新疆东戈壁钼矿弱胶结层元素分布规律研究

以新疆东戈壁钼矿为例,研究矿体上方弱胶结层不同粒级土壤中元素分布规律及成因,主成矿元素活动态赋存形式,为金属活动态测量法在戈壁荒漠区寻找钼矿提供依据。本次研究发现,Mo、Cu等成矿及伴生元素在弱胶结层(10~40 cm)中倾向于向两"极"富集,即最粗粒级(-4~+20目)和最细粒级(-160目)含量较高。在粗粒级中富集与粗粒岩屑保留了原岩矿化信息有关;在细粒级中富集与细粒土壤中粘土矿物、铁锰氧化物能有效捕获从深部矿体迁移上的活动态金属元素,形成元素含量二次叠加有关。活动态Mo、W元素主要赋存于水提取态中,活动态Cu主要赋存于铁锰氧化物态中。在大面积基岩出露的剥蚀戈壁区,采集弱胶结层粗粒岩屑样品即能反映异常;在覆盖区进行钼矿地球化学调查时,采集弱胶结层中细粒级样品为佳,能有效捕捉深部含矿信息。     

荒漠戈壁区地表疏松层中元素的分布规律

通过对荒漠戈壁区不同矿区地表疏松层中元素的分布规律研究发现:主要成矿元素和指示元素均在近地表疏松层中富集,同时,在粒级分布上又倾向于细粒级(-160目)富集,可见,在对荒漠戈壁区进行区域地球化学调查中,采集弱胶结层(10~40 cm)细粒级样品(-160目)为最佳采样介质,这样能有效地捕捉深部含矿信息。     

金属活动态测量在东戈壁钼矿找矿效果研究

戈壁覆盖区常常出现较厚的覆盖层和坚硬钙积层,采用常规地球化学测量方法找矿效果不理想,金属活动态测量法对该区域不同类型隐伏矿体有良好的指示效果,但对隐伏型钼矿床指示效果研究较少。以新疆东戈壁钼矿为例,对比研究弱胶结层土壤中Mo,W和Cu元素全量和金属活动态含量对矿体的指示效果,探讨元素在土壤中主要存在形式。研究发现,在剥蚀戈壁区采集-4~+20目粗粒级土壤样品,可有效指示隐伏矿体,在堆积戈壁区采集-160目细粒级土壤样品,并测试成矿元素金属活动态含量,可有效指示深部隐伏矿体。钼矿体上方弱胶结层细粒级土壤中存在活动态的二次叠加含量,其中活动态Mo,W元素主要赋存于水提取态中,活动态Cu元素主要赋存于铁锰氧化物态中。     

活性水系沉积物的冻结采样技术应用于矿产勘查及环境研究

本文比较了活性水系沉积物的冻结采样技术与常规采样技术，经统计分析，１０种氧化物和２１种微量元素在两种技术之间全部都存在着显著的差异。在１２２个采样点上所得到的氧化物重量百分比和微量元素含量表明：冻结采样可得到具有代表性的沉积物样品。每个采样点为了获得对沉积物中氧化物重量百分比和元素含量具有代表性的评估，需要小于５０％的冻结样品，相反，常规采样由于冲洗和淘洗细粒级沉积物，致命用以常规地球化学分析的沉     

吐哈盆地砂岩型铀矿战略性地球化学调查与评价

超低密度战略性深穿透地球化学方法可以有效地圈定大规模地浸砂岩型铀矿.地表弱胶结层细粒物质的强烈吸附和离子交换性能使得深部迁移上来的活动态铀元素得以保存富集,可做为获取盆地中隐伏砂岩型铀矿信息的有效采样介质.铀钼组合异常是砂岩型铀矿的最显著标志.利用超低密度地球化学方法在整个吐哈盆地共圈出3个铀地球化学省,其中两处位于吐鲁番盆地周边,一处位于哈密盆地东南缘.新发现的哈密-骆驼圈子和鄯善县东南部地球化学异常极具寻找新的大型砂岩型铀矿找矿前景.     

