共查询到20条相似文献，搜索用时 78 毫秒
1.
江西德兴朱砂红斑岩铜矿流体包裹体研究 总被引：1，自引：0，他引：1
内容提要：朱砂红斑岩铜矿位于德兴斑岩铜矿矿集区的西北方向,紧邻铜厂铜矿。本文在前人有关德兴铜矿研究基础上,以铜矿流体包裹体为研究内容,通过野外详细的岩芯采样,室内石英斑晶、石英脉和方解石脉中包裹体测试及数据整理分析后初步发现：朱砂红斑岩铜矿流体包裹体大致可以分成五大类型（富液型包裹体、富气型包裹体、含CO2气液两相型包裹体、含子矿物多相型和固液两相型）;相比铜厂整体成矿温度略低,盐度略高;由成矿流体压力47.27~184.47MPa,推导出成矿深度达2~4km,以及激光拉曼测试结果—流体中含有CO2、H2S和CH4等挥发分气体,它们可能与Au等元素的运移成矿有关。因此,从包裹体性质推测朱砂红铜矿不只是斑岩铜矿,可能是浅成热液斑岩型铜金矿床。此外,朱砂红矿区成矿流体来源至少有两种：高温岩浆流体和大气降水。伴随流体演化期次大致可以划分出三个成矿阶段：硅酸盐硫化物阶段、石英-硫化物阶段（即主成矿阶段,温度：200~340℃,盐度：2.0~15wt.%NaCl）、碳酸盐-硫酸盐硫化物阶段。同时,均一温度、盐度及压力等暗示在流体演化和成矿过程中岩浆流体发生过沸腾或不混溶作用。 相似文献
2.
岔路口超大型斑岩钼矿床位于大兴安岭北部,是目前中国东北地区最大的钼矿床,矿体赋存于中酸性杂岩体及侏罗系火山-沉积岩内,其中花岗斑岩、石英斑岩、细粒花岗岩与钼矿化关系密切.流体包裹体研究表明,岔路口矿床主要发育富液两相包裹体、富气两相包裹体和含子矿物多相包裹体.花岗斑岩石英斑晶中流体包裹体的形成温度集中在230 ～ 440℃和470～510℃两个温度区间,盐度分别介于0.7％ ～ 53.7％ NaCl eqv和6.2％～61.3％ NaCl eqv两个区间;成矿早阶段钾长石-石英-磁铁矿脉中流体包裹体的形成温度集中在320～440℃、盐度介于4.2％ ～ 52.3％NaCl eqv;成矿中阶段石英-辉钼矿脉和角砾岩中流体包裹体的形成温度集中在260～410℃、盐度介于0.4％～52.3％ NaCleqv;成矿晚阶段石英-萤石-方铅矿-闪锌矿脉中流体包裹体的形成温度集中在170～320℃、盐度介于0.5％ ～ 11.1％ NaCleqv.成矿流体具高温、高盐度及高氧逸度的特征,总体上属于富F的H2O-NaCl±CO2体系.成矿流体的δ 18Ow值为-4.5‰～3.2‰,δDw值为-138‰～-122‰,表明成矿流体为岩浆水与雨水的混合流体.金属硫化物的δ34S值介于-1.9‰～+3.6‰,均值为+1.6‰,表明成矿物质主要来自深源岩浆.多期次的流体沸腾作用是该矿床的主要成矿机制. 相似文献
3.
西藏甲玛铜多金属矿床成因研究——来自流体包裹体的证据 总被引：1，自引：0，他引：1
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。 相似文献
4.
