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Semi-hierarchical correspondence cluster analysis and regional geochemical pattern recognition 总被引：3，自引：0，他引：3
Hongjin Ji Daoming Zeng Yanxiang Shi Yangang Wu Xisheng Wu 《Journal of Geochemical Exploration》2007,93(2):109-119
Semi-hierarchical correspondence cluster analysis (SHCCA), firstly developed in this paper, extracts the main advantages of correspondence analysis, hierarchical and non-hierarchical cluster analysis, and unifies the R- and Q-mode cluster analysis of large data set. A systemic program to recognize the regional geochemical patterns is built up based on this method. With this program, the complex tasks for data interpretation can be achieved by simple processes, and important geochemical information can be displayed by a single diagram, i.e. the multivariate regional geochemical image. As one of the applied examples of this program, the regional geochemical pattern recognition for a shallow covered area around Tahe in Heilongjiang Province is introduced. The results show that many hidden geochemical patterns related to the lithologies, structures, ore-forming conditions and prospecting targets etc are revealed by the geochemical image, and that the main geochemical patterns are related with certain geological and gravitational patterns. By finding contrasts between geochemical patterns and geological or gravitational patterns, the SHCCA results assist the geological mapping in this area. Geochemical data obtained in Chinese regional geochemical exploration provides useful information regarding geology and minerals, and the method described in this paper provides a new way to examine this type of resource. 相似文献
2.
铜石金矿田地球化学找矿模型 总被引：6，自引：1，他引：6
从基岩地球化学及水系沉积物地球化学的角度研究了铜石金矿田金的异常特征。运用对应聚类、因子分析和马氏距离等多元统计分析方法进一步研究了金组合元素异常特征，建立了归来庄金矿环、线叠加地球化学异常找矿模型。 相似文献
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分形奇异(特征)值分解方法与地球物理和地球化学异常重建 总被引：15，自引：4，他引：11
地球物理和地球化学异常是找矿的重要依据.地球物理和地球化学异常取决于地层、构造在成矿时间上的多样性与空间上排列、叠置的复杂性.地层、构造因素是构造、岩浆、沉积与成矿地球化学等多种动力学过程的综合反映.这些岩石和构造的因素以及动力过程相互渗透和影响决定了最终地质、地球物理与地球化学场.本文提出的在GIS环境下实现的分形奇异值分解(MSVD) 异常重建方法, 不仅可以提取地球物理和地球化学等异常, 而且能够进一步刻画其中的线性和环状构造、细微的局部纹理结构特征.该方法首先对地球物理和地球化学等网格数据进行二维矩阵的奇异值分解, 之后用左特征向量矩阵与右特征向量矩阵的直积构造一个正交完备基.地球物理和地球化学二维数据可以投影到该正交基上, 其投影系数是矩阵的奇异值.在该正交完备空间的某些子空间上对地球物理和地球化学等数据进行滤波.为了选择子空间, 本文定义了上述正交完备基中的能谱密度、能谱半径(或尺度) 与能量测度.在此基础上与空间域及频率域类比, 探讨了能量测度与能谱密度呈现分形(fractal和bifractal) 规律.利用分形关系的间断点, 设计分形奇异值重建算子, 实现对地球物理和地球化学异常的分解.以加拿大NovaScotia南部布格重力异常与As地球化学异常为例, 采用MSVD方法分解Au、Wu -Sn -U等已知矿有关的地球化学异常.发现重建异常能很好地用于解释已知矿点的分布规律.重建的地球化学异常显现了地球化学中的线状和环状异常; 重建的布格重力异常有效勾勒出原图中不易发现的纹理结构, 这些纹理结构可以合理地解释已知矿点在侵入岩体内及其周围的分布规律.应用实例表明, 该方法不仅可以从起因复杂的异常中区分出背景、异常场, 还可以识别代表了成矿源岩、流体、运移通道、赋存空间等异常因素引起的纹理、结构与构造特征.同时实现了GIS环境下交互可视化的MSVD处理与解释系统, 增强了地质异常定量分析的实用性与可操作性. 相似文献
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为利用矿区地球化学数据进行找矿靶区预测,采用了对应聚类分析方法。以山东省平度地区旧店金矿3号脉的实例,说明该方法的实施过程和应用效果。结果表明,该方法以简单步骤和单一图件揭示了在多元地球化学数据中隐藏的核心信息,正确识别了元素含量较低地段的隐伏矿体,为隐伏矿靶区预测探索了一种新的途径。 相似文献
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Vijay S. Tripathi 《Journal of Geochemical Exploration》1979,11(3):263-275
