赛木隆地区水系沉积物地球化学特征及找矿

为了研究青海省赛木隆地区找矿远景,基于工作区最新1∶5万水系沉积物地球化学测量数据,总结分析了元素丰度特征、元素的离散特征、元素的共生关系特征,并对主要异常进行评序,认为工作区主要成矿元素是Au、W、As、Hg、Sb、Mo。结合区域成矿地质条件,优选了3处成矿远景区,为工作区以后的地质勘查提供了重要的指导作用。     

河南省太古界水系沉积物地球化学特征

根据１：５０万《河南省地球化学图说明书》的资料,用元素背景值,浓集比率（Ｋ）、叠加系数（Ｋ０）、叠中强度（Ｄ）等判别参数,对河南省太古界水系沉积物地球化学特征作了粗浅研究：太古界的元素背景值与克拉克值相比,Ａｕ、Ｃｕ、Ｍｏ、Ｎｉ偏低,而Ｂｉ、Ａｓ明显偏高,太华群中Ａｕ、Ａｇ、Ｃｕ、Ｐｂ等元素后生叠加、分异作物特强。太古界是本省主要矿源层和赋矿层位。     

大巴山地区水系沉积物地球化学特征及找矿方向

大巴山地区跨秦岭、扬子两个一级构造单元,基于1:5万水系沉积物测量成果,统计计算了成矿元素地球化学参数,分析研究了元素分布特征、元素相关性及异常元素组合特征,认为研究区Pb、Zn、Ba、Cu、Mn找矿潜力较大,推断研究区所在的秦岭构造单元成矿类型主要为与震旦系—下寒武统黑色岩系有关的低温热液锌铜矿和沉积型钡矿;研究区所在的扬子构造单元成矿类型主要为与寒武系碳酸盐地层有关的低温热液铅锌矿和与震旦系碳酸盐岩有关的沉积型锰矿;在此基础上,划分出杨家坪—葛洞钡锌成矿远景区、镇坪钡锌成矿远景区、黄安坝—迷魂阵锌铜成矿远景区、百羊坪铅锌成矿远景区和修齐镇—石坊乡锰成矿远景区。     

西榆皮铅矿一带水系沉积物地球化学特征

黄利用水系沉积物地球化学测量进行多元素信息找矿是十分经济有效的手段之一,对寻找新矿体及老矿扩大远景储量尤为重要。     

青海北祁连中南沟水系沉积物地球化学特征

青海北祁连中南沟高山切割明显,坡下植被发育,属高寒草甸景观,不利于颗粒物质的机械迁移。该地区不同粒级水系沉积物中成矿元素变化趋势一致,含量衰减迅速且在细粒级富集,并主要为硫化物相。研究结果说明,在该地区常规水系碎屑沉积物测量方法存在一定问题。由于草甸发育,颗粒物质迁移受到抑止,水系碎屑沉积物仅出现在2~3级水系。因此,在普查阶段可能会漏掉许多矿化信息;由于受其分布所限,详查阶段无法保证采集到真正的水系沉积物,只能用坡积物代替,导致采样介质不统一。     

大兴安岭森林沼泽景观区水系沉积物的地球化学特征

水系沉积物是森林沼泽景观区区域化探扫面的主要采样介质.通过从介质颗粒特征、岩矿屑组分特点和元素含量变化3个方面探讨了其地球化学特征,重点研究了有机质的存在对水系沉积物中元素迁移的影响.     

四川岔河地区水系沉积物地球化学特征及找矿方向

岔河锡矿是四川省最大的锡矿床.为寻求岔河地区锡矿找矿突破,对其开展了 1∶5万水系沉积物测量.通过测试数据特征分析及因子分析等,研究元素组合特征,结果表明:Ag-Pb-Zn、Bi-F-W-Sn、Cu-Ni3组主成矿元素分别具有相似的富集规律,其中Sn、W等中高温元素富集规律极为明显,元素异常空间分布叠合性较好.通过累积频率法、迭代法综合分析确定异常下限值,在此基础上编制元素异常图,并圈定9个综合异常.通过开展异常综合评价,优选出岔河和方家综合异常区为成矿远景区.通过成矿地质条件分析及矿产综合检查,在岔河成矿远景区新发现矽卡岩型钨锡矿脉一条,在方家成矿远景区新发现石英脉型钨矿脉十数条,其地质特征与钨矿床"五层楼+地下室"找矿模型具一定的相似性,具有较好的钨、铜、铅、钼等多金属矿找矿前景.     

