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1.
. Toverud 《Journal of Geochemical Exploration》1987,28(1-3)
Regional exploration for pegmatite hosted Sn-mineralization in Sweden by LKAB Prospektering has, since the early 1980s, generally been based on the use of heavy-mineral concentrates from till collected by roadside sampling. The average sampling density has been 0.5–1.0 sample/km2, but with an uneven distribution of sample points within areas investigated.Planning of the regional sampling grid in this study has been based on a statistical analysis to answer the following question: What sample density and grid-spacing should be used to hit an anomalous target with the highest possible probability.The statistical analysis indicates that using a rectangular grid, 750 × 1,500 m (0.88 sample/km2), the probability of intersecting an anomalous target is 100%. Heavy-mineral till concentrate sampling using this grid design in northern central Sweden in 1981 revealed one single, extremely high sample with 4,622 ppm Sn indicating mineralization in the area north of the village of Järkvissle.In 1982–1983, while boulder tracing up-ice from the anomalous regional sample point, cassiterite and spodumene-bearing boulders and outcrops were found. Two parallel mineralized pegmatites within an area of approximately 5,000 m2 with grades of 0.04–0.07% Sn and 0.40–0.92% Li2O have recently been located NW of Järkvissle.Semi-regional (250 × 500 m) and local (20 × 20–160 m) sampling of till gave some anomalous values of Sn and Li in concentrates, which to some extent could be correlated with mineralized boulders and outcrops, and also indicated new targets for drilling.The results from a simplified sample preparation technique for heavy-mineratl till concentrates show that a new device, named the Goldhound, can be used in future geochemical prospecting for Sn and Li in Sweden. 相似文献
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Heavy-mineral geochemistry and its use in prospecting are based on the fact that some ore minerals (e.g. cassiterite, scheelite, wolframite, chromite, pyrochlore and columbite-tantalite) have a higher specific gravity than the common rock-forming silicates and are highly resistant to weathering in the secondary environment. Till, the most common type of surficial deposit in Finland, is relatively homogeneous and thus constitutes an appropriate sampling material for heavy-mineral geochemical studies. This is especially true in reconnaissance prospecting.The present work concentrates on the interpretation of heavy-mineral anomalies by reference to mineralogical and mineral chemistry data. Tetrabromoethane and a Frantz Isodynamic Separator were used to divide the heavy-mineral samples into subfractions, after which the minerals present were identified by light microscopy, scanning electron microscopy combined with energy-dispersive X-ray spectrometry, electron microprobe techniques and X-ray diffraction.Applications of the methods at three tin anomaly sites in southern Finland are described. The results successfully predicted the presence of a greisen in one area and a pegmatite in another. Those for the third area were somewhat contradictory, the mineralogical composition of the samples suggesting a greisen source for the tin while the composition of the cassiterite pointed to a pegmatite or granite source. 相似文献
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O. Selinus 《Journal of Geochemical Exploration》1983,19(1-3)
Alteration zones in host rocks surrounding mineral deposits have long been used as indicators of ores, and recent studies have stressed the importance of the chemical distribution patterns or haloes. These may be more pronounced than mineral alteration and therefore detectable over greater distances.There are, however, several problems involved in this type of prospecting. One is the possible presence of several geochemical populations in the analyzed samples. Only some of these populations reflect the haloes which one wants to detect, while others only disguise the haloes. One solution is to use multivariate statistical analysis to discriminate between the different populations.In the Stollberg orefield, central Sweden, these prospecting methods are presently in use. Here, located within Precambrian volcanic rocks, several small and large stratiform zinc-, lead- and iron ores are situated in the same stratigraphic zone and within 6 km of each other. Drifts