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西藏曲水县达布斑岩铜(钼)矿床成岩成矿年代学研究 总被引：1，自引：0，他引：1
本文采用锆石LA-ICP-MS微区U-Pb测年技术,对冈底斯成矿带东段曲水县达布斑岩Cu(Mo)矿床北部达布矿区含矿斑岩体、南部显角囊含矿花岗闪长斑岩岩体进行了年代学研究,通过对3件岩体样品中单颗粒锆石的分析,达布主矿体花岗闪长斑岩样品206Pb/238U年龄加权平均值为16.5±0.05Ma(n=15,MSWD=3),达布主含矿体二长花岗斑岩样品年龄为16.1±0.13Ma(n=15,MSWD=1.03),南部显角囊矿体花岗闪长斑岩年龄为16.2±0.04Ma(n=13,MSWD=0.0064)。对达布矿床斑岩Cu(Mo)矿床主矿体中4件辉钼矿样品,显角囊矿体中6件辉钼矿样品,分别进行了Re-Os同位素测试,等时线年龄分别为14.6±0.50Ma(MSWD=0.35,主矿体)、14.8±0.23Ma(MSWD=1.3,显角囊)。结合前人研究以及本次测年结果认为:1)达布斑岩铜(钼)矿床岩体侵位的年龄应限定在16Ma左右,成矿时代为14Ma左右,成矿时间差小于0.86Ma,与区域上"成矿瞬时发生"的成矿规律是一致的;2)矿床产出于印度-亚洲大陆板块后碰撞伸展环境。 相似文献
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冈底斯带东段的念青唐古拉地区除了发育许多大中型铅锌矿床外,还发育大型钼矿床,前者被认为是始新世成矿作用的产物,后者则被认为是古新世斑岩型钼矿床。在该区规模最大的亚贵拉铅锌矿床评价过程中,不仅发现铅锌矿化与石英斑岩体关系密切,而且在岩体内发现了规模较大的辉钼矿脉。应用LA-ICP-MS对石英斑岩锆石微区U-Pb年龄和微量元素进行了测定,90%的测点Th/U比值较高,阴极发光图像显示锆石内部发育明显的环带构造,具岩浆成因特点。2件石英斑岩样品的锆石206Pb/238U加权平均年龄分别为(65.8±1.3)Ma(MSWD=3.0)、(68.6±1.7)Ma(MSWD=1.8),表明岩体形成于晚白垩世。在野外实地调研的基础上,结合石英斑岩体微量元素含量以及前人对钼矿体的辉钼矿Re-Os年龄测定,认为辉钼矿化、铅锌矿化均与石英斑岩岩浆热液密切相关,但亚贵拉钼矿化与沙让斑岩钼矿化有别。念青唐古拉地区在晚白垩世可能发生铅锌成矿作用以及钼成矿作用。 相似文献
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西藏沙让斑岩钼矿床锆石SHRIMP定年和角闪石Ar-Ar定年及其地质意义 总被引：5，自引：3，他引：2
采用SHRIMP锆石微区U-Pb测年及角闪石40Ar-39Ar测年对冈底斯成矿带东段工布江达县沙让斑岩钼矿区的角闪石闪长岩体进行了年代学研究。对角闪石闪长岩中单颗粒锆石11个样品点分析,其206Pb/238U年龄范围在(45.39±0.77)～(52.7±3.3)Ma之间,加权平均值为(47.17±0.41)Ma,(n=11,MSWD=2.0)。对角闪石样品采用40Ar-39Ar阶段升温测年,年龄谱呈马鞍形,说明角闪石样品存在过剩氩,加权平均年龄(55.10±0.79)Ma不具地质意义,最低坪年龄(53.25±0.60)Ma接近但大于角闪石的结晶年龄。综合前人研究结果,笔者认为:①角闪石闪长岩体形成年龄为(53.25±0.60)Ma,属于喜马拉雅期,相当于始新世,岩体侵入时间早于含矿主岩体斜长花岗斑岩的形成时间。②受后期花岗斑岩体侵入热事件的影响,锆石的蜕晶化作用导致年龄偏小,角闪石Ar-Ar法最低坪年龄基本代表成岩年龄。③斑岩钼矿的形成与主碰撞期岩浆底侵作用有关,始新世早期,冈底斯成矿带的地壳已经增厚到可以产生地壳熔融的厚度,形成斑岩钼矿。④冈底斯成矿带存在40～65Ma的主碰撞期,显示出念青唐古拉成矿带具... 相似文献
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《矿物岩石地球化学通报》2018,(6)
斯弄多铅锌矿床位于南冈底斯-念青唐古拉成矿带北缘铅锌银多金属矿带上,该矿床铅锌矿化与矿区花岗斑岩密切相关,为典型的热液脉型-矽卡岩型铅锌矿床。为厘定其成岩成矿时代,本文对矿区花岗斑岩进行了锆石LA-ICP-MS U-Pb年龄测定。结果得到2组年龄,一组年龄介于(75.1±1.8)～(77.7±1.8)Ma之间,加权平均年龄为(75.7±0.9)Ma(MSWD=0.27,n=11),可能反映岩浆在岩浆房演化过程中结晶的锆石年龄;另一组年龄为(67.5±1.4)～(69.4±1.4)Ma,加权平均年龄为(68.8±1.2)Ma(MSWD=0.31,n=6),代表花岗斑岩真实的结晶年龄,这一花岗斑岩的年龄(68.8±1.2)Ma明显早于冈底斯带内主碰撞期形成的矽卡岩型矿床。结合该成矿带其他矿床的成岩、成矿年龄,本文认为南冈底斯-念青唐古拉成矿带在印-亚大陆碰撞早期或新特提斯洋壳俯冲晚期,也伴有较强的铅锌多金属成矿作用。 相似文献
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西藏蒙亚啊铅锌矿床成矿年龄及其地质意义 总被引：2，自引：0，他引：2
本文利用LA-ICP-MS锆石U-Pb法和石英ESR法对冈底斯北带中的蒙亚啊铅锌矿床进行了年龄测定。LA-ICP-MS测试结果显示矿区的花岗斑岩结晶年龄为14.3±0.3 Ma(MSWD=2.6);矿石中与硫化物共生的石英ESR测试结果指示矿床大致形成于(10.0±1.0)Ma~(13.6±1.4)Ma。两种年龄结果比较相近,且与冈底斯巨量斑岩铜矿化时间一致。据此,蒙亚啊矿床很可能为岩浆热液交代形成的矽卡岩型矿床,为冈底斯斑岩-矽卡岩成矿系统的一部分。 相似文献
