共查询到20条相似文献，搜索用时 31 毫秒
1.
《International Geology Review》2012,54(8):664-693
This article surveys the geographical distribution of metal ores, grouped into six categories: iron, manganese, chromium, silver-lead-zinc, copper and tin. The author reviews the occurrence of these ores throughout the world, and their association primarily with broad geotectonic zones. The essential information is encompassed in six maps. Legends explain the classification of the deposits by age (metallogenic eras), type and paragenetic associations of minerals. The symbols for these various classifications of ores are superimposed on maps showing the zones of Precambrian (cratonal), Paleozoic, Mesozoic and Cenozoic folding. The particular interest of this paper is that the author has made this survey as a preliminary to dividing the earth's surface into metallogenic provinces (of which he distinguishes 21), giving a brief discussion of each and showing its connection to areas of different ages and geotectonic structures. The ultimate aim is to construct “prognostic maps”, or maps drawn on such a basis that they may be used to predict the occurrence of a given ore or ores in a given region. — Paul T. Broneer 相似文献
2.
Pavel V. Koval 《Journal of Geochemical Exploration》1984,21(1-3)
Regional lithogeochemical surveys can be used to determine the geochemical characteristics of particular tectonic regions as well as mapping geochemistry in relation to geology and ore deposits at a larger scale. Regional lithogeochemistry is of particular value for assigning signatures to associations of igneous rocks which are related geochemically and geologically.The application of regional lithogeochemistry to mineral exploration is reviewed here with particular reference to the Mesozoic magmatic province of Mongolia. Geochemical data for granitoids are shown to have particular application to: (1) the classification and grouping of rocks of similar petrochemical and mineral compositions; (2) the compilation of tectonic and metallogenic maps; (3) the identification of metallogenic provinces and ore zones; and (4) predictive modelling to identify ore-bearing associations. Moreover, such data can be used to estimate the probable types and sizes of ore bodies associated with particular geochemical rock types. Regional lithogeochemistry thus forms an essential basis for prospecting for mineral deposits. 相似文献
3.
《Applied Geochemistry》2001,16(7-8):963-983
The <2 mm fraction of 605 samples of the C-horizon of podzols collected from an area of 188,000 km2 in the European Arctic was analysed for more than 40 chemical elements. The results were used to construct geochemical maps which showed clear regional distribution patterns, notwithstanding the very low sample density of 1 site per 300 km2. Some of these patterns fit established lithological boundaries. Others fit lineament structures in the area and underline the relative importance of certain tectonic directions some of which have not yet been delineated on existing geological maps. Some mark large-scale hydrothermal events and related alteration. Finally, some are connected with prominent, known ore deposits occurring in the area. However, several large deposits and even famous metallogenic provinces (Fe, Ni/Cu) are hardly, or not at all, reflected in the regional geochemical maps. In their present definitions geochemical provinces and metallogenic provinces are thus not necessarily related. Special geochemical features can occur at very different scales. The term geochemical province is so imprecise in terms of processes leading to regional-scale geochemical features that it should be avoided. Low-density geochemistry can be used to aid the interpretation of the geological evolution of large regions. It can also be used to find prospective areas within such regions. 相似文献
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Regional geochemical maps in Finland have been produced from many different programmes. The scale of sampling, the material collected and the analytical methods used varied according to the aim of the study. The entire country was covered at a reconnaissance scale using glacial till, groundwater, surface water and organic stream sediments as sampling media. Glacial till was sampled throughout the country at a regional scale. Local scale mapping and detailed geochemical studies are carried out in selected areas. The main analytical methods have been ICP-AES and ICP-MS, but other methods were used when necessary. In assaying solid material, both total decomposition and strong acid (aqua regia) leaching were used. The results are stored in ALKEMIA, a database developed in the geochemistry department of the Geological Survey of Finland. The data are available as tabulated ASCII files and as digital image files on diskettes, or as various types of symbol and colour maps from desired areas or map sheets. Two examples of the application of geochemical mapping data in prospecting and in environmental research are presented. Indications of the presence of gold and multiple-sulphide ore deposits have been the most useful results obtained from a prospecting standpoint. On the environmental side, reconnaissance scale geochemical mapping data gave more reliable information on the base cation concentration than bedrock maps, making them particularly valuable in devising an acidification assessment model. 相似文献
6.
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
7.
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
8.
