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1.
黄沙坪铅锌多金属矿床赋存在下石炭统石磴子组灰岩与花岗斑岩接触带及附近的层滑断裂系统中,成因上与黄沙坪花岗质岩石关系密切。其成矿时代以往都是用矿体附近的花岗质岩石(花岗斑岩、石英斑岩等)或蚀变矿物年龄来间接推断的。文章采用高精度的辉钼矿Re-Os等时线定年法,直接测得矽卡岩型矿体的矿化年龄为(153.8±4.8)Ma,与前人获得的含矿矽卡岩中金云母的K-Ar年龄(153~157 Ma)一致。结合黄沙坪岩体及含矿矽卡岩型矿体的稀土及微量元素地球化学特征,得出以下认识:该矿床的成矿年龄在154 Ma左右;成矿作用与花岗斑岩关系密切,它们都是华南燕山早期大规模成岩成矿作用高峰期的产物。  相似文献   

2.
湖南宝山是一个 Cu-Mo-Pb-Zn-Ag 多金属矿床,成因上与花岗斑岩、花岗闪长斑岩关系密切,矿床以宝岭倒转背斜(宝山中区)为中心,空间上具有明显的蚀变与矿化分带,其中心部位(宝山中区)的矿体产在花岗闪长斑岩(花岗斑岩)的内外接触带,围岩蚀变主要为矽卡岩化,成矿元素组合以 Cu-Mo 为主,而宝山东区、宝山西区及北部的财神庙矿区则主要为产于石炭系碳酸盐岩中的铅锌艰矿化。通过对与成矿作用关系密切的花岗闪长斑岩中锆石 SHRIMP U-Pb 同位素测年,获得了高精度的花岗闪长斑岩的成岩年龄为158±2Ma (MSWD=0.26,Probability=0.61,n=12),与前人(伍光英等,2005)的 SHRIMP 数据合并计算则可得到一个161±1Ma(MswD=0.66,Probability=0.42,n=23)的高精度 U-Pb 和谐年龄。该年龄可以代表宝山矿区中酸性小岩体的成岩年龄。通过对含矿矽卡岩中辉钼矿 Re-Os 同位素测年,获得辉钼矿的成矿年龄为160±2Ma。因此,本文认为宝山矿床成岩与成矿具有同时性,花岗闪长斑岩与宝山矿床的形成有成因联系。通过对区域上已获得的成岩-成矿年龄资料的综合对比分析,表明湘南乃至整个南岭中段地区中生代大规模岩浆作用与成矿第一高峰期为155~165Ma,宝山多金属矿床正是华南这一高峰期的产物。这为进一步研究区域成矿规律提供了重要同位素年代学依据。  相似文献   

3.
山西刁泉矿床是五台山-恒山矿集区内最为典型的斑岩-矽卡岩型多金属矿床,然而人们对该矿床斑岩和矽卡岩型矿化之间的成因联系及其成矿流体演化的认识还存在较大的争论.利用LA-ICPMS原位微区分析技术开展了对花岗斑岩和含矿矽卡岩中榍石的U-Pb同位素和微量元素分析,并测定了矿区侵入岩中锆石的U-Pb年龄.黑云母石英二长岩和花岗斑岩的锆石U-Pb定年结果表明其侵位时间分别为137.3±1.2 Ma和133.5±2.0 Ma,其中花岗斑岩的年龄与热液榍石的U-Pb年龄(133.6±2.2 Ma和132.8±2.5 Ma)在误差范围内完全一致,表明花岗斑岩与矽卡岩型铜银矿化关系密切.榍石中Sn元素的含量变化表明刁泉铜银多金属矿床成矿过程中氧逸度经历了一个升高的过程,然后又逐渐下降.  相似文献   

