首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 109 毫秒
1.
西藏吉塘花岗岩地球化学特征及成因   总被引:7,自引:2,他引:5  
沿澜沧江结合带发育一条长达1000余千米的印支期澜沧花岗岩带,吉塘岩体位于该带北段,产出在吉塘以西约3km,轴向NNW,侵位于古元古代吉塘群变质岩系中,长70km,宽2~10km、出露面积341km2。主要由花岗闪长岩和二长花岗岩组成,Rb-Sr等时线年龄值为220Ma。本文对吉塘岩体开展了系统的岩石地球化学特征分析。研究结果表明吉塘岩体为过铝质钙碱性S型花岗岩,吉塘岩体在岩石化学组成上,SiO2含量63%~71%,平均66.5%,Na2O含量2.8%~4.2%,K2O含量1.7%~3.4%,铝饱和指数A/CNK=1.09~1.48,CIPW标准矿物中刚玉1.5%~5.6%,微量元素组成类似于片麻岩质的中地壳。(87Sr/86Sr)i值为0.7280~0.7395,εNd(i)为-14.1~-16.2,指示岩浆源区为地壳物质,成因上与俯冲作用无关,Nd同位素亏损地幔模式年龄(tDM)在2.0Ga左右,与昌都陆块变质基底古元古代吉塘群的原始形成年代相当,岩体Sr、Nd同位素组成也与变质基底吉塘群片麻岩一致,综合分析认为,岩浆源岩为变质杂砂岩成分的古元古代吉塘群片麻岩,其原岩建造主要是火山弧成因的英安岩或英安质火山碎屑岩,微量元素组成指示为黑云母脱水熔融。分析认为岩浆形成于地壳加厚增温环境下的地壳深熔作用,构造上与板块碰撞后的环境相联系。支持澜沧江构造带为冈瓦纳与扬子大陆边缘多岛弧系统的边界即古特提斯主洋盆的观点。澜沧江洋的闭合时间早于澜沧花岗岩带的形成年龄220Ma,根据构造带上相关研究成果,倾向于认同碰撞时间在280Ma左右。  相似文献   

2.
赵瑞幅  郭敬辉  彭澎  刘富 《岩石学报》2011,27(6):1607-1623
恒山高级片麻岩地体位于华北克拉通中部构造带,主体是形成于晚太古代~2.5Ga的TTG片麻岩和少量变质火山沉积岩,并且经历了古元古代末~1.85Ga的高级变质作用。近年来,在恒山片麻岩地体中识别出一套钾质花岗岩小侵入体群,主要岩性是角闪石二长花岗岩和黑云母二长花岗岩。本文针对这套花岗岩,采用LA-ICP-MS和Cameca 1280型离子探针进行锆石U-Pb定年,获得角闪石二长花岗岩岩浆锆石谐和年龄2052±17Ma和2084±4Ma,黑云母二长花岗岩岩浆锆石谐和年龄2060±18Ma和2083±15Ma。它们在误差范围内一致,代表花岗岩的形成时代。花岗岩锆石Hf同位素和全岩Nd同位素亏损地幔模式年龄分别为2.48~2.60Ga和2.43~2.68Ga,与围岩TTG片麻岩模式年龄范围基本一致。εHf(t) 和εNd(t)主要分布范围分别为-6.0~0.6和-3.3~-1.7,未显示同期幔源物质的添加。据此可以推断,这些钾质花岗岩是恒山晚太古代TTG岩石在~2.1Ga部分熔融的产物。该期岩浆活动在华北克拉通已识别出多处,恒山地区的这期岩浆活动显示了地壳重熔特征。结合五台、阜平等地对于同期事件的研究,我们推测这些区域上~2.1Ga的岩浆活动形成于拉张裂解环境中。  相似文献   