Rosa Anna Corsaro Susanna Falsaperla Horst Langer 《International Journal of Earth Sciences》2013,102(4):1151-1164
We present the application of a classification method based on Kohonen maps and fuzzy clustering to geochemical analyses of volcanic products erupted on Mt. Etna from 1995 to 2005. Based on 13 major and trace elements, the classification allows a new way to visualize distinct compositional features of magma both considering long period as well as single eruptive events, such as in 2001 and 2002–03 flank eruptions. Products of the various vents do not necessarily form homogeneous groups, but show clear trends of chemical evolution with time. Using a convenient color code, the graphical visualization of the results in just a single picture allows the rapid identification of the compositional features of each sample and their comparison with all the products analyzed in the 10-year-long time span. This single picture accounts for the mutual interactions of the 13 components avoiding shortcomings of classical low-dimensional plots where components relevant for the discrimination have to be found in a priori study of many diagrams. On the basis of the synoptic information provided by pattern classification, we identify links between the products of different eruptive vents which deliver a reliable picture of a multifaceted plumbing system, in agreement with geochemical and geophysical evidence reported in literature. The analysis of the 13-dimensional data set using the Kohonen maps and fuzzy clustering simultaneously turned out to be straightforward and easy. Accordingly, the results of this application will be useful also as a contextual data set for new data in future ongoing eruptive episodes. 相似文献
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黄铁矿作为成矿热液活动的产物,是热液金矿床中最为重要的载金矿物,其成分标型特征记录了大量矿床成因信息。在分类总结了各类型热液金矿床关键地质特征的基础上,采用比较矿床学的研究思路,较为系统地分析了不同类型热液金矿床中主成矿期或与金矿化同期的黄铁矿的主微量元素及组合特征、(Fe+S)As特征、δFeδS特征、AsCoNi特征以及热电性特征。结果表明,不同类型热液金矿床中的黄铁矿成分特征具有显著差异,彼此显示出特征性的成因标型特征,可作为判别热液金矿床成因的依据。结合各类热液金矿床形成的构造背景,提出热液金矿床是研究大陆动力学的理想对象。通过这些研究,初步建立了不同类型热液金矿床地质与黄铁矿成分标型特征之间的耦合关系,为今后热液金矿床成因的判别和黄铁矿标型特征的进一步研究提供一定的参考。 相似文献
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V.S. Samoilov 《Journal of Geochemical Exploration》1991,40(1-3)
A great deal of data is available on the geochemistry of the carbonatite family as well as diverse sedimentary, metamorphic and endogenic carbonate rocks. The distinctive geochemical features of carbonatites are expressed first of all in their simultaneous enrichment in Sr, Ba, ree and V. Since the carbonatite family is related both to alkaline petrogenesis and a mantle origin, these associations allow distinction of carbonatites from the large variety of other carbonate rocks. At the same time, carbonatites associated with different types of alkaline rocks under different geologic-tectonic settings differ in contents of a number of elements (Sr, Ba, Nb, ree, Pb, Zn, P). These differences permit the geochemical classification of various rock associations of carbonatites. This geochemical classification is of practical interest because the ore productivity of the various associations is different. 相似文献
11.
化探异常信息识别是化探数据分析最重要的任务之一, 也是化探数据在资源勘查领域受到广泛关注的最重要原因, 前人对化探异常信息识别做过大量研究, 这些研究中的大多数主要关注化探示踪元素的含量, 近而根据含量指标计算异常阈值, 而对示踪元素在空间中的分布特征关注较少。本文选择 1: 20万比例尺的克拉玛依幅为研究区, 根据区内金矿的矿床地球化学特征选择Ag、As、Au和Sb等4种元素为本区内金矿的示踪元素, 以地球化学元素分散晕形成理论为依据, 使用GIS技术和Matlab软件绘制研究区内4种金矿示踪元素的综合地球化学异常图。结果表明, 与传统阈值方法得到的化探异常图相比, 本文得到的化探异常图能够更好地指示研究区内已知金矿。 相似文献
12.