金属活动态提取技术在十红滩铀矿的应用

通过十红滩铀矿上方土壤中铀的存在形式研究发现,能指示深部隐伏矿信息的铀酰络阳离子富集在地表覆盖物弱胶结层细粒级粘土中,可占全铀比例的17%～40%。提取土壤中吸附与可交换相的铀可以有效指示矿体,在铀矿体上方,存在明显的铀、钼活动态异常。从而证明金属活动态技术可用于寻找隐伏金属矿床。     

金窝子矿带戈壁覆盖区化探深穿透找矿方法研究

以金窝子金矿带为例，重点研究东天山地区戈壁覆盖层的分带结构、成分、性质和成因，以及金等成矿元素在干旱景观区表生迁移与矿化信息的传递机制。通过垂直剖面分析查明，戈壁覆盖层主要由坡-冲积层和冲-洪积层互层构成，其中坡-冲积层属当地风化产物，包含局部矿化信息，称为砾土戈壁；而冲-洪积层为运积物。两层均普遍经受戈壁化作用，形成以石膏为主的钙积层障。两互层均包含金等元素的矿化信息：在大比例尺详查找矿中采集坡-冲积成因的砾土戈壁层粗粒级(20—40目)，能够揭示局部矿化地段；而在小比例尺区域地球化学测量中采集冲-洪积层中的细粒级(-160目)样可以圈定区域金矿化带。     

高山峡谷区影响土壤测量找矿效果的元素表生活动特性研究

研究发现，高山峡谷区内土壤中元素的表生活动以表生富集作用为主，元素表征富集作用的程度、富集层位和粒级等受矿化作用和自然风化作用双重影响。非矿化地段土壤中元素的表生富集程度较矿化带处土壤中元素表生富集程度更强；矿化带处B层土壤比A层土壤中元素的富集强度稍大，元素明显地富集在粗粒级组分中；近矿（化）带的非矿化地段，A、B两层土壤仍受到矿化组分的影响，A层土壤比B层土壤受到的影响更加明显，粗粒级组分比细粒级组分反映敏感，C层土壤中元素在细粒级组分中轻微富集。根据本次研究结果，调整了高山峡谷区土壤测量工作方法，经试点测量验证，找矿效果良好。     

巴西Potiguar和Reconcavo断陷盆地河流、三角洲和浊积砂岩储层成岩非均质性与储层质量

Ｐｏｔｉｇｕａｒ和Ｒｅｃｏｎｃａｖｏ盆地位于巴西东北部海岸附近，为早白垩世发育的断陷盆地，其中烃类储层主要是河流和湖相（三角洲和浊流）砂岩。其成岩要素有机械渗滤粘土、方解石、白云石和绿泥石，而且成岩要素在井间和油田规模内显示不同的分布模式。这种分布特征即成岩非均质性是根据薄片、岩芯、测井和岩石物性资料研究得出的。在井间规模内，砂体几何形态和成岩要素的关系是以储层非均质性为主要特征，表现为：（１）机械渗滤粘土（ＭＩ）主要分布在河流相储层中，并沿古河道方向分布，使储层产生强烈分隔性；（２）方解石胶结物出现在砂泥岩接触面附近（环边分布）或散布在砂岩层内（分散分布）；（３）白云石胶结物主要沿砂岩交错层理的纹层分布，导致有效水平渗透率降低一个数量级；（４）自生绿泥石在细粒砂岩中引起渗透率降低，而在粗粒砂岩中影响较小，其结果导致储层渗透率结构发生重大改变。在油田规模内，成岩非均质性包括：（１）河流相储层中成岩特性呈层状分带；（２）三角洲相储层中碳酸盐胶结物向烃类聚集边界增加；（３）在浊积岩储层中，河道充填式和叶状体式沉积砂体中碳酸盐胶结物有固定的分布模式。把成岩要素的分布和影响结合到井间和油田规模的地质模型中对获得真正     

新疆巴喀勒萨依砂岩型铜(银)矿的发现及其地质意义

通过1：10万水系沉积物综合异常查证，在河谷的水系洪积物中发现孔雀石化中粒砂岩之转石，按照转石找矿法进行矿源层追索，新发现砂1岩型铜（银）矿产于上石炭统科古琴山组微细粒-中细粒砂岩中，是阿吾拉勒地区新发现的一种铜（银）矿床类型．发现铜（银）矿（化）体15条，矿体中铜与银呈正相关关系．该矿床的发现对阿吾拉勒地区普查找矿具有重要的地质意义．     