山西中条山铜矿峪斑岩型铜矿床成矿流体特征 总被引：2，自引：1，他引：1
铜矿峪铜矿床位于中条山铜多金属成矿带,是目前中国最古老的斑岩型铜矿床之一。基于详尽的野外地质调查,结合流体包裹体岩相学、显微测温、群包裹体成分和碳、氢、氧、硫同位素分析等研究,探讨铜矿峪铜矿床成矿流体来源、性质及其演化和成矿物质来源。铜矿峪铜矿床的成矿阶段可划分为红钠化(石英-钠长石)阶段,钾长石-石英阶段,石英-硫化物阶段,石英-碳酸盐阶段(石英-方解石-硫化物阶段和石英-铁白云石-硫化物阶段)和碳酸盐阶段。流体包裹体类型主要有富液相气液两相包裹体(Ⅰ型)、含子晶包裹体(Ⅱ型)和CO2包裹体(Ⅲ型),还有少量的富气相包裹体(Ⅳ型)和液相包裹体(Ⅴ型),成矿流体系统早期为中高温、高氧逸度、富CO2的岩浆热液,中阶段经过流体沸腾、温度降低、氧逸度降低、CO2逸失等过程演化为还原性流体,使得大量金属硫化物沉淀,最后由于大气降水的不断加入和降温等过程,形成晚期的低温、中低氧逸度、低盐度、贫CO2的大气降水热液。氢、氧同位素组成(δ18OH2O值变化范围为6.5‰～-1.10‰,δD值变化范围为-99‰～-58‰)显示,从早阶段到晚阶段,成矿流体从以原生岩浆水为主,到晚期大气降水为主。9件硫化物样品δ34S值变化于1.1‰～4.8‰,平均值为2.44‰。表明成矿物质具有深源的特征。 相似文献
5.
桂花冲铜矿床是铜陵矿集区沙滩脚矿田内新发现的一个以斑岩型矿化为主的矽卡岩-斑岩复合型铜矿床。文章对该矿床的矿床地质和斑岩型矿化成矿流体进行了初步研究,旨在查明该矿床成矿流体的演化过程。根据脉体的穿切关系及矿物共生组合,桂花冲铜矿斑岩型矿化成矿过程可划分为钾化、硅化、石英黄铁矿、石英多金属硫化物和碳酸盐5个阶段。硅化阶段主要发育纯气体、含子矿物及富气相包裹体,石英黄铁矿阶段主要发育纯气体、富液相、富气相及含子矿物包裹体,石英多金属硫化物阶段及碳酸盐阶段主要发育富液相包裹体。从硅化阶段至碳酸盐阶段,成矿流体由高温(472.9℃)、高盐度(47.7%~74.0%)的岩浆热液逐渐向中低温(140.2~280.3℃)、低盐度(1.6%~7.7%)的岩浆热液和大气降水的混合流体演化,成矿过程中流体经历了沸腾及混合作用,混合作用是导致铜沉淀的主要机制。 相似文献
6.
黑龙江省三矿沟矽卡岩型铁铜矿床流体包裹体研究 总被引：11，自引：2，他引：9
对黑龙江省三矿沟矽卡岩型铁铜矿床内花岗闪长岩中石英斑晶、硫化物阶段及石英-碳酸盐阶段的石英、方解石中流体包裹体的岩相学、显微测温学和显微激光拉曼光谱分析等的研究结果表明,流体包裹体有富液相、富气相和含子矿物多相包裹体3种类型;花岗闪长岩石英斑晶中的含子矿物多相包裹体均一温度均值为4320C,盐度在30.92 wt%～63.91 wt%NaCl eqv.之间,平均为52.96 wt%NaCl eqv.,代表了高温、高盐度岩浆流体;硫化物阶段形成的黄铜矿磁铁矿矿石中流体温度主要介于323～424℃之间,盐度介于8.95 wt%～62.51 wt%NaCl eqv.之间;硫化物阶段形成的黄铜矿矿石中流体温度主要介于333～441℃之间,盐度介于8.28 wt%～65.32 wt%NaCl eqv.之间;石英-碳酸盐阶段流体温度主要介于124～140℃之间,盐度介于1.65 wt%～4.34 wt%NaCl eqv.之间.铁铜矿石均形成于高温、高盐度阶段,以岩浆热液为主,在成矿晚期,由于大气降水的混合,形成了少量低温、低盐度流体,成矿流体以富Na、K、Ca、Cl-和CO~2_3-的高盐度流体为特征,主体属于NaCl-H_2O-CO_2-H_2S-CH_4体系.成矿流体在300～400℃区间内发生了强烈的沸腾作用,导致大量金属硫化物和少量金属氧化物沉淀,沸腾作用对三矿沟铁铜矿床的形成起到至关重要的作用. 相似文献
7.
