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1.
Ternary (triangular) diagrams show the compositional variation of three end-members, recalculated to 100%, and represent the projection into two dimensions of three or more components (since an end-member may represent the sum of more than one original component), and hence multiple space. During the present century they have been of particular importance in chemistry, the earth sciences, colour-mixing and the studies of colour that underlie the development of geochemical colour maps. Such concepts can be traced back to Newton's Opticks although he did not use an explicit ternary theory of colour mixing. Development of the trichromatic theory of colour deficiency began with Mariotte in the 17th century and was definitively established by Maxwell in the 1850s. These colour theorems underlie the development in recent years of the colour maps now in widespread use in geochemistry. The progress of regional geochemical mapping in the British Isles has gone hand-in-hand with the development of computer software and hardware. The use of multi-element colour-combined geochemical maps can be traced from early work at Imperial College by Webb and his co-workers (1964–79) to its later application in the British Geological Survey's Geochemical Atlas series (from 1983 onwards). Between 1955 and 1975 the use of ternary diagrams came to be commonly used in studies of mineralogical composition, including economic minerals, petrology, classification, and phase relationships. In igneous petrology, the quartz–alkali-feldspar–plagioclase-feldspathoid double-triangle has achieved increasing international acceptance. We illustrate these applications with examples pertinent to the Northern Highland Caledonides, with particular emphasis on the lamprophyres and associated rocks. Two distinct multivariate trends of variation are shown to be present which may warrant further investigation to elucidate their bearing on Caledonian mineralisation. 相似文献
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The distribution of As in a variety of sample materials was studied at different scales, from continental to local, combining published data sets with the aim of delineating the impact and relative importance of geogenic vs. anthropogenic As sources. Geochemical mapping of As with a variety of sample materials demonstrates that variation is high at all scales (local to continental) – from sample densities of 400 sites per km2 to 1 site per 5000 km2. Different processes govern the As distribution at different scales. A high sample density is needed to reliably detect mineralisation or contamination in soil samples. In both cases the impact on the much larger geochemical background variation is limited to a local scale. Distribution patterns in geochemical maps on the sub-continental to continental scale are dominated by natural variation. Given that the geochemical background is characterised by a high variation at all scales, it appears impossible to establish a reliable single value for “good soil quality” or a “natural background concentration” for As for any sizeable area, e.g., for Europe. For such a differentiation, geochemical maps at a variety of scales are needed. 相似文献
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Xiang Sun Jun Deng Qingjie Gong Qingfei Wang Liqiang Yang Zhongying Zhao 《Journal of Geochemical Exploration》2009
Kohonen neural network (KNN) and factor analysis are applied to regional geochemical pattern recognition for a Pb–Zn–Mo–Ag mining area around Sheduolong in Qinghai Province, China. Prior to factor analysis, the geochemical data are classified by KNN. The results demonstrate that the 4-factor model accounted for 67% of the variation in the data. Factor F1, a Pb–Zn–Mo factor and Factor F4, an Au–Ag factor, correlates with monzonitic granite intrusions and particularly with Pb–Zn–Mo–Ag mineralization within those rocks. Factor F2, an As–Co factor, correlates with metamorphic rocks of paleoproterozoic Baishahe formation. Factor F3, a Bi–Cu factor, correlates with granodiorite intrusions. The factor score maps suggest a revised location of faults and their mineralization significance in coarse geological map. The approach not only effectively interprets the geological significance of the factors, but also reduces the area of exploration targets. 相似文献
4.
