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1.
Geochemical Mapping—Evolution of Its Aims, Ideas and Technology   总被引：1，自引：1，他引：0  
The development of geochemical mapping progressed from local geochemical prospecting through regional geochemical exploration and regional geochemical mapping to national and global geochemical mapping. This paper discusses the evolution of aims, ideas and methodology of geochemical mapping in Western countries, Russia and China. The sophistication of geochemical mapping methodology will make great contributions to solving resources and environmental problems in the 21^st century.  相似文献   

2.
Digital Element Earth   总被引：3，自引：0，他引：3  
The resources and environmental problems are the two most fundamental issues facing all nations in the world. Everything in and on the Earth – minerals, animals and plants – is made from one, or generally some combination of, chemical elements, which are scientifically listed in the periodic table. Thus it is important to understand the present abundance and spatial distribution of all the elements across the Earth’s surface. Such kinds of data can only be obtained at present and for the foreseeable future by on-earth geochemical mapping at all scales. The 30-year efforts made by Chinese geochemists in carrying out multi-element, multi-media, multi-scale geochemical mapping projects to delineate 39–76 element distribution at home and abroad culminated in a successful case of high-quality geochemical data acquirement. The new idea for a four-level plan for global geochemical mapping was advanced to obtain global data in the foreseeable future and the collection of updated geochemical information. Such information needs to be easily accessible not only by the science community, but also by industry, agriculture, governments, and even individuals, by all who would make an effort to promote sustainable living on our planet. The concept of a Digital Element Earth (DEE) fulfills the aims.  相似文献   

3.
Conventional geochemical exploration for gold deposits has not always been very satisfactory, especially for buried and blind ones. New considerations and methodology in sampling, analysis and interpretation have been developed in China during the past decade. Important considerations for unconventional gold exploration in this paper are that (1) gold is active in surface environments; (2) gold occurs not only as discrete grains, but also as ultrafine particles (submicron?to nanometer-sized particles of gold) and other complex forms; (3) regional low anomalies and superimposed anomalies over buried gold deposits are produced by ultrafine gold grains and other complex forms of gold. The methodology based on these considerations has been developed both in regional and in local geochemical exploration for gold. Examples of the preliminary application of these methods in two areas covered by transported overburden are given.  相似文献   

4.
More than 40 national and regional geochemical mapping projects in the world carried out from 1973 to 1988 do not conform to common standards. In particular they have many analytical deficiencies. In the period 1988 to 1992, the International Geochemical Mapping project （Project 259 of UNESCO＇s IGCP Program） prepared recommendations designed to standardize geochemical mapping methods. The analytical requirements are an essential component of the overall recommendations. They included the following： 71 elements should be analyzed in future mapping projects; the detection limits of trace and ultratrace elements must be lower than the corresponding crustal abundances; and the Chinese GSD and Canadian STSD standard sample series should be used for the correlation of global data. A proposal was also made to collect 5000 composite samples, at very low sampling densities to cover the whole Earth＇s land surface. In 1997 an IUGS Working Group on Global Geochemical Baselines was formed to continue the work which began with IGCP 259. From 1997 up to now, new progress has been made especially in China and FOREGS countries under the aegis of this working group, including the study of suitable sampling media, development of a multi-element analytical system, new proficiency test for selection of competent laboratories and role of wide-spaced mapping in mineral exploration. One of the major problems awaiting solution has been the inability of many laboratories to meet the IGCP recommendations to generate high quality geochemical maps. Fortunately several laboratories in China and Europe have demonstrated an ability to meet the requirements and they will be well placed to render technical assistance to other countries.  相似文献   