Deep-penetrating geochemistry of the Tuwu copper deposit, northwestern China

Desert terrains in northern China are covered by widespread regolith sediments which mask geochemical signals from ore bodies and are major obstacles to mineral exploration. There is a critical need to study the vertical distribution of elements in this regolith and to establish optimum sampling and analytical methods. The aim of this study is to understand the dispersion and variation of elements throughout the cover in a vertical profile. The results demonstrate that the main elements show a distribution pattern of enrichment in clay layers in the vertical profile, i.e., most elements tend to be enriched in the most upper part of the profile above the orebodies except for some elements like Cu, Ca and Ag. Meanwhile, both fine (-160 mesh) and coarse (+20 mesh) fraction samples from clay-rich horizons are favorable samples and selective leaching of the elements absorbed on clays or oxide coatings is effective for localizing buried deposits. The distribution of active Cu and Mo is quite different because chalcopyrite is weathered into Cu sulfate and CuCO3, and is precipitated in alkaline environments in a layer below close to the surface. Mo is soluble in the alkaline environment so it can penetrate the caliche layer and be enriched on the surface of soil enriched with weakly cemented clay.     

Geochemical-geomorphological Evidence for the Provenance of Aeolian Sands and Sedimentary Environments in the Hunshandake Sandy Land, Eastern Inner Mongolia, China

Identifying the provenance of aeolian sediments in the Hunshandake Sandy Land is of great importance for understanding the formation of the dune fields in the mid-latitudes and for deciphering information about desert’s responses to global change. By determining the major and trace elements concentrations of aeolian sands in three grain size fractions from the central and western parts of the Hunshandake Sandy Land, we systematically study the provenance and the depositional history of aeolian sands in this desert environment. Our results show that aeolian sands from the Hunshandake Sandy Land are enriched in SiO2 and are depleted in many other elements compared to those of the Upper Continent Crust (UCC). Variations of the immobile elements ratios like Zr/Hf, La/Yb, Th/Nb, La/Nb,LaN/YbN , GdN/YbN are relatively large in the coarse and medium fractions but minor in the fine fractions. Eu anomalies are quite different in the coarse fractions, but mostly positive in the medium fractions and all negative in the fine fractions. Decreasing tendency of Zr concentrations from the west to the east in the Hunshandake Sandy Land is evident in the coarse sands but rather weak in the fine grain size fractions. Our geochemical data indicate that the sources for the coarse and medium fractions of aeolian sands are diverse, influenced by local geology and geomorphology, while the fine sand fractions are more homogenous due to intensive mixture mainly by aeolian processes. Various ratios of immobile elements suggest that these sands should be sourced primarily from the surrounding mountains by fluvial/alluvial processes rather than from any remote territories. Aeolian sands with Ce negative anomalies are widely distributed in the Hunshandake Sandy Land, indicating that aquatic environments have occurred extensively prior to the occurrence of the dune field.     

Microscopic morphology and elemental composition of size distributed atmospheric particulate matter in Urumqi, China

Microscopic morphology and elemental composition of atmospheric particulate matter (PM) in 13 different size fractions from 0.01 to 10 μm were studied using a Field Emission Scanning Electron Microscope with Energy-Dispersive Spectrometer (FESEM–EDX). The relative mass fractions exhibited a bimodal distribution with a major mode in the fine range (0.18–1 μm) and a minor mode in the coarse range (>1 μm), suggesting that the major pollution of PM is fine particles in this area of Urumqi atmosphere. The PM could be classified as follows: aluminosilicate/silica mineral, Si–Al rich fly ash, Fe oxide particle, Ti dominant particle, sulfate/carbonate crystal, carbonaceous aerosols (including soot, organic carbon, tar ball and irregularly shaped carbon). The soot and organic carbon with anthropogenic sources are dominant types in fine range samples (<1 μm). The natural source minerals and secondary synthesized sulfate/carbonate crystals were accumulated in the coarse range (>1 μm). Elemental composition of various types of particles (0.056–5.6 μm) was also analyzed by EDX. C, S, O, N, Si, Al, Fe, Ca, Na, K, Mg, Cl, F, Hg were detected in most samples. Si, Al and Ca accumulated in coarse fractions, while S and Hg mainly accumulated in fine fractions. Concentrations of 15 metallic elements in size range from 0.1 μm to 5.6 μm were divided into three groups based on their possible sources. (1) The crustal elements (Al, Mg, Fe, Mn and V), mainly present in coarse particles (>1 μm); and (2) the anthropogenic source elements (Ca, Ni, As, Cu, Pb, Cd and Hg). The concentrations of Ca and Ni increased with increasing particle size, while As, Cu, Pb, Cd and Hg showed opposite trends. As, Cu, Pb, Cd and Hg accumulated mainly in fine fraction (<1 μm). (3) The multi sources elements (Cr, Co and Se) possibly come from both natural and anthropogenic sources. High levels of heavy metals, especially Hg in nanosize particles, may pose great risk to human health.     

