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1.
Conventional stream sediment sampling in which sediments are taken from the active channels during reconnaissance regional geochemical surveys in gold exploration has over the years failed to delineate prospective target zones in northern Ghana, where the relict is flat. Whereas the technique has been successful in the south western Ghana, which is characterised by moderate to high relief, generally the savannah north is associated with low relief, commonly with flat topographies and generally decoupled stream channels. Geochemical comparison of active stream and overbank sediments in this study demonstrate that active stream channels may contain contaminated materials of recent origin, but overbank sediments, except for the uppermost horizons, represent alluvial regolith of earlier depositional cycles over time. Based on gold value repeatability, composite samples taken from the overbank sediment layers were relatively less erratic and are considered to be an appropriate geochemical medium in delineating potential regional gold targets for follow up. The results show that overbank sediment sampling can be used as a cost-effective method to define broad anomalous zones; and the technique must be considered useful during reconnaissance geochemical surveys in the savannah regions. 相似文献
2.
This paper summarizes advances since 1987 in the application of glacial sediment sampling to mineral exploration (drift prospecting) in areas affected by continental or alpine glaciation. In these exploration programs, clastic glacial sediments are tested by geochemical or mineralogical methods to detect dispersal trains of mineral deposit indicators that have been glacially transported from source by mechanical processes. In glaciated terrain the key sampling medium, till, is produced by abrasion, crushing and blending of rock debris and recycled sediment followed by down-ice dispersal ranging from a few metres to many kilometres. As a consequence of the mid-1980s boom in gold exploration, the majority of case studies and regional till geochemical surveys published in the past decade deal with this commodity. Approximately 30% of Canada and virtually all of Fennoscandia have been covered by regional till geochemical surveys that aid mineral exploration and provide baseline data for environmental, agricultural, and landuse planning. The most profound event in drift prospecting in the last decade, however, has been the early-1990s explosion in diamond exploration which has dramatically increased the profile of glacial geology and glacial sediment sampling and stimulated changes in sampling and analytical methods. 相似文献
3.
Discovery and exploration of the Gosowong epithermal gold deposit, Halmahera, Indonesia 总被引：1，自引：0，他引：1
J. C. Carlile G. R. Davey I. Kadir R. P. Langmead W. J. Rafferty 《Journal of Geochemical Exploration》1998,60(3):207-227
The Gosowong epithermal gold deposit, on the island of Halmahera in eastern Indonesia, is located in an area of primary tropical rain forest with no previous history of gold mining or record of gold mineralisation. The deposit occurs in a newly recognised mineral district which contains a number of epithermal vein systems and at least two centres of low-grade porphyry style Cu–Au mineralisation. Several zones of argillic and advanced argillic alteration have been noted which may be related to additional centres of mineralisation. Gosowong is classified as a low-sulphidation epithermal quartz vein. Bonanza-grade gold–silver mineralisation is developed in shoots over a 400-m strike section of the vein system. Three types of veining are recognized; quartz–adularia veins and breccias; quartz–chlorite–illite veins and breccias; and crystalline or chalcedonic quartz vein stockworks. The area was targetted using a simple geological concept and the deposit was discovered and tested using basic exploration techniques commonly applied in the rugged tropical terrains of Indonesia. Sequential exploration methods comprised reconnaissance drainage sampling of stream sediment, BLEG and float media, ridge and spur soil sampling, prospect scale grid soil sampling, hand trenching and diamond drilling. Lapse time from identification of the initial reconnaissance anomaly to an inferred resource estimate of almost 1 million ounces of gold was less than 3.5 years. This case history illustrates that very detailed exploration is necessary to locate high-grade vein-type gold deposits in a tropical environment, but demonstrates that such resources still remain to be discovered in the relatively under-explored Neogene magmatic arcs of Indonesia. 相似文献
4.