in the area go down to 575 m. Approximately 3000 rock samples collected from outcrops, drill cores and drifts were analyzed for 35 elements by XRF and IDES (Image Dissector Echelle Spectrometer). These samples represent an area of 3 × 9 km to a depth of 600 m.Due to the presence of several geochemical populations, the raw data are difficult to interpret. After reducing the skewness of the data, factor analysis was performed and, in general, distinct multi-element zonations were detected. Factor scores were used as the input for discriminant analysis. In this manner chemical haloes were obtained which have an extension of more than one kilometer in all directions around the various ore types in the area. The ores can thus be detected at considerable distances. On the basis of these findings, some promising new prospects have been discovered. 相似文献
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新疆东昆仑是我国西部地质工作程度较低地区之一,白干湖钨地球化学块体的确定及白干湖钨锡矿床的发现成为该区矿产勘查中突破性的进展.文章概述了白干湖钨地球化学块体的地质、矿产及地球化学特征.对该块体与成矿的关系进行了探讨,认为钨地球化学块体为白干湖钨锡矿床的形成提供了丰富的成矿物质,钨的成矿与岩浆的演化有着密切的成因关系.指出白干湖钨锡矿床有望成为超大型矿床,新疆东昆仑地区有望成为我国一个新的钨矿远景区和新的钨矿产区. 相似文献
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湘中芭蕉冲金矿区为低山丘陵地球化学景观区,位于羌塘-扬子-华南板块东北缘,区内已查明4个工业矿体,矿体受断裂构造控制。本文以该矿为基础进行湖南省中低山丘陵景观区土壤地球化学找矿研究,以供同行参考。在该区完成土壤地球化学测量30 km,采集土壤样品1435件,样品采集深度在30~40 cm,部分采集深度为40~50 cm,成分均为土壤B层。利用多元统计学方法,对Au、Ag、Pb、Zn、As、Sb、Hg七种元素进行R聚类分析、因子分析及地球化学参数统计,确定Au、Ag为主成矿元素,Pb、As为找矿指示元素,运用衬值异常推断了隐伏构造位置,圈定单元素异常39处,综合异常区6处。通过地质工程查证,证明了衬值异常推测的含金构造的存在,发现芭蕉冲F_(2)含金构造和工业矿体,实现该区域的找矿突破。 相似文献
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In 1982 and 1983 a surficial geology and overburden geochemistry survey was carried out on the Sisson Brook Mining Licence in York County, about 55 km northwest of Fredericton, New Brunswick, Canada.On the Sisson Brook Mining Licence three zones of W-Mo-Cu mineralization have been outlined; Zones I and II contain mainly wolframite with chalcopyrite and pyrrhotite, whereas Zone III has mainly scheelite and molybdenite.The glacial history of the area was studied during 1982 and 1983 to provide a framework for interpreting the geochemical results. Ice movement varied from 160° ± 10° towards the south during the Main Bantalor phase (maximum ≈ 13,500 y.B.P.) to 130° ± 10° toward the southeast during the Late Bantalor phase. Rapid changes in dominant pebble lithologies occur immediately upon crossing bedrock contacts. This suggests a very short distance of transport on the property. The glacier, butted against the Nashwaak Ridge, quickly sheared bedrock debris up into the body of the ice by compressive flow. Upon melting, some of this debris was deposited a short distance from source. Some debris appears to have been sheared up higher into the ice sheet, transported over the Nashwaak Ridge, and deposited approximately 8 km down-ice with no interconnecting dispersal train.In 1982, a geochemical orientation survey was carried out to determine which element(s) and sample medium could best and most economically be used in the search for W-Mo-Cu mineralization. Within the property area, both whole till <2000 μm (−10 mesh) samples and heavy mineral concentrates clearly defined the zones of mineralization (W, Mo, Cu) and associated geochemical dispersal trains (W, Mo, Cu, As, F). In later work, samples were not analyzed for As and F because this provided no additional information. The geochemical contrast between values in whole till samples derived from subcropping mineralization and those derived from barren bedrock is adequate to outline mineralization. Geochemical analysis of the whole till was used in later work because the sample preparation costs are considerably lower than those for heavy-mineral concentrates. Soils were not used because trace element patterns were diffuse, with the highest values occurring at variable distances down-ice from mineralization.In 1983, the objective was to better define glacial dispersal from the known mineralization and to explore for additional mineralization. Data from this program indicates a W dispersal train in whole till samples 300–400 m long. Tungsten values up to 1400 ppm and Mo values up to 260 ppm in whole till occur immediately down-ice from the main subcropping W-Mo mineralization. The element associations (i.e. W-Mo-Cu and W-Mo) in the till reflect the elemental composition of the source mineralization (i.e. Zones I and II and Zone III).Backhoe trenching is a useful and cost-effective technique to expose Quaternary sediments. Examination of the overburden sections provides an understanding of the glacial history which aids in tracing geochemical dispersal trains up-ice to bedrock source. 相似文献