云南铂族元素找矿基础问题 总被引：9，自引：2，他引：9
云南省铂族元素矿床成矿地质条件较好，已有不少已知矿床、矿点、找矿信息及地球化学异常。找矿重点以基性超基性岩型为主，也应考虑其它类型，如热液型、黑色页岩型、煤岩型等。找矿重点地区除在峨眉山玄武岩分布区及其周边外，应注意康滇地轴中部及边缘中新生代断裂带通过的地区。峨眉山玄武岩分布区外围的卡林型金矿和浅成低温热液型矿床分布区亦值得重视，如滇东南地区。此外，寒武系黑色岩系及含磷层位的含铂性是一个具有挑战性的新课题，值得加强研究。云南铂族元素矿床的成矿时代，可能从元古代到新生代均有，对云南找铂来说非常有利，其它省区无法与之相比。新生代构造可能将深埋的矿体错动到浅部，找矿中需要特别注意。不妨“沿河找矿”。第四纪的风化壳中是否有铂族元素的富集也可探索。 相似文献
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围绕覆盖区矿产综合预测的基本思路和关键方法问题,讨论了非线性矿产预测理论和方法如何在覆盖区矿产综合预测中发挥作用,重点介绍了成矿奇异性理论与非线性矿产预测方法在覆盖区矿产预测“弱信息”提取、“复合叠加信息”分解、“缺失和不完整信息”融合等关键问题中的应用.结合正在实施的中国地质调查局“覆盖区矿产综合预测”计划项目,介绍了三方面的研究进展:(1)覆盖层中地球化学元素迁移机理与覆盖层对地表地球化学异常的屏蔽和衰减作用;(2)如何识别由于覆盖层影响而造成的“弱”且“复杂”的地球化学异常;(3)如何综合具有缺失或不完整的多元勘查信息以达到提高覆盖区矿产综合预测精度、降低预测不确定性的目的.以东天山戈壁沙漠覆盖区海相火山岩型铁矿、大兴安岭南部草原覆盖区铁多金属矿、武夷山层控矽卡岩型铁矿等矿床预测为例,介绍了综合预测方法的应用过程和应用效果.研究结果表明,奇异性理论和分析方法可以有效地用于提取水系沉积物地球化学和地球物理(重、磁)弱异常,合理分解复合叠加异常,在此基础上,采用地球化学和地球物理异常的数据融合技术,分别建立了推断铁镁质火山岩、中酸性侵入岩、矽卡岩和热液蚀变等成矿或控矿地质要素的综合信息模型,以及基于综合预测要素建立的覆盖区矿产预测后验概率证据权模型和模糊逻辑模型.应用结果显示,介绍的预测方法不仅可以在出露区圈定成矿远景区,而且在戈壁沙漠覆盖区及第三、第四系松散沉积物覆盖区等均可圈出具有重要资源潜力的远景区,这些远景区往往会被传统的预测方法所遗漏. 相似文献
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Genetic Analogy Between Sediment—Hosted Gold Deposits and Sediment—Hosted Copper Deposits in Southwest China 总被引：1，自引：0，他引：1
The sediment-hosted copper deposits according to the authors‘ study were formed from connate formation water during the post-sedimentary or diagenetic stage while the sediment-hosted disseminated gold deposits are unanimously considered to be of post-sedimentary hydrothermal origin.Therefore,apart from their own individulities.These two types of deposits must share some characters in common.Comparisons are attempted,in this paper,between the sediment-hosted copper deposits in southwest China and the Triassic sediment-hosted disseminated gold deposits in the Yunnan-Guizhou-Guangxi Triangle in terms of geological and geochemical features. 相似文献
15.
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
16.