青海省滩北雪峰地区水系沉积物地球化学特征及找矿预测

文章基于滩北雪峰地区1∶5万水系沉积物地球化学测量数据,分析了元素富集特征,并通过因子分析、聚类分析确定了异常元素组合特征,在工区圈定地球化学综合异常24处。结合工区地质背景分析认为,区内Au、Ag、Cu、Ni、Pb找矿潜力较大,提出了3处成矿远景区：①莲花石沟北成矿远景区,以Au、Ni为主成矿元素,异常与地质、构造关系密切,是寻找与构造相关的金-铜镍多金属矿的有利地段;②小盆地成矿远景区,主要分布于古元古界金水口岩群地层区,异常构造关系密切,是寻找热液型金、铜矿的有利地区;③山间沟成矿远景区,含矿的主要地层为奥陶系祁漫塔格群,是寻找热液型、构造破碎蚀变岩型金、铜矿产的有利地段。     

西藏尼雄地区水系沉积物地球化学特征及异常分布规律

西藏尼雄地区位于拉达克—冈底斯拉萨—腾冲陆块,区内已发现尼雄特大型富磁铁矿、日阿中型铜多金属矿等矿床.文章以1：5万水系沉积物地球化学调查为基础,总结水系沉积物地球化学特征及分布规律.研究发现区内成矿作用与亲铜元素和铁族元素有关,二叠系昂杰组、拉噶组是区内金矿的有利地层,敌布错组是寻找银、锌、铅、镉矿产的最佳地层,所圈化探异常与已有矿（化）点区域套合较好.     

甘肃武都赵家庄地区水系沉积物地球化学特征及评价

赵家庄地区位于南秦岭加里东—印支褶皱带南缘,文县—康县—略阳断裂带北侧,属迭部—武都成矿带东段。笔者从区域地质背景和矿区地质特征入手,重点分析了赵家庄地区的水系沉积物金异常晕,表明该区水系沉积物晕分布与构造展布方向一致,金异常晕对地层的选择性明显;通过对水系沉积物测量中Au、Ag、As、Cu、Zn、Mo、Pb、W、Sb、Bi、Hg等11种元素指标进行R型聚类分析和相关性分析,得出Au和As的相关性最好,Mo与Zn、Bi与Pb相关性密切,Sb、Cu、Ag、相关性较好;而Hg与其它元素相关性不显著。区内可选用Au,As,Mo,Zn 4种元素做为代表性指标进行综合分析成矿预测。     

Geochemistry and behavior of REE in stream sediments close to an old Sn-W mine,Ribeira, Northeast Portugal

The abandoned Sn-W Ribeira mine, northeast of Portugal, contained quartz veins with cassiterite, wolframite, scheelite, pyrite, arsenopyrite, sphalerite, chalcopyrite, manganocolumbite, bismuthinite, native bismuth, phosphates and carbonates. The exploration took place on the northern slope of the Viveiros stream, which is an affluent of the Sabor River. The waste-rock dumps and tailings were deposited on the hillside, close to the mine and are nowadays exposed to significant weathering and erosion, as they are not vegetated. The eroded material is transported by the Viveiros stream toward the Sabor River. A seasonal stream drains the tailings. The stream sediments samples were collected along the Viveiros stream, in the seasonal stream, in a seasonal spring at the bottom of the tailings, in the Sabor River and in other streams not affected by mine workings, following the mine influence along the Viveiros stream and in the Sabor River (1.2 km away from the mine workings). The data show that the degree of pollution increases along the Viveiros stream, especially in winter. The highest degree of pollution is for As, In, W, Sn and Bi. The sediments from the drainage of the main tailings are particularly polluted during winter, by Bi, In and Sn. The sedimentary precipitate from the spring is polluted in Cu, As, In, Sn, Ta, W, Bi, Zn, Nb, Ag, Sb and Ta. The sediments from the Sabor River are significantly polluted by As, Ag, In, Sn, W and Bi. The sediments from the regional streams, Viveiros stream and Sabor River have similar REE (NASC normalized) patterns (ΣREE = 131.7–185.9 mg/kg, La_N/Lu_N = 1.23–1.42 and Eu/Eu* = 1.02), while those from the seasonal stream, crossing the main tailings, are enriched in REE (ΣREE = 250.3–283.6 mg/kg, La_N/Lu_N = 1.6–2.09 and Eu/Eu* = 0.96). The general decrease in La_N/Lu_N values with increase in total Fe₂O₃ can be explained by the partitioning of HREE to the solid Fe-oxides phase. The sedimentary precipitate and coatings, which are mainly formed by Fe-oxy-hydroxides, but also contain jarosite, are impoverished in all REE. The impoverishment can be explained by the release of REE from the surface of the Fe-oxy-hydroxides, which occurs due to a local lowering of pH, caused by jarosite dissolution. During successive alternate cycles of wet and dry conditions, takes place the formation of Fe-oxy-hydroxides and jarosite in the sedimentary precipitate and coatings. The subsequent dissolution of jarosite releases acidity, thus promoting de-sorption of REE from the Fe-oxy-hydroxides mineral phases.     