运用扫描电镜和压汞法研究江汉盆地古新统—白垩系砂岩储层孔喉结构及定量参数特征 总被引：4，自引：2，他引：2
通过储集层的孔喉结构来评价储层已广泛运用于油气开发,但目前尚未运用于钾盐储层的评价。本文利用扫描电镜和压汞法获得的大量储层孔隙、孔喉实验数据,研究了江汉盆地古新统—白垩系富钾卤水砂岩储层的孔喉类型和结构、毛细管压力曲线,以及孔喉定量特征参数。研究表明,古新统沙市组砂岩储层以Ⅱ类孔隙结构为主,排驱压力平均值为2.72 MPa,孔隙度平均值为6.32%。而白垩系红花套组砂岩储层以Ⅰ、Ⅱ类孔隙结构为主,Ⅰ类排驱压力平均值为0.28 MPa,孔隙度平均值为16.99%,渗透率为87.79×10~(-3)μm~2;Ⅱ类排驱压力平均值为1.103 MPa,孔隙度平均值为10.02%,渗透率为18.83×10~(-3)μm~2。通过综合分析孔喉定量特征参数(如最大汞饱和度、最大孔喉半径、中值半径、退汞效率等)来评价储层质量,认为古新统沙市组砂岩类型以粉砂岩为主,储层质量较差,属于特低孔低渗储层;白垩系红花套组砂岩类型以细砂岩为主,储层质量较好,属于低孔低渗储层。本研究为该区富钾卤水储层评价以及进一步勘探开发提供了可靠的地质依据。 相似文献
5.
作为赋存于花岗岩中钨锡矿化勘探指南的流体包裹体异常——前景展望 总被引：1，自引：0，他引：1
Andrew H Rankin 《岩石学报》2007,23(1):3-14
Studies of the distribution and abundance of fluid inclusions in granitic quartz associated with granite-hosted Sn-W mineralization of the British Isles reveal local and regional scale anomalies.At a sampling interval of c.5～50m,inclusion abundances increase towards zones of vein and stockwork mineralization exemplified by case history examples from exploration prospects in the Mourne Mountains of Northern Ireland and the Carrock Fell mining district of northwestern England.These steam aureoles provide a greater exploration target than the zone of visible alteration and mineralization and the lithogeochemical halo.But it is important to link them to geochemical data on fluid inclusion compositions,such as the semi-quantitative data from decrepitation-linked,ICP-AES (D-ICP)analysis,to optimize their exploration potential.Regional scale fluid inclusion anomalies,based on sampling intervals of c. 2km from the Sn-W mineralized granites of southwest England also broadly correlate with zones of intense mineralization in some areas. Regional-scale D-ICP analyses of quartz from SW England granites did not provide any convincing regional scale anomalies linked to mineralization except for positive boron anomalies around the centrally-mineralized Birch Tor area of the Dartmoor granite.Follow-up D-ICP analysis of quartz from stream sediments from this area,however,could be used to discriminate between samples related to mineralization from those draining unmineralized areas,using multivariate statistical analysis.At the present stage of development, the main contribution of fluid inclusion studies to mineral exploration is mostly limited to the conceptual stage where they continue to contribute to ore genetic theory and models.Costs and lack of knowledge transfer between research scientists and mineral explorationists limit their direct use during regional and target selection stages of exploration.Analysis of steam sediment quartz,using the more sensitive ICP-MS technique as a variant of the D-ICP method,appears to offer the greatest potential for future development as an exploration tool. 相似文献
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洋中脊热液硫化物勘探技术的滞后,严重制约了对海底热液硫化物资源的勘探开发。以我国西南印度洋硫化物勘探合同区域采集的25个表层沉积物样品为研究对象,基于主量、微量和稀土元素检测数据,采用元素含量特征、相关性分析、元素对比值、特征元素三角图解,以及稀土元素分馏特征值等手段,开展沉积物热液信息研究。结果表明:样品所代表的大部分研究区域内主要为钙质生物沉积,部分样品元素地球化学特征受沉积物中玄武岩风化碎屑的影响,龙旂热液区的部分样品中表现出一定的热液迹象,稀土元素分馏特征和配分模式、（Al+K）?Mg?（Fe+Mn）三角图解可较好地指示热液活动。研究不仅为我国在西南印度洋的硫化物勘探提供基础数据参考,同时也是对海底热液硫化物勘探的沉积物地球化学找矿理论和方法的初步探索。 相似文献
8.
