Secondary dispersion patterns of fluoride in the osor area,Province of Gerona,Spain

The distribution of fluoride in spring and stream waters, stream sediments and soils of the Osor district, Province of Gerona, northeastern Spain, has been studied. Fluoride was determined by use of a fluoride-sensitive electrode. This potentiometric method has been found useful for geochemical exploration for fluorite because of its simplicity and high sensitivity.Investigations of the fluoride contents of natural waters and stream sediments resulted in the discovery of new fluorite mineralizations.Secondary dispersion patterns of soils have been studied. Different analytical procedures to extract the fluoride have been used. The application of the methods in geochemical exploration surveys is discussed.     

江苏丰,沛,铜地区高氟地下水不成因探讨

通过该区太古界一新生界氟的地层地球化学剖面及岩浆岩和土壤中氟的丰度的研究,论证了该区为一高氟的地球化学区。根据重矿物对比研究和地貌分析,阐明了泰沂隆起区太古界和元古界的高氟古老岩系为该区土壤沉积物源,黄河多次泛滥堆积（粘土矿物对氟的吸附）对土壤氟起了叠加富集的作用。研究揭示该区土壤水溶氟较高,经降水淋滤和浸取作用氟转入地下水,并在凹陷区或河间洼地中聚集,水体停泄、蒸发浓缩形成高氟地下水区。     

浅覆盖区隐伏萤石矿找矿预测:以内蒙古赤峰俄力木台为例

内蒙古赤峰地区发育一系列受断裂控制的热液脉型萤石矿床,区内成矿地质条件优越,找矿潜力较大。本文利用地质特征-地球物理-地球化学-遥感解译(地-物-化-遥)综合找矿方法进行浅覆盖区萤石矿体的定位预测研究,对寻找隐伏矿床和探寻萤石接替资源具有重要意义。俄力木台地区是林西水头萤石成矿带的南段延伸,第四系覆盖严重,是开展浅覆盖区隐伏矿体找矿预测方法实践的理想地区。研究区域的萤石矿体在垂向上呈现分带特征,自上而下分为硅质顶盖、头部矿体、中部矿体和尾部矿体4部分。俄力木台地区的硅质顶盖露头以发育强硅化角砾岩、次生石英岩和石英网脉带为特征,头部矿体露头见萤石粗脉体产出,二者矿化露头的高差30~50 m。WorldView-2遥感影像揭示俄力木台地区含矿断裂带的空间展布与线性变化特征,矿化带中-北段呈近SN向,南段主要呈NNE-NE向。地-物-化综合剖面中矿化露头、甚低频低阻异常带、便携式X射线荧光分析土壤Ca元素高值异常带和土壤偏提取地球化学测量F元素高值异常带分布一致,该异常组合可作为本区含矿断裂带和隐伏萤石矿体的重要预测标志。结合甚低频电磁测量扫面,俄力木台断续出露的矿化蚀变带与SN向甚低频低阻异常带相吻合,预示该区可能发育隐伏-半隐伏萤石矿体。在俄力木台东段重点预测地带布置的钻孔见矿效果良好,目前揭露的部位为硅质顶盖、头部矿体或构造狭缩带,较高品位的萤石主矿体尚未揭露,其深部具有良好的资源潜力和找矿前景。     

中国区域化探若干基本问题研究：1999—2009

1999—2009年,中国区域化探发生了根本性改变。主导思想是以地球化学理论为指导研究区域化探方法技术问题和进行矿产资源潜力评价。区域化探方法技术研究的基本要求是最大限度保持原生地球化学分布特征,表生地球化学条件下采样物质问题是区域化探方法研究的核心,样品采集应以代表地质找矿信息的基岩物质成分为原则,在全国范围内最大限度地保持采样物质的一致性。基于成矿地球化学理论建立资源潜力地球化学评价方法和实行地质找矿定量预测,使勘查地球化学从单纯方法手段上升到指导地质找矿的理论高度。主要标志是在全国建立完整的区域化探工作方法技术系统和实行样品分析质量全程监控。在区域化探高精度数据基础上绘制与出版精美的地球化学图集,使区域地球化学图精确地反映地质背景分布与异常特征,促进区域化探数据信息深度开发和利用,建立具有从区域、普查到详查进行全过程独立开展资源调查、评价和预测的方法技术体系和工作程序。区域化探长期支撑中国地质找矿工作,是整个地质找矿工作的先导。随着新一代地区和全国地球化学图的形成,将在基础地质和成矿规律研究以及揭示重大地质事件等方面提供新的发现、新的认识和新的观点,对于未来中国勘查地球化学和整个地质工作产生重要影响。     

