江西武山矽卡岩型铜矿床成矿流体演化及其成矿意义

江西武山铜矿床是长江中下游多金属成矿带内重要的矽卡岩型矿床之一。文章对该矿床中的流体包裹体进行了详细研究,重点分析了成矿流体的演化过程及其成矿意义。根据野外地质产状和室内岩相学特征,将武山矽卡岩型铜矿床热液成矿过程分为气成-高温热液期和热液期,前者包括矽卡岩阶段和磁铁矿阶段,后者包括石英-硫化物阶段和碳酸盐阶段。其中,石英-硫化物阶段是该铜矿形成的主要阶段,可进一步细分为辉钼矿-石英和黄铁矿-黄铜矿-石英2个阶段。岩相学观察显示,包裹体类型有Ⅰ型含子矿物包裹体(L+V+S)、Ⅱ型气液两相包裹体(L+Ⅴ)和Ⅲ型气相包裹体(Ⅴ)。气成-高温热液期的石榴子石中流体包裹体数量不多,但Ⅰ型、Ⅱ型和Ⅲ型包裹体都有;而热液期的石英与方解石中流体包裹体数量众多,以Ⅱ型包裹体为主。从早期矽卡岩阶段至碳酸盐阶段,成矿热液经历了从高温(378~518℃)、高盐度[ω(NaCl_(eq))介于17.3%~45.1%)向低温(113~250℃)、低盐度[ω(NaCl_(eq))介于3.4%~11.9%]的持续演化。热液演化过程中发生了流体沸腾作用和岩浆热液与大气降水的混合作用。其中,矽卡岩阶段的水-岩作用、沸腾作用与矽卡岩的形成密切相关,而成矿阶段的沸腾作用与混合作用可能是铜矿床形成的重要机制。H、O同位素研究表明,各成矿阶段的成矿流体以岩浆水为主,但随着成矿作用的进行,大气降水在成矿流体中的体积质量逐渐增大。     

滇东北乐红大型铅锌矿床流体包裹体地球化学

乐红铅锌矿床是扬子地块西南缘滇东北铅锌(银)多金属矿集区中的典型代表之一。通过对该矿床不同成矿阶段闪锌矿、石英、重晶石和方解石中流体包裹体岩相学、显微测温学和显微激光拉曼探针等测试,阐述了该矿床成矿流体性质和演化特征,并探讨了其成矿过程。研究发现,该矿床流体包裹体主要包括4类:Ⅰ类气相、Ⅱ类水溶液相(由Ⅱa型-富液相气液两相、Ⅱb型-富气相气液两相、Ⅱc型纯液相组成)、Ⅲ类含CO_2三相(V_(CO_2)+L_(CO)+L_(HO))及Ⅳ类含子矿物(L+V+S)包裹体。结果显示,重晶石阶段的均一温度为240.3~319.3℃,w(NaCl_(eq))为2.24~2%~1~20.73%,表现出中高温-中低盐度流体性质;白云石-黄铁矿-石英阶段具有中-高温(219.8~310.1℃),中盐度(w(NaCl_(eq))为7.02%~17.61%)特征;闪锌矿-方铅矿-黄铁矿阶段,包括S1闪锌矿具有中温(217.8~292.2℃)-中盐度(w(NaCl_(eq))为8.81%~16.71%)性质;S2闪锌矿具有中低温(180.2~241.3℃)-中盐度(w(NaCl_(eq))为7.73%~18.47%)性质;S3闪锌矿具有中低温(140.4~227.4℃)-中低等盐度(w(NaCl_(eq))为0.35%~19.21%)的流体性质,通过该阶段中含CO_2三相包裹体测试,估算成矿压力和成矿深度分别为45~74.9 MPa(平均58.2 MPa)、1.7~2.8 km。方解石阶段均一温度为165.3℃,中等盐度,w(NaCl_(eq))为11.28%,表现出低温-中等盐度的特征。不同成矿阶段的包裹体温度大致反映了该矿床成矿流体从早阶段至晚阶段,呈现中高温、中低盐度→中温、中等盐度→中低温、中低盐度的演化过程;早期高温-低盐度深部流体在热动力和构造应力驱动下大规模运移,受断裂构造影响发生减压沸腾作用,同时与大气降水发生混合,成矿流体物化性质陡变引起铅锌硫化物等的沉淀,并最终形成矿床。该研究为揭示矿床流体性质、演化及矿床成因提供了证据,深化了"构造-流体‘贯入’成矿"模型,亦对深化矿床成矿机制与指导找矿预测具有重要意义。     