Seyed Ahmad Meshkani Behzad Mehrabi Abdolmajid Yaghubpur Younes Fadakar Alghalandis 《Journal of Geochemical Exploration》2011
In regional exploration programs, the distribution of elements in known mineral deposits can be used as a guide for the classification of deposits, search for new prospects and modeling ore deposit patterns. The Sanandaj–Sirjan Zone (SSZ) is a major metallogenic zone in Iran, containing lead and zinc, iron, gold, copper deposits. In the central part of the SSZ, lead and zinc mineralization is widespread and hitherto exploration has been based on geological criteria. In this study, we used clustering techniques applied to element distribution for classification lead and zinc deposits in the central part of the SSZ. The hierarchical clustering technique was used to characterize the elemental pattern. Elements associated with lead and zinc deposits were separated into four clusters, encompassing both ore elements and their host rock-forming elements. It is shown that lead and zinc deposits in the central SSZ belong to two genetic groups: a MVT type hosted by limestone and dolomites and a SEDEX type hosted by shale, volcanic rocks and sandstone. The results of elemental clustering were used for pattern recognition by the K-means method and the respective deposits were classified into four distinct categories. K-means clustering also reveals that the elemental associations and spatial distribution of the lead and zinc deposits exhibit zoning in the central part of the SSZ. The ratios of ore-forming elements (Sb, Cd, and Zn) vs. (Pb and Ag) show zoning along an E–W trend, while host rock-forming elements (Mn, Ca, and Mg) vs. (Ba and Sr) show a zoning along a SE–NW trend. Large and medium deposits occur mainly in the center of the studied area, which justify further exploration around occurrences and abandoned mines in this area. The application of a pattern recognition method based on geochemical data from known mineralization in the central SSZ, and the classification derived from it, uncover elemental zoning, identify key elemental associations for further geochemical exploration and the potential to discover possible target areas for large to medium size ore deposits. This methodology can be applied in a similar way to search for new ore deposits in a wide range of known metallogenic zones. 相似文献
17.
作者对“沉积成矿系列”的研究和划分,考虑到一系列因素,如岩相古地理环境、地球化学、生物地球化学、气候、水动力条件以及大地构造和岩浆作用的叠加等。沉积成矿系列中的矿床类型、矿床规模、富矿分布、成矿系列的完整性都受到上述因素综合制约。文章详述了“盆地外”和“盆地内”,还原和氧化对系列的影响不同,并着重强调“盆地内”“还原”环境的重要性。文中指出微生物在局部还原微环境中对造矿作用的意义;层控型沉积成矿系列中蒸发岩和白云岩所起的“封闭”作用大致可与石油-天然气的“生、储、盖”三条件类比。 相似文献
18.
论火山碎屑流和涌浪堆积的特征和成因模式：以浙东南沿海地区为例 总被引：1，自引：1，他引：1
本文根据野外地质特征、岩相学特征以及岩石化学和地球化学特征,将火山碎屑流和涌浪堆积归纳为三种不同的岩相组分,即次火山型熔结凝灰岩组合、涌浪型熔结凝灰岩组合和灰流型熔结凝灰岩组合。对这三种不同的岩相组合,特别是其中的熔结凝灰岩的各类特征分别进行了详细论述和相互对比,并在此基础上提出了一个火山碎屑流和涌浪堆积的综合成因模式。 相似文献
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资源定量评价发展方向展望 总被引：8，自引：0，他引：8
DonaldA.Singer 《地球科学》2001,26(2):152-156
未来的资源定量评价希望能够评估未发现矿产资源的量、价值并对其进行定位预测, 以能够表达矿产资源的经济潜力和不确定性.近年来金属价格的长期下跌提出了对更大型的矿床的需求.敏感度分析表明了减少评价中不确定性和风险的最有效途径是降低有关吨位估计因素的不确定性.到目前为止, 在评价中所有可能造成误差的因素中, 那些与吨位估计误差有关的因素是最重要的.鉴于吨位模型的绝对重要地位以及矿床模型是吨位最有效的预测手段, 正确地选择矿床模型是控制误差最重要的途径.地表大部分地区被大面积裸露的岩石和沉积物所覆盖.由于很多出露地表的矿床已经被发现, 人们开始把注意力转向盖层下面岩石可能显露的矿化信息上.这些区域的资源评价必需依靠对其周边地区的外推、地下覆盖岩石新的地质填图或者通过在其他成功勘探区获得的经验进行类推.盖层对评价的不确定性以及评价的方法与程序都具有深远的影响, 因为地下地质现象的不可见性和地球物理方法所获得的是一种被削弱了的信息.许多早期的评价方法都是基于从那些出露地表的矿床中总结出的地球化学和地球物理变量之间的关系而进行的, 而现在我们同样需要研究基于地下隐伏矿床的勘探经验.矿床模型在资源定量评价中的重要地位基于以下两个原因: (1) 大多数矿床类型具有明显不同的品位和吨位分布; (2) 不同的矿床类型出现在不同的地质背景中, 而这种背景可从地质图中进行区分.在综合利用地质、矿产、地球物理和地球化学等地学信息进行资源评价及矿床勘探中, 矿床模型起着至关重要的作用.品位和吨位模型以及定量描述、经济和矿床密度模型的发展将有利于减少这些新的评价的不确定性. 相似文献