基于GIS的证据权模型在秦岭～松潘金矿潜力预测中的应用

数据驱动的证据权法被用来进行金矿潜力制作。为了确定秦岭~松潘金矿的潜力区,需利用地质、地球化学、地球物理等数据。数据采集、图形处理、空间分析都是在GIS平台上进行的。预测结果表明,证据权法在综合不同空间数据上是有效的,最终的预测图件圈出了最有利的矿化区,可用于进一步勘查研究。     

Thematic integration of spatial data sets to delineate favourable zones for uranium exploration in Gangpur basin and parts of Kunjar and Darjing basins,Odisha

Surface exploration techniques have been key contributors in discovering mineral deposits over the past three decades. However, in the last decade there has been a growing emphasis on integrating remote sensing, geological, geophysical and geochemical exploration techniques to compliment them in identifying concealed deposits. Successful integrated exploration requires putting mappable petrophysical property contrasts in terms of geological and geochemical process that could be associated with different mineralisation environment. The Precambrian Gangpur basin comprising volcanic free sedimentary sequence is considered as a potential geological setting for hosting uranium mineralisation. The Gangpur basin with metasediments of low to medium metamorphic grade classified as the Gangpur Group are known for hosting manganese, limestone and lead-zinc deposits. Uranium mineralization is reported in limonitic carbonaceous phyllite and sheared quartzite of Kumarmunda Formation at Jhamankele-Bhalulata areas. Several uranium anomalies have been associated with gossan at Kaedarpani, Jamdra and in ferruginised laterite at Badekachar, Jarmal, Jhagarpur, Kadorpani, Karamabahal, Tetelkela & Kumtinunda. In the present study geological, geophysical and remote sensing data sets are processed and integrated with other available data to delineate target zones for uranium exploration. Even though direct detection of uranium mineralisation remains unresolved in exploration strategy, instead it is becoming increasingly instructive to focus on mapping suitable depositional environments. The enhanced satellite imagery is interpreted in terms of thematic layers viz. trend lines, lineaments, faults and geological contacts. The aeromagnetic data is processed and interpreted thematic layers of magnetic breaks and linears from total magnetic intensity (TMI), the reduced to pole (RTP), tilt derivative and amplitude of analytical signal grid images. The radiometric data is processed based on their broad lithology and radio-elemental distribution maps viz. count maps, ratio maps, ternary (%K-eTh-eU) and eU/K ? eU/eTh ? eU images are generated to aid in mapping uranium favourability zones. The favourability image zones with high eU/K, eU/eTh and eU counts zones are classified into class based on statistics and anomalous high zones are picked up as uranium favourable locales. The thematic layers of geological contacts, lineaments and faults interpreted from satellite imagery, magnetic linears interpreted from aeromagnetic data and uranium favourability zone extracted from Airborne Gamma Ray Spectrometric (AGRS) data are overlaid. Based on spatial association of favourable features few locals are delineated for uranium exploration.     

The use of helium in mineral exploration

A literature review of the source and occurrence of helium shows that it can, under favorable conditions, lead to the discovery of radioactive ore deposits, oil and gas pools, and fracture zones associated with mineral occurrences. Analytical results show that anomalous helium is present in groundwaters and near uranium occurrences and thus can aid in the identification of uranium occurrences or prospective target areas for uranium exploration.     

综合找矿方法在粤东单竹坑铅锌银矿勘查中的应用

粤东单竹坑矿区位于曾公嶂铅锌多金属矿集区,周边已发现多个多金属矿床,区域找矿前景优越。根据区域物化探异常圈定了找矿远景区,结合矿区的地质成矿特征,选择有利地段开展大比例尺物化探扫面和地质填图,逐步明确了找矿靶区,查明了矿体的走向和分布范围。在此基础上,针对性地布置了CSAMT测深,推断了矿体的深部形态、规模和产状,为钻探工程验证提供了可靠的依据。通过钻探验证,在矿化带内的物化探综合异常浓集中心,发现了多个高品位铅锌银多金属矿体,找矿成果丰硕。地-物-化综合找矿方法在单竹坑矿区的应用是行之有效的,对区域上同类型矿床的勘查工作起到了一定的借鉴作用。     