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One hundred twenty-eight samples of heavy-mineral fractions from sand-size sediments whose mineralogy was previously studied by A. Ayalon, were chosen for this geochemical study. The samples represent the stream sediments along the coastal belt from Elat to Sherm el-Sheikh. This study supplements the geochemical study of A. Zilberfarb and R. Bogoch on the Precambrian terrain of Sinai.The mineral composition of the samples was determined by X-ray diffraction and optical microscopy. In all samples, 14 elements were analyzed: B, Co, Cr, Cu, Ga, Mn, Mo, Nb, Ni, Pb, Sn, Ti, V and Zr. Seven magnetic fractions were separated from twenty of these samples and in these fractions 14 to 20 elements were analyzed, according to the sample. The chemical determinations were mainly by DC emission spectrography.The results were submitted to factor analysis and to association analysis (D. Gill and co-workers). Since the environment is typically arid, there is relatively little chemical weathering. The combined results of both statistical analyses show clearly that three types of source areas can be differentiated: sandstone, metamorphic and granitic terrain. Furthermore, a distinct Mn anomaly was found in the Sherm el-Sheikh area. 相似文献
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大通沟南山属于阿尔金南缘成矿亚带金鸿山—茫崖金、铜、钨多金属找矿预测区,其地球化学和地球物理异常发育,具有优越的成矿地质条件及良好的找矿潜力。鉴于大通沟南山地处高寒山区,地理环境恶劣、野外地质调查工作困难等问题,文章利用多源遥感卫星数据,在其区内开展了全面的地质解译以及蚀变信息提取工作,并结合已有的地质矿产及物化探资料,对区内的成矿地质条件及找矿远景进行了分析预测,圈定了3处遥感找矿远景预测区,可为后期野外地质找矿工作提供帮助。 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.
Three periods in the development of geochemical methods for ore prospecting in Bulgaria may be distinguished — initial (1954–1960), middle (1961–1969) and contemporary (since 1970) — which are characterized by successively increasing numbers of samples and improving methods of geochemical data evaluation. Geochemical methods have been recognized as effective, rapid and relatively cheap methods for prospecting for ore deposits (Cu, Pb, Zn, Au, W, Mo, etc.), some nonmetalliferrous raw materials (fluorite, barite, phosphorites) and hydrocarbons. They are used in all stages of exploration at scales from 1:200,000 to 1:200. They have contributed to the elucidation of the ore perspectives in many regions, and a number of new ore bodies and deposits have been discovered.Basic geochemical methods applied to ore prospecting in the country utilize soil and rock to detect secondary and primary aureoles. Stream-sediment surveys, hydrochemical and atmochemical methods are of more restricted use. Samples are analyzed by emission spectrometry, atomic absorption and other methods. A united system of computerized processing of geochemical data has been developed, including automatic drawing of geochemical maps.Interpretation of the data consists in selection of prospective geochemical anomalies and prognostication of the composition, morphology, depth and industrial significance of hidden ore bodies. The main problem in the mathematical processing of data is the presentation of polydimensional results from analyses in the form of generalized quantities — multiplicative or additive geochemical indicator ratios for the type of mineralization, coefficients of zoning, intensity, etc. The geochemical indices for evaluation of the newly found anomalies are derived through studies of the primary geochemical aureoles of typical standard ore deposits.Residual secondary soil aureoles in most cases are well correlated in composition and structure with the ore bodies and primary aureoles which have generated them. Their successful use is related to the landscape-geochemical conditions in the ore regions. Micro- and macro-chemical zoning of ground waters and different concentration of soluble components in different elevation belts are used for evaluation of hydrochemical anomalies. 相似文献
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以江西省武宁县石门寺钨铜矿区燕山期和晋宁期岩体风化作用过程中W、Cu等元素的表生地球化学行为为研究对象,通过反映风化程度的化学风化指数CIA、风化作用过程中组分得失的估算、不同介质中W、Cu等成矿元素的含量变化及大离子亲石元素表生地球化学行为等方法的研究表明,石门寺钨铜矿区2个时期岩体元素淋失与风化强度有关,土壤剖面中碱金属、碱土金属元素大量淋失,而W、Cu等成矿元素在土壤B层中显著富集;从岩石到土壤、再到水系沉积物风化过程中,W、Cu等成矿元素含量逐渐升高,为此,一级水系沉积物和B层土壤是赣北九岭W、Sn、Cu、Mo多金属矿集区地球化学找矿的绝佳采样介质,是矿集区内找矿新突破的有效手段。 相似文献
14.
