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1.
Cheng Zhizhong Xie Xuejing Pan Hanjiang Yang Rong 《Geostandards and Geoanalytical Research》2014,38(2):211-223
Over 3 million samples were collected from southern China at a density of 1–2 stream sediment samples per square kilometre as part of the Regional Geochemistry National Reconnaissance (RGNR) programme of China initiated in the late 1970s. Approximately 5244 composite samples of stream sediments from twelve provinces of southern China were prepared from the original RGNR samples collected from a territory with an area of 2300000 km2 at a density of one composite sample per 1:50000 map sheet (about 400 km2). Seventy‐six elements were determined by the geoanalysis laboratory of Henan Province (platinum‐group elements) and by the Institute of Geophysical and Geochemical Exploration (IGGE) laboratory for the remainder. Internal quality and external quality control methods were applied to ensure that the analytical data were comparable. Statistics were used to derive the mean and background values and indicate the average concentrations of the seventy‐six elements. Comparisons were made against the mean values obtained from stream sediments, floodplain sediments, overall sediments and overall soils of the entire territory of China. The concentrations of Hg, Cd, rare earth elements and 24 other elements were higher than their background for the whole of China. In contrast, the concentration of Na2O, CaO, Ba and Sr were lower in the stream sediments in southern China than their whole China background. 相似文献
2.
Geochemical mapping in China 总被引：5，自引：0，他引：5
China's National Geochemical Mapping Project (Regional Geochemistry-National Reconnaissance, RGNR project) was initiated in 1979. From 1978 to 1982, cooperative research projects were carried out for the preparation and distribution of standard reference samples and for the development of field sampling techniques, multi-element analytical methodology and a unified data quality monitoring procedure. Large pilot surveys were also commenced in several provinces. After five years of technical preparation, the project came into its full implementation. More than 5 million km2 of Chinese land surface has been covered by this project. During 1993–1995, another national geochemical project, under the name of ‘Environmental geochemical monitoring network and dynamic geochemical maps in China’ as a pilot survey to choose the suitable sampling medium for the global geochemical mapping application, was carried out in China. The remarkable achievements of China's geochemical mapping projects are widely recognized. Nearly 66% of new discoveries of economic mineralization by MGMR were attributed to the RGNR project. New concepts and new methodologies have emerged through these projects. They also made a great contribution to the international activity toward standardization of geochemical mapping methodology and the possible realization of wide-spaced global geochemical mapping. 相似文献
3.
To develop a technique of implementing global ultra-low density geochemical sampling and as a contribution to the International Geochemical Mapping Program (IGCP Project No. 259), an orientation study in the use of deep (lower-layer) overbank sediments was conducted in Jiangxi Province of Southeast China in 1989–1990. Ninety-four samples were collected at depths of 50 to 120 cm from overbank terraces at an average density of 1 site per 1800 km2. The total area of sampled catchment basins is approximately equivalent to 18% of Jiangxi Province. Most of the samples were collected at outflow sites of catchment basins with areas of 100 to 800 km2. The samples were analyzed for 39 elements.The representativity of wide-spaced lower-layer overbank sediment sampling is discussed from various perspectives; the following features have been observed: (1) Widespaced lower-layer overbank sediment data and the data from China's national geochemical mapping (RGNR) project show similar geochemical patterns for W, Sn, Pb, Cu and Zn. (2) The results of wide-spaced lower-layer overbank sediment sampling demonstrate that catchment basins with areas of 100 to 800 km2 are suitable sample site locations for the global geochemical reference network. (3) Wide-spaced lower-layer overbank sediment sampling is a fast and cost-effective way to identify geochemical provinces and has strategic significance in mineral exploration. (4) There is a significant correlation between the W content of wide-spaced lower-layer overbank sediment samples and the presence of W mineralizations within the catchment basins. (5) The distributions of Ni, Cr and V in wide-spaced lower-layer overbank sediment samples distinctly reveals the boundary between the Yangtze sedimentary platform and the South China Caledonian fold system in Jiangxi Province. (6) Distributions of Rb and Be coincide with the Yanshan granites, which are closely related to the major ore-forming episodes in Jiangxi Province. 相似文献
4.