Geochemical background and baseline values of toxic elements in stream sediments of Campania region (Italy)

In this paper are discussed the baseline geochemical maps of elements harmful to human health, using concentration values of 2389 stream sediment samples collected over the Campania region (Southern Italy). Each sample was digested in aqua regia and analysed by ICP-MS. For compilation of baseline geochemical maps, a recently developed multifractal inverse distance weighted (lDW) interpolation method and spectral analysis (S-A) was applied, using a new geochemistry dedicated GIS software (GeoDAS). The aim of this study is to discriminate between the geogenic natural content (background) and the anthropogenic contribution in the collected sediments. The definition of background values, in contrast to baseline values, is very important in determining the extent of polluted areas in countries like Italy, where environmental legislation has not yet established intervention limits for stream sediments.     

Geochemical features of rocks,stream sediments,and soils of the Fiume Grande Valley (Calabria,Italy)

The role of both natural weathering and anthropogenic pollution in controlling the distribution of major oxides and several trace elements in soils, stream sediments, and rocks of the Fiume Grande catchment was evaluated. The contents of major oxides and trace elements in soils appear to be governed by weathering and pedogenetic processes, although the use of fertilizers in agriculture could also partly affect K₂O and P₂O₅ contents. Stream sediments have concentrations of major oxides (except CaO) very similar to soils, as relevant amounts of soil materials are supplied to the stream channels by erosive phenomena. In contrast, stream sediments have concentrations of Cr, Co, Ni, Zn, As, and Pb significantly higher than those of soils, probably due to different conditions and rates of mobility of these elements within the three considered matrices and/or disposal of wastes in the drainage network. Comparison of the concentrations of PHEs in soils with the maximum admissible contents established by the Italian law shows that these limits are too restrictive in some cases and too permissive in other ones. The approach of setting these limits with no consideration for the local geological–geochemical framework may lead to improper management of the territory and its resources. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

闽西震旦系上统变质火山岩的地球化学特征及其大地构造背景

福建西部震旦系上统变质火山岩属钙碱性系列。ＲＥＥ分布模式均呈向右倾斜的曲线,具Ｅｕ负异常,富集大离子系亲石元素和亏损地幔岩相容元素,（８６）Ｓｒ／（８７）Ｓｒ初始值０．７１０５～０．７１２６,显示陆壳重熔生成的岩浆特点。它们是在浙南－闽西北加里东期挤压碰增造山作用中陆壳重熔岩浆上升喷发产物。     

新疆塔什库尔干县赞坎铁矿外围水系沉积物地球化学特征及找矿方向

通过塔什库尔干县赞坎铁矿外围地区水系沉积物地球化学特征及其元素相关性的研究表明,元素(地球化学)异常(高值区)严格受塔阿西-色克布拉克断裂带,以及泥盆纪地层、热液活动、岩脉等因素联合控制。根据异常特征与成矿地质条件,圈定了4处成矿远景区,即赞格尔铅银钨多金属成矿远景区(Ⅰ_1)、西若钨锡钼铜多金属成矿远景区(Ⅱ_2)、盖家克铬镍铜金多金属成矿远景区(Ⅱ_3)和哈尼沙里地金多金属成矿远景区(Ⅱ_4),为下一步找矿工作指明了方向。     

Geochemical characteristics of modern river sediments in Myanmar and Thailand: Implications for provenance and weathering

The elemental composition of organic matter and the major and trace element compositions of stream sediments from Myanmar (Ayeyarwady and Sittaung rivers) and Thailand (Mekong and Chao Phraya rivers, and their tributaries) were determined to examine their distributions, provenance, and chemical weathering processes. Higher total organic carbon (TOC) and total nitrogen (TN) contents in the finer grained sediments indicate hydrodynamic energy may control their distributions. TOC/TN ratios indicate inputs of both aquatic macrophyte and higher vascular plant material to the river sediments. The major element abundances of the sediments are characterized by predominance of SiO₂ in coarser fractions and a marked negative correlation with Al₂O₃, representing primary grain size primarily control on SiO₂ content. Marked depletion of most labile elements (Na₂O, CaO, K₂O, Ba and Sr) relative to UCC (upper continental crust), indicate destruction of feldspar during chemical weathering in the source area or during transport. However, enrichment of some high field strength elements (Zr, Th, Ce and Y) relative to UCC and higher Zr/Sc ratios indicate moderate concentration of resistant heavy minerals in finer-grained samples. Discriminant diagrams and immobile trace element characteristics indicate that the Mekong, and Chao Phraya river sediments were largely derived from felsic sources with compositions close to typical rhyolite, dacite/granodiorite, UCC, I- and S-type granites. Relative enrichment of ferromagnesian elements (e.g. MgO, Cr, Ni) and high Cr/V and low Y/Ni ratios in Ayeyarwady and Sittaung sediments indicate the presence of a mafic or ultramafic component in their sources. The ICV (Index of Compositional Variability), CIA (Chemical Index of Alteration), PIA (Plagioclase Index of Alteration), α^Al, Rb/Sr and K₂O/Rb ratios indicate that the Ayeyarwady and Sittaung sediments record low to moderate degrees of chemical weathering in their source, compared to moderate to intense chemical weathering in the Mekong and Chao Phraya river basins. These results are compatible with existing major ion data for river waters collected at the same locations.     