西藏尕尔穷-嘎拉勒铜金矿集区流体包裹体特征及成矿作用研究

西藏革吉县尕尔穷-嘎拉勒铜金矿集区位于班公湖-怒江缝合带西段南缘。矿集区主要由矽卡岩型铜金银矿体、铁氧化物铜金矿体和斑岩型钼铜矿(化)体等组成,其中主矿体矽卡岩型铜金矿体受闪长质岩体和碳酸盐岩的控制。根据矿物组合关系,将矿集区内各类热液脉体分为早、中、晚3个阶段,中阶段为主成矿阶段。研究表明,早、中阶段石英中流体包裹体以水溶液包裹体和三相包裹体为主,其次为CO_2包裹体;晚阶段仅发育富液相的水溶液包裹体。早阶段流体包裹体的均一温度集中在403~540℃之间,盐度ω(NaCl_(eq))介于15.2%~59.3%;中阶段流体包裹体的均一温度集中在205~398℃之间,盐度ω(NaCl_(eq))介于1.9%~45.8%;晚阶段流体包裹体的均一温度集中在122~264℃之间,盐度ω(NaCl_(eq))介于3.0%~16.4%。显微激光拉曼测试结果显示,流体包裹体的气相成分以H_2O、CO_2、N_2为主,液相成分以Na~+、K~+、Ca~(2+)、Cu~(2+)、Fe~(3+)及Cl~-、HCO_3、CO_3~(2-)等为主,子矿物主要为石盐、钾盐、黄铜矿、方解石、赤铁矿等。成矿流体从早阶段到晚阶段,由高温高盐度的CO_2-H_2O-NaCl体系向中低温中低盐度的H_2O-NaCl体系演化。主成矿阶段不同类型、不同相比包裹体具有相近的均一温度,相同类型包裹体具有相近的均一温度,但是均一方式各异,显示流体不混溶或沸腾特征。流体不混溶或沸腾作用使得CO_2、H_2S等挥发分大量逃逸,导致大量硫化物沉淀,是尕尔穷-嘎拉勒铜金矿集区铜金富集成矿的原因。     

云南哈播斑岩铜(-钼-金)矿床流体包裹体研究

哈播斑岩Cu-(Mo-Au)矿床产于哀牢山富碱斑岩带的南段,形成于青藏高原后碰撞阶段构造转换环境,属于陆-陆碰撞型斑岩矿床.根据脉体的交切关系,确定哈播矿床各种脉的演化序列为早期石英脉→石英-黄铜矿脉→石英辉钼矿脉.脉中流体包裹体的岩相学、显微测温和激光拉曼光谱分析等研究结果显示,各期脉中均有富气相包裹体、富液相包裹体和含子矿物多相包裹体,各种包裹体的气相均含有CO2、SO2、H2O等气体.各期脉中多种包裹体并存并具有相似的均一温度范围,富液相包裹体均一温度149～427℃,盐度ω(NaCleq)6.0％～15.0％;富气相包裹体均一温度205～405℃,盐度ω(NaCleq) 3.4％～19.0％;含子矿物多相包裹体均一温度305～516℃,盐度w(NaCleq) 33.5％～61.0％.哈播矿床的初始成矿流体由稳定共存、不混溶的低盐度流体和高盐度流体组成,高盐度流体是哈播矿床成矿元素迁移的主要载体.成矿流体在400℃左右发生“二次沸腾”、分相,温度下降和挥发分持续逃逸可能是Cu-Au成矿的诱因.Mo元素在成矿流体多次沸腾、分相过程中,持续优先分配进入高盐度流体中而逐步富集;温度下降,使含钼硫化物在流体中溶解度降低、沉淀,形成石英-辉钼矿±黄铜矿脉.     