Geochemical dispersion of gold related to copper-gold mineralization in northeastern Thailand

The nature of gold dispersion in soils and stream sediments associated with a copper-gold-mineralized system in northeastern Thailand has been investigated as a basis for identifying appropriate geochemical exploration techniques for the search for comparable deposits in similar environments.Soils were collected with varying relationships to mineralization as a basis for determining sample representativity, size distribution of gold, variation with soil horizon and possible pathfinder elements. Similarly, stream sediments were collected to estimate sample representativity, size distribution of gold, variation of gold with depth in the stream sediment profile and to compare the relative recoveries of gold in field-panned and laboratory-prepared heavy-mineral concentrates. Samples were analyzed for Au and potential indicator elements by a variety of methods but mostly by instrumental neutron activation analysis.Results indicate the consistent distribution of fine-grained gold in soils which allows Au analysis of relatively small samples from B-horizon soils to be used effectively and reliably to identify the surficial patterns of gold mineralization in the study area. Anomalous patterns of other indicator elements, Co, As, Cu, Sb, W, Pb, Zn, Ag, Fe and Mn, may contribute additional information regarding type of mineralization. This finding indicates the effectiveness of soil surveys in gold exploration, particularly in areas of deep weathering where fresh bedrock exposures are infrequent.Unlike soils, size distributions of gold in stream sediments, as a result of the local flow regime, vary both between sampling sites and at depths within a sampling site. Exploration requires Au analysis of the fine fraction (minus 63 μm) of active stream sediments to reduce the problem of sampling representativity. The presence of coarse-grained gold in the stream channel has drawn attention to the possible benefit of using the conventional field-panning method as a semiquantitative technique for providing immediate results. However, highly erratic distribution of pannable gold on a very local scale together with variable proportions of the total gold recovered in field-panned or heavy-mineral concentrates highlights a potentially serious drawback of the method. Combination of analysis of the minus 63 μm fraction and field panning appears warranted to cover the possible existence of gold of a wide size range in stream sediments.The overall results indicate the utility of geochemical exploration techniques in the search for gold mineralization. However, particular care is necessary in the design and implementation of geochemical techniques to ensure maximum reliability of exploration.     

冀北步古沟一带萤石矿地物化找矿技术方法组合研究

地物化综合信息在热液充填型萤石矿找矿的应用探索具有重要意义。本文以冀北步古沟一带萤石找矿为例,通过综合物化探方法进行有效性试验,总结该地区萤石矿地物化找矿技术方法组合。在地质调查基础上,系统开展了1:5万水系沉积物地球化学测量、1:1万土壤剖面测量、高精度磁法测量、天然电场选频测量、电阻率联合剖面测量及高密度电阻率测量等找矿技术方法探索。结果表明,1:5万水系沉积物测量及1:1万土壤剖面测量等化探方法可辅助锁定找矿目标区;高精度磁法及天然电场选频测量,可初步判定断裂的位置;电阻率联合剖面及高密度电阻率法测量可进一步探测含矿断裂构造的位置、产状及延伸。通过以上试验研究,建立了冀北地区萤石矿地物化找矿技术方法组合,经工程验证在研究区内新发现萤石矿点1处,取得了较好的效果。实践表明,该套地物化找矿技术方法组合可进一步指导冀北地区的萤石矿找矿工作。     