Data fusion and porphyry copper prospectivity models,southeastern Arizona

Mineral exploration programs commonly use a combination of geological, geophysical and remotely sensed data to detect sets of optimal conditions for potential ore deposits. Prospectivity mapping techniques can integrate and analyse these digital geological data sets to produce maps that identify where optimal conditions converge. Three prospectivity mapping techniques – weights of evidence, fuzzy logic and a combination of these two methods – were applied to a 32,000 km² study area within the southeastern Arizona porphyry Cu district and then assessed based on their ability to identify new and existing areas of high mineral prospectivity. Validity testing revealed that the fuzzy logic method using membership values based on an exploration model identified known Cu deposits considerably better than those that relied solely on weights of evidence, and slightly better than those that used a combination of weights of evidence and fuzzy logic. This led to the selection of the prospectivity map created using the fuzzy logic method with membership values based on an exploration model. Three case study areas were identified that comprise many critical geological and geophysical characteristics favourable to hosting porphyry Cu mineralisation, but not associated with known mining or exploration activity. Detailed analysis of each case study has been performed to promote these areas as potential targets and to demonstrate the ability of prospectivity modelling techniques as useful tools in mineral exploration programs.     

江西玉华山地区铀矿综合信息找矿模型研究

玉华山地区是赣杭构造带西南段重要的铀矿找矿远景区之一,毗邻中国最大的火山岩型铀矿田——相山铀矿田。玉华山地区基底变质岩、岩浆岩、断裂构造、热液活动和铀矿化特征指示区内具有较大的找矿潜力。与相山矿田对比,两者成矿条件基本相同,但在火山活动、晚期热液活动强度、剥蚀程度等方面存在较大差异。玉华山地区地球化学与地球物理异常特征表明,区内U-Th-Mo化探综合异常、正负磁异常交替和放射性正异常等异常叠加区是铀矿勘查的重点区域。同时,在成矿条件、地球化学条件与地球物理条件的基础上,构建了研究区综合信息找矿模型,为区内铀矿勘查工作提供了理论与实践依据。笔者认为为山—筒山断裂带是今后资源量突破所在,建议部署相关勘探工程,查明铀资源量。     

Condensing multi-element reconnaissance geochemical data from south Greenland using empirical discriminant analysis

Empirical discriminant analysis classified multivariate data from 2174 geochemical reconnaissance samples from South Greenland, so that they were related to known geological units or characterized as outliers. Training sets, comprising 514 samples from 14 geologic units were selected in order to reflect only the background conditions of each geological unit. A smoothing parameter of 0.5 maximized correct classification of the training sets and extracted a reasonable number of outliers (289, 13% of the samples) representing geographically grouped anomalies. Plots of the geochemical samples classified into the geological units corresponded well to the geological map.Q-mode cluster analysis classified the 289 outliers into 30 groups with different element associations. All types of mineral occurrence known in South Greenland could be recognized amongst the clusters. For example, there were seven clusters which were characterized by samples with high U values and different associated elements each one related to a different type of U mineralization. Another cluster containing samples with high Zr, Nb, and Y values reflects recently discovered pyrochlore mineralization. Other clusters were explained on the basis of geological units which were too small to be mapped or included amongst the training sets.Empirical discriminant analysis successfully reduced the multivariate data to one map, which made it easier to evaluate the varying element levels over the different geological units. Incorrectly classified samples require follow-up in order to appraise the accuracy of the geological mapping. Classification of the outliers by cluster analysis assists both in identifying samples influenced by mineral occurrences and in predicting the type of mineralization to be expected, thereby substantially aiding in the selection of areas for mineral exploration.     