江西香炉山矽卡岩型白钨矿矿床成因与流体特征

香炉山白钨矿矿床位于江西修水县城西北35 km处,是一座超大型白钨矿矿床。文章通过对该矿床蚀变矿化特征的研究,表明香炉山白钨矿矿床的矿化类型主要为矽卡岩型,其次为蚀变岩型(云英岩化型)。根据产状和岩相学特征进一步可将矿床的矿化过程划分为3个阶段:①矽卡岩化阶段;②白钨矿-白云母-石英阶段;③石英-硫化物阶段。流体包裹体测温结果显示,矽卡岩化阶段均一温度为354~518℃,峰值为465℃,ω(NaCl_(eq))为6.88%~13.4%;白钨矿-白云母-石英阶段均一温度为225~408℃,峰值为340℃,ω(NaCl_(eq))为2.41%~12.28%;石英-硫化物阶段均一温度为185~344℃,峰值为280℃,ω(NaCl_(eq))为2.41%~11.58%。该矿床的成矿流体为典型的中-高温、中低盐度流体体系。流体中富含F、P、H_2O等挥发分对成矿的运移和富集起到一定的作用,而CO_2对钨的迁移作用不大。流体包裹体岩相学及测温结果揭示了流体在矽卡岩阶段经历沸腾或不混溶过程,含F、低盐度、成矿流体呈酸性,有利于钨矿的沉淀,这些是含矿流体内钨迁移与成矿的重要因素。     

赣南茅坪钨矿床黄玉单晶流体包裹体研究

文章以赣南茅坪大型钨矿床成矿早阶段形成的黄玉单晶为研究对象,对其中的流体包裹体开展了岩相学、显微测温以及激光拉曼光谱研究。结果显示,茅坪钨矿床黄玉单晶中的流体包裹体以富液两相包裹体为主,同时发育有单相包裹体、富二氧化碳的三相包裹体以及含子矿物包裹体。其中,含子矿物包裹体发育是本矿床黄玉中包裹体的重要特征,子矿物成分有方解石、石英、石盐等;流体包裹体的均一温度介于200~509℃之间,峰值位于420~500℃之间,盐度w(NaCl_(eq))为4.32%~19.22%,峰值介于17%~19%,较前人获得的石英脉型钨矿床成矿温度和盐度均高出许多,其峰值(420~500℃)在一定程度上衔接了石英脉型黑钨矿高温阶段的演化历史;黄玉单晶中包裹体还具有富含CO_2、CH_4、N_2等挥发分的特征。综上所述,笔者认为石英脉型钨矿的成矿流体在早阶段具有高温、中高盐度、富挥发分、富含多种离子的特征。     

内蒙古呼扎盖吐钼矿床成矿流体特征及成矿机制

内蒙古呼扎盖吐钼矿床是得尔布干成矿带上新发现的一座斑岩型钼矿床,钼矿体分布在燕山早期花岗闪长岩岩体内及其流纹岩接触带中,矿床以辉钼矿化和黄铁矿化为主,伴随有铅锌矿化和少量的黄铜矿化。成矿过程主要分为4个阶段：硅化阶段、石英- 辉钼矿阶段、石英- 多金属硫化物阶段和石英- 方解石阶段。流体包裹体可分为富液相包裹体、富气相包裹体、含子矿物的多相包裹体和含CO2的三相包裹体4种类型。以主成矿阶段为研究重点,对不同成矿阶段（Ⅱ→Ⅳ阶段)矿脉中石英/方解石中的包裹体进行了显微测温和激光拉曼探针分析。结果显示：石英- 辉钼矿阶段,包裹体均一温度主要集中在280~400℃之间,盐度变化范围在2. 57%~51. 68%。该阶段富气相包裹体、含子矿物的多相包裹体和含CO2的三相包裹体共存,L型包裹体液相成分主要为H2O- NaCl,V型包裹体气相成分除H2O为主外,部分还含有CO2,含石盐子晶的三相包裹体,检测到不透明子矿物黄铜矿的峰值。发育铅锌矿化和黄铜矿化的石英- 多金属硫化物阶段,包裹体均一温度集中在180~280℃之间,盐度变化范围为0. 18%~9. 73%。成矿晚期石英- 方解石脉中仅发育L型的气- 液两相流体包裹体,均一温度集中在140~240℃之间,盐度变化范围为0. 35%~7. 17%。结合最新研究成果,本文认为该矿床初始流体是中等盐度和密度的岩浆流体,在主成矿阶段由于压力释放发生流体沸腾作用,成矿流体系统的物理化学条件和氧化- 还原环境发生骤变,导致辉钼矿和其他硫化物等成矿物质在脉状裂隙中发生卸载沉淀。     