A contribution to geochemical prospecting for fluorite

With fluorine as indicator, eight different extraction methods were tested for their suitability in geochemical prospecting for fluorite in stream sediments. Since this material can be regarded as coarse-grained, clastic fragments derived from the bedrock - i.e. granites, gneisses, and fluorite veins as well - it was concluded that the fluorine content of the stream sediments comes mostly from fluorine-bearing bedrock minerals. Anomalous samples contain fluorine predominantly as fluorite from fluorspar mineralization.Five of the commonest fluorine-bearing minerals - fluorite, mica, apatite, amphibole and tourmaline - were treated with the different extractants and with various times of reaction and mineral grain size. Fluorine analysis was by ion-selective electrode. The ratio cx-F (fluorite) vs. cx-F (mica, apatite) was found to be a useful measure of the applicability of the respective method.In order to test this conclusion 41 stream sediment samples (−177 microns −80 mesh) from the area under investigation were treated with eight different extractants.The most suitable extraction solution - boric acid solution - was used for the reconnaissance stream sediment survey in an area of 400 km² in the southeastern part of the Black Forest (F.R. Germany).     

Developments of geochemical methods for ore prospecting in Bulgaria

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.     

浙西北地区萤石矿床成因及找矿方向

近年来浙西北地区在岩浆期后热液型萤石矿床勘查中取得重大突破,先后探明常山、淳安、开化、安吉等地多个大中型萤石矿床。这些矿床主要分布在燕山期(早白垩世)花岗岩类内外接触带中,成矿作用与岩浆侵入活动密切相关。通过对浙西北地区7个典型矿床进行矿床地质特征、成矿岩体及控矿构造研究,探讨岩体与萤石成矿之间的关系,将萤石矿床成因初步划分成2个亚类:与A型花岗岩有关的岩浆期后热液型萤石矿床和与I型花岗岩有关的岩浆期后热液型萤石矿床。通过对该区萤石矿床成矿物质来源、成矿温度、萤石稀土地球化学特征、成矿时代与成矿构造环境分析,较系统总结了浙西北主要萤石矿床的成因。在此基础上,结合区域F元素地球化学特征及剩余重力异常特征,提出本区萤石矿的找矿方向为高氟岩体分布区、F元素异常区及剩余重力异常负值区。     

辽宁萤石矿成矿条件和成矿规律探讨

辽宁是国内萤石重要产地之一,分布着阜新哈尔套-义县地藏寺、辽阳隆昌—金州杏树屯两个萤石成矿带,带内已发现大中型矿床7处、中小型矿床和矿(化)点60余处。通过对辽宁萤石成矿特征和地层、侵入岩、构造等控矿条件与成矿关系的分析,认为萤石成矿类型为中低温岩浆期后热液充填交代型,围岩类型主要为碳酸盐岩和硅酸盐岩;萤石成矿时期为燕山期、印支期和华力西期,且以燕山期为主;萤石矿体多赋存在花岗岩岩体内部断裂带或与围岩外接触带的断裂带位置。依据萤石矿床的地质特征和成矿规律,结合构造、岩石与围岩、地球物理与地球化学等找矿标志,圈定出6个成矿远景区。     

土壤地球化学测量在甘肃北山白头山铷矿找矿中的应用

白头山铷矿床是甘肃北山地区新近发现的典型花岗伟晶岩脉型铷稀有金属矿床,以该矿床为研究对象,开展了土壤地球化学测量方法技术研究。初步确定花岗伟晶岩脉型铷稀有金属矿床的岩石和土壤中的通用指示元素组合为Rb、Be、Bi、Tl、Li、K 2O;北山地区勘查铷稀有金属矿床的土壤地球化学测量的最佳采样粒级为-4~20目,最佳采样层位为残积层。试点测量结果表明,研究确定的土壤地球化学测量方法可以完整地圈定已知的铷矿化范围,迅速缩小找矿靶区,为后续异常查证等工作布署提供准确的地球化学依据,为北山地区找寻铷稀有金属矿产提供了一种新的方法技术。同时试点测量在已知矿区外围发现了新的具有找铷矿前景的靶区,有望获得新的找矿进展,为同类地区寻找铷稀有金属矿产提供了示范。     

1/万不规则测网土壤地球化学测量方法在安图金星金矿床中的应用及效果

通过1/万不规则测网土壤地球化学测量方法在安图县金星金矿勘查区的实施,发现了一批具有找矿意义的土壤地球化学金异常。根据元素地球化学特征和土壤地球化学特征分析,结合地质成矿条件,确定有望找矿区段,并进行了槽探工程揭露,发现了金(银)矿化体,取得了较好的找矿效果。实践证明1/万不规则测网土壤地球化学测量找矿方法在本区是行之有效的。     