Soil samples collected in the vicinity of a small sulfide mineralization were analyzed for Cu, Zn, Cd, Pb, Ag, Mn, Ni, Co, Cr, and Mo. Factor analysis was used to study the interrelationships among these variables. Selective removal of some samples prior to factor analysis proved to be an important tool in exposing “hidden” relationships between samples, variables, and factors. It has been demonstrated that factor analysis is a suitable technique for data reduction in geochemical exploration since factor scores can be used, instead of raw variables, for interpretation of field observations and location of anomalies. 相似文献
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U. Kramar 《Journal of Geochemical Exploration》1995,55(1-3)
In stream sediment and soil surveys, samples represent mixtures of components from different geological environments. Such mixed samples are misclassified when using conventional “hard” cluster methods. In fuzzy clustering, each sample is allowed to belong to several clusters. Similar to element concentrations, these cluster contributions can be displayed in contour maps (e.g. kriging maps). The amount of an element that is explained by the cluster contribution and element residuals can be calculated. The modified fuzzy clustering algorithm called “limited fuzzy clusters” used in this paper avoids negative residuals.Stream sediment data of Sierra de San Carlos, Tamaulipas, Mexico are used to demonstrate the possibilities of limited fuzzy clustering in geochemical exploration and mapping. From the different drainage systems, 681 stream sediment samples were taken and analyzed for 24 elements. A nineteen-element data set was used to calculate limited fuzzy clusters and element residuals. The contribution values for the clusters and element residuals are displayed in contour maps. All geological units were outlined by the cluster contributions. Extended anomalies are characterized by their own cluster. Small anomalies are clearly identified from the element residuals. 相似文献
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我国积累的大量高质量、多元素、多尺度的地球化学数据,为矿产勘查与环境评价提供了有效的数据支撑。如何对这些数据进行二次开发和再利用,提取有价值的地球化学异常信息并带动找矿突破,是缓解当前矿产资源短缺的重要途径之一。在覆盖区和深部的找矿实践中,由于矿体埋深和覆盖层的影响,往往在表生介质中形成弱小的地球化学异常,识别和评价弱小地球化学异常是当前勘查地球化学数据处理的重要方向之一。本文围绕地球化学异常信息的提取和评价,主要从以下几个方面讨论了相关的国内外研究进展和发展趋势:勘查地球化学数据处理与异常识别方法和模型,勘查地球化学数据闭合效应的影响及其解决方案,基于大数据和机器学习的勘查地球化学数据处理以及弱小地球化学异常的识别和评价。研究发现,在地质环境的约束下,基于大数据思维和机器学习相结合的方法,注重地球化学空间分布模式与已发现矿床的相关关系,同时使用所有地球化学变量能有效刻画具有非线性特征的地球化学空间分布模式,可识别出传统方法无法识别的异常,为开展地球化学空间模式识别与异常提取提供了新的途径。 相似文献
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通过选取描述油气化探综合异常的各种特征参量，借助模糊数学工具，利用最优聚类中心所具有的代表特征，建立分级指标，对油气化探综合进行分级评价。鄂尔多斯盆地油气化探综合异常的评价实例结果表明，利用油气化探综合异常各种特征参量进行动态聚类分级评价是可行的。 相似文献
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在地球化学样品多元素分析过程中,为了实现地球化学异常点抽查和整批测试质量监控的双重目的,本文提出了一种基于地球化学异常统计的多区间分元素组异常点抽样方法。该方法主要包括:(1)按照正态分布或对数正态分布假设,对各元素,将该元素的测量值集,划分为离群低值区间、累积频率分布区间(有多个区间)和离群高值区间,统计每个样品中各元素测量值所属区间;(2)将测量元素分为几个元素组,统计各元素组中每个样品的总异常元素数、高异常元素数和低异常元素数;(3)对Au元素组,设置各个区间的抽检比例,随机抽取异常点抽检样品;对其他元素组,按照"总异常元素数"为第一顺序、"高异常元素数"为第二顺序和"低异常元素数"为第三顺序,按降序排序所有样品,顺序抽取异常点抽检样品;(4)必要时进行分析批补充抽检样品。该方法兼顾了地球化学异常和实验室测试"异常"的抽查;同时考虑非异常点抽查和分析批平衡抽检,有效解决了有限抽样数量和抽样代表性不足两者之间的矛盾;并开发了EXCEL应用程序,应用于实验室地球化学样品分析异常点抽检取得了满意效果。 相似文献