The suitability of floodplain sediment as a global sampling medium: evidence from China 总被引：2，自引：0，他引：2
Research undertaken by IGCP 259 (International Geochemical Mapping) indicates that wide-spaced sampling is a fundamental concept of international geochemical mapping as it appears to provide the only practical way to obtain a relative rapid (10–20 years) overview of global geochemistry. The main aim of this study is to test the suitability of floodplain sediment as a global sampling medium.Thirteen floodplain sediment samples and 13 stream sediment samples were taken at the exit of 13 super large drainage basins (SCB). The areal extents of these basins are in the order of 1000–10,000 km2. Within each SCB, 3–11 stream sediment samples each representing a component catchment basin (CCB) of 100–1000 km2 were also taken. Fourty nine elements were analyzed. The results were compared with the average values derived from calculating thousands of stream sediment data available from China's National Geochemical Mapping (RGNG) program. Strong similiarities were demonstrated in distribution and trends among the three levels of data. The set of floodplain sediment data shows great coincidence with RGNR stream sediment data. 相似文献
5.
Antimony in the environment: Lessons from geochemical mapping 总被引：2，自引：0，他引：2
The distribution of Sb in a variety of sample materials, including soils, plants and surface water, 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 Sb sources. Geochemical mapping demonstrates that variation is high at all scales – from the detailed scale with sample densities of many sites per km2 to the continental-scale with densities of 1 site per 5000 km2. Different processes govern the Sb distribution at different scales. A high sample density of several samples per km2 is needed to reliably detect mineralisation or contamination in soil samples. Median concentrations are so low for Sb in most sample materials (below 1 mg/kg in rocks and soils, below 0.1 mg/kg in plants, below 0.1 μg/L in surface water) that contamination is easier to detect than for many other elements. Distribution patterns on the sub-continental to continental-scale are, however, still 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 Sb 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
6.
Delineation of geochemical blocks for undiscovered large ore deposits using deep-penetrating methods in alluvial terrains of eastern China 总被引：1，自引：0，他引：1
Many large ore deposits have been discovered in eastern China along the Circum-Pacific Rim. However, alluvium, which covers most of the terrain, prevents a complete assessment of the mineralization potential by geological and conventional geochemical approaches. Two deep-penetrating geochemical methods—collection of nanoscale metals in earthgas (NAMEG) and selective leaching of mobile forms of metals in overburden (MOMEO) have been used to investigate the possibility to delineate geochemical blocks generated from large ore deposits buried by alluvial terrains. A wide-spaced sampling was carried out in an area of approximately 250 000 km2 at density of one sample per 400–800 km2. The soil samples were subjected to MOMEO leaching and were analyzed for Au, Ag, Cu, Pb, Zn, Fe, and Mn by atomic absorption spectrometry (AAS). The earthgas samples were analyzed for 17 elements by INNA. The results show that water-extractable metals by MOMEO processing can give prominent expression to concealed deposits and can delineate large-scale geochemical anomalies in the alluvial terrains. The distribution of gold in earthgas is situated along the largest deep fault systems and the concentration centers distribute in the secondary faults on the both sides of the deep fault systems. 相似文献
7.
文章以浙江省平湖市为典型三角洲平原区,开展了多种尺度、不同采样方法的对比试验。结果表明,田块内土壤元素分布较为均匀,小范围内元素的空间分异性较小,而田块之间土壤元素含量差异性明显增加;Hg,Cd等典型污染元素空间分异性较强,而人为污染扰动较弱的元素的空间分布较为均一;不同采样方法取得的区域性资料,其统计值接近,空间分布模式也相似,但有些元素仍有较明显差异。因此,中大比例尺地球化学调查时,应根据调查研究的目标任务,充分考虑地块分布、土壤类型和土地利用方式,选择合理的采样点。土壤样品可采取多坑点采集、多子样组合的方式,以保证样品的代表性,同时减少分析测试工作量。 相似文献
8.
Hilde Maritz H. C. C. Cloete Jacobus H. Elsenbroek 《Geostandards and Geoanalytical Research》2010,34(3):265-273
The Council for Geoscience (CGS, South Africa) has a statutory mandate to carry out regional geochemical mapping in South Africa that needs to be rapidly and accurately analysed. Both simultaneous X-ray fluorescence spectrometry (S-XRF) and a newly developed method using inductively coupled plasma-mass spectrometry (ICP-MS) were employed. Various trace elements that could not previously be analysed by S-XRF can now be analysed by ICP-MS for the regional geochemical mapping programme, e.g., Cd, Mo, Te and Li. Using both techniques, the CGS aims to report element distributions for some fifty elements. To ensure that element concentration levels correlate over map boundaries, quality control measures in the sampling, sample preparation and analyses were of critical importance. This paper aims to discuss the sample preparation and quality control measures as applied to the ∼5500 samples of the Giyani and Tzaneen 1:100000 scale map sheets sampled at a density of one soil sample per km2. ICP-MS batch- and instrumental drift-correction procedures will be discussed. As a final step, geochemical data were overlain over simplified geological maps using geographical information system software. These maps complement existing geological information of South Africa, help in the identification of exploration targets, test exploration models and initiate further geological research. 相似文献
9.
