峡东地区埃迪卡拉系黑色页岩的微量元素和Fe同位素特征及其古环境意义

通过分析宜昌峡东地区九龙湾剖面埃迪卡拉系陡山沱组黑色页岩的微量元素和Fe同位素组成,对埃迪卡拉纪海洋的氧化还原状态进行了制约。黑色页岩氧化还原敏感元素的富集系数以及U/Th、V/(V+Ni)、V/Cr值等在陡山沱期存在着明显的演化趋势。这些趋势显示陡山沱组二段下部水体处于氧化的状态,陡山沱组二段上部水体处于还原状态,陡山沱组四段黑色页岩发育在氧化环境中。同时,陡山沱组二段下部黑色页岩富集重的Fe同位素,表明黑色页岩来自于海水的铁主要是以Fe3+的氧化物或氢氧化物形式沉淀的,进一步说明这个时期的水体处于氧化状态。综合黑色页岩微量元素和Fe同位素信息,显示在埃迪卡拉纪陡山沱早期海水经历了先氧化后还原的过程,陡山沱晚期海水变得氧化了。这种特征与埃迪卡拉纪陡山沱期生物群的出现和演化相对应,说明海洋的氧化为埃迪卡拉纪生物的出现和演化提供了前提条件。     

湘西黑色岩系地球化学特征和成因意义

本文采用ＧＣ－ＭＳ,ＩＣＰ－ＭＳ,形态硫分析,硫同位素,物相分析等方法综合研究了湘西晚震旦世－早寒武世黑色岩系的地球化学特征和形成条件,湘西黑色岩系以富有机物质为特征,其来源为藻,菌类生物,形成于缺氧环境。缺氧标志包括有机碳,黄铁矿含量,硫同位素,稀土元素的分布,δＵ,ＤＯＰ和生物标志物等参数,在黑色页岩中富集Ｖ,Ｎｉ,Ｍｏ等微量元素,并在局部地区形成具有工业价值的矿床,研究认为,生物,有机质对一     

黑色页岩成矿作用——IGCP254项活动及最新进展

1987年2月在巴黎,国际地质对比计划常委会第15次会议顺利地通过了254项“黑色页岩成矿作用”(1987—1991)的立项决议。1987年10月在捷克斯洛伐克Jesenik成立了以J.Pa(?)ava为主席的执行机构,包括美国、苏联、澳大利亚、芬兰、法国、联邦德国、匈牙利、波兰、委内瑞拉、中国和印度等在内的各国工作小组。目前,已有24个国家的300多位科研人员参加了IGCP项工作。 该项目的最终目标首先是揭示黑色页岩建造的各种特征,包括恢复古环境和古地理条件、古构造位置及地球化学特征等。各个     

低钙质黑色页岩的物质来源

沉积岩中元素的富集取决于每个元素的化学性质。这些元素是风化作用、沉积作用、成岩作用、石化作用和低级变质作用的产物。但是人们认为,不活泼的碎屑物质组分具有初始火成源的特征。这一认识对研究黑色页岩的物质来源有很大帮助。为了确定低钙质(CaCO_3<1％)海相黑色页岩中碎屑花岗质和火山物质的来源,采用研究火成岩的典型微量元素判别图来检验那些表面上化学性质不活泼(即不受成岩作用、氧化还原作用和低级变质作用的影响)微量元素的富集。通过对寒武纪至侏罗纪完整的地层剖面中约200个黑色页岩样品的中子活化分析获得叮化学分析数据。La—Th—Sc三角图解能鉴别出微量元素来自上地壳、陆壳,或是洋壳(Taylor和Mclennan,1985)。所有低钙质黑色页岩样品都集中在上地壳的区域内。人们普遍用Th—Hf—Co三角图来鉴别它们是来自上地壳还是整个陆壳,或是洋壳。在黑色页岩形成的环境中,由于Co元素对氧化还原很敏感,故在三角图解中,用一个不活泼的化学元素(如Rb)替代Co是必要的。取代以后,所有黑色页岩样品均集中在上地壳的区域内。为了确定花岗质组分的来源(Pearce等,1984),样品在Ta—Yb图解和Rb—(Yb+Ta)图解上的投点都集中在边缘分离火山弧花岗岩(VAG)、同碰撞花岗岩(Syn—COLG)与板块内花岗岩(WPG)三者的交界处。大部分样品落于火山弧花岗岩域内,无洋脊花岗岩(ORG)出现。Wood等(1979)的Th—Hf/3—Ta三角图解证实了海相黑色页岩中少量的微量元素来自玄武岩。黑色页岩的投影点很集中,且集中在高Th含量区域,但落于各种玄武岩区域之外,说明黑色页岩来自大陆壳。     