Field analysis of heavy metals by portable digital voltammeter

Water samples and acid extractions of stream sediments, gossans, soils and crushed pisolite samples have been analyzed in the field, using a portable digital voltammeter. This instrument, which uses the polarographic technique of anodic stripping voltammetry, can analyze to a sensitivity of 1 ppb in waters and acid extractions — equivalent to approximately 1 ppm in solid samples. The technique is at present suitable for analysis of Cd, Ph, Cu, Bi (and Zn if Cu is at low concentrations); future developments could extend the instrument capabilities to include Hg, Ag, Au, As, Sb and other elements of interest to the exploration geochemist. Water samples can be analyzed directly in the analytical cell of the instrument; for rocks, soils and biological materials an acid extraction procedure must be employed, and an aliquot of the acid extract added to the 40ml of cell electrolyte. Where a partial extraction technique is employed, e.g. by using HCl and ascorbic acid, the technique clearly does not provide total elemental analyses for the solid material. However, comparison of field results with conventional analytical methods (e.g. AAS) suggests that the technique is sufficiently accurate for the use of in-field, inter-active sampling (i.e. where the results of analysis are used to influence future sampling locations and densities) to be considered in certain types of geochemical exploration programs.     

基于传统吸附烃概念的烃类检测新技术

烃类是地表油气地球化学勘查地下油气藏的直接指标.目前我国油气化探中常用的酸解烃法检测出的烃类,不应定义为"吸附烃",它是介质吸收的产物,属结合态烃类,应定义为"吸收烃".地表酸解烃异常十分稳定,重现性好,能够很好地证明地质历史上曾经有过的烃类运移过程,但在反映目前深部油气信息方面具有多解性.针对酸解烃法的弱点,依据烃类垂向运移理论和物质吸附作用原理,自行设计开发、研制了一套吸附烃脱气装置,建立了土壤吸附烃提取新技术和检测方法.该方法有利于在近地表获取油气系统的动态信息,强化烃类测量法对其信息源的探测,可以提高地表油气化探预测油气分布的成功率.     

A geomicrobiological study of soils collected from auriferous areas of Argentina

Geomicrobial and geochemical studies were carried out in Argentina (Patagonia, Chubut Province) on four Au and polymetallic sulfide vein-type deposits. A horizon soils were analyzed for Bacillus reacting to lecithin [Bacillus L.(+)], Au and 12 additional elements. In two of the four sampling sites, exhibiting known and relatively simple mineralized structures, Bacillus L.(+) populations are clearly related to Au, As, Pb, Zn, Cu-sulfide mineralization. In areas containing more complex mineralized structures, the spatial relationship between Bacillus L.(+) and metals in the A horizon is more difficult to interpret. Results of a factor analysis performed on all analytical data (n = 130) suggest a partial relationship between Bacillus L.(+) and Au-As-Y pedochemical associations located above known Au mineralization. Bacillus L.(+) was first analyzed in Argentina in December 1994 and re-analyzed in Belgium five to seven months later. Most of the Bacillus contents (85%) of the Belgian tests are higher than those determined in Argentina. The present results and data of a previous study in Mexico (Melchior et al., 1994a; Melchior et al., 1994b) suggest that this may be the result of temperature variations during sample storage between periods of microbial analysis. From a strictly analytical point of view, the geomicrobial method is not an accurate, reproducible technique. However, Bacillus L.(+) can be used as a microbiological indicator of Au and polymetallic mineralization at a reconnaissance-level regional survey. At a local scale, this microbiological tool should be combined with classical exploration techniques such as soil geochemistry. It is recommended that the collection of all A horizon samples (for microbial study) should be accompanied by B or C horizon soils (for potential geochemical study, after prioritizing targets) so that a second field sampling program does not have to be undertaken.     

Geochemical process of fluorine in soil

Fluorine is in the dynamic balance of two geochemical processes, enrichment and leaching, reflecting the adsorption and desorption of fluoride by clay minerals, respectively. The two geochemical processes of fluorine in soil are influenced by factors including geochemical characteristics of soil and clay minerals, pH and sanity of soil solutions, climate, grazing and agriculture activities. Main factors controlling enrichment and leaching process of fluorine in soil can be found with interaction consideration.     