大兴安岭锡矿带是中国北方唯一成型的锡多金属成矿带。新近发现的内蒙古维拉斯托锡多金属矿床位于大兴安岭南段,隶属中亚造山带东段的兴蒙造山带。该矿床为一典型的大型斑岩型热液脉型锡多金属矿床,矿区内锡矿化主要赋存于石英斑岩体顶部及其上部的石英脉中。矿床成矿阶段包括石英斑岩体内的滴状锡锌矿化阶段、石英斑岩体上部石英脉中的辉钼矿矿化阶段、石英锡石黑钨矿阶段和石英多金属硫化物阶段。流体包裹体研究结果显示：流体包裹体类型主要为气液两相包裹体,尤其是富液相包裹体,其次为含子矿物的三相包裹体。斑岩体内矿化阶段流体包裹体均一温度为324~333 ℃,盐度为6.5%~7.5% NaCleqv,密度为0.73~0.74 g/cm3;石英脉型矿化阶段包裹体均一温度为201~324 ℃,盐度为3.4%~9.9% NaCleqv,密度为0.73~0.92 g/cm3。包裹体显微测温分析结果显示该矿区成矿流体具有中高温、低盐度、中密度的特征。激光拉曼光谱分析表明,气液两相包裹体液相成分主要为H2O,气相成分主要有H2O、CO2和CH4。氢氧同位素研究结果表明该矿床石英斑岩体上部石英脉矿化阶段的成矿流体为岩浆水和大气降水混合来源,以岩浆水为主。岩浆流体与大气降水的混合以及流体演化中的降温过程是该矿床矿石沉淀的主要机制。 相似文献
8.
云南哈播斑岩铜(-钼-金)矿床流体包裹体研究 总被引：3，自引：3，他引：0
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. 相似文献
9.
德兴铜厂斑岩型铜金矿床热液演化过程 总被引：13，自引：2，他引：11
德兴铜矿是中国东部大陆环境最具代表性的大型斑岩铜矿,由朱砂红、铜厂及富家坞三大矿床组成,其中的铜厂矿体以富金而别具特色.在前人研究基础上,本文通过系统的野外观测、详细的岩芯编录和全面的岩相学研究,厘定了铜厂矿床的脉体类型和形成顺序,系统地开展了各类脉体的流体包裹体研究,查明了成矿流体的演化过程,再塑了岩浆-热液矿化过程.初步识别出德兴矿床3组脉体类型,分别记录了三个不同阶段的蚀变-成矿过程:早期A脉分为4类,形成于成矿早期斑岩尚未固结时,伴有大规模的钾化和黑云母化甚至磁铁矿化;中期B脉可分为7类,形成于斑岩体固结后的大规模裂隙事件发育期,B脉石英呈梳状对称生长、黄铁矿以中心线生长;后期D脉共有3类,发育于成矿晚期,系雨水大量加入和硫化物大量淀积产物.观察发现,所有A、B及D脉沉淀过程中,均伴随大量的岩浆流体出溶、热液蚀变、流体挥发等热液活动、各脉均捕获了同体系内富含的热液流体.详细显微镜鉴定表明,各类脉体的脉石矿物石英内发育的大部分包裹体与世界典型斑岩铜矿床的矿化特征相似,从成矿早期A脉到成矿晚期D脉包裹体的类型发生如下变化:早期以LVH(含单子晶或多子晶包裹体发育,包裹体中还见有金属硫化物)+富气相包裹体为主→中期以含单子晶包裹体+富气相包裹体为主,以及含有少量富液相包裹体→成矿晚期,以富液相包裹体+少量富气相包裹体.包裹体显微测温结果总体上指示了温度、压力及热液成分在各类脉体的形成过程的变化规律,从早期到晚期温度和盐度逐渐降低,热液成矿作用明显经历三个阶段:早期岩浆未完全固结,温度达到800～600℃以上,压力较高(140～50MPa),发生强烈的钾硅酸盐化;中期,由于岩浆冷凝结晶,岩体顶部围岩裂隙发育,静岩压力向静水压力发生转换,温度下降到450～550℃,压力陡然从55～40MPa下降至20MPa(B脉);而D脉形成时,发生大规模绿泥石-水云母化,温度下降至350～375℃,压力完全降低至20MPa以下;最后,与成矿作用无关的热液活动了两次,峰值温度分别是320～300℃和180～200℃,形成了无矿碳酸盐脉、石英脉及黑云母. 在成矿过程中,成矿热液也从形成A/B脉时以岩浆热液为主,转变为形成D脉时以雨水、地下水为主.与世界典型斑岩型铜矿床相比,德兴斑岩铜矿床的蚀变-矿化系统基本一致,都由强硅酸盐蚀变带--青磐岩蚀变带--泥岩蚀变带等构成,在不同的蚀变阶段形成了具有特色的不规则形状A脉、脉石矿物梳状对称的B脉及粗颗粒大脉型D脉.德兴铜厂铜金矿各成矿阶段内主要成矿流体特征及其演化过程基本类似于世界典型斑岩矿床.但是,也存在不同之处,在铜厂铜金矿的A、B及D脉都发育了少量CO_2包裹体,表明德兴铜厂成矿过程中CO_2参与成矿作用,世界其它斑岩型矿床或没有报道发育 CO_2 包裹体(杨志明等,2008),或者仅在其中某个阶段发现了少量CO_2包裹体(Harris et al., 2004).CO_2包裹体参与成矿是否有特殊指示意义,须进一步的工作才能得出正确的结论. 相似文献