3.
杨文强  刘良  丁海波  校培喜  曹玉亭  康磊 《岩石学报》2012,28(12):4139-4150
迪木那里克花岗岩侵入到南阿尔金迪木那里克浅海相沉积地层中,岩性为钾长花岗岩。地球化学数据显示该花岗岩具有高SiO2、高钾、高铝的特征,富集Rb、Th、K、La、Zr,亏损Ba、Ta、Nb、Sr、P、Ti,属于弱过铝质高钾钙碱性系列,具有S型花岗岩的特征;其源岩为杂砂岩,熔融温度和压力约为>800℃与~10kbar。锆石εHf(t)介于-3.52~0.95,LA-ICP-MS 锆石 U-Pb 定年确定其形成时代为452.8±3.1Ma。迪木那里克花岗岩的形成时代明显晚于南阿尔金高压-超高压变质岩的峰期变质时代(486~504Ma),而与超高压岩石的退变质时代(455Ma)基本一致,又与形成时代为467Ma的长沙沟-清水泉一带裂谷型层状镁铁质-超镁铁质杂岩体伴生,其成因可能是阿尔金深俯冲陆壳板片发生断离后,深部地幔物质上涌导致地壳杂砂岩熔融的产物,具有同折返岩浆作用的特点。结合以往研究,南阿尔金俯冲碰撞杂岩带中早古生代花岗岩的演化期次可初步划分为:1)约500Ma,与高压-超高压变质岩的峰期变质时代一致,形成于陆-陆碰撞造山作用过程中的陆壳相互叠置加厚阶段;2)为466~451Ma,与超高压岩石的退变质时代大致相当,形成于深俯冲陆壳断离后的伸展构造背景;3)为426~385Ma,形成于碰撞造山作用结束后的伸展减薄阶段。  相似文献   

4.
福建漳州角美花岗岩与闪长质包体的岩石成因及意义   总被引:3,自引:2,他引:1  
本文选择福建沿海漳州地区的角美花岗岩和包体进行了锆石U-Pb年代学和Hf同位素地球化学研究。结果表明,黑云母花岗闪长岩(106.4±1.8Ma)和岩体中的闪长质包体(105.6±1.0Ma 和106.5±1.0Ma)具有相同的锆石U-Pb年龄,为同期岩浆作用的产物,它们都是高钾钙碱性系列偏铝质岩石。花岗闪长岩具有相对较为均一的锆石Hf同位素组成(εHf(t)=2.2~3.7),表明其为新生地壳部分熔融的产物。闪长质包体具有更亏损的锆石Hf组成(εHf(t)=0.9~5.5)。地球化学数据结合野外证据表明岩体形成过程中经历了岩浆混合作用。福建沿海地区96~106Ma岩浆作用的发育处于古太平洋板片俯冲造成的伸展背景。  相似文献   

5.
西藏早侏罗世聂荣岩体中偏基性包体与酸性寄主岩的岩浆源区性质和岩石成因以及相互关系尚未得到很好约束,直接限制了对聂荣微陆块在早侏罗世特提斯构造岩浆演化中的作用的认识。为探讨这一问题,本文对采自聂荣地区的一对花岗岩及其闪长岩包体样品进行了锆石U-Pb定年和原位Hf同位素分析。寄主花岗岩的结晶年龄为185.1±1.5Ma,闪长岩包体的结晶年龄为183.6±1.1Ma,指示酸性岩浆和基性岩浆同时侵位。寄主花岗岩的锆石εHf(t)值介于-17.8~-0.9,其Hf同位素地壳模式年龄变化于1.3~2.4Ga,闪长岩包体的锆石εHf(t)值和Hf同位素地壳模式年龄值分别分布于-11.9~-2.9和1.4~2.0Ga,均表现出很大的变化范围。同时于~185Ma结晶的两种岩浆锆石Hf同位素的不均一性和继承锆石的出现,指示了聂荣微陆块早侏罗世中期发生了古老基底深熔或重熔的熔体和富集岩石圈地幔来源的岩浆间的混合,之后再与围岩混染的岩浆作用过程。  相似文献   

