西藏热昌金矿地质及物探化探特征

西藏洛隆县热昌金矿为近年来在那曲—洛隆弧前盆地新发现的贵金属矿点。运用地质、物化探等勘查手段,圈定35个单元素异常,5个综合异常带;发现8条金矿化体,矿(化)体金品位0.315×10~(-6)～1.75×10~(-6),单样金品位最高达4.63×10~(-6)。通过对矿床地质及物化探特征进行综合分析,认为热昌金矿体赋存于花岗斑岩构造裂隙及与地层接触部位,受断裂及岩体控制。花岗斑岩西段深部存在低阻高激化的异常,地球化学异常Au、Cu、W等多元素套合性好,在花岗斑岩体边界及内部破碎带部位,矿化富集。热昌金矿的发现,为洛隆弧前盆地区域性找矿提供了积极的线索。     

Partitioning and speciation of chromium, copper, and arsenic in CCA-contaminated soils: influence of soil composition

This study focused on the influence of soil composition and physicochemical characteristics on the retention and partitioning of Cu, Cr and As in nine chromated copper arsenate (CCA) artificially contaminated soils. A statistical mixture design was used to set up the number of soils and their respective composition. Sequential extraction and modified solvent extraction were used to assess Cu and Cr partitioning and As speciation [As(III) or As(V)]. It was found that peat had a strong influence on CEC (232 meq/100 g), on buffer capacity and on Cu and Cr retention, whereas kaolinite's contribution to the CEC was minor (38 meq/100 g). Average metal retention in mineral soils was low (58% for Cu and 23% for Cr) but increased dramatically in highly organic soils (96% for Cu and 78% for Cr). However, both organic and mineral soils demonstrated a very high sorption of added As (71-81%). Levels of Cu and Cr in a soluble or exchangeable form (F1) in highly organic soils were very low, whereas the levels strongly bound to organic matter were much higher. Conversely, in mineral soils, 47% of Cu and 18% of Cr were found in F1. As a result, Cr and Cu in moderately and highly organic contaminated soils were present in less mobile and less bioavailable forms, whereas in mineral soils, the labile fraction was higher. The modified method used for selective determination of mineral As species in CCA-contaminated soils was found to be quantitative and reliable. Results revealed that arsenic was principally in the pentavalent state. Nevertheless, in organic soils, arsenite was found in significant proportions (average value of 29% in highly organic soils). This indicates that some reduction of arsenate to arsenite occurred since the original species in CCA is As(V).     

新疆哈密黑山金矿物化探异常特征及找矿预测

黑山金矿"又称宝东金矿"处于沙泉子断裂以南的中天山地块,为2016-2017年"1:5万沙泉子幅矿产地质调查"新发现的金矿点,处于北西向和北东向断裂交汇部位,赋存于编号为SHS-15岩屑测量综合异常中,对重点地段通过槽探工程结合物探高磁精测剖面和激电测深成果实施了钻探验证.认为金矿化带赋存于晚古生代中酸性火山岩组,其次...     

沟系土壤地球化学测量在西准包古图乃比克金矿中的应用

乃比克金矿位于新疆西准包古图地区,该金矿是通过对1∶5万水系沉积物异常区开展沟系土壤地球化学测量,对土壤异常高值点采用“溯源追踪”与构造识别的方法,同时借助手持X荧光分析仪,对识别出的构造蚀变带的含金性进行分析,优选较好地段布置地表槽探工程发现的.对地表浅覆盖、沟系较发育的中低山丘陵区找矿,沟系土壤测量是行之有效的方法.     

青海都兰县洪水河口金矿地质-地球化学特征及找矿模型

洪水河口金矿位于柴达木盆地南缘,东昆仑(造山带) Fe-Pb-Zn-Cu-Co-Au-W-Sn-石棉成矿带上。目前金矿储量达4. 88 t,金平均品位4. 21 g/t。依据1∶2. 5万地球化学测量资料,结合地质特征,对洪水河口地区7种元素的分布、相关性、组合异常等特征进行了分析研究,圈出1处金综合异常,通过对异常初步查证,圈定出1条大型金矿化蚀变带,1条金矿化体,说明1∶2. 5万地球化学测量可以在该区发挥很好的找矿指导作用,同时建立了该区地质地球化学找矿模型,指出了下一步找矿方向。     

综合物化探技术集成在层控型铅锌矿勘查中的应用--以湘西太阳山铅锌矿勘查为例

为了研究综合物化探方法集成在层控型铅锌矿勘查中的应用,文章以湘西渔塘铅锌矿田太阳山矿区为例,开展土壤次生晕、地电化学剖面、瞬变电磁法集成方法实验,快速圈定了矿化带异常,查明了物化探异常与成矿有关的地质特征,为工程验证提供了依据,取得了理想的地质找矿效果。说明综合物化探技术集成在层控型铅锌矿勘查快速评价中发挥了重要的指导作用。     

Effect of untreated urban effluents on the accumulation of toxic metals in river sediments under tropical conditions: Funa River,Kinshasa, Democratic Republic of the Congo

The objective of the present study was to assess the status of surface sediments from Funa River. Sediment samples were characterized for physicochemical parameters, including grain size, organic matter and toxic metals. The result revealed high metal concentrations in river sediments, reaching values of 154.19, 186.00, 1105.34, 3.69, 548.02 and 5.45 mg/kg for Cr, Cu, Zn, Cd, Pb and Hg, respectively. A strong correlation was observed between analysed metals and organic matter suggesting that these contaminants could have originated from common sources with a similar transport pathway. Based on the Sediment Quality Guidelines for the Protection of Aquatic Life, Funa River is considered as highly polluted with toxic metals indicating the potential environmental and human health risk. The results of this research represent a useful tool to assess the sediment quality of urban river receiving system which can be applied to similar environment.     