10.
青海赛什塘铜矿床流体包裹体研究 总被引：4，自引：1，他引：3
对青海赛什塘铜矿床内与成矿有关的矽卡岩中石榴子石、透辉石及硫化物石英脉中流体包裹体的岩相学、显微测温学和显微激光拉曼光谱分析等的研究结果表明,流体包裹体有富液相、富气相和含子矿物多相包裹体3种类型;早期矽卡岩阶段均一温度436～562℃,盐度为34 wt ％～45wt％NaCl eqv.,代表了高温、高盐度岩浆流体;退变质阶段均一温度322～419℃,盐度为15wt ％～39 wt％NaCl eqv.;硫化物阶段均一温度235～366℃,盐度5wt％～36wt％NaCl eqv..激光拉曼光谱分析结果表明,包裹体中气相成分以CH4、H2S、CO2和H2O为主.成矿流体属于中高温、高盐度的NaCl-H2O-CO2-CH4体系,在290～360℃之间发生了强烈的流体沸腾作用,导致大量的金属硫化物沉淀,成矿流体的沸腾作用是导致铜矿床形成的重要因素. 相似文献
11.
S. Viswanathan K. Surya Prakash Rao B. Mahabaleswar 《Journal of the Geological Society of India》2013,82(6):621-627
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. 相似文献
12.
奥地利安东帕有限公司 《岩矿测试》2009,28(3):306-306
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 相似文献
13.
14.
E. M. Prasolov S. A. Sergeev B. V. Belyatsky E. S. Bogomolov K. A. Gruzdov I. N. Kapitonov R. Sh. Krymsky V. O. Khalenev 《Geochemistry International》2018,56(1):46-64
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. 相似文献
15.
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. 相似文献
16.
17.
Alexander E. C. Broberg J. S. Kehren A. R. Graziani M. M. Turri W. L. 《Environmental Geology》1993,22(4):353-361
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. 相似文献
18.
Mercury,arsenic, antimony,and selenium contents of sediment from the Kuskokwim River,Bethel, Alaska,USA 总被引：1，自引：0，他引：1
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. 相似文献
19.
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. 相似文献
20.
岩石密度和超高压岩石折返速率 总被引：1，自引：3，他引：1
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。 相似文献