6.
广山花岗杂岩体主体部分由中粒碱长花岗岩和侵入其内部的细粒碱长花岗岩组成,LA-MC-ICP-MS锆石U-Pb定年显示其形成年龄分别为162.4±0.9Ma和156.3±0.7Ma,表明岩体为燕山期多期次岩浆活动产物。两期岩体为高钾钙碱性系列,A/CNK值为0.95~1.05,属准铝质-弱过铝质花岗岩类;稀土含量中等,强Eu亏损,呈略右倾的海鸥型稀土配分模式,均为A2型花岗岩。锆石Hf同位素研究表明,εHft)变化范围主要集中在-4.35~0之间,均为负值,二阶段模式年龄tHf2(Ma)变化范围主要集中于1219~1478Ma,反映其源区物质来源于中元古代地壳物质。结合前人研究成果,本文认为华南燕山早期晚阶段A型花岗岩形成于由碰撞造山向板内(非造山)环境转换的后造山拉张阶段。  相似文献   

7.
秦岭晚中生代花岗岩时空分布、成因演变及构造意义   总被引:34,自引:14,他引:20  
王晓霞  王涛  齐秋菊  李舢 《岩石学报》2011,27(6):1573-1593
秦岭晚中生代花岗岩主要发育于秦岭北部的华北地块南缘和北秦岭,南秦岭仅有零星出露。本文报道了3个晚中生代大岩体的年代学和其中2个岩体的地球化学和同位素数据,并系统收集了发表的相关资料,对秦岭晚中生代花岗岩进行了初步总结。华北地块南缘蓝田花岗岩的锆石LA-ICPMS U-Pb年龄为133±1Ma, εNd(t)=-11.8~-18.3, 锆石εHf(t)=-37.7~-5.7。 北秦岭构造带中牧护关花岗岩的锆石LA-ICPMS U-Pb年龄为 150±1Ma, εNd(t)=-7.6~-11.4, 锆石εHf(t)=-7.3~-17.4;蟒岭花岗岩的锆石SHRIMP U-Pb年龄为149±2 Ma。 依据收集到的26个锆石U-Pb和3个黑云母Ar-Ar年代学资料, 秦岭晚中生代花岗岩浆的演化可分为2个阶段:第一阶段为160~130Ma(晚侏罗世-早白垩世), 以I-型花岗岩为主, 主要发育于华北地块南缘和北秦岭,在南秦岭仅零星分布;第二阶段为120~100Ma(早白垩世中晚期), 以I-A过渡型和A-型花岗岩为主,主要分布在华北地块南缘的东部和北秦岭,出露面积比第一阶段小。第一阶段(160~130Ma)花岗岩主要形成于古老地壳物质的部分熔融,并有年轻幔源组分的参与,形成于挤压向伸展转换的构造环境。第二阶段(120~100Ma)花岗岩的形成除了古老地壳物质的部分熔融外,有更多的年轻幔源组分加入,发育于陆内伸展环境。花岗岩的同位素特征显示,从华北地块南缘到南秦岭,底基物质中年轻组分有增加的趋势,花岗岩的物源受深部地壳物质组成特征的控制。  相似文献   

8.
本文对江达-维西火山岩浆弧德钦岩体的寄主岩石——花岗闪长岩及其镁铁质微粒包体(MME)——闪长岩进行了详细研究。二者LA-ICPMS锆石U-Pb年龄分别为254.6±1.8Ma和253.5±1.6Ma,二者形成时代一致。地球化学研究结果表明,花岗闪长岩富K2O和Na2O,且K2O>Na2O,富Al2O3,A/CNK平均为0.96;闪长岩富K2O和Na2O,但K2O2O,富Al2O3和MgO,A/CNK平均为0.72;花岗闪长岩的稀土总量低于闪长岩,二者轻重稀土分馏明显,配分曲线为右倾的轻稀土富集型;二者均富集大离子亲石元素而亏损高场强元素Nb、Ta等;二者均具有相对较高的Mg#(58.8~65.8),并具有相对较高的相容元素Cr、Ni含量(花岗闪长岩平均值分别为115×10-6和31.6×10-6,闪长岩平均值分别为398×10-6和98.2×10-6;花岗闪长岩和闪长岩176Hf/177Hf的平均值分别为0.282383和0.282287,二者εHf(t)平均值分别为-8.3和-11.8,反映了二者属于I型花岗岩,可能为岩浆混合作用的产物。地球化学特征及Hf同位素组成一致显示岩浆来源于地壳的部分熔融,伴有不同比例的地幔物质加入,形成于弧陆碰撞-后碰撞的构造背景,暗示金沙江结合带在~255Ma已经进入了弧陆碰撞-后碰撞的地质时期。  相似文献   