1:20万区域化探方法核心技术"取样粒级"的讨论 总被引：2，自引：0，他引：2
内蒙古区域化探扫面采用水系沉积物测量(或土壤测量),取粗粒级样品,取得了较好的地质找矿效果,但局部景观区找矿效果受到了一些影响.我国南北方水系沉积物中元素含量呈"U"形分布,反映了南北方不同的风化类型,以及所取不同粒级样品的物质成分也不同;取粗粒级和细粒级样品均可能有化探异常显示,采用-5～+20目(0.9 mm≤A＜4 mm)和-120目(A＜-0.125 mm)组合粒级作为采样粒级.为提高工效,取样时可以采用-5目(或-20目)全粒级物质,也能获取更多的找矿信息.这种取样粒级技术,也适宜于全国各种不同的景观区的不同尺度的水系沉积物测量和土壤测量的化探工作. 相似文献
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深县凹陷位于冀中坳陷中部,其构造复杂,沉积类型多样,而多年来人们对凹陷内的油气圈闭(尤其是岩性地层圈闭)类型与分布规律缺乏统一认识,不利于在这类复杂断陷盆地内开展精细油气勘探。深县凹陷可划分为5个构造区带,各构造区带具有不同的沉积格局,这是各区带内油气圈闭类型存在差异的关键因素。总结出该凹陷主要发育构造圈闭、岩性圈闭、地层圈闭及潜山圈闭等4大类8亚类圈闭类型,这些圈闭类型与本区的构造沉积格局存在响应关系。其中,构造圈闭发育范围较广,主要集中在二级构造凸起带上,以深南背斜和榆科背斜为主,断块和断鼻圈闭构成了主要的圈闭类型;潜山圈闭主要发育在北部缓坡带中的深泽—刘村低凸起与何庄—深西潜山带;而岩性圈闭与地层圈闭主要发育在两个潜山带的侧翼以及南部的白宋庄洼槽带和深南背斜的两翼,这与砂砾岩透镜体、上倾尖灭砂体的分布及构造背景有关。 相似文献
11.
构造地球化学测量在找金中的应用 总被引：4，自引：0，他引：4
通过马庄山地区构造地球化学测量找金试验和在特克斯县１５号水系沉积物异常区开展构造地球化学测量的推广应用证明：构造地球化学测量工作,以遥感地质构造解译为先导,民裂裂构造裂隙充填物及蚀变岩石为采样介质,较岩石地球化学测量更具有矿直接性。 相似文献
12.
Peter M. D. Bradshaw Ian Thomson Barry W. Smee Jan O. Larsson 《Journal of Geochemical Exploration》1974,3(3):209-225
This paper deals briefly with the principles of geochemical migration in the secondary (soil, sediment) environment, a knowledge of which is essential to a correct interpretation of exploration geochemical data. Examples are given which illustrate that the principles which apply in the more easily interpreted tropical areas, also apply in the more complicated glaciated regions. Any person employing exploration geochemistry in geomorphologically complicated areas, is well advised to study data from strictly residual soil areas where the fundamentals of geochemical migration are more easily observed. From this base it is easier to understand the additional complications of geochemistry in mountainous and glaciated terrain. Of the variety of exploration geochemical techniques which can be used, this paper deals specifically with two: soil profile sampling, and different strengths of acid extraction of metal from samples. Examples from the different environments are compared and contrasted. 相似文献
13.
Samples of stream sediments and aquatic mosses were collected from nine sites across several mineralized zones at the southeasternmost extension of the Idaho Cobalt Belt. Because the steepness of the terrain and the attendant high flow rate of the streams made it difficult to obtain adequate sediment samples, mosses were considered as an alternative sampling medium. The results not only showed that the Cu and Co content of the mosses correlated almost perfectly with that of the sediments, but that the contrast between samples taken from mineralized and background areas was greater in mosses, especially for Co. Maximum concentrations of 35,000 μg/g Cu and 2000 μg/g Co were observed in the ash of mosses, compared to maximum concentrations of 1700 μg/g and 320 μg/g, respectively, in the associated sediments. Species identification was considered unimportant, which should dispel some reluctance to use mosses in mineral exploration. 相似文献
14.