云南昆阳磷矿黑色页岩微量元素特征及其地质意义

昆阳磷矿是我国下寒武统黑色页岩中赋存的最大的磷块岩矿床。为了探讨磷块岩及上覆黑色页岩的源区性质及古海洋的氧化还原环境,本文对梅树村组中谊村段的磷块岩、石岩头段的黑色页岩以及筇竹寺组玉案山段的砂质黑色页岩的地层剖面进行了岩石地球化学研究。发现昆阳剖面磷矿区的下寒武统黑色页岩Th-Zr和Th-Y/Ho比值以及Y-Y/Ho比值与陆源碎屑物质更为接近,石岩头段黑色页岩样品的稀土元素总量平均为174×10^-6,与大陆壳稀土总量的平均丰度基本一致。稀土配分模式也十分类似,说明陆源碎屑物质来源比海水自生来源占的比重更大。受陆源碎屑物质的影响,Ni/Co,V/Cr和V/（V+Ni）等氧化还原敏感元素比值并不能很好的指示古海洋的沉积环境。但石岩头段黑色页岩的氧化还原敏感元素相对大陆壳具有一定程度的富集,并且富集程度不强烈,Ce具有轻微的负异常,反映了黑色页岩可能形成于次氧化环境。     

Enrichment and Origin of Some Trace Elements in Black Shales from the Early Cambrian in Eastern Guizhou Province

The analysis is based on the elemental geochemistry, ¹³C, ¹⁸O isotope and lithology combination of the black shale, a set assemblage mud and carbon of lithology , in East Guizhou. The coordinated change in spider diagrams of race elements suggests those elements have the same source. The ¹³C, ¹⁸O isotopes, mode of REE partition and characteristic enrichment of elements assemblage in carbonaceous shale show that the deep thermal fluid is added, and the shelf sea basin edge with distribution of hydrothermal activity is propitious to precipitation of ore elements. Evidence from the ³⁴S isotope and redox-sensitive elements show that the hydrostatic hypoxia environment is also conducive to precipitation of elements. The lithologic features (phosphorus, coal-bearing layers) and high content of organic carbon indicate that the deposits are influenced by the upwelling ocean current.     

Some Observations on the Determination of Gold and the Platinum-Group Elements in Black Shales

This research compares various ways of applying oxidative chemical decomposition to the analysis of gold-bearing black shale ores from the Russian Natalka and Sukhoj Log deposits. This study was conducted as part of the certification program for the Russian candidate black shale reference materials SLG-1 and SCHS-1 and also because of the paucity of data available on the determination of the platinum group elements (PGE) in analogous sample types. We report direct evidence of PGE volatilisation from black shale materials when processed in the presence of oxygen. We also developed a comprehensive analytical scheme for the quantitative determination of PGE in all phases (gaseous and ash) produced during slow combustion of carbonaceous materials in oxygen.
This study has shown that during combustion in oxygen at 600 °C, PGE contained in the Natalka black shale ores are lost as gaseous reaction products. Thus, the volatilized PGE (recovered in traps) account for up to 14% Pt, 40% Pd, 40% Ru and 10 % Ir relative to their total concentrations in a carbonaceous concentrate. It was also established that in the process of combustion, Au quantitatively remains in the ash cake.
In order to avoid the deleterious effects of oxygen on the volatility of the PGE, we propose a new comprehensive sample decomposition method based on the application of fluoroxidants such as BrF₃ and KBrF₄. This method was validated using samples of black shale ores and their processing products by comparing our results with those obtained independently using sealed autoclave processing of the same materials. It was shown that PGE in black shale ores and their processing products not only exist in commercially exploitable quantities but that a small proportion of PGE compounds are soluble in alcohol. We propose that in gold-bearing black shale ores, PGE are present as organometallic compounds.     