The Bayesian approach is an effective method of identifying the probability of mineralogical and geochemical type (MGT) mineralization of trace elements in galena, pyrite and other distributions in ore mineralization. Monomineralic samples have been identified using a computer-based Bayesian method and exploration geochemical techniques of Au deposits for MGT. In order to employ the method, a data bank was used consisting of the results of analysis of more than 12,000 monomineralic samples collected from the main hydrothermal Au deposits in Tajikistan (a territory of CIS). The Bayesian approach applied to geochemical data, such as posterior probabilities and discriminant analysis, provide numerical and graphical means through which the relationships between the trace elements and samples can be studied. The method used here, along with GIS, to find MGT can be used as geochemical indicators of regions with Au mineralization. The results of analyzing 100 monomineralic samples of pyrite from the Au–Ag Shkolnoe deposit (Tajikistan) show a multi-MGT anomaly superposition which is a combination of three MGT: (1) Au–Ag type (85% and more), (2) Au–sulfide-polymetallic type (46%), and (3) Au–sulfide type (40%). Mineralogical and geochemical maps (MGM) can be drawn based on results of MGT anomalies in a GIS environment. These maps can replace traditional metallogenic maps. The advantage of MGM substitutions is that a qualitative tool is replaced by a quantitative one. This helps one to make optimal managerial and more economical decisions. 相似文献
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《International Geology Review》2012,54(12):1593-1610
The geology of the Central Kamchatka ore zone, with particular reference to the petrology on chemical composition of the rock units, is the first part of this two-part paper. Although the paper is not clearly divided into two parts, the second and major section deals with the chemistry, alteration, and chemical alteration which has occurred as the result of hydrothermal alteration. The author has illustrated the changes in chemical composition by the use of "Input-output" variation diagrams. The paper illustrates the development of hydrothermally altered rocks in the Central Kamchatka ore zone, both horizontally and vertically, and is proffered as an aid to mineral exploration in that area. The relationship of mineral facies and a combination of mineral facies to ore mineralization is also discussed.--M. A. Klugman. 相似文献
7.
Software for presentation of geochemical data on maps has been integrated into a user-friendly package, ALKEMIA, at the Geological Survey of Finland (GSF). ALKEMIA contains procedures for generating dot maps, colour surface maps, shaded relief maps, and vector images, and for interpolating and smoothing irregularly gridded data. Combining dots and colour surfaces provides a means of visually integrating up to three variables on a map, revealing the spatial relationships between them. The methods employed are described in detail, particularly the moving weighted median, which has been widely used at the GSF for interpolating and smoothing geochemical and other numerical data. Several geochemical and oncological atlases and series of maps have been produced with these methods. 相似文献
8.
Analysis of geochemical maps and their legends permits the proposal of several ways of improving their information content. Firstly, coherent and comparable classification of the objects to be presented must be developed. This classification should be based on strictly defined quantitative geochemical features of the objects; natural associations, anomalous elements, rocks, ore deposits and ore-bearing areas. Secondly, the most informative features of objects must be selected and uniquely displayed with a standard set of symbols. These symbols must be clear, readily understood and logically connected. The third requirement is that maps must be prepared in accordance with the tasks they are intended to deal with, must be optimally scaled, and display only appropriate information.One possible way of meeting the above-mentioned requirements, is proposed in a system of geochemical discrimination and related map presentation methods. The latter involves black hachures for the geological base, and directed colour lines and other features of colour hachures to characterize geochemical associations. Ore deposits may be characterized on the basis of eight most meaningful features encoded in one complex hieroglyph-like symbol constructed from easily understood and memorable components. This type of construction facilitates the computerized analysis of maps and makes them far more useful for prognosis, genetic reconstruction and resource evaluation. 相似文献
9.
Our aim is to give a short introduction of the use of phase diagrams in order to rationalise general principles of surfactant self-assembly. These can be rationalised in terms of geometrical constraints: volume, surface and curvature. Binary (two components: surfactant and water) and ternary systems (surfactants, water, oil) are considered separately. Models for solubilisation, to be understood within the general principles and not as tabulated data, are presented. Finally, some examples of application of solubilisation in formulation are given. To cite this article: F. Testard, T. Zemb, C. R. Geoscience 334 (2002) 649–663. 相似文献
10.