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粤北大宝山斑岩钼钨矿床赋矿岩体锆石LA-ICP-MS U-Pb年龄与矿床形成动力学背景分析 总被引：4，自引：0，他引：4
粤北大宝山斑岩钼钨矿床赋矿岩体出露面积0.18km2,矿化主要以细脉状及浸染状产于斑岩及其内外接触带中。系统的薄片观察表明,该岩体岩性比较复杂,有碱长花岗斑岩、普通花岗斑岩、白云母二长花岗斑岩及白云母花岗闪长斑岩。本文分析了碱长花岗斑岩及白云母二长花岗斑岩锆石LA-ICP-MSU-Pb年龄,碱长花岗斑岩锆石年龄为166.6±2.1Ma,MSWD=1.17;白云母二长花岗斑岩锆石年龄为166.2±3.1Ma,MSWD=2.3。两个样品的锆石U-Pb年龄基本一致,表明大宝山斑岩钼钨矿床岩体形成于燕山早期。据斑岩矿床年龄、斑岩矿床在十杭带时空分布特征及华南地区中生代构造背景,提出大宝山斑岩钼钨矿床岩体的形成可能与侏罗纪太平洋洋壳向南西俯冲而引发的的十杭带深断裂构造活动复活有关。 相似文献
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冷水坑斑岩型银铅锌矿床是中国目前唯一的典型斑岩型银铅锌矿床,对于该矿床的成矿斑岩的形成时代至今仍没有精确的年龄数据。本文通过对冷水坑斑岩型银铅锌矿床成矿斑岩(花岗斑岩)样品中的锆石11个测试点的SHRIMP锆石U-Pb年代学研究,得出206Pb/238U加权平均年龄为(162.0±2)Ma(MSWD=1.4),因此,认为冷水坑花岗斑岩的形成年代为(162.0±2)Ma。冷水坑含矿斑岩成岩年龄与成矿年龄高度一致,成岩年龄与成矿作用开始时间差异不明显。此外,由冷水坑矿床成岩和成矿年龄数据推断出矿化持续时间约27Ma。 相似文献
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洞中拉铅锌矿床是念青唐古拉山地区扎雪—亚贵拉成矿带内新发现的矿床,矿区出露的花岗斑岩侵入体与洞中拉铅锌多金属矿床的形成密切相关。为精确限定其形成时代,笔者对洞中花岗斑岩进行单颗粒锆石SHRIMPU-Pb定年,结果显示其206Pb/238U加权平均年龄为(124.4±1.9)Ma(MSWD=5.09),该年龄对应于冈底斯—念青唐古拉火山岩浆岩带东段的早白垩世岩浆活动事件(介于109~130Ma),与扎雪—金达铅锌多金属矿成矿带内出露的花岗类岩体年龄(120~130Ma)一致。结合区域资料,洞中拉花岗斑岩是早白垩世弧间裂谷伸展作用下地壳挤压增厚局部熔融的产物。为念青唐古拉地区早白垩世岩浆侵位活动以及铅锌铜钼多金属矿产找矿方向研究提供了重要证据。 相似文献
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岗讲铜钼矿床是西藏冈底斯成矿带中段典型的斑岩型矿床,岗讲矿床成岩成矿时代、岩浆演化过程及其与成岩成矿关系尚不明确,利用LA-ICP-MS锆石U-Pb定年方法对岗讲矿区主要岩体二长花岗斑岩、花岗闪长斑岩和英云闪长玢岩成岩时代进行研究,获得锆石U-Pb年龄加权平均值分别为16.6±0.3 Ma (MSWD=0.94,n=10)、16.1±0.2 Ma (MSWD=1.07,n=12)、14.4±0.4 Ma (MSWD=1.12,n=7);同时采用辉钼矿Re-Os同位素测年方法首次对岗讲矿床石英硫化物脉中的辉钼矿进行定年,获得12件辉钼矿Re-Os同位素模式年龄集中于13.24±0.20 Ma~13.55±0.22 Ma,加权平均年龄为13.4±0.1 Ma (MSWD=0.65),等时线年龄为13.6±1.6 Ma (MSWD=1.2).结果表明:(1) 岗讲矿区复式岩体侵入序列为含巨斑黑云二长花岗岩-二长花岗斑岩-花岗闪长斑岩-流纹斑岩 (深部定名为英云闪长玢岩),成岩时限为16.6~14.4 Ma,成矿时代为13.4 Ma左右,成岩成矿是一个连续的岩浆演化过程;(2) 辉钼矿中Re含量为155.4~171.1 μg/g,均值为162.9 μg/g,指示其成矿物质中有幔源成分的加入;(3) 矿床产出于中新世印度-亚洲大陆碰撞后伸展构造环境. 相似文献
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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
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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
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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
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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
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《Applied Geochemistry》2001,16(2):137-159