A geochemical investigation was carried out mainly in a 14-km thick sedimentary sequence of late Precambrian age. The project included analysis of rock samples and drainage samples for Cu, Co, and Zn. The drainage samples were heavy-mineral concentrates and stream sediment samples.The results for the drainage sediments distinguish three well defined cupriferous horizons in the sedimentary column. Lithogeochemical studies of quartzites, pelites, and carbonates confirm that the anomalous values obtained in the drainage sediments arise from several Cu-mineralized horizons.The study has shown that geochemical prospecting appears to be well suited to Cu prospecting in Central East Greenland under arctic climate conditions even with a low sampling density of one sample per 5–10 km2 for the drainage samples, and one sample per 10–100 m of the sedimentary stratigraphic column for the rock samples. 相似文献
10.
固体矿产地球化学勘查进展与成果 总被引：4，自引：0，他引：4
为庆祝第三十届国际地质大会在北京召开,让世界各国地质同行们了解中国地矿部门固体矿产地球化学勘查工作的进展,本文主要介绍我国地球化学勘查的成果。近十五年来已完成区域化探覆盖面积517万km2,中比例尺化探普查面积约90万km2,发现各类化探异常约4.3万处,通过检查化探异常和工程验证发现具工业价值的大、中、小型矿床569处,找矿效果非常显着,特别是化探找金、银矿方面取得突破性成果,化探方法技术不断提高和广泛推广。特殊景观区的野外工作方法、化探样品微量、痕量元素测试方法技术、化探异常的查证方法及化探数据处理与成图等方面均接近或达到国际水平。回顾过去,地球化学勘查进展迅速,成果丰硕,技术水平不断提高。展望未来,地球化学勘查目标明确,任务繁重,地质找矿潜力巨大。 相似文献
11.
Guidelines for a low-density geochemical survey were described in 1990 by the Western European Geological Surveys. A low-density geochemical survey of Hungary was carried out in 1991–1995. The results are useful for future surveys and for the IGCP 360 project ‘Global Geochemical Baseline’. In regions with well-developed drainage systems in Hungary, 196 catchment basins of approx. 400 km2 were delineated and flood-plain deposits sampled at their outlets. The samples were taken from 0 to 10 cm and from 50 to 60 cm depths. Samples were analysed by ICP-AES and AAS techniques in two laboratories. A Geochemical Atlas of Hungary is in preparation that will show the distribution of 25 elements in the two sampled layers. Maps for the lower layer represent regional geochemical baseline values and a geochemical subdivision of the country (maps showing the distribution of element associations) was made on the basis of factor variables. Maps constructed from the data of the upper sampling level show us the present state of contamination of the surface. The results of this survey have contributed to the establishment of guidance values for soils prepared by the Hungarian Ministry of the Environment in 1995. Safe levels were established for As, Cd, Cr, Cu, Hg, Pb and Zn and regional environmental loads plotted. Differences between the median values of the two levels are generally small. However, the concentrations of certain elements like P, Pb and S are significantly greater in the upper layer reflecting contamination from agriculture. In certain regions, the rate of sedimentation was fairly fast such that the environmental effects of ore mining in Transylvania and southern Slovakia as well as those of heavy industry in northern Hungary can be observed in samples from the lower level. The main factor controlling the geochemical pattern in Hungary is the predominance of young (Pleistocene or Miocene) clastic sediments at the surface. Approx. 90% of the surface is covered by these young sediments. This kind of survey has the disadvantage of not providing enough contrast to differentiate geologically dissimilar areas but it has the advantage to provide regional surface background geochemical data and it helps to outline areas of possible surface contamination. Based on the results of this survey we conclude that it would be much better to sample smaller, but geologically homogeneous areas in mountainous terrain to obtain data characteristic of the geochemical background of lithologic units. This approach would mean a sampling density of a few tens of km2/sample for hilly areas, and a few hundred km2/sample for lowland areas. 相似文献
12.