广东河源地区放射场特征初探

本文是在初步整理河源地区物化探资料的基础上，通过与已知铀矿床、矿点的对比后所总结的点滴认识。     

基于证据权重法的沱沱河地区铅锌银矿成矿预测

在总结三江北段沱沱河地区成矿规律的基础上,通过GIS平台提取地层、构造、岩浆岩、重力、航磁、化探、遥感异常多元地质找矿信息,建立沱沱河地区铅锌银矿的预测模型,采用MRAS系统中的证据权模块进行预测,对有利成矿区进行圈定。根据单元网格后验概率值的大小划分了3级成矿远景区,共圈定了6个Ⅰ级、7个Ⅱ级和9个Ⅲ级成矿远景区。预测结果表明,83%的已知矿床(点)位于预测的成矿远景区内。除了包含已知矿床(点)的预测区外,沱沱河地区尚有4个Ⅰ级、5个Ⅱ级和4个Ⅲ级远景区目前仍未发现铅锌银矿床(点)。由于这些远景区与已知矿床(点)具有相似的成矿条件,有望实现重大找矿突破,应在今后的勘探工作中得到足够的重视。     

Mineral potential mapping for rare earth elements mineralization with AHP method in the Kerman-Kashmar Tectonic Zone,Central Iran

One of the major strengths of a GIS is the ability to integrate and combine multiple layers of geoscience data for producing mineral potential maps showing favorable areas for mineral exploration. Once the data is prepared properly, the GIS, jointly with other statistical and geostatistical software packages, can be used to manipulate and visualize the data in order to produce a mineral prospectivity map. Many spatial modeling techniques can be employed to produce mineral potential maps. This paper demonstrates a technique to define favorable areas for REE mineralization with AHP technique using geological, geochemical, geophysical, alteration and faults density spatial data in the Kerman-Kashmar Tectonic Zone of central Iran. The AHP is a powerful and flexible multi-criteria decision-making tool for dealing with complex problems where both qualitative and quantitative aspects need to be considered. This approach is knowledgedriven method and can be applied in other areas for conventional use in mineral exploration.     

山东焦家金成矿带三维预测模型及靶区优选

为了实现焦家金成矿带资源的可持续开发利用,应用三维地质建模技术指导深部找矿工作迫在眉睫。文章从山东焦家金成矿带区域地质背景入手,全面收集研究区已有的地质、矿产、物探、化探等科研成果资料,结合前人的成矿理论研究,分析和总结有利成矿、控矿地质条件,并应用该区深部物化探信息资料,建立综合信息定量找矿模型,采用“立方体预测模型”及地质统计学方法推断深部成矿空间,实现真正意义的定位定量定概率的资源预测评价。预测结果表明,该成矿带深部找矿金资源量达842.88 t,具有较好的开发利用潜力。更重要的是,圈定了7个尚未开发的成矿有利靶区,并结合探矿工程模型,提出了具体的勘查建议,为深部找矿提供了科学依据。     

贵州铜仁地区锰矿定量预测与评价

应用地质、化探、物探、遥感等手段和资料进行多元信息成矿预测已成为找矿工作的重要方法。以贵州铜仁地区锰矿为研究对象,基于研究区与成矿相关的多元信息,建立区域找矿模型;运用GIS技术对多元信息进行综合处理并提取有利成矿信息,形成找矿标志专题图层,构成找矿预测指标集;利用证据权重法建立锰矿综合预测模型,结合研究区成矿地质条件、已知锰矿床（点）等因素,确定找矿有利地区,并圈定7个远景区,为发现大规模锰矿产地提供参考。     

Data- and knowledge-driven mineral prospectivity maps for Canada's North

Data- and knowledge-driven techniques are used to produce regional Au prospectivity maps of a portion of Melville Peninsula, Northern Canada using geophysical and geochemical data. These basic datasets typically exist for large portions of Canada's North and are suitable for a “greenfields” exploration programme. The data-driven method involves the use of the Random Forest (RF) supervised classifier, a relatively new technique that has recently been applied to mineral potential modelling while the knowledge-driven technique makes use of weighted-index overlay, commonly used in GIS spatial modelling studies. We use the location of known Au occurrences to train the RF classifier and calculate the signature of Au occurrences as a group from non-occurrences using the basic geoscience dataset. The RF classification outperformed the knowledge-based model with respect to prediction of the known Au occurrences. The geochemical data in general were more predictive of the known Au occurrences than the geophysical data. A data-driven approach such as RF for the production of regional Au prospectivity maps is recommended provided that a sufficient number of training areas (known Au occurrences) exist.     