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Geochemical data are typical compositional data which should be opened prior to univariate and multivariate data analysis. In this study, a frequency-based method (robust principal component analysis, RPCA) and a frequency-space-based method (spectrum–area fractal model, S–A) are applied to explore the effects of the data closure problem and to study the integrated geochemical anomalies associated with polymetallic Cu mineralization using a stream sediment geochemical dataset collected from the Zhongteng district, Fujian Province (China). The results show that: (1) geochemical data should be opened prior to RPCA to avoid spurious correlation between variables; (2) geochemical pattern is a superimposition of multi-processes and should be decomposed; and (3) the S–A fractal model is a powerful tool for decomposing the mixed geochemical pattern. 相似文献
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区域化探原生背景与异常形成于相互独立的地质过程。在岩性复杂区,不同地质单元内背景与异常的成因可能完全不同,划定统一的背景上限显然是不科学的,合理的解决方案是分区确定化探背景上限。这里提出一种采用主要造岩元素为指标,采用快速聚类分析方法划分地质单元并分别计算背景上限的简便方法。以1:200 000郴县幅化探数据为例进行试验,结果表明,该方法能有效地去除不同地质体类型背景对异常的影响,不仅能突出矿区异常,也能削弱高背景区非矿致异常,缩小靶区面积,识别微弱异常。 相似文献
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Xu Yaguang Cheng Qiuming Department of Earth Atmospheric Science York University North York Ontario Mj P Canada 《中国地质大学学报(英文版)》2000,11(2)
The commonesttask in m ineral exploration is to separateanomalies to reflect distinct geochemical processes (and geo-physical objects) such as m ineralization of various types.Thispaper introduces the recently- developed“multifractal- spec-trum”filters(MSF) for separating various types of geochemi-cal and geophysical anomalies from their the background basedon the distributions of their two- dimensional power spectra(Cheng et al.,1999) . The processing of lake- sediment geo-chemical data an… 相似文献
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为了进行地球化学异常的识别与提取,针对化探数据的特点,本文提出了一种将高维降维技术——投影寻踪分类(PPC)模型与实数编码遗传算法(RCGA)相结合的计算方法,分析了运用RCGA-PPC模型进行化探异常识别与提取的关键技术问题,并在MATLAB环境下开发了该方法的软件应用模块。以云南个旧地区水系沉积物地球化学数据为例,选取区域内Sn、Cu、Pb、Zn、As、Cd等主要成矿元素及与成矿关系密切的9种元素作为计算变量,利用RCGA-PPC模型对其进行处理和异常识别。研究表明:RCGAPPC模型中最佳投影值较高的地区与该区域实际矿床(点)吻合情况较好。该模型对化探异常的识别能力较强,是一种有效的化探多元素综合异常识别与提取方法。 相似文献
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Three discriminant function models are raised and cross-compared in order to distinguish geochemical patterns characteristic
for the Drava River floodplain sediments. Based on data representing total element concentrations in samples collected from
alluvium (A), terrace (T), and unconsolidated bedrock (B) at the border of a floodplain, four element clusters emerged accounting
for discrimination between the referred groups of sediments. The most prominent is contaminant/carbonate cluster characteristic
for alluvium. The other two are: silicate cluster typical for unconsolidated geological substrate (Neogene sedimentary rocks);
and naturally dispersed heavy metal cluster separating terrace from the former two groups. Models introducing depth intervals
and single profiles as grouping criteria reveal identical sediment-heavy metal matrices. The second important issue of this
paper is possibility of reclassification of samples originally assigned to one of the a priori defined groups of sediments,
based on established geochemical pattern. The mapped geological units can be reconsidered by the post hoc assignments to a