R. Swennen J. van der Sluys R. Hindel A. Brusselmans 《Journal of Geochemical Exploration》1998,62(1-3)
A geochemical survey of Belgium and Luxembourg was carried out as part of an international research project entitled ‘Regional geochemical mapping of Western Europe towards the year 2000'. The aim of this research was to map regional background geochemical patterns based on pristine or at least pre-industrial overbank samples and to deduce regional information on the degree of environmental pollution of floodplain and present-day river sediments. Over the entire study area (about 33,000 km2), 66 overbank sites have been sampled. Catchment areas range between 60 and 600 km2. At each site an overbank profile has been dug out in the immediate vicinity of the river and described in detail. A first composite sample was taken 5–25 cm below the surface. This sample is supposed to represent deposition over the last centuries. Human interferences in this interval are often inferable based on changed sedimentary characteristics and the presence of anthropogenic particles such as charcoal, slags and brick fragments. A second composite sample was taken at depth, usually >1.5 m below the surface over an interval of about 20 cm. In most sites, the profile characteristics allowed to assume pre-industrial or even pristine conditions for this lower overbank sample. In some profiles this was confirmed by 14C-dating and/or by the absence of anthropogenic particles. Finally, a present-day stream sediment was sampled on the site to infer the actual pollution status. After drying at 80°C, disaggregation and sieving, the <125 μm fractions of the three sediment samples were analysed by XRF for major elements and several trace elements. Lower overbank samples generally show a direct link with the geological substrate and allow to assess natural background concentrations. Results from the mapping exercise as well as from the statistical analyses display a clear contrast between the northern part of Belgium where Cenozoic unconsolidated sandy and silty formations dominate which are especially vulnerable for erosion, and the southern part of Belgium and Luxembourg where Paleozoic and Mesozoic sandstones, carbonates, marls and shales are the prevalent lithologies. Here the shales are the most intensively eroded lithologies. This is especially reflected in the element patterns of Al2O3, MgO, K2O, Ga, Ni, Rb, Sc and V which negatively correlate with SiO2. Despite the human related pollution, the geological contrast between north and south Belgium is still recognisable in the geochemical pattern of the upper overbank and present-day stream sediment samples for the above-mentioned elements. Furthermore there is a clear increase in heavy metal contents (Zn, Cd, Pb, Cu), As and in certain locations in Ba from the lower to the upper overbank sediment, as well as to the present-day stream sediment. The relative increase in element content allows to assess the degree of pollution and helps to define those drainage areas where more detailed research is needed. 相似文献
13.
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
14.
B.L. Farrell 《Journal of Geochemical Exploration》1984,22(1-3)
This paper reviews some aspects of the use of “loam” (soil) concentrates in geochemical surveys in arid, deeply weathered environments.An orientation survey at a small Ni-Cu-Co prospect in Western Australia has shown that discrimination between mineralized and unmineralized samples could be achieved using Ni, Cu, Co, Cr, Zn, As, Sn, Sc, Ti, Yb and Y in the coarse fraction of heavy concentrates. However, at the same prospect the best contrast for Ni, Cu and Co in surface samples was provided by analysis of the same fraction following a cold ammonium citrate/hydroxylamine hydrochloride digestion.At a nearby, larger prospect, some 54 km2 in area, concentrates were separated, by jigging, from bulk soil samples, themselves composites of representative subsamples. Sampling at a density of 4 samples per km2 revealed 1–2 km2 size anomalies of Cu, Ni, Co, Cr, As and Au which could be related, variously, to known Ni-Cu and Au mineralization.In Botswana, analysis of concentrates, separated by tabling from samples collected at a density of 1 sample per 7.5 km2 over an area of 5400 km2, identified distinctive geochemical districts. Enhanced values of Au and of Cu-Ni in the concentrates were relatable to known mineralization and the results suggested that there were also Sn-W-Mo-Bi (granitoid) and Au-Pb-Zn-Bi-Sn (volcanogenic) associations which could lead to new prospecting targets. Anomalies of certain elements (for example, Cu in an ultramafic environment) may be more readily detected in surface material by “enrichment indexing” the concentrate data. 相似文献
15.
Over 450 samples were collected around four Proterozoic porphyry-type occurrences and analyzed for 30 elements. Relatively broad primary halos are associated with all four occurrences in spite of their moderate size and grade. The halos are characteristic of each particular occurrence depending on the geological and geochemical conditions. Copper forms extensive and highly contrasted anomalies, whereas Mo anomalies are of limited size. Gold, Zn, Pb, As, and Sb seem to be useful pathfinders for slightly eroded or blind occurrences. Pyritization and wall-rock alteration are weaker than in Phanerozoic porphyry deposits, consequently, S halos are small and often erratic. K2O, Rb, and SiO2 produce weak anomalies near the core of the occurrences. A density of a few tens of samples per km2 is required for detailed follow-up exploration.The host granitoids have normal chemical compositions outside the mineralized areas with low and constant background contents of ore elements and are thus very suitable for lithogeochemical exploration. On a regional scale a density of one to five samples per km2 is sufficient to identify mineralized intrusive phases and areas, because the porphyrytype occurrences were formed by extensive hydrothermal processes, which produced scattered anomalies over large areas. 相似文献
16.