综合物化探在招平断裂带中段金矿深部找矿的应用

招平断裂带是胶东三大金矿带之一。研究范围位于招平断裂带中段(招远城至夏甸金矿),可控源音频大地电磁测深特征呈相对低阻,视电阻率等值线同等向下弯曲,间距变大及由陡变缓部位为成矿有利部位;构造叠加晕研究是采用相关分析及格式法,确定大尹格庄和夏甸金矿床元素轴向分带序列,前缘晕元素为As、Sb、Hg、B,近矿晕元素为Au、Ag、Cu、Pb、Zn和尾晕为Bi、Mo、Mn、Co。据前、尾晕共存准则和前缘晕强度趋势准则预测深部还有盲矿存在。通过地质及物化探工作成果,建立了地质-物探-化探综合找矿模型,确定深部找矿靶区,为下一步的找矿工作指明方向。     

Occurrence of arsenic in core sediments and groundwater in the Chapai-Nawabganj District, northwestern Bangladesh

Groundwater and core sediments of two boreholes (to a depth of 50 m) from the Chapai-Nawabganj area in northwestern Bangladesh were collected for arsenic concentration and geochemical analysis. Groundwater arsenic concentrations in the uppermost aquifer (10-40 m of depth) range from 2.8 μg L⁻¹ to 462.3 μg L⁻¹. Groundwater geochemical conditions change from oxidized to successively more reduced, higher As concentration with depth. Higher sediment arsenic levels (55 mg kg⁻¹) were found within the upper 40 m of the drilled core samples. X-ray absorption near-edge structure spectroscopy was employed to elucidate the arsenic speciation of sediments collected from two boreholes. Environmental scanning electron microscopy and transmission X-ray microscopy were used to investigate the characteristics of FeOOH in sediments which adsorb arsenic. In addition, a pH-Eh diagram was drawn using the Geochemist's Workbench (GWB) software to elucidate the arsenic speciation in groundwater. The dominant groundwater type is Ca-HCO₃ with high concentrations of As, Fe and Mn but low levels of NO₃⁻ and SO₄²⁻. Sequential extraction analysis reveals that Mn and Fe hydroxides and organic matter are the major leachable solids carrying As. High levels of arsenic concentration in aquifers are associated with fine-grained sediments. Fluorescent intensities of humic substances indicate that both groundwater and sediments in this arsenic hotspot area contain less organic matter compared to other parts of Bengal basin. Statistical analysis clearly shows that As is closely associated with Fe and Mn in sediments while As is better correlated with Mn in groundwater. These correlations along with results of sequential leaching experiments suggest that reductive dissolution of MnOOH and FeOOH mediated by anaerobic bacteria represents an important mechanism for releasing arsenic into the groundwater.     

Exceptional arsenic (III,V) removal performance of highly porous,nanostructured ZrO2 spheres for fixed bed reactors and the full-scale system modeling

Highly porous, nanostructured zirconium oxide spheres were fabricated from ZrO₂ nanoparticles with the assistance of agar powder to form spheres with size at millimeter level followed with a heat treatment at 450 °C to remove agar network, which provided a simple, low-cost, and safe process for the synthesis of ZrO₂ spheres. These ZrO₂ spheres had a dual-pore structure, in which interconnected macropores were beneficial for liquid transport and the mesopores could largely increase their surface area (about 98 m²/g) for effective contact with arsenic species in water. These ZrO₂ spheres demonstrated an even better arsenic removal performance on both As(III) and As(V) than ZrO₂ nanoparticles, and could be readily applied to commonly used fixed-bed adsorption reactors in the industry. A short bed adsorbent test was conducted to validate the calculated external mass transport coefficient and the pore diffusion coefficient. The performance of full-scale fixed bed systems with these ZrO₂ spheres as the adsorber was estimated by the validated pore surface diffusion modeling. With the empty bed contact time (EBCT) at 10 min and the initial arsenic concentration at 30 ppb, the number of bed volumes that could be treated by these dry ZrO₂ spheres reached ∼255,000 BVs and ∼271,000 BVs for As(III) and As(V), respectively, until the maximum contaminant level of 10 ppb was reached. These ZrO₂ spheres are non-toxic, highly stable, and resistant to acid and alkali, have a high arsenic adsorption capacity, and could be easily adapted for various arsenic removal apparatus. Thus, these ZrO₂ spheres may have a promising potential for their application in water treatment practice.     

刚果(金)马诺诺(Manono)东部某伟晶岩型铌钽矿地质特征

矿区地处于基巴拉褶皱带刚果(金)马诺诺东部,成矿地质条件优越。通过系统地质工作,发现该区矿床为LCT(锂-铯-钽)花岗伟晶岩型矿床,区内共圈定矿体2条,分别为Ⅰ-1和Ⅱ-1,铌钽金属资源量约1万t,锡金属资源量约20万t。矿体均呈层状、似层状,严格受伟晶岩控制产出。矿石类型主要为风化矿石和原生矿石,矿石矿物主要为铌钽铁矿、铌钽锰矿等。该区矿体规模大,矿物以铌钽矿为主,同时伴生少量锂、锡和铍,经济价值高。通过后期进一步的勘查工作,资源量将会进一步扩大。     

Non-linear analysis for the freezing–thawing situation of the rock surrounding the tunnel in cold regions under the conditions of different construction seasons, initial temperatures and insulations

In this paper, based on the governing differential equations of the problem of temperature field with phase change, the finite element formulae of this problem are obtained from Galerkin's method. An illustrative example of the temperature field in cold region tunnel under the conditions of the different construction seasons, different initial temperatures, different thicknesses and thermal conductivity of insulation material is provided. Then some significant results are presented, which can provide a reference for actual tunnel engineering designs in cold regions.