variogram models are finite, and sometimes, the optimal shape of the model can not be fitted, leading to reduced estimation accuracy. In this paper, a new method is presented to automatically construct a model shape and fit model parameters to experimental variograms using Support Vector Regression (SVR) and Multi-Gene Genetic Programming (MGGP). The proposed method does not require the selection of a variogram model and can directly provide the model shape and parameters of the optimal variogram. The validity of the proposed method is demonstrated in a number of cases. 相似文献
20.
用变差函数研究重磁场的区域变化特征.变差函数的变程反映重磁场的相干范围, 块金效应反映随机干扰, 基台值反映变异程度.重磁场的理论模拟说明: 重力场的相干范围大于磁场, 重磁场变程主要取决于场源深度, 浅源重磁场变差函数近似为球状模型或指数模型, 深源重磁场近似为连续性更好的高斯模型.磁场场源深度近似等于变程的一半, 重力场场源深度近似等于变程的四分之一.湖北大冶铁矿垂直分量磁异常具有几何各向异性, 北西-南东走向, 变差函数推测磁铁矿平均深度为250m.磁异常小波多尺度分解细节和逼近部分磁场具有协调几何各向异性, 变差函数的各阶场源深度估计结果与功率谱估计结果吻合. 相似文献