different group if geological border between alluvium and terrace or between terrace and bedrock can not be established geologically
with absolute certainty. 相似文献
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The threshold between geochemical background and anomalies can be influenced by the methodology selected for its estimation. Environmental evaluations, particularly those conducted in mineralized areas, must consider this when trying to determinate the natural geochemical status of a study area, quantifying human impacts, or establishing soil restoration values for contaminated sites. Some methods in environmental geochemistry incorporate the premise that anomalies (natural or anthropogenic) and background data are characterized by their own probabilistic distributions. One of these methods uses exploratory data analysis (EDA) on regional geochemical data sets coupled with a geographic information system (GIS) to spatially understand the processes that influence the geochemical landscape in a technique that can be called a spatial data analysis (SDA). This EDA–SDA methodology was used to establish the regional background range from the area of Catorce–Matehuala in north-central Mexico. Probability plots of the data, particularly for those areas affected by human activities, show that the regional geochemical background population is composed of smaller subpopulations associated with factors such as soil type and parent material. This paper demonstrates that the EDA–SDA method offers more certainty in defining thresholds between geochemical background and anomaly than a numeric technique, making it a useful tool for regional geochemical landscape analysis and environmental geochemistry studies. 相似文献
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近年来钴资源的战略地位急剧提升,钴资源勘查也日益受到重视.但钴的成矿作用特殊,极低密度地球化学填图能否为钴资源勘查提供可靠依据有待研究.对全国基准计划获得的深层汇水域沉积物钴地化异常开展研究,建立矿床与异常空间位置指数,定量评价矿床与异常相对位置关系.发现钴异常的形成主要受（超）基性岩控制,少数与矿化作用有关,个别钴异常与泥质岩和次生富集等因素有关.中国与欧洲（FOREGS计划）结果均表明,风化型、热液型、岩浆型钴矿床与钴异常空间对应关系依次减弱.在此基础上,结合中国钴成矿地质背景,在华南钴成矿带、华北克拉通北缘东段等圈定了若干钴成矿远景区. 相似文献
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This paper deals withR-mode cluster analysis for more than 6000 analytical data from the samples of tectonite and mineralized rocks using the method
of multivariate statistical analysis on the basis of division of the tectonic fault systems in the Malage Ore Field andR-mode factor analysis for the analytical data from tectonite samples collected along various directions of the faults according
to fourteen variables related to the mineralizing elements which are selected in terms ofR-mode cluster analysis from the chemical composition of tectonites. Thus the distribution characteristics of primary halo
anomalies have been revealed with respect to the metallogenetic elements Sn, Cu, and Pb, Zn. The tecto-geochemical features
are shown by the primary halo anomalies, thus providing the theoretical basis for metallogenetic forecast in the ore field. 相似文献
20.
敖汉旗幅为赤峰地区的黄土覆盖区,在该区进行1：5万区域地球化学调查工作以水系采样为主,土壤为辅.为便于研究,水系粒级采用-10~+60目,土壤样品采用-10目粒级.因采样介质不同,所代表的化学意义不同,测试中产生系统误差.对不同采样介质的测试数据以Au元素为例分别进行统计,确定不同采样地区的背景值,并利用不同的系统误差校正方法对土壤采样区与水系采样区进行系统误差校正,以求在满足异常分析的同时更低程度遗漏厚黄土覆盖区低缓弱异常.3种校正方法在保证水系沉积物异常条件下,对黄土区异常都有一定程度弱化.标准化方法弱化的程度相对小,对刻划黄土区地球化学信息最接近,衬度变换与中位数变换校正后对黄土区地球化学信息反映弱. 相似文献