西藏多龙矿集区地堡那木岗铜(金)矿床流体包裹体特征及矿床成因

地堡那木岗铜(金)矿床位于西藏多龙矿集区,探明储量达大型规模;矿床的成矿过程分为岩浆作用阶段、钾长石-硫化物阶段、石英-多金属硫化物阶段、碳酸盐-黄铁矿阶段和氧化作用阶段,其中石英-多金属硫化物阶段和碳酸盐-黄铁矿阶段为主要成矿阶段;为查明成矿流体特征,确定矿床成因类型,对取自深部矿石中的碳酸盐脉(均为碳酸盐-黄铁矿成矿阶段含黄铁矿黄铜矿石英脉)开展流体包裹体的岩相学观察和显微测温分析。分析结果表明,上述矿物中主要发育富液相、富气相和含子矿物三相包裹体。其中,富液相包裹体的均一温度与盐度分别为:t=80~600℃、w(NaCl,eq)=4.48%~18.79%;富气相包裹体的均一温度和盐度分别为:t=240~560℃、w(NaCl,eq)=5.09%~9.73%;含子矿物三相包裹体的均一温度与盐度分别为:t=240~560℃、w(NaCl,eq)=36%~72%。综合分析认为,地堡那木岗铜(金)矿床成矿流体发生了强烈的沸腾作用,流体沸腾作用是该矿床的重要成矿机制。通过与国内外典型斑岩型矿床与高硫化型浅成低温热液矿床的流体包裹体特征进行对比,其与斑岩型矿床的中高温、高盐度流体特征相似。因此,推测地堡那木岗矿床的成因类型为斑岩型铜(金)矿床。     

西藏甲玛铜多金属矿床成因研究——来自流体包裹体的证据

甲玛铜多金属矿床位于西藏冈底斯斑岩铜矿带东段,是近年来勘探发现的超大型斑岩-矽卡岩型铜多金属矿床。通过冷热台显微观察与测温、扫描电镜、激光拉曼探针测试,对甲玛矿床各成矿阶段典型矿物的流体包裹体研究表明,成矿流体富含挥发分,临界相均一的流体来自岩浆超临界流体出溶,主成矿阶段具有沸腾包裹体组合特征,有机质包裹体荧光效应显著。显微测温结果显示,岩浆-热液阶段斑岩中石英斑晶的流体包裹体均一温度范围为250～540℃,含石盐子晶高盐度包裹体盐度范围为35～61(wt%)NaCl.eq,中等盐度的临界均一的气液包裹体盐度范围为3～29(wt%)NaCl.eq,岩浆期后热液阶段斑岩、角岩中石英脉的流体包裹体均一温度范围为210～410℃,盐度范围为33～41(wt%)NaCl.eq,与其不混溶共生的中低盐度气液两相流体包裹体盐度范围为5～25(wt%)NaCl.eq。矽卡岩阶段矿物均一温度范围为130～360℃,盐度范围为3～41(wt%)NaCl.eq,从岩浆热液过渡阶段到石英-硫化物阶段均一温度与盐度呈阶梯式降低趋势。斑岩体石英的流体包裹体中含有较多黄铜矿子矿物,岩浆结晶分异过程中已经具成矿元素的富集。激光拉曼探针测试结果显示,成矿早期至主成矿期矿物流体包裹体气相成分主要为CO2、CH4和N2,各阶段矿物流体包裹体气相成分具有继承性。成矿流体为高温度高盐度,富含CO2、CH4的流体。成矿流体主要源于岩浆,后期混有大气降水。当岩浆热液上升时因压力的突然释放造成高温含矿热流体发生减压沸腾,CO2和CH4等气体大量逃逸,导致成矿物质快速沉淀。矿床在成因上与岩浆-热液成矿作用密切相关。     