4.
黄沙坪矿床是湖南最大的铅锌矿床。矿区内岩浆活动复杂,矿化类型齐全,成矿元素多样,是湘南地区斑岩-矽卡岩-热液脉型Cu多金属与W-Sn多金属复合成矿作用的典型代表。为厘清区内不同花岗质岩石的时间格架、源区特征及其与成矿的关系,本次研究对黄沙坪矿区的不同类型花岗岩进行了系统的锆石LA-ICP-MS U-Pb定年和Hf同位素组成研究,研究表明,英安斑岩、二长花岗斑岩和石英斑岩的侵位年龄分别为158.5±0.9Ma、155.2±0.4Ma、160.8±1.0Ma,石英斑岩内花岗质岩石包体可能形成于220.4±1.2Ma。另外,在二长花岗斑岩锆石中发现古元古代-新太古代的继承锆石核。不同花岗质岩石中,中晚侏罗世锆石的εHf(t)值为-7.6~-3.2,Hf同位素两阶段模式年龄为1.7~1.4Ga,表明该区花岗质岩浆主要源自中元古代的古老基底物质部分熔融。继承锆石中接近0的εHf(t)负值(-1.5~-0.07)和εHf(t)正值(0.5~6.5)暗示形成这些古老继承锆石的初始物质中有幔源物质的加入。黄沙坪矿区不同类型花岗质岩石的锆石年龄和Hf同位素特征表明,英安斑岩、二长花岗斑岩、石英斑岩可能是同源同时期岩浆演化的产物,与矿床成矿年龄(154~159Ma)接近,反映其成岩成矿具有密切的时空联系。花岗岩中存在多组古老的残留锆石,暗示了黄沙坪地区自新太古代以来经历了复杂的岩浆作用,这可能是区内Cu-Pb-Zn-W-Mo-Fe多金属复合型矿床形成的关键要素。  相似文献   

5.
东昆仑祁漫塔格地区是青海省重要的矽卡岩型铁多金属成矿带,小圆山矽卡岩型铁多金属矿位于青海祁漫塔格东段,其成矿作用与斜长花岗斑岩关系密切,矿体产于斜长花岗斑岩的外接触带。利用LA-MC-ICP-MS锆石U-Pb定年技术,获得斜长花岗斑岩加权平均年龄为(216.9±1.9)Ma(n=16,MSWD=2.9),厘定其形成时代为晚三叠世。岩石地球化学研究表明,斜长花岗斑岩为过铝质高钾钙碱性系列岩石。岩石明显富集大离子亲石元素(Rb、K)、LREE和活泼的不相容元素(如U、Th),相对亏损高场强元素(如Nb、Ta、P、Ti),显示了轻稀土元素强烈富集的右倾式稀土配分型式,呈明显负Eu异常。综合青海祁漫塔格地区已有年代学资料和区域地质构造演化特征,认为小圆山斜长花岗斑岩可能形成于后碰撞构造阶段,为区域东昆仑造山带晚古生代—早中生代构造旋回的产物。  相似文献   

6.
甲玛是西藏冈底斯成矿带规模大、品位富的超大型矿床,也是勘查和研究程度最高的矿床之一。其中,南坑矿段由于富含高品位的矽卡岩型铜铅锌矿石,且具大型规模,已被纳入矿区首采矿段之一,然而关于其控岩控矿机制以及其与主矿段的耦合关系却仍不明确。本次基于详细的钻孔编录和野外地质证据,判定其成矿作用与中新世的花岗闪长斑岩等中酸性斑岩体有关,结合高精度的U-Pb年代学分析,厘定含矿花岗闪长斑岩结晶年龄为(15.5±0.3)Ma,与辉钼矿成矿年龄(15.23±0.22)Ma一致。南坑矿段作为甲玛矿床多中心复合成矿作用模型的重要组成部分,其矽卡岩矿体主要产于林布宗组角岩与多底沟组大理岩之间的层间接触带,属于中新世岩浆热液活动的产物。矿体形成后,受滑覆构造及次级断裂影响,矿体发生错断或破坏。对于南坑矿段后续的勘查评价,应注意与含矿斑岩和矽卡岩的蚀变与矿化分带特征,定位致矿热液中心。  相似文献   

7.
村前铜多金属矿床是产于钦杭成矿带东段的重要的斑岩-矽卡岩矿床,含矿岩体为黑云母斜长花岗斑岩和斜长花岗斑岩,具有多次侵入特点及钙碱性岩石的地球化学特征.本研究采用了LA-ICP-MS技术,首次对含矿的斜长花岗斑岩岩体中的锆石进行了U-Th-Pb同位素分析,获得其成岩年龄为(169.3±1.1 )Ma.这一年龄与钦杭成矿带中德兴花岗闪长斑岩、银山石英斑岩、冷水坑花岗斑岩、桐村花岗斑岩等岩体的年龄十分接近,揭示在钦杭成矿带175~156Ma经历了一次大规模的岩浆侵位与成矿事件,形成了众多与埃达克质或钙碱质花岗岩有关的斑岩-矽卡岩型铜多金属矿床,进一步说明钦杭成矿带在此时期在同一岩浆-动力背景下形成了斑岩-矽卡岩型铜多金属矿成矿系列.  相似文献   