基于GIS的多元信息成矿预测研究——以赤峰地区为例

由于找矿难度越来越大,应用地质、地球物理、地球化学、遥感等资料进行综合信息成矿预测是目前找矿工作发展的一个重要趋势。GIS技术已成为多元信息深层次提取与综合,实施综合信息成矿预测的有效工具。文中以赤峰地区有色金属资源成矿预测研究为例,在总结区域成矿规律的基础上,以地质异常致矿理论为指导,利用GIS平台提取地质、地球物理、地球化学、遥感多元地质找矿信息,并利用航磁、重力资料进行隐伏构造、岩体等相关地质找矿信息的推断与解释,进一步丰富和深化成矿地质背景与深部找矿信息。在此基础上,建立多元地质异常信息找矿模型,采用证据权模型进行多元找矿信息的综合,对有利成矿区进行圈定。预测结果显示,在赤峰地区北部有三条北东-南西向的有利成矿区带,在南部有一条北西-南东向有利成矿区带,已知的86%的矿床或矿点位于这些有利区内,显示出良好的预测效果。本文的研究思路、方法为多元信息成矿预测研究提供了参考,其成果为赤峰地区的有色金属资源勘探开发提供了科学依据。     

A Novel Approach in Hydrogeochemical Exploration for Uranium Mineralization: an Example from West Central Sinai, Egypt

Groundwater in contact with ore deposits may acquire a chemical composition that could be used as a guide for exploration. Eight well-water samples are collected from a known uranium-mineralized area near Abu Zenima, west central Sinai to examine the applicability of using the hydrogeochemical technique in the search for uranium mineralization in similar arid areas. The analytical chemical data of the ground water is compared with ground radiometric measurements. The obtained results indicate that groundwater affected by uranium mineralization has a specific relativity of major anions expressed essentially as SO4>Cl>HCO3 and to a lesser extent as Cl>SO4>HCO3, associated as a rule with low magnesium content. This association constitutes a signature of uranium mineralization on the composition of groundwater in west central Sinai and could be used as an important exploration guide in the search for uranium deposits in similar areas. Anomalies in Ni, Fe, Zn and Cr and other pathfinder elements in groundwater can furnish geochemical guides to uranium ores. The immobile trace element anomalies, including Zn, Ni and Fe are strongly distributed near the orebody; whereas the relatively mobile trace elements, including Co, U, V and Cr, constitute the dispersion haloes away from the orebody. A new hydrogeochemical discrimination diagram is constructed to be used as a quick and cost effective exploration tool in the search for uranium occurrences in environmentally similar arid areas. Based on the obtained results, a new site for uranium occurrence, west of W. Baba, is delineated and recommended for future detailed geological and geochemical surveying.     

2004年新疆地质矿产勘查进展及2005年工作思路

2004年新疆地质勘查工作在铜镍、金、铅锌、锑、钨、铁、煤和非金属等矿产勘查方面取得了重要进展，发现了一批矿产地，扩大了矿床远景，增加了资源储量，确定了一批有找矿前景的重要成矿区带、基础地质研究工作也有新发现和新认识，2005年地质勘查工作将继续坚持“主攻天山，深化阿尔泰山，开拓昆仑、阿尔金山”的总体布局和“区划、区调、物化探、勘查、科研五统一”的工作原则，主攻煤、富铁、铜镍、富铅锌、金、铀等国家和自治区急需的矿产及具有大型．超大型找矿前景和显开发效益的矿床．围绕找矿部署，开展基础性地质矿产调查工作和矿产资源评价工作；服务矿山开发，开展商业性矿产勘查工作；采取突出重点、加大投入、强化综合找矿、加强生产科研联合攻关等措施，努力实现地质找矿新突破。     