湖南锡田钨锡多金属矿床流体包裹体研究

锡田钨锡多金属矿床是南岭钨锡成矿带的重要组成部分。文章主要针对石英脉型钨锡矿和云英岩型钨矿中的石英流体包裹体进行了显微测温和激光拉曼光谱分析,流体包裹体分为4类:富液相两相水溶液包裹体(L型)、富气相两相水溶液包裹体(V型)、V_(CO_2)-L_(CO_2)-L_(H_2O)三相包裹体(C型)和含子晶三相包裹体(S型)。石英脉型钨锡矿均一温度为240~440℃,ω(NaCl_(eq))为1.4%~9.5%,云英岩型钨矿均一温度为370~470℃,且富锡石样品均一温度(t_h:310~420℃,ω(NaCl_(eq))为4.3%~9.5%)略高于富黑钨矿样品(t_h:240~340℃,ω(NaCl_(eq))为1.4%~7.7%)。流体包裹体气相成分主要为CO_2、CH_4、N_2。结合流体包裹体显微测温、激光拉曼光谱分析结果和野外矿床地质特征,探讨了成矿流体中N_2、CH_4的源区、W和Sn的赋存状态以及其成矿机制。W以一系列钨酸、钨酸根离子、碱金属钨酸盐赋存于流体中,Sn主要赋存状态为Sn(+2价)-Cl络合物。石英脉型钨锡矿因流体上升至花岗岩体或围岩的构造裂隙中,成矿流体与围岩相互反应以及与地壳流体与大气水混合,其p、t急剧下降以及流体pH值变化,导致黑钨矿沉淀,成矿流体从还原环境转为氧化环境致使锡石沉淀成矿。云英岩型钨矿有效成矿机制是流体沸腾或不混溶。     

Wavelength-dispersive X-ray fluorescence spectrometric determination of Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites

Komatiites are mantle-derived ultramafic volcanic rocks. Komatiites have been discovered in several States of India, notably in Karnataka. Studies on the distribution of trace-elements in the komatiites of India are very few. This paper proposes a simple, accurate, precise, rapid, and non-destructive wavelength-dispersive x-ray fluorescence (WDXRF) spectrometric technique for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites, and discusses the accuracy, precision, limits of detection, x-ray spectral-line interferences, inter-element effects, speed, advantages, and limitations of the technique. The accuracy of the technique is excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Zr, Nb, Ba, Pb, and Th and very good (within 4%) for Y. The precision is also excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th. The limits of detection are: 1 ppm for Sc and V; 2 ppm for Cr, Co, and Ni; 3 ppm for Cu, Zn, Rb, and Sr; 4 ppm for Y and Zr; 6 ppm for Nb; 10 ppm for Ba; 13 ppm for Pb; and 14 ppm for Th. The time taken for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in a batch of 24 samples of komatiites, for a replication of four analyses per sample, by one operator, using a manual WDXRF spectrometer, is only 60 hours.     

高压微波消解法测定醋酸纤维过滤器采集的微尘粒子中的砷镉钴铬铜铁锰镍铅钒锌

最新的流行病学研究表明,空气中较高浓度的悬浮细颗粒可能对人类的健康有不利的影响。根据该项研究显示,由于心脏病、慢性呼吸问题和肺功能指标恶化而导致死亡率的升高与细尘粒子有关。这些研究结果已经促使欧盟于1999年4月出台了限制空气中二氧化硫、二氧化氮、氧化氮、铅和颗粒物含量的法案(1999/30/EC),对各项指标包括对可吸入PM10颗粒的浓度提出了新的限制性指标。PM10颗粒是指可以通过预分级器分离采集的气体动力学直径小于10μm的细颗粒。目前研究的兴趣重点逐步偏向PM2.5这些更细微颗粒物,PM2.5这种颗粒物对健康有明显的不利影响。在欧盟指令2008/50/EC中,对PM10和PM2.5都提     