8.
湘南铜山岭铜多金属矿田位于钦杭成矿带的中部,矿床主要产于铜山岭岩体接触带及其附近。本文对矿田内的岩体和矿床进行了精细的年代学研究,分别获得铜山岭Ⅰ号岩体的花岗闪长斑岩SHRIMP锆石U-Pb年龄为157±2 Ma(MSWD=1.20);铜山岭矿床石英脉型矿体中的辉钼矿Re-Os模式年龄为161±1 Ma(MSWD=0.21);桥头铺矿床矽卡岩型矿体中的辉钼矿Re-Os模式年龄为155±3 Ma(MSWD=1.5)、石榴子石Sm-Nd等时线年龄为155±8 Ma(MSWD=0.41)。成岩与成矿年龄在误差范围内基本一致,说明铜山岭矿田成岩成矿具有同时性,它们之间具有密切的成因联系。辉钼矿中Re含量(32.95×10~(-6)~59.45×10~(-6))指示成矿作用可能与壳幔混合作用有关。这为进一步研究区域成矿规律提供了重要同位素年代学依据。  相似文献   

9.
戴盼  吴胜华  丁成武 《岩石学报》2018,34(9):2598-2614
王坞斑岩型Mo-Cu矿床位于北武夷地区,地处钦杭构造岩浆成矿带北段。目前钻孔信息显示,该矿床的矿体主要由网脉状石英-辉钼矿-黄铜矿矿石组成,也含少量的浸染状和细脉浸染状Cu-Mo矿化,主要的蚀变作用包括硅化、绢英岩化和绿泥石化。矿区内隐伏燕山期的花岗斑岩脉及石英闪长玢岩脉。本文对该矿床的花岗斑岩进行了LA-ICP-MS锆石U-Pb测年,对主要矿石类型(网脉状石英-辉钼矿矿石)中的辉钼矿进行了Re-Os同位素测年。结果显示,花岗斑岩的锆石U-Pb年龄为136. 7±2. 2Ma,辉钼矿的Re-Os同位素模式年龄为132. 6±1. 8Ma~134. 5±2. 0Ma,加权平均值为133. 7±0. 94Ma,对应的Re-Os等时线年龄为134. 8±2. 1Ma。花岗斑岩的锆石U-Pb年龄和辉钼矿的Re-Os年龄在误差范围内基本一致,且花岗斑岩和矿体之间具有密切的空间关系,指示王坞Mo-Cu矿床的Mo矿化可能与矿区内的花岗斑岩存在密切的成因联系。北武夷地区主要的斑岩-矽卡岩和岩浆热液脉型Cu-Mo多金属矿床的成岩成矿年龄数据的统计结果显示,北武夷地区的Cu-Mo-Pb-ZnAg成矿作用主要集中在燕山期,可被划分为150~165Ma和140~125Ma两个阶段。结合区域构造背景资料,王坞Mo-Cu矿床形成于早白垩纪伸展的构造背景下。  相似文献   

10.
松树南沟金矿床是北祁连造山带中段大坂山成矿带内的一个中型金矿床。金矿体主要赋存于肉红色花岗闪长斑岩及其接触带附近的玄武安山岩中。通过对该花岗闪长斑岩的年代学研究,探讨了成岩与成矿的关系及岩石形成的构造环境。该花岗闪长斑岩中锆石LA-MC-ICP-MS U-Pb加权平均年龄为442±1 Ma,MSWD=0.32,属早志留世,成矿与花岗闪长斑岩具有密切的时空关系。综合分析认为,松树南沟金矿成岩成矿作用发生于北祁连洋向南侧中祁连陆块俯冲的构造环境,具有斑岩型矿床的特征。该研究对在该区进一步找矿具有重要意义。  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.
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.
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   

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.
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.
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   

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.
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   

20.
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   

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