华南钦杭结合带燕山期岩浆活动异常活跃,且具有较明显的成矿专属性。近年来微区测试技术日益成熟,积累了大量锆石微量数据。通过全体数据挖掘的思维方法,对前人发表的数据进行了进一步数据挖掘,利用锆石稀土元素对岩体成矿潜力进行判别,探讨有效的找矿地球化学标志。利用Python语言编程,对采用的13种稀土元素及元素比值进行穷举式组合,获得了4095个二元图解及121485个三元图解,并设计筛选算法,自动筛选出能有效区分锆石母岩成矿类型的图解。结果表明,锆石稀土元素含量及比值图解对不同成矿类型岩体的区分程度各异:与Ce、Eu有关的地球化学指标可以较清晰地对斑岩铜矿和钨锡(锡)矿床进行判别,这可能与岩体的氧逸度和含水量有关。此外,还挖掘出一些新的元素组合图解,如Dy/Lu-Er/Lu、Gd/Dy-Er/Yb等,可以有效区分岩体成矿类型,其隐含的地球化学机制尚待进一步解释。地球化学数据挖掘结果可以作为找矿标志使用,为华南燕山期岩浆-热液矿床研究及找矿勘查提供了科学依据,也是大数据技术在矿床学方面应用研究的积极探索。 相似文献
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Identifying geochemical anomalies from background is a fundamental task in exploration geochemistry. The Gangdese mineral district in western China has complex geochemical surface expression due to complex geological background and was chosen as a study area for recognition of the spatial distribution of geochemical elements and separating anomalies from background using stream sediment geochemical data. The results illustrate that weak anomalies are hidden within the strong variance of background and are not well identified by means of inverse distance weighted; neither are they clearly identified by the C–A method if this method is applied to the whole study area. On the other hand, singularity values provide new information that complements use of original concentration values and can quantify the properties of enrichment and depletion caused by mineralization. In general, producing maps of singularities can help to identify relatively weak metal concentration anomalies in complex geological regions. Application of singularity mapping technique in Gangdese district shows local anomalies of Cu are not only directly associated with known deposits in the central part of the study area, but also with E–W and N–E oriented faults in the north of the study area. Both types of anomalies should be further investigated for undiscovered Cu mineral deposits. 相似文献
12.
Lu-Hf同位素体系及其岩石学应用 总被引：120，自引：174，他引：120
Lu-Hf是近几年来发展极为迅速的一门同位素定年和地球化学示踪技术。本文对这一同位素体系的发展历史、岩石学应用和存在的问题进行了全面的评述,对目前常见的样品溶解、质谱测定和激光剥蚀技术进行了全面介绍。虽然Lu-Hf同位素的发展历史可划分为TIMS、hot-SIMS、MC-ICPMS三个阶段,但MC-ICPMS仪器的出现,使Hf同位素发展速度明显加快。在介绍了Lu-Hf同位素的基本地球化学行为和基本原理之后,本文对这一同位素体系在岩石学上的应用作了全面的介绍,内容包括含石榴石和磷灰石岩石的同位素定年、早期大陆地壳形成与演化、不同端元地幔的性质及成因、岩浆作用过程的Hf同位素鉴别、区域地球动力学演化、变质作用过程中的Hf同位素变化等。最后对Lu的衰变常数、测定标准(JMC475溶液和固体锆石/斜锆石标准)的Hf同位素组成及Hf同位素的封闭温度等问题进行了讨论。 相似文献
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Forster, A. and Culshaw, M.G., 1990. The use of site investigation data for the preparation of engineering geological maps and reports for use by planners and civil engineers. Eng. Geol., 29: 347–354.
In modern cities hundreds of site investigations have been carried out before the construction of roads, offices, factories and housing estates. The results of these investigations represent a large resource of geological and geotechnical information worth millions of pounds. Much of this information is lost, or is not accessible, because of confidentiality; that which is available will be of variable content and quality. The geographical and stratigraphical distribution will also be uneven. However, maps, and resumés of the engineering behaviour of the geological materials in an area, can be produced to guide planners and to help engineers at the earliest stage of development.