硅酸盐类样品中硅、铁、铝、钛、锰、钙、镁、钾、钠和磷的x射线荧光光谱测定

本文拟定了一种以熔融法制备样片,用X射线荧光光谱测定硅酸盐类样品中Si、Fe、Al、Tj、Mn、Ca、Mg、K、Na、P等元素的分析方法。在对不同靶材X光管和分光晶体实验对比的基础上,选择了最佳的测量条件。该法具有快速、准确,测量范围广,检测限低,价格便宜等优点。经过近百个各种类型标样或管理样品的分析对比表明,本法不仅适用于硅酸盐类岩石样品的分析,还适用于铁矿、铝土矿、碳酸盐类岩矿样品以及水泥、耐火材料等样品的分析。     

Isotopic systematics of He,Ar, S,Cu, Ni,Re, Os,Pb, U,Sm, Nd,Rb, Sr,Lu, and Hf in the rocks and ores of the Norilsk deposits

This paper reports the first results of a study of 11 isotope systems (³He/⁴He, ⁴⁰Ar/³⁶Ar, ³⁴S/³²S, ⁶⁵Cu/⁶³Cu, ⁶²Ni/⁶⁰Ni, ⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd, ^206–208Pb/²⁰⁴Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others.     

Viscous, cohesive, non-Newtonian, depositing, radial slurry flow

Mining induced subsidence can significantly affect mining costs where major surface facilities and natural environment need to be protected. Overburden grout injection is a technology used to control coal mine subsidence by injecting the mine waste material extracted from the coal back into the inter-burden rock during longwall mining. The flowing slurry is here categorised as a nonlinear viscous cohesive (Bingham plastic) fluid. During longwall mining the grout slurry is pumped into the separated beds of the rock mass through a central vertical borehole, which is drilled deep into the inter-burden rock strata above the coal seam. However, a blockage can occur in the injection system when the slurry velocity falls below a certain critical threshold velocity, indicating a material phase change from cohesive-viscous to cohesive-frictional. In situ field injection tests through boreholes have been simulated at a smaller scale at the CSIRO laboratory in Brisbane by pumping the slurry through a radial disk (gap = 4 mm) from its centre. Laboratory experiments indicate a general, nonlinear, cohesive, viscous, frictional model for shear behaviour of the slurry, in which the material shear parameters are functions of the disk radial distance. Complete dimensional and dimensionless analytical solutions have been developed based on an approach related to Bingham–Herschel–Bulkley fluid mechanics. The derived formulae include relations for minimum pump pressure, local pressure and pressure gradient, wall shear stress, volume rate, velocity and velocity gradient. The theoretical results match the experimental measurements. The experiments covered slurries with maximum particle sizes of 0.5 to 2 mm with about 50% being larger than 100 µm. The viscosities at the various solids concentrations were measured with a standard torsion viscometer. This study differs from the previous research in several distinct aspects, namely, consideration of the variable shear parameters rather than fixed values, inclusion of total nonlinear behaviour, and implementation of a friction function to mimic behaviour of the deposited and consolidating stiff slurry, which can cause a significant pressure rise as a result of the increased shear resistance.     

硅酸盐中铁、锰、钛、钙、钾、磷、硅、铝、镁、钠、锶、铷、钡的X-射线荧光光谱定量测定

本文介绍样品经四硼酸锂熔融制成玻璃小饼。采用Lachance模式和理论a系数来校正元素间的效应,由3080E型X-射线荧光谱仪和DF-350B数据处理系统完成硅酸盐中十三个项目的测定。     