5.
The Task Group on Global Geochemical Baselines,operating under the auspices of both the International Union of Geological Sciences(IUGS) and the International Association of Geochemistry(IAGC),has the long-term goal of establishing a global geochemical database to document the concentration and distribution of chemical elements in the Earth's surface or near-surface environment.The database and accompanying element distribution maps represent a geochemical baseline against which future human-induced or natural changes to the chemistry of the land surface may be recognized and quantified.In order to accomplish this long-term goal,the activities of the Task Group include:(1) developing partnerships with countries conducting broad-scale geochemical mapping studies;(2) providing consultation and training in the form of workshops and short courses;(3) organizing periodic international symposia to foster communication among the geochemical mapping community;(4) developing criteria for certifying those projects whose data are acceptable in a global geochemical database;(5) acting as a repository for data collected by those projects meeting the criteria for standardization;(6) preparing complete metadata for the certified projects;and(7) preparing,ultimately,a global geochemical database.This paper summarizes the history and accomplishments of the Task Group since its first predecessor project was established in 1988.  相似文献   

6.
Regional stream sediment surveys at a 1:200,000 scale reveal positive and negative regional multi-element geochemical anomalies over medium to large copper-polymetallic orefields of different genetic types in China. Regional geochemical anomalies of orefield refer to those geochemical anomalies that are related to metallogenesis of an orefield in a certain area. The anomaly area is typically 10 to 100 km2. The regional multi-element anomalies related to mineralization can be divided into three groups, that is, the ore-element anomaly association, indicator element anomaly association, and metallogenic environmental element anomaly association. Their common spatial distributions over ore deposits or orefields possess unique structures.The model of spatial structure of regional multi-element geochemical anomalies (RAGSS) of an orefield delineates structural feature possessed by orderly spatial distributions of different groups of multi-element anomaly associations related to orefield metallogenesis. It is  相似文献   

7.
Outlines of New Global Geochemical Mapping Program   总被引：3，自引：1，他引：2  
<正>Since 1988,great efforts and enthusiasm had been paid by applied geochemists in the implementation of global geochemical mapping through the International Geological Correlation Program's Projects 259 and 360,and the Task Group on‘Global Geochemical Baselines' established by the International Union of Geological Sciences(IUGS),in collaboration with the International Association of Geochemistry(IAGC).But how to use extremely low-density sampling to obtain a global picture of the distribution of most elements in the periodic table in a reasonably short time is still a great challenge faced by the applied geochemistry community.It will depend on the continuous development of new mapping concept,and the advisable and courageous innovation of methodology for searching other suitable sample media and sampling layout.Based on the encouragement results obtained from the representativeness study of delta sediments conducted at the mouth of Yangtze River,and at the mouths of its four major tributary,it is expected to broadly apply the geochemical fractal self-similarity nature to main rivers and their estuaries with catchments up to hundreds of thousands or over a million square kilometers in the world.With this new mapping concept,a new outlines of a Global Geochemical Mapping Program was advanced and the establishment of an International Research Center of Global Geochemical Mapping was also suggested to facilitate the programs implementations.  相似文献   

8.
Through lead isotope geochemical mapping in the Yunnan-Guizhou area geochemical steep zones (GSZ) have been established, which clearly reveal the junction relationship of the Cathaysian, Yangtze and Indo-China plates. GSZ are closey related to gravity Mono gradient zones and lithospheric thickness. The GSZ between the Yangtze and Cathaysian plates is consistent with the Shizong-Mile tectonic belt, where island arc basalts are well developed. The Yangtze-Indo-China GSZ is parallel to the Jingdong-Mojiang volcanic belt in rift-island arc environments. The evidence of geology, geophysics and geochemistry all indicates that Cathaysia was subducted towards the Yangtze plate and that the Yangtze plate was underthrust beneath the Indo-China, which took place from the Early Carboniferous to the Early Triassic.  相似文献   

9.
The regional lithospheric chemical heterogeneity in-ers that the East Qinling and its adjacent cratonic re-ions,as suggested by some authors,belong to twoeotectonic units,the North China subdomain includinghe North China Craton and its southern continentalhargin(the North Qinling Belt),and the Yangtzeanubdomain comprising the Yangtze Craton and itsorthern continental margin(the South Qinling Belt).In the North Qinling Belt the metamorphosedolcanic rocks and graywackes of the Early Paleozoicanfeng Group south of the Early Proterozoic QinlingGroup show geochemical characteristics resemblinghose of the are volcanies and are graywackes,espectively.The Early Paleozoic granites intruding in hehe Qinling Group also show similar geochemical fea-tures and similar compositional polarities to theare-type granites.The Erlangping Group north ofthe Qinling Group is a volcanic-sedimentary sequenceproduced in an Early Paleozoic back-are basin basedon geochemical evidence.It is therefore believed thatthe North Qinling B  相似文献   