广东凡口铅锌矿区灰岩风化土壤指示元素富集粒度及存在形式研究

通过广东凡口铅锌矿区灰岩风化残积土壤指示元素富集粒度和存在形式的研究,证实了指示元素在粗、细两端元粒级富集的倾向。但小于200目的细粒级富集稳定性更好。建议将野外直接过200目筛网的土样送交分析。证实了铁锰氧化物是指示元素的主要载体相。锰氧化物比铁氧化物更富集成矿元素。采用土壤重砂的电磁性部分作为样品介质或采用部分提取的方法,均可提高土壤地球化学异常衬度和分析灵敏度。     

荒漠戈壁区超低密度地球化学调查与评价——以东天山为例

中国的干旱荒漠戈壁区,约占国土面积的1/4.自然特点是极其干旱,沙漠和戈壁广布,土壤呈碱性.大部分面积尚未进行区域化探扫面工作,即使进行工作的地区,由于风成沙和土壤碱性的影响,结果并不理想,难以了解整个地区资源潜力.超低密度地球化学方法经过近10年发展,已经显示它不受地表覆盖物影响,能够快速有效地圈定战略靶区.因此,超低密度地球化学方法被用于东天山1.5×105km2的调查试点研究,发现弱胶结层是干旱荒漠区超低密度调查的有效采样介质,并且深部含矿信息主要赋存在细粒级部分和氧化地球化学障中,使用细粒级部分与提取氧化物膜中的金属元素相互补充可以有效地识别含矿信息.使用超低密度地球化学方法可以达到迅速、有效圈定有利于大型矿床或矿集区战略靶区的目的.通过1.5×105km2地球化学调查,制作了30余种元素地球化学图,填补了东天山部分地区地球化学空白.新发现远景Cu、Au、U和W异常10余处,并发现东天山存在3条Cu异常带东天山北带、中带和南带,其中土屋铜矿和黄山铜镍矿都位于中带,新发现的维权铜矿位于南带,北带还有待于进一步证实.相信这些异常的发现,对今后整个东天山矿产勘查的战略部署具有重要意义.     

钙质碎屑对热带海滩砂粒度参数的影响分析

钙质碳酸盐碎屑是热带海滩沉积物的重要组成部分,其物理特性与海滩中的石英颗粒差异明显。对海南岛东部文昌铜鼓角两侧海湾海滩砂样采用除钙和不除钙两种预处理方法,使用Mastersizer 2000激光粒度仪和筛析法进行粒度分析,结果表明:除钙以后粒度频率曲线主体朝细偏,但在粒度频率曲线细尾(4~9)会新增一小峰;去钙前后粒度参数存在明显的线性相关,平均粒径、分选系数和偏态的相关系数依次降低;粒度参数的组合变化以“平均粒径变细、分选系数变好、偏态朝细偏”为主,但仍存在其他的组合变化;在对类似于铜鼓岭周边环境的海滩进行沉积物粒度分析及动力环境研究时,需要了解钙质碎屑含量和颗粒组成。     

安徽宿松、繁昌地区武穴组沉积特征

通过对昌都地块古生代至中生代沉积岩相，沉积组合，古地理及生物群落与生物的深入研究及现有成果，提出了沉积地质与构造演化的五个阶段，以古中元古代的宁多群为代表的前寒武纪结晶基度形成阶段；以青泥洞群为代表的早古生代褶皱基底形成阶段，晚古生代台地型沉积为代表的稳定地块及火山弧至弧后盆地形成，演化阶段，中生代前陆盆地形成发展阶段及喜山期走滑拉分盆地发展阶段，同时，表明了介于冈瓦纳和劳亚两个超级大陆之间的特提     