Bellechester,Minnesota, USA,lagoon collapses

Bellechester, Minnesota, is a small community of approximately 155 residents located on the county line between Goodhue and Wabasha counties in southeast Minnesota's karst region. Bellechester is served by a 21-year-old wastewater treatment facility (WWTF) consisting of three waste-stabilization ponds. On 28 April 1992 six sinkholes were discovered to have drained cell 2 of the WWTF resulting in the loss of approximately 8.7×10⁶ 1 of partially treated effluent and about 600 m³ of soil into previously undetected subsurface voids of unknown dimensions. In the week following the collapse, approximately 200 water wells located within a 5-km radius of the WWTF were sampled in an after-the-fact, emergency sampling program. Twelve samples with elevated fecal coliform levels, 18 samples with nitrate-nitrogen greater than the 10 mg/1 standard, and no samples with elevated chlorides were found. However, the elevated levels could not be unambiguously attributed to the WWTF collapse. This is the third WWTF to fail by sinkhole collapse in southeast Minnesota since 1974. All three collapsed lagoons have been located in similar geomorphic and stratigraphic settings. However, at least two lagoons have collapsed in the adjacent area in northeast Iowa, and these lagoons are located at different stratigraphic positions. Twenty-two WWTFs constructed in southeast Minnesota's karst region in the last 25 years have been identified as subject to potential sinkhole collapse. An unknown but significant number of manure storage lagoons, flood control structures, etc., have also been constructed in the karst region and are at risk. Public agencies are beginning to develop plans to deal with the risk associated with existing and future waste lagoons in this environment. The critical hydrogeologic parameters that can be used to prioritize the risk of collapse at existing facilities include: (1) the lithology of the first bedrock beneath each lagoon, (2) the thickness of surficial materials between the lagoon and the bedrock surface, (3) the presence and construction of liners (seepage rate), and (4) the proximity to existing sinkholes.     

Mercury,arsenic, antimony,and selenium contents of sediment from the Kuskokwim River,Bethel, Alaska,USA

The Kuskokwim River at Bethel, Alaska, drains a major mercury-antimony metallogenic province in its upper reaches and tributaries. Bethel (population 4000) is situated on the Kuskokwim floodplain and also draws its water supply from wells located in river-deposited sediment. A boring through overbank and floodplain sediment has provided material to establish a baseline datum for sediment-hosted heavy metals. Mercury (total), arsenic, antimony, and selenium contents were determined; aluminum was also determined and used as normalizing factor. The contents of the heavy metals were relatively constant with depth and do not reflect any potential enrichment from upstream contaminant sources.     

滇东南花岗岩与锡、银、铜、铅、锌多金属矿床的成因关系

滇东南锡、银、铅、锌多金属矿床主要分布在个旧、白牛厂、都龙3个矿区,而滇东南较大的3个花岗岩体又分别出露在3个矿区或附近.花岗岩体均形成于燕山晚期,岩石化学、矿物成分相似,富含锡、银、铅、锌、钨、铜等成矿元素.矿床主金属元素组合与岩体之间的距离由远而近出现由锡、钨、(铍、铌、钽)→锡、钨、(铁)、铜、铟→锡、铅、锌、银、铟、(锑)有规律的变化.花岗岩浆是成矿物质来源和成矿热源.岩浆侵入初期使上覆地层隆起产生背斜(凹陷部位成向斜);同时使地层产生一系列裂隙、压性断层或层间断裂;岩浆侵入晚期,这些断层再次活动,表现为张性,岩浆产生的含矿热液沿由其活动所造成的断裂迁移、充填、交代、沉淀而形成矿床.     

岩石密度和超高压岩石折返速率

在常温常压条件下对中国大陆科学钻CCSD主孔100-3000米岩心样品进行了密度测量,建立了密度连续剖面,并界定了不同超高压岩石的密度值。通过对比高温高压物性实验资料,岩石密度随着退变程度增强而降低,榴辉岩密度变化序列为3.52g/cm3→3.49g/cm3→3.07g/cm3→2.93g/cm3。超高压长英质岩石密度变化序列为3.00g/cm→2.80g/cm3→2.65g/cm3。上述实验资料是讨论不同折返阶段岩石所受浮力的基础,为研究折返速率大小提供了基本参数。本文通过折返板块运动平衡时,上浮力与粘滞力平衡这一关系式,定量研究了大陆俯冲板块的折返速率,认为密度差产生上浮力从而引起折返,温度对板块折返速率的影响最为显著;密度差大小、折返角度、折返板块大小对折返速率也有直接的影响。定量模拟分析表明,在温度高于850℃时,板块的折返速率可以超过100mm/a;当温度降至700℃时,折返速率则低于1.5mm/a。作者认为在折返早期,温度较高,板块快速折返至60-70km榴辉岩相深度;随着传导散热,温度降低,板块以较慢的速率折返至中下地壳。折返速率的估算表明,浮力是板块折返第一阶段(从>100km深部折返至<40km的中下地壳)的主要驱动力。