10.
This study focused on the geochemical distribution patterns and ecological effects of Cd and other heavy metals such as As, Hg, Cr, Cu, Ni, Pb, and Zn in rock, soil, water, sediment and crops in the area of the Three-Gorges Reservoir within Chongqing, and aimed at the protection of ecological environment and rational application of the local lands. This study found that the metals of Cd, Hg and Pb presented pollution in the surface environment along the Yangtze River, that is Cd〉Hg〉Pb （Cu）〉Zn〉As〉Ni〉Cr. The pollution of Cd in sediment was mainly attributable to the regional black shales, and partly to the urban sewage and garbage. The geochemical modes of metals in the sediment varied. Cr, Hg, Ni, and Pb mainly existed as residues, and Cd as carbonate. Cd exited as a high proportion in the modes of ion-exchange, carbonate, and iron-manganese oxidation, up to 63 percent. The contents of heavy metals in soiland sediment were correlated to the host clay minerals, such as illite, montmorillonite, kaolinite and chlorite. It is shown that Cd was transported with clay minerals in the Yangtze River over long distance and formed the regional anomaly. In the abnormal area of Jianping in Wushan County, higher Cd contents are reported in the local crops and local villagers＇ hairs than from the background areas.  相似文献   

11.
The China Geological Survey carried out 1:250000 regional geological surveys of the Qinghai-Tibet Plateau from 1999 to 2005.With a total investment of 300 million yuan,more than 1000 geologists were involved annually to conduct mapping at a grid of one line to every four km along the Kunlun Mts-Altyn Shan-Tanggula Shan,Kokoxili-Qiangtang,Gangdese,Yalun Zangbu River,and finally to the Himalayan ranges.The extensive mapping culminated in a total of 112maps covering an area of 152 square kilometers.Based on this success,the China Geological Survey launched another program,the "Integration and Comprehensive Study of Basic Geological Survey Result(s) in the Qinghai-Tibet Plateau".The program lasted from 2006 to 2010 and has yielded copious research results,making big strides in upgrading our understanding of the Qinghai-Tibet Plateau.The achievements are manifold.  相似文献   

12.
Regional Geochemical Division—A Tool for Delineating Geochemical Block   总被引：2，自引：0，他引：2  
INTRODUCTIONGeochemists need to study the spatial distribution of theassociations of the geochemical elements(AGE) to delineatethe geochemical blocks or recognize geochemical anomalies inregional geochemical exploration.Regional geochemical divi-sion (RGD) is a mapping technique for the division of thestudy area into slices where the natural AGEs are relativelysimple and uniform.A practical approach to RGD is to digital-ly devide the collected geochemical samples into groups bymeans o…  相似文献   

13.
The geochemical composition of sandstones in the sedimentary basin is controlled mainly by the tectonic setting of the provenance, and it is therefore possible to reveal the tectonic setting of the provenance and the nature of source rocks in terms of the geochemical composition of sandstones. The major elements, rare-earth dements and trace elements of the Mesozoic-Cenozoic sandstones in the Lanping Basin are studied in this paper, revealing that the tectonic settings of the provenance for Mesozoic-Cenozoic sedimentary rocks in the Lanping Basin belong to a passive continental margin and a continental island arc. Combined with the data on sedimentary facies and palaeogeography, it is referred that the eastern part of the basin is located mainly at the tectonic setting of the passive continental margin before Mesozoic, whereas the western part may be represented by a continental island arc. This is compatible with the regional geology data. The protoliths of sedimentary rocks should be derived from the upper continental crust, and are composed mainly of felsic rocks, mixed with some andesitic rocks and old sediment components. Therefore, the Lanping Mesozoic-Cenozoic Basin is a typical continental-type basin. This provides strong geochemical evidence for the evolution of the paleo-Tethys and theb asin-range transition.  相似文献   