Reproducibility of overbank sediment sampling was tested in twenty-nine floodplains in Europe, ten in Greece and nineteen in Norway, by the collection of duplicate pairs of samples. Distances between duplicate sites in Greece were 60 to 100 m, and in Norway 100 to 200 m. In Norway the same nineteen floodplains were sampled by a second team for the purpose of investigating differences in sampling variability and technique. Total element contents were determined in all samples. Paired samples were compared by calculating Spearman's rank correlation coefficient on the raw analytical data, and one-way analysis of variance on the log-transformed data. Pairs of overbank sediment samples collected from different floodplains by the Hellenic team and the first Norwegian team showed high rank correlations and low within-basin variability (sampling and analytical variance). Statistical results of the second Norwegian team were comparatively poorer; both Spearman's rank correlation coefficient and one-way analysis of variance, showed very low positive to negative correlations and high within-basin variation, suggesting a non-uniform distribution of elements in the Norwegian overbank sediment sequences and differences in the sampling technique of the two teams. Nevertheless, careful location of sample sites, as has been done by the Hellenic and the first Norwegian teams, reduces considerably the sampling variability, and the overall sampling reproducibility for most elements is very good for distances up to 100 m in Greece and 200 m in Norway, provided correlated overbank sediment sequences are sampled. The implication of this study for multinational regional geochemical mapping is that overbank sediment sampling must be carried out by well-trained professional teams of exploration geochemists, and where possible by one sampling team for the whole country. 相似文献
15.
分析了区内的水系沉积物地球化学参数特征及其元素的相关性,认为元素(地球化学)异常(高值区)严格受东昆中断裂带、东昆南断裂带、布青山南坡乌断裂带,以及阿尼玛卿蛇绿岩带和东昆中蛇绿岩带,古-中元古代地层、岩体接触带、热液活动、脉岩等因素联合控制。根据异常特征与成矿地质条件,圈定了找矿远景区5个,且为该区下一步的找矿工作指明了方向。 相似文献
16.
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
17.
构造转换带储集体发育的主控因素——以准噶尔盆地腹部侏罗系为例 总被引：1，自引：0，他引：1
本文以准噶尔盆地腹部侏罗系储集砂体分布特征为例,探讨构造变换带优质储层的形成机制与变形特征,开展构造转换带的构造-沉积-成岩作用等对物源、砂体、岩石物理等的控制作用的研究。盆地构造转换带控制主要物源与水系,进而控制沉积体系的发育特征;构造转换带与坡折带共同控制沉积相带展布;构造转换带、坡折及沉积层序格架联合控制砂体时空展布及其储层质量:在大的构造转换带、高坡降比的坡折等条件下,在低位域沉积期发育冲积扇、辫状河和曲流河沉积等,形成大规模的储集体,在高位域沉积期发育较大规模三角洲沉积等。对构造转换带的综合研究,可深化对坳陷盆地沉积体系发育规律认识,进而提高对油气储集体的预测精度,对陆相湖盆沉积学及其油气勘探开发具有重要指导和参考价值。 相似文献
18.
DONG Yongguan ZHANG ChuanlinNanjing Institute of Geology Mineral Resources East Zhongshan Rd. Nanjing Jiangsu 《《地质学报》英文版》2000,74(3):582-586
The Aktubaik gold deposit lies in the Altay middle-high mountains area, Xinjiang, hosted by the Pa-laeo- and Mesoproterozoic Xemirxek Group. It is the first gold deposit found in Precambrian rocks in Altay. The deposit is controlled by the NW-trending fracture-alteration zone, in which rocks have been strongly altered and bleached. The main wall-rock alterations include silicification, sericitization (muscovitization), carbonation, pyritiza-tion and tourmalinization. Several gold mineralization zones of this type have been found in the study area. The dominant gold mineral is native gold, which is distributed very unevenly, so special methods such as peeling and bulk sampling are required in exploration. The discovery of this gold deposit has laid a foundation for gold exploration in Precambrian rocks in the Altay middle-high mountains area, Xinjiang. 相似文献
19.
根据不同的构造环境分阶段介绍了转换带的发展史.以几何形态、构造规模、应力背景等不同的分类标准阐述了不同学者对转换带的分类.基于前人所做出的分类模式,并结合断层的生长机制,提出了转换带参考动态演化的综合分类模式.通过对比分类标准,将前人所作出的具有代表性的分类模式进行了整理与对应.探讨了影响转换带发育的一系列控制因素,包括基底结构、岩性等.列举了转换带研究尚未很好解决的一些问题,如影响范围的界定,分类未考虑沉积中心的位置,未揭示动态演化的过程等.下一步的研究发展趋势应该基于分类标准综合考虑多种因素,进行动态发展的定量分析及反演,使转换带类型与沉积水系分布和油气分布能够更好地一一对应,以更好地对油气勘探开发进行预测和指导. 相似文献