Shilts, W. W. 1977 06 01: Geochemistry of till in perennially frozen terrain of the Canadian shield - application to prospecting.
Geomorphological (drumlins, ribbed moraine) and geochemical features associated with till in the District of Keewatin are arranged in belts or dispersal trains paralleling the main direction of ice flow. Both types of features can be related to chemical and physical characteristics of specific types of source rocks.
For dispersal studies in perennially frozen terrain, till samples were collected from mudboils at spacings of approximately 1.6 km. The texture of till samples varies significantly from sample site to sample site because of varying source-rock lithologies and periglacial processes. Thus, because fractions coarser than clay are mostly quartz and feldspar and contain very little metal after weathering in the active layer, they were removed by centrifugation so as not to mask the 'true' relative metal contents of samples. The clay-sized fraction was separated from till samples and analyzed on the assumption that it contained scavenging phases that adsorb cations in proportion to those released by weathering of mineralized particles that were originally physically dispersed by glacial action.
Dispersal patterns of copper, zinc, nickel, and uranium were derived for approximately 1000 samples evenly distributed over a 2500 km2 grid. From these maps, large dispersal trains of copper and nickel were found, and known areas of high potential for uranium and Cu-Zn mineralization were clearly indicated. 相似文献
Geomorphological (drumlins, ribbed moraine) and geochemical features associated with till in the District of Keewatin are arranged in belts or dispersal trains paralleling the main direction of ice flow. Both types of features can be related to chemical and physical characteristics of specific types of source rocks.
For dispersal studies in perennially frozen terrain, till samples were collected from mudboils at spacings of approximately 1.6 km. The texture of till samples varies significantly from sample site to sample site because of varying source-rock lithologies and periglacial processes. Thus, because fractions coarser than clay are mostly quartz and feldspar and contain very little metal after weathering in the active layer, they were removed by centrifugation so as not to mask the 'true' relative metal contents of samples. The clay-sized fraction was separated from till samples and analyzed on the assumption that it contained scavenging phases that adsorb cations in proportion to those released by weathering of mineralized particles that were originally physically dispersed by glacial action.
Dispersal patterns of copper, zinc, nickel, and uranium were derived for approximately 1000 samples evenly distributed over a 2500 km
15.
在新疆东昆仑祁漫塔格地区新发现大量的以Fe,Cu,Pb,Zn,W,Sn为主的多金属矿床(点),铅锌矿床便是其中之一。文章通过对维宝矿区区域成矿地质条件、区域化探异常特征,以及铅锌矿赋矿地层、产出特点、矿化特征、围岩蚀变及成矿物质来源的初步分析,认为维宝地区具备寻找大型铅锌矿床的地质、地球化学条件,Pb-Zn成矿地质条件优越,具有很好的找矿前景;归纳出铅锌矿床的找矿标志,建立了铅锌矿床的经验找矿模型;指出了区内铅锌矿床的找矿方向和找矿靶区,并针对不同类型的矿床提出了下一步的工作建议。 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
18.