Five hundred and ninety-eight samples of terrestrial moss (Hylocomium splendens and Pleurozium schreberi) collected from a 188,000 km2 area of the central Barents region (NE Norway, N Finland, NW Russia) were analysed by ICP-AES and ICP-MS. Analytical results for Al, B, Ba, Ca, K, La, Mg, Mn, Na, P, Rb, Si, Sr, Th, U and Y concentrations are reported here. Graphical methods of data analysis, such as geochemical maps, cumulative frequency diagrams, boxplots and scatterplots, are used to interpret the origin of the patterns for these elements. None of the elements reported here are emitted in significant amounts from the smelting industry on the Kola Peninsula. Despite the conventional view that moss chemistry reflects atmospheric element input, the nature of the underlying mineral substrate (regolith or bedrock) is found to have a considerable influence on moss composition for several elements. This influence of the chemistry of the mineral substrate can take place in a variety of ways. (1) It can be completely natural, reflecting the ability of higher plants to take up elements from deep soil horizons and shed them with litterfall onto the surface. (2) It can result from naturally increased soil dust input where vegetation is scarce due to harsh climatic conditions for instance. Alternatively, substrate influence can be enhanced by human activity, such as open-cast mining, creation of ‘technogenic deserts’, or handling, transport and storage of ore and ore products, all of which magnify the natural elemental flux from bedrock to ground vegetation. Seaspray is another natural process affecting moss composition in the area (Mg, Na), and this is most visible in the Norwegian part of the study area. Presence or absence of some plant species, e.g., lichens, seems to influence moss chemistry. This is shown by the low concentrations of B or K in moss on the Finnish and Norwegian side of the (fenced) border with Russia, contrasting with high concentrations on the other side (intensive reindeer husbandry west of the border has selectively depleted the lichen population). 相似文献
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Marta L. PATINO-DOUCE Alberto PATINO-DOUCE Mazhar QAYYUM Roger L. NIELSEN 《Geostandards and Geoanalytical Research》1994,18(2):195-198
We have developed a set of four synthetic standards for the rare earth and high field strength elements designed for use in the determination of those elements in silicates. The base material is a glass nominally at the eutectic of the MgO-Al2 O3 -SiO2 ternary system. The nominal doping level was 2 wt% of the elements as oxides. To avoid problems associated with peak interference, the elements were doped in four separate glasses. 相似文献
20.
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