湘西北下寒武统黑色岩系地球化学特征

对湘西北下寒武统黑色岩系进行了系统的地球化学研究,结果表明:SiO2的含量范围为10.54%～87.10%,平均为51.15%。稀土总量范围较大,为92.70～737.84μg/g,平均为312.73μg/g,LREE相对富集,HREE亏损。Ce呈弱至中等负异常,Eu大部分呈弱的正异常。稀土元素标准化曲线呈弱的帽状形态,较为平缓。微量元素Ni、Mo、Ba、V含量高,主要含矿岩石为磷块岩,而不是炭质页岩。成矿作用以热水作用为主,成矿环境不局限于浅海环境。     

Jurassic Black Shales Facies from Qiangtang Basin (Northern Tibet):Rare Earth and Trace Elements for Paleoceanographic Implications

The Biluo Co and Amdo 114 station, northern Tibet, cropping out the Early Toarcian and Middle-Late Tithonian (Jurassic) organic-rich black shales, have been a focus to petroleum geologists in discussing their oil-producing potential. This paper first reports the trace elements and rare earth elements to discuss the paleoenvironments, redox conditions and sedimentary mechanisms of those black shales. Both sections exhibit variation in trace element abundances with concentrations <0.1 ppm to 760 ppm, mostly enriched in V, Cr, Ni, Cu, Zn, Mo, Ba and U. Element ratios of Ni/Co, V/Cr, U/Th and V/(V+Ni) plus U were used to identify redox conditions. The shale-normalized rare earth element (REE) patterns are characterized by the flat-shale type with instable Ce anomalies and very weekly positive Eu anomalies. Positive Ceanom values are significant with values varying between –0.064 and 0.029 in Biluo Co, which may be interpreted as release of REE and input of riverine terrestrial matter with rich Ce (resulting in pH change) during the anoxic conditions. In the middle parts of Amdo 114 station, distinct negative Ceanom values are observed (?0.238 to ?0.111) and associated surface water warming were interpreted as being related to a major sea level rise. In contrast, the formation of the black shales in the lower and upper part of the studied succession took place during a cooler (Ceanom values >–0.10), lower surface water productivity, and lower sea-level stage. Thus, we emphasize the role of different factors that control the formation of local and regional black shales. The most important factors are sea-level fluctuations and increasing productivity.     

湘中HJC铀矿区黑色页岩土壤重金属污染地球化学分析

本文以湘中HJC铀矿区黑色页岩土壤为研究对象,对黑色页岩土壤重金属污染进行了地球化学分析。通过测制A、B、C、D等土壤剖面并系统取样,借助ICPMS等分析技术,对土壤、成土母岩、玉米等进行了系统的主量元素、重金属和其他微量元素（稀土元素）分析。结果表明,矿区黑色页岩土壤具富Al2O3、Fe2O3,而贫CaO、Na2O的化学组成特征,其化学风化指数CIA值在79~84之间。土壤因继承成土母岩的元素富集特征而富集V、Cr、Co、Ni、Cu、Zn、Mo、Cd、Sn、Sb、Tl、Pb、Th、U等多种重金属,其中Mo、Cd、Sb、U的富集最强。土壤重金属综合富集指数（EI值）在3~9之间,各剖面EI值大小顺序是：D>A>B>C, 以D剖面土壤重金属综合富集最强。土壤重金属污染富集因子（F）评价结果显示：矿区土壤普遍存在Cd、Mo、Sn、Sb、U等重金属污染,其中Mo、Cd、Sb等的污染最强,达显著（3级,2 < F < 20）污染程度以上。重金属污染效应既表现为Sc、Cd、Sn、Sb、U、Tl、Pb等生物毒性重金属在玉米中的富集,又表现为Mo、Co、Ni、Cu、Zn等生物有用金属在玉米中的明显亏损。黑色页岩即为土壤重金属污染的污染源。土壤重金属污染与重金属在成土母岩和土壤中的富集程度(Ks、EI、F)、重金属的活动性（Change%）等多种因素有关。重金属污染主影响因子的Pearson相关系数分析显示：Cd对土壤构成持久性污染,Mo、Sn、Sb、U等的污染程度可随土壤风化的进行因淋失而趋于降低,而Zn、Mn、Ba、Co、Ni、Th等目前未达到污染水平的重金属则可因次生富集而在未来引发污染。     