Geochemical characteristics of fine and coarse fractions of sediments in the Yarlung Zangbo River Basin (southern Tibet,China)

Tracing sources of aeolian sediment is key to reconstructing earth surface processes in arid areas and interpreting the paleoenvironmental significance of aeolian sequences. However, the difference of geochemical characteristics between different fractions of sediments in the Yarlung Zangbo River Basin (YZRB) is still unclear, so we want to identify which fraction of sediments is more suitable for tracing sediment sources. Considering the long distance between different wide valleys in the YZRB, we wonder whether there is any difference between these wide valleys in terms of geochemical characteristics of sediments. Forty-three surface sediment samples in the YZRB are collected, and the grain-size distributions and the major-element composition for 37 samples and the trace and rare earth element composition for the coarse (75–500 μm) and fine (<?75 μm) fractions of all samples are determined. The results reveal the following: (1) the fine fractions of the deposits contain more environmental information, suggesting that the fine fractions cannot be directly compared between different climate zones for provenance identification and that appropriate coarse fractions, based on the grain-size distribution of the targeted sediments, are more ideal for tracing sediment sources; and (2) geochemical characteristics of various sediment types show spatial heterogeneity. The coarse and fine fractions of the loose sediment samples can be divided into two regional groups based on geochemical characteristics: the Maquanhe zone in the upper reach, the Xigaze, Shannan and Mainling zone in the middle reach, which is consistent with the geological background of the YZRB; (3) aeolian deposits in the YZRB are a local origin and predominantly derived from the adjacent loose sediments, and fluvial sediments in the upper reach contribute little to the aeolian sands in the middle reach.     

Patterns of rare earth and other trace elements in different size fractions of clays of Campanian–Maastrichtian deposits from the Portuguese western margin (Aveiro and Taveiro Formations)

The Upper Cretaceous (Campanian–Maastrichtian) Taveiro and Aveiro Formations belong to the northern sector of the Lusitanian basin (Portuguese western margin). The Taveiro Formation was deposited in alluvial fans, including mud flow beds, lakes and sinuous rivers. The Aveiro Formation was deposited in a flat region with low hydrodynamics channels, with the formation of a barrier island-tidal system. The reconstruction of this sedimentary basin may be difficult due to its complex architecture. This work aims a methodology to be used in the reconstruction of Cretaceous sedimentary environments of the Lusitanian basin, through the establishment of geochemical patterns of different size fractions of those deposits. Chemical analysis was performed by instrumental neutron activation analysis (INAA), and the mineralogical composition obtained by X-ray diffractometry (XRD). The whole rock and different size fractions (? ≥ 125 μm, 63–125 μm, 20–63 μm, 2–20 μm and ? < 2 μm) of selected samples were studied aiming the rare earth elements (REE) and other trace elements distribution and its correlation with the grain size and mineralogy.The results obtained for the studied Cretaceous sediments showed that REE patterns and other trace elements distribution in the different size fractions may be used as a tool to differentiate deposits within and between sedimentary formations. Within the Taveiro Formation, REE are concentrated in the silt fractions (20–63 μm and 2–20 μm) of the Reveles deposit, and in the clay size fraction of S. Pedro deposit, which is richer in kaolinite. The 1st transition elements, particularly Zn, are correlated with the presence of smectite in the clay fraction of Reveles deposit. In the sand and silt size fractions (>2 μm) of samples from Taveiro Formation correlations were found between: Ga and 1st transition elements, and phyllosilicates; Cs and mica; and Rb and Ba, and K–feldspars.The Bustos deposit (Aveiro Formation) samples are very fine-grained and with a high proportion of the fine silt fraction where REE are concentrated, especially the heavy ones. Incorporation of MREE, Co and U in carbonates of the coarser fraction appears to occur. The abundances of the 1st transition elements, Ga and As, are correlated with phyllosilicates.Significant differences were found in the trace elements patterns of the various analysed size fractions of the Lusitanian basin of Cretaceous sediments, between and even within formations, which can be used as a methodological approach for a fine paleogeographic reconstruction.