张八岭群火山岩地球化学特征及其构造学意义

安徽滁州张八岭地区的张八岭群分为2组。一是下部北将军组,以千枚岩和片岩为主;二是上部西冷岩组,主要为一套变质火山岩系。张八岭岩群的细碧-石英角斑岩系主要发育于西冷岩组中,具多旋回特点。细碧-石英角斑岩系以石英角斑岩为主,细碧岩次之,角斑岩类稀少。该岩系的火山岩富碱、富钠,具双峰值特征,其主量元素、微量元素和稀土元素地球化学特征表明,它形成于非造山张性环境,为裂陷槽,是与晚元古代罗迪尼亚(Rodinia)超大陆裂解有关的岩浆作用的产物。     

Mineral deposits and Cu–Zn–As dispersion–contamination in stream sediments from the semiarid Coquimbo Region,Chile

This paper presents Cu–Zn–As geochemical data from stream sediment surveys carried out in the three main watersheds of the Coquimbo Region of Chile. This mountainous semiarid realm occupies an area of 40,656 km² between 29° and 32°S. Given that the area has a long historical record of mining activities, important environmental disturbances were expected. However, despite the detection of three major geochemical anomalies for Cu, Zn, or As, only one can be unmistakably linked to the development of mining–metal recovery procedures (Andacollo–Panulcillo). An investigation of the other two anomalies (Elqui and Hurtado) reveals three major causes that fully or partially account for them: (1) the type of ore deposit and associated hydrothermal alteration; (2) the regional structural setting (intensity of fracturing); and (3) climate–landscape. Cu–Au–As epithermal deposits/prospects along the so-called El Indio belt are here regarded as the sources of both the Elqui and Hurtado anomalies. The strong advanced argillic alteration present in some of the epithermal deposits/prospects of the El Indio belt may have induced the loss of the buffering capacity of rocks, and therefore favoured metal dispersion during later oxidation–leaching of sulphides. This applies to the Elqui and Hurtado anomalies. Conversely, given that the potassic, propylitic and phyllic alterations do not affect the buffering capacity of rocks, only minor metal dispersion is observed in relation to the Los Pelambres porphyry copper deposit. Besides, the epithermal belt is located within a highly fractured Andean domain (3,000–4,000 m of altitude), which may have conditioned the fast unroofing of ore deposits, contributed to enhanced circulation of meteoric waters, and eventually, to strong oxidation, and leaching of metals. Metal dispersion is aggravated during rainy years in response to strong El Niño episodes.     

黑龙江东部完达山地区水系沉积物地球化学特征及成矿预测

完达山地区位于中国东北地区东部,主要由一套近南北走向的玄武岩、堆晶岩、(超)基性熔岩、硅质岩和泥质岩组成,为中国东部唯一的中生代海相地层发育区,出露有太平洋板块俯冲形成的增生杂岩组合。研究区矿产资源丰富,已发现中型矿床1处,小型矿床4处,找矿前景较好。在全区1∶20万水系沉积物测量基础上,对完达山地区16种成矿元素进行相关性分析、聚类分析、因子分析、单元素异常分析和组合异常分析。分析结果表明,Au、Ni、Cr、Bi、Hg异常高值点多、离散性强,地质及地球化学条件优越,成矿潜力强。Au成矿作用主要与中酸性岩浆岩相关,Ni、Cr成矿作用主要与(超)基性岩浆熔离作用相关。在此基础上,结合区内地质、构造、物探和已知矿床(点)等信息,优选出4处成矿远景区,即258高地金成矿远景区、八里桥—仙人台铜镍钨锡成矿远景区、四平山—358高地金银成矿远景区和跃进山—先锋北山金银铜铁成矿远景区,为完达山地区整体找矿工作部署和区域成矿规律研究提供科学依据。