9.
西藏驱龙矿区早侏罗世斑岩的Sr-Nd-Pb及锆石Hf同位素研究   总被引:8,自引:3,他引:5  
近年的研究基本揭示,在冈底斯南缘存在一条晚三叠世-侏罗纪的花岗岩带,其成因认识有助于恢复青藏高原中生代演化历史,但却存在争议。为此,本文选择拉萨东部驱龙早侏罗世花岗斑岩开展Sr-Nd-Pb及锆石Hf同位素研究,调查岩浆源区特征,以期查明岩浆成因。分析结果显示,驱龙早侏罗世斑岩具有相对较低的87Sr/86Sr初始比值(0.7029~0.7050)、正的εNd(t)(平均0.7)和锆石εHf(t)值(2.6~8.2),表明岩浆来自新生地壳物质的部分熔融。综合对比发现,冈底斯南部晚三叠世-早侏罗世花岗岩的锆石Hf同位素在500km宽的范围内显示出由西向东亏损程度逐渐减弱、甚至变得富集的规律,表明在此类花岗岩的形成过程中,成熟地壳组分的贡献自西向东逐渐增多。这既可因南部拉萨地体基底Hf同位素组成的东西向不均一所引起,也可能因东段驱龙、米林等地花岗岩更靠近古老的拉萨微陆块所致。  相似文献   

10.
老牛山杂岩体位于华北地块南缘。野外侵入关系和锆石LA-ICP-MS U-Pb定年显示,其由晚三叠世(印支期)和晚侏罗(燕山期)花岗质岩石组成。印支期岩石类型为石英二长岩、石英闪长岩和粗粒黑云母二长花岗岩,年龄分别为223±1Ma、222±1Ma和214±1Ma; 燕山期为中粒-中粗粒黑云母二长花岗岩和细粒-中细粒黑云母二长花岗岩,年龄分别为152±1Ma和146±1Ma。印支期石英闪长岩、石英二长岩的SiO2相对含量低、富碱、高铝,为钾玄系列,准铝质Ⅰ型花岗岩;印支期粗粒黑云母二长花岗岩具富硅、碱、高铝、低镁的特点,属于高钾钙碱性系列,为准铝质-过铝质Ⅰ型花岗岩;燕山期黑云母二长花岗岩具高硅和铝、富碱,低镁的特点,为高钾钙碱性系列,准铝质Ⅰ型花岗岩。组成老牛山杂岩体的花岗岩从早到晚SiO2含量由低变高,MgO、CaO和Na2O由高变低。各期次岩石均表现出稀土元素总量较高,轻稀土元素明显富集,轻、重稀土元素分馏明显,具有较弱的铕异常。两期花岗质岩石均富集大离子亲石元素(K、Rb、Ba、Sr),而相对亏损高场强元素(Nb、Ta、P)。印支期花岗质岩石的全岩εNd(t)为-11.3~-14.87,tDM为1.7~1.9Ga,锆石的εHf(t)为-9.57~-25.11,tDM2为1863~2841Ma;燕山期花岗岩的全岩εNd(t)为-13.32~-16.83,tDM为 1.7~1.9Ga,锆石的εHf(t)为-18.28~-24.79,tDM2 为2360~2767Ma,表明该杂岩体的源区物质以壳源物质为主,可能与太古宙太华群相似,印支期有年轻地幔物质贡献。  相似文献   

11.
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.
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。  相似文献   

13.
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   

14.
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.
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。  相似文献   

16.
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   

17.
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   

18.
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   

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.
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   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号