贵州西部煤层中若干有害微量元素的分布及迁移富集规律

煤中有害微量元素不仅影响煤的加工利用,而且对生态环境及人类健康有极大危害,本文利用现代分析测试手段,对贵州西部晚二叠世主采煤层中的有害微量元素Ａｓ,Ｆ,Ｈｇ,Ｐｔ,Ｃｄ等的含量,分布赋存状态及其迁移富集规律进行了研究。     

湘中安化黑色页岩土壤玉米的元素地球化学分析

利用等离子质谱(ICP-MS)等分析技术,对产于安化东坪、烟溪黑色页岩土壤上的玉米进行元素地球化学分析.结果.表明:尽管东坪、烟溪黑色页岩土壤重金属元素富集的程度及其元素组合特征明显不同,但生长在其上的玉米有相似的主量元素和重金属元素的富集特征.玉米中Cd、Cr、Sc、Tl、Zn等重金属相对富集,以Cd的富集尤为明显;而Ba、Co、Cu、Fe、Mo、Ni、Pb、Sb、U、V等重金属相对亏损.黑色页岩土壤重金属污染的环境地球化学效应表现为Sc、Cr、Cd、Tl等生物毒性重金属元素在玉米中富集,而Ba、V、Co、Ni、Mo、Rb、Sr等生物必需微量金属在玉米中亏损.     

Experiment of Coal Leaching and Study of the Separation of Trace Elements

Leaching is an important way of separation of trace elements from coal. Based on leaching experiments, the content of trace elements separated out from coal is related to their existing state and content in coal, the duration of leaching process, temperature of leaching liquor and its acidity and basicity. The higher the temperature of leaching liquor and the longer the leaching time, the higher the contents of separated trace elements will be. In the course of leaching, the pH values of leaching liquors change and different trace elements are affected differently by the pH values.     

西太平洋海山磷酸盐的常量、微量和稀土元素地球化学研究

本文对主要取自于西太平洋我国调查区内不同海山、不同水深、不同产状的13个磷酸盐样品进行了常量、微量和稀土元素测定,以探讨与大洋富钴结壳密切伴生的磷酸盐的常、微量和稀土元素地球化学的特征。分析结果表明,调查区磷酸盐中主要氧化物的平均值与赤道太平洋的相近,暗示两者可能有相似的形成环境和形成机制。磷酸盐中微量元素Sr、Ba、Co、Cu、Ni及U丰度分别变化于862×10~(-6)～2181×10~(-6)、29×10~(-6)～3429×10~(-6)、6.3×10~(-6)～115×10~(-6)、23×10~(-6)～263×10~(-6)、12×10~(-6)～825×10~(-6)及4×10~(-6)～11×10~(-6),丰度多数低于泥质岩平均值,其CaO/P_2O_5、F/CO_2、Sr/P_2O_5值及常量、微量元素间的相关关系,清晰地显示了磷酸盐的种类、成分与结构、形成的地质背景和元素的主要组合特征。磷酸盐的稀土丰度为136.50×10~(-6)～853.70×10~(-6);Ce~*变化于0.01～0.18之间;(Ce/Yb)_N值变化于0.01～0.21之间。研究证实,不同产状磷酸盐的稀土元素配分模式基本一致,曲线相互平行,基本不呈现交叉现象,均呈Ce强烈亏损,轻、重稀土分馏程度大及重稀土富集的型式。调查区、赤道太平洋、中太平洋磷酸盐的稀土元素丰度、Ce~*、Ce/Yb值以及它们与海水稀土元素配分模式相似的特征,也进一步显