In this paper the authors discuss the use of the data contained in site investigation reports to prepare engineering geological maps and illustrate this by reference to recent applied geological mapping projects carried out by the British Geological Survey. 相似文献
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遥感岩石学的研究及其进展 总被引：10，自引：1，他引：10
结合近几年来的研究实践以及国内外大量研究成果的分析，提出了遥感地质学中的一个重要分支科学－－“遥感岩石学”的概念及定义，介绍了遥感岩石学的三个重要研究内容：（１）岩石，矿物的光谱特征研究；（２）机载遥感数据的岩石信息提取与识别；（３）星载遥感数据的岩石信息提取与识别，并对遥感岩石学的未来发展作了展望。 相似文献
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B.S.帕利沃尔 《沉积与特提斯地质》1995,(2):82-89
ＩＧＣＰ—２６９—ＳＥＤＢＡ项目──全球沉积岩数据库是一个对沉积学有很大价值的极好国际项目．以挑剔的眼光来看待这一数据库时，发现ＳＥＤＢＡ的信息不足；需要改进。这些不足包括：（ｌ）信息空间不足；（２）信息含糊；（３）信息的分类整理不当；（４）缺乏对信息的详细分类；（５）无关的和不需要的信息。其次，ｓＥＤＢＡ仅局限于沉积岩。为了将ｓＥＤＢＡ应用于沉积学，使其更为有用、更具意义，有必要进行一些改进。这些改进包括：（ｌ）岩性图和岩相图ｏ（２）盆地构造一沉积演化阶段图；（３）盆地构造图；（４）补充垂向岩性剖面和岩性测井记录；（５）沉积构造序列；（６）该地区的地质剖面；（７）其它重要图片。 相似文献
18.
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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This study utilizes three major data sources: distribution of geological units; density, type, age and distribution of mineral deposits; and elemental analyses from regional geochemical stream sediment surveys to define parameters that ‘characterize’ tectonic terranes in northern British Columbia. A similar approach could be applied anywhere in the Canadian Cordillera.This area, NTS map sheets 104N, 104O and 104P along the British Columbia-Yukon border, forms a transect through allochthonous terranes into North American rocks. These are: the allochthonous island-arc Stikine, oceanic Cache Creek, cataclastic Yukon/Tanana, and island-arc Quensel terranes, the pericratonic Dorsey terrane; the parautochthonous oceanic Sylvester allochthon; and the autochthonous miogeoclinal North American Cassiar terrane. Plutonic rocks of Jurassic-Cretaceous to Tertiary age intrude all terranes.Data sources used in the study are geological base maps and reports, the Ministry of Energy Mines and Petroleum Resources' mineral deposit database (MINFILE) and analytical data from the National Regional Geochemical Survey stream sediment and water sampling program.Geological maps were compiled from various sources and plotted to act as bases for geochemical and mineral deposit overlays for analysis and interpretation.Geochemical samples were separated into background and anomalous populations and compared according to their source terranes. We found that mean concentrations from background sample populations for some elements are statistically distinctive for different terranes. Unfortunately, elemental correlation coefficients for the terranes are similar so cannot be used to characterize each terrane.Data on mineral deposits and occurrences were compiled from minfile and other sources. Particular attention was paid to deposits with histories of production or significant reported reserves. Deposits were sorted by type and commodity to produce synoptic metallogenic maps.The combined data from geological, geochemical and mineral deposit databases form a strong tool for interpreting and predicting patterns of mineralization. 相似文献
20.
Digiacomo Flavia Tobler Dominique J. Held Thomas Neumann Thomas 《Geochemical transactions》2020,21(1):1-22
The study presented in this work emerged as a result of a multiyear regional geochemical survey based on low-density topsoil sampling and the ensuing geochemical atlas of Croatia. This study focuses on the Dinaric part of Croatia to expound the underlying mechanisms controlling the mobilities and variations in distribution of potentially harmful elements as observed from different environmental angles. Although serious environmental degradation of the vulnerable karst soil landscapes was expected to occur chiefly through the accumulation of various heavy metals, the most acute threat materialized through the soil acidification (Al-toxicity) affecting the entire Dinaric karst area. This picture surfaced from the analysis of all three investigated discriminant function models employing the abovementioned environmental criteria selected autonomously with respect to the evaluated soil geochemistry, namely, geologic setting, regional placement and land use. These models are presented by not only the characteristic discriminant-function diagrams but also a set of appropriate mathematically derived geochemical maps disclosing the allocations of potential threats to the karst soil landscapes posed by soil acidity. 相似文献