Use of partial dissolution techniques in geochemical exploration

Application of partial dissolution techniques to geochemical exploration has advanced from an early empirical approach to an approach based on sound geochemical principles. This advance assures a prominent future position for the use of these techniques in geochemical exploration for concealed mineral deposits. Partial dissolution techniques are classified as single dissolution or sequential multiple dissolution depending on the number of steps taken in the procedure, or as “nonselective” extraction and as “selective” extraction in terms of the relative specificity of the extraction. The choice of dissolution techniques for use in geochemical exploration is dictated by the geology of the area, the type and degree of weathering, and the expected chemical forms of the ore and of the pathfinding elements. Case histories have illustrated many instances where partial dissolution techniques exhibit advantages over conventional methods of chemical analysis used in geochemical exploration.     

离子选择电极法测定土壤中水溶性氟提取液温度的控制方式

采用超声提取法对样品进行预处理,利用离子选择电极法测定土壤中的水溶性氟,超声空化热效应会造成提取液温度升高,检测结果不稳定,不能如实反映土壤中水溶性氟含量,对土壤环境中氟的监测造成困扰。因此,选择有效的控制提取液温度方式至关重要。本文通过记录直接超声、加冰袋、加冰水、冷却循环水四种温度控制方式提取液温度变化确定出最佳温度控制方式;选取具有稳定性和代表性的土壤有效态成分分析标准物质测定土壤水溶性氟含量,以验证最佳温度控制方式的合理性和有效性;同时分析了提取过程中提取液pH值变化,探讨温度对土壤中水溶性氟提取量影响的原因。结果表明:冷却循环水温度控制方式可有效将提取液温度控制在25±2℃内,该方式的相对误差(8.9%)明显小于直接超声(14.1%);提取液pH值无明显变化,测定结果稳定可靠。     

Assessment of massive sulphide base metal targets using lead isotopes in soils

An assessment is made of the use of lead isotopes in soils as an exploration tool for concealed lead-rich base metal massive sulphide deposits, using four case histories in southeast Australia as examples. Case history 1 covers soil profiles (< 1 m depth) unrelated to mineralization in which the lead isotope ratios exhibit variation with depth and are different from those for massive sulphide deposits. Case history 2 covers six shallow (< 0.4 m depth) profiles from two traverses over the concealed Elura Zn-Pb-Ag deposit in central western New South Wales. For one traverse over completely concealed (blind) sulphides, no isotopic or geochemical signature of the orebody could be detected. In two profiles from the other traverse, for depths of 0.15 m and 0.3–0.45 m, the lead isotopic ratios in the soils are identical with those in the ore (the target isotope ratios). Case history 3 covers two occurrences of Silurian volcanogenic Cu-Zn-Pb mineralization at the Benambra prospect in northeast Victoria. The isotopic ratios for the soils are identical with those in the sulphides and the isotopic signature of the sulphides is also detectable in traverses where no obvious surface anomaly is developed. Case history 4 is an undrilled anomaly in Silurian shales and felsic volcanics where the isotope ratios in B horizon soils are consistent with those of the target isotopic signature.The information from these case histories suggests that the lead isotopic analysis of soils will be a useful exploration tool for concealed mineralization, although at the present stage of research it appears that its application may be limited to shallowly buried (< 100 m) targets or deeply buried targets with an extensive oxidation profile. Its main advantage over conventional geochemical techniques is its ability to discriminate between similar geochemical anomalies arising from different styles of mineralization, as illustrated by an example from Benambra.     

物化探综合找矿方法在西口沟钼矿勘查中的应用

通过梳理、筛选1∶20万区化异常,结合成矿地质背景,选择具有良好找矿前景的化探异常,利用1∶5万水系沉积物测量进一步缩小了找矿靶区。在此基础上,综合应用1∶1万土壤测量等地球化学方法及激电中梯测量、激电测深等地球物理方法,在物化探异常对应较好及矿化发育地段,择优开展钻探工程验证,最终发现了西口沟钼矿,取得了较好的找矿效果。这说明综合运用物化探方法找矿是可行、有效的,对于区域上寻找同类型矿床具有很好的借鉴意义。