中国化探走向2000年 总被引：4，自引：0，他引：4
总结了80年代中国化探的成就与不足之处。目的是更好的对中国化探走向2000年进行战略部署。中国的区域化探全国扫面计划在80年代取得了重大成就。已覆盖了400万km2的面积,发现了600余新的矿化产地,其中158个已成为新的有工业价值的矿床。研制了适用于乾旱、半乾旱、高寒山区、卡斯特及黄土覆盖地区的野外工作方法。研制了高效率低检出限的多元素分析系统及质量监控方案。所有这一切使得中国在系统进行地球化学填图工作方面在全世界居于领先地位,并带动了中国化探的全面发展。主要的不足之处是从80年代后半叶起,研究工作在指导整个这项计划的作用逐渐削弱,而整个计划逐渐变成纯生产性的例行工作。地球化学填图将成为地学及勘查地球化学新前沿已为国际上许多杰出科学家所承认。中国在填图技术以及信息累积上所占有的优势将给中国勘查地球化学家在90年代提供激动人心的新机会。简略的提出了一些新的研究方向。 相似文献
17.
A radionuclide-excited energy-dispersive X-ray fluorescence (EDXRF) device has been used for geochemical mapping of soils over the Orberg deposit of the Kaiserstuhl carbonatite near Schelingen. About 500 samples were collected from an area of 0.2 km2. The mobile EDXRF equipment was used in field laboratories to determine twelve trace elements (Cu, Zn, As, Rb, Sr, Y, Zr, Nb, Ba, La, Ce and Pb) quantitatively, and the major components K2O, CaO, TiO2, MnO and Fe2O3 semiquantitatively. Additional information on bulk chemistry was obtained by determining the average atomic number from scattered radiation. An attempt is made to identify the different carbonatite subcrops in this area by use of trace element patterns and inter-element relationships. Since part of the survey area is covered with loess, relations and ratios between elements were used to estimate the dilution effect due to loess. 相似文献
18.
Geochemical patterns from local to global 总被引：5，自引：0，他引：5
The historical development of geochemical exploration is, in a sense, a process of progressive enlargement of areal coverage by exploration projects and progressive widening of sampling space. Along with this process, a hierarchy of geochemical patterns from small to large is gradually discovered and understood. In this paper, we try to summarize systematically the whole hierarchy of geochemical patterns from local, regional, provincial, megaprovincial to global, using examples obtained in China.Local anomalies (various types of dispersion halos, trains and fans) within areas not exceeding a few km2, can be delineated when sampling is done with very close intervals in limited areas. Regional anomalies within areas of tens to hundreds km2 and threshold values lower than local anomalies can be identified only when large areas of more than thousands of km2 are mapped with wider space sampling. Geochemical provinces with areas of thousands or tens of thousands of km2 can be discovered if even larger areas, of more than tens or hundreds of thousands of km2, are covered with very low density sampling. More than millions of km2 should be covered in order to discover geochemical megaprovinces somewhere in the world. Such megaprovinces are often associated with extraordinarily large mineral resources. If ultra-low density geochemical mapping can be carried out across national boundaries on a continental or global scale, we could find even broader geochemical patterns which will reflect the global tectonic features.The classification of geochemical patterns according to their sizes is necessary because it will be extremely useful in planning sampling layout in order to hit targets of certain size ranges. This in turn is arranged in different geochemical projects for achieving specific aims. 相似文献
19.
《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
20.
该数据集依托中国地质调查局“山东莱州-招远地区金矿整装勘查区矿产调查与找矿预测”项目,在充分收集地质、物探、化探、遥感及矿产等资料基础上,开展毕郭幅矿产地质调查。项目共采集1 875件水系沉积物样品,采样粒级为-10～+80目,平均采样密度4.5个/km2。采用电感耦合等离子质谱法（ICP-MS）、原子荧光光谱法（AFS）、粉末发射光谱法（ES）和石墨炉原子吸收光谱法（GF-AAS）分析了16种元素,最终形成1：50 000山东毕郭幅地球化学数据集,数据集包含有1 875件样品×16种元素的原始分析数据表格一个,图集一套（含有1张矿产地质图、一张采样点位图和16张元素地球化学图）。区内共新发现单元素地球化学异常149处,综合异常10处,结合地质、矿产、物探、化探、遥感等信息并圈出金矿找矿靶区5处。 相似文献