14.
The development of Early Cretaceous mafic dikes in northern and southern Jiangxi allows an understanding of the geodynamic setting and characteristics of the mantle in southeast China in the Cretaceous. Geological and geochemical characteristics for the mafic dikes from the Wushan copper deposit and No. 640 uranium deposit are given in order to constrain the nature of source mantle, genesis and tectonic implications. According to the mineral composition,the mafic dikes in northern Jiangxi can be divided into spessartite and olive odinite types, which belong to slightly potassium-rich calc-alkaline lamprophyre characterized by enrichment in large ion lithophile elements (LILE) and light rare earth elements (LREE), large depletion in high strength field elements (HSFE) and with negative Nb, Ta and Ti anomalies, as well as 87Sr/86Sr ratios varying from 0.7055 to 0.7095 and 143Nd/r44Nd ratios varying from 0.5119 to 0.5122.All features indicate that the magma responsible for the mafic dikes was derived mainly from metasomatic lithosphere mantle related to dehydration and/or upper crust melting during subduction. Differences in geochemical characteristics between the mafic dikes in northern Jiangxi and the Dajishan area, southern Jiangxi were also studied and they are attributed to differences in regional lithospheric mantle components and/or magma emplacement depth. Combining geological and geochemical characteristics with regional geological history, we argue that southeast China was dominated by an extensional tectonic setting in the Early Cretaceous, and the nature of the mantle source area was related to enrichment induced by asthenosphere upwelling and infiltration of upper crust-derived fluids responding to Pacific Plate subduction.  相似文献   

15.
This paper presents a method of establishing a hydrothermal ore-forming reaction system.On the basis of the study of four typical hydrothermal deposits,the following conclusions concerning geochemical dynamic controlling during hydrothermal mineralization have been sions concerning geochemical dynaamic controlling during hydrothermal mineralization have been drawn:(1)The regional tectonic activities control the concentration and dispersion of elements in the ore-forming process in terms of their effects on the thermodynamic nature and conditions of the ore-forming reaction system.(2)During hydrothermal mineralization the activites of ore-bearing faults can be divideb into two stages:the brittle splitting stage and the brittle-tough tensing stage,which would create characteristically different geodynamic conditions for the geochemical thermodynamic ore-forming system.(3)The hydrothermal ore-forming reaaction system is an open dynamic system.At the brittle splitting stage the system was so strongly supersaturated and unequilibrated as to speed up and enhance the crystallization and differentiation of ore-forming fluids.And at the brittle-tough tensing stage,the ore-forming system was in a weak supersaturated state;with decreasing temperature and pressure the crystallization of oreforming material would show down,and it can be regarded as an equilibrated state.(4)In the lates stages of hydrothermal evolution,gold would be concentrated in the residual ore-forming solution.The pulsating fracture activite in this stage led to the crush of pyrite ore and it was then filled with gold-enriched solution,forming high-grage“fissure”gold ore.This ore-forming process could be called the coupling mechanism of ore formation.  相似文献   

16.
The mechanism that controls regional mineralization must be governed by a series of geochemical reactions in relation to the source system of magmatism.In this respect,the geological bodies must have been overprinted by various kinds of tracers in terms of either chemical elements or isotopes.For this reason,the problem may be better approached by treating the lithosphere as a whole with due considerations given to the various tracer elements and isotopes and the various media of the magmatism(magmatic as well as sedimentary rocks).Presented in this paper are the results of this attempt based on a great wealth of available data concerning the source system of Mesozoic magmatism in the Middle and Lower Yangtze Valleys and adjacent areas.  相似文献   