勘查地球化学工作的进展 总被引：1，自引：0，他引：1
地球化学勘查,主要是利用先进的微量元素测定技术,系统地研究各种天然物质(如岩石、疏松沉积物、水系沉积物、水、气体、生物等)中元素的分布和分配特征,从而获得找矿信息的一种找矿方法。在我国,从五十年代初期至今三十多年来,化探工作从无到有,化探队伍由小到大,建立了一支有一定基础的专业队伍,初步形成了我国自己的方法技术体系,获得了丰硕的地质—找矿成果。 相似文献
19.
The results described relate to an investigation into the nature of Au dispersion in glacial till, undertaken to identify optimum search techniques for use in exploration for Au mineralization.The diversity of Au mineralization, in terms of the host rock lithologies, mineralogy and grain size of the Au, would be expected to give rise to differences in the secondary response in the associated overburden. Common exploration procedures involve the analyses of the heavy-mineral fraction or a particular size fraction of the tills. However, having regard to the expected variable response of Au in associated glacial till, attributed to variations in primary mineralization, effective exploration requires that the methodology employed is capable of locating all types of Au mineralization.Bulk till samples were collected from various sites associated with the Owl Creek deposit near Timmins and the Hemlo deposits. Grain size analyses were carried out on the till samples and on the heavy-mineral concentrates. The concentration of the Au in the various fractions was determined by Instrumental Neutron Activation Analysis.Preliminary results allow a number of provisional conclusions to be drawn:
- 1. (1) Grain size analysis of the −2 mm fraction of tills indicates that the silt and clay fraction constitutes 20–50%, whereas, in contrast, the equivalent heavy-mineral concentrates are dominantly composed of the coarser −500 + 63 μm material.
- 2. (2) The amount of Au present in the heavy-mineral concentrates of tills represents only a minor proportion of the total Au in the original till samples. In addition, the proportion of the total Au recovered in the heavy-mineral concentrate varies from 4 to 15%. Both factors indicate that caution is necessary in interpreting the significance of heavy-mineral Au data.
- 3. (3) Examination of the size distribution of Au within the heavy-mineral concentrate indicates that the majority of the Au is contained in the −125 μm fraction.
- 4. (4) The concentration factor (the original sample weight divided by the heavy-mineral concentrate weight) varies up to 7-fold between samples due presumably to the differing proportions of heavy minerals. Hence, in Au deposits of equivalent economic significance this gives rise to varying Au concentrations in heavy-mineral concentrates according to the quantity of heavy minerals present. Significant interpretation can only be achieved by re-expressing the Au contents of heavy-mineral concentrates in terms of the absolute amount of Au in heavy-mineral concentrates.
- 5. (5) A comparison of the heavy-mineral concentrates produced by different laboratories indicates marked differences in the weight of the heavy-mineral concentrate, the Au concentration of the heavy-mineral concentrate, the total weight of Au in the heavy-mineral concentrate and the size distribution of the Au in the heavy-mineral concentrate.
- 6. (6) Analysis of the −63 μm silt and clay size fraction indicates anomalous Au contents within this fraction of the tills collected from Owl Creek and Hemlo, extending over 500 m down-ice from mineralization at Hemlo.
- 7. (7) Analysis of the −63 μm silt and clay size fraction is suitable for the detection of fine-grained Au deposits that are not amenable to detection on the basis of heavy-mineral concentrate analyses.
- 8. (8) The analysis of the silt and clay fraction reduces the sample representativity problems associated with analyzing coarser fractions.
- 9. (9) A comparison of the Au distribution in heavy-mineral concentrates and the −63 μm fraction of till down-ice from the Owl Creek deposit indicates broadly similar dispersion patterns.
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古铜陵地区是长江中下游成矿中重要的多金属成矿区,有着独特的多位一体、"层".带"结合、多矿种、多种成因类型复合的成矿地质环境,产生了丰富的接触交代与层控式夕卡岩-热液充填交代的块状硫化物型的铜、金、银、硫等内生矿产,成为国内外地学研究的热点地区.本文从铊元素的地球化学研究探寻其作为金(铜)矿床的探途元素的可能,从本区一些主要矿床中过铊与金(铜)相关性的研究,得出铊与金(铜)密切正相关的结论,并进行了微量元素铊在找矿方面应用的一些初步探读者论坛,指出下一步找矿方向及预测靶区. 相似文献