基于随机森林的四川省会理地区“拉拉式”铜矿成矿预测

四川省会理-会东矿集区是我国著名的铜资源基地。近年来,随着找矿勘查工作的深入,又提交了多处大中型铜矿床,表明该地区仍具有较大的找矿潜力。本文基于获取的地质、化探和物探数据,应用随机森林(Random Forest,RF)方法,在研究区开展"拉拉式"铜矿成矿潜力预测,取得了较好的效果:随机森林模型预测的平均袋外误差率为6. 25%,受试者工作特征曲线(Receiver Operating Characteristic Curve,ROC)的AUC值为0. 938。利用偏依赖图(Partial Dependence Plot,PDP)分析解释了预测变量与已知矿床(点)的响应关系,按平均精度下降法排序预测要素的重要性,对"拉拉式"矿床的找矿预测工作具有重要意义的前4个变量依次为:Cu元素含量,中-晚元古代(超)基性岩体临近度,Ni元素含量和PC2因子得分。从成矿地质条件角度分析,河口群地层无疑是"拉拉式"铜矿的重要找矿预测要素,但在随机森林模型中的重要性排序相对靠后。究其原因,一方面是与其它连续数值型预测要素不同,河口群地层是二值(0～1)变量;另外,河口群地层的分布范围受覆盖层的影响较大。根据随机森林模型生成的拉拉地区成矿有利度信息,圈定了6处找矿远景区。红铜山-落凼-红泥坡-姜驿高成矿有利度区带呈北北东向展布,主体上与研究区内重要的地质-地球化学-地球物理预测要素异常空间分布一致;其中蒿枝坝-落凼-红泥坡-姑鲁迷找矿远景区是本区已探明铜矿的主要分布区,其内还有进一步勘探的潜力;同时,该异常区呈半环形态,结合地质勘探揭示的变质火山岩厚度分布,及其西部受一组后期北北东向走滑断裂限制的特点,显示出古火山活动中心在西部,并可能存在被切割分离的另一半环异常,这为该地区后续地质研究和铜矿勘查指明了方向。     

物化探在新疆西昆仑铅锌矿预查中的应用

以已知矿体上物化探异常特征为依据,对区内其他物化探异常进行了分类与解释推断,圈定了四条矿化体.     

兰坪盆地成矿预测中的多源信息定量分析

在提倡地球数字化的今天，为了满足地质找矿勘探的需求，成矿预测的技术和方法将面临着更新的挑战，以往那种定性分析的方法将很难满足成矿预测的精度，因此，对原有资料的数字化是很有必要的。矿产信息具有多源性，而任何一种技术和手段都不可能准确无误地预测矿床的存在、规模、形态等，鉴于此，文章把各种有利于矿床形成的变量[遥感地质构造，地质异常、物化探及已查明的矿床（点）等]进行成矿有利度得分和多源信息综合定量分析，在此基础上进行1：20万小比例尺综合成矿预测，并圈定出了金顶等6个找矿远景区。这些研究成果为进一步认识本区成矿地质环境，指导找矿提供了有利的证据，将大大提高成矿预测的精度，具有广泛推广的实际价值。     

辽宁省北二十家子铜金矿地质特征与成矿预测

辽宁北二十家子铜金矿位于华北地台北缘的朝阳-赤峰金矿成矿带,区内多个蚀变岩型铜金矿(化)点受北西向、北东向断裂构造控制.土壤地球化学测量共圈定3类异常,其中Ⅰ类异常4处,Ⅱ类异常8处,Ⅲ类异常16处.在化探异常显示良好的区域进行了物探工作,其中物探高电阻率区域与化探Ⅰ类异常区重合,物探激电中梯和激电测深共圈定3个异常区...