17.
The protection system of products of geographical origin has become one hot subject with which various countries throughout the world are concerned. Results of element-Pb isotope geochemical mapping indicate that there emerge a number of famous-brand high-quality product groups of geographical origin in China. The environment of production of China’s famous-brand white spirits of geographical origin at the Sichuan-Guizhou border is still a mystery to be solved. China has two main communities of white spirits of geographical origin, i.e., the most famous are Moutai and Wuliangye spirits. By element-Pb isotope geochemical tracing, we can establish the natural background geological, geographical and geochemical scientific data mark ers in close relation with source areas. Research on the product of geographical origin, named Kaempferia galangal L. in the Shuangjiao district, Yangchun, Guangdong Province, showed that the trace elements have an excellent heritance between Kaempferia galangal L. and soil in this area, and the trace elements are highly effective for tracing the origin.  相似文献   

18.
The theory of dissipative structures is applied in this paper to probing into the dynamics, temporal struc-tures and spatial structures of ore-forming processes and the inherent relationships among them. Areas of oreformation are large dynamic systems in development and evolution. The core of ore formation is the "onset ofore-forming processes". and the crux of it is the "transition from mineralization to ore formation". The theoryof bifurcation and theory of fluctuation make possible the access to the solution of this problem. The multiord-er or successive bifurcation of dissipative structures introduces dynamic geochemical processes into geosciencesand inverses the dynamic evolution and temporal rhythms of ore-forming processes. The localization ofdissipative structures introduces dynamic geochemical fields into geosciences and brings to light the causes andmechanisms of the formation and development of geochemical areas of ore formation (regions and zones of oreformation) and their spatial dynamic patterns.  相似文献   

19.
The pertochemistry and Sm-Nd isotopic compositions and the geochemical characteristics of REE,U,Th,etc..in the Late Proterozoix and Early Palaeozoic strata in northwestern Jiangxi and western Zhejiang provinces are described in this paper.It seems to be sure that the middle Proterozoic strata of southeastern China are low in the degree of matrration .The strata contain much mantle-derived material.At the end of Late Proterozoic there was an abrupt turn with respect to the crustal geochemical evolution of the eastern part of South China .Since then ,the geochemical environment has undergone a change from a simple reducing environment to a complex oxidizing-reducing environ-ment, which would be geochemically beneficial to the formation of Late Sinian to Early Cambrian U-bearing formations.  相似文献   

20.
The petrology, geochronology and geochemistry of the mafic enclaves in the Mid-Late Triassic Jiefangyingzi pluton from Chifeng area, southern Inner Mongolia, in China are studied to reveal their petrogenetic relationship with the host pluton. Furthermore, the coeval magmatic assemblage and its petrogenesis on the northern margin of the North China craton(NCC) are studied synthetically to elucidate their tectonic setting and the implications for the destruction of the NCC. Zircon U-Pb dating reveals that the mafic enclaves formed at 230.4 ± 2.2 Ma, which is similar to the age of the host pluton. The most basic mafic enclaves belong to weak alkaline rocks, and they display rare earth element(REE) and trace element normalized patterns and trace element compositions similar to those of ocean island basalt(OIB). In addition, they have positive εNd(t) values(+3.84 to +4.94) similar to those of the Cenozoic basalts on the northern margin of the NCC. All of these geochemical characteristics suggest that the basic mafic rocks originated from the asthenosphere. Petrological and geochemical studies suggest that the Jiefangyingzi pluton and the intermediate mafic enclaves were formed by the mixing of the asthenosphere-derived and crust-derived magmas in different degrees. The Mid-Late Triassic magmatic rocks on the northern margin of the NCC could be classified into three assemblages according to their geochemical compositions: alkaline series, weak alkaline–sub-alkaline series and sub-alkaline series rocks. Petrogenetic analyses suggest that the upwelling of the asthenosphere played an important role in the formation of these Mid-Late Triassic magmatic rocks. Basing on an analysis of regional geological data, we suggest that the northern margin of the NCC underwent destruction due to the upwelling of the asthenosphere during the Mid-Late Triassic, which was induced by the delamination of the root of the collisional orogeny between Sino-Korean and Siberian paleoplates in Late Permian.  相似文献   

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