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1.
北山独龙包地区晚石炭世陆缘弧岩浆作用——花岗闪长岩锆石U Pb年龄及地球化学证据 总被引：1，自引：0，他引：1
本文报道了北山地区独龙包南花岗闪长岩的LA-ICP-MS锆石U-Pb年龄与全岩地球化学,以确定其形成时代、岩石成因及构造环境。花岗闪长岩中的锆石呈短柱状或近等轴粒状,具典型的振荡环带,Th/U值介于0.42~0.75之间,指示岩浆成因。对岩浆锆石的定年结果显示,独龙包南花岗闪长岩形成于303.4±2.1 Ma。该期花岗闪长岩的Si O2含量为63.73%~69.12%,Na_2O=3.69%~4.03%,K_2O=2.23%~2.73%,全碱(Na_2O+K_2O)为6.08%~6.44%,Al2O3含量较高(14.83%~15.89%),K2O/Na2O为0.58~0.74,A/NCK=0.91~0.99;该区花岗闪长岩富集轻稀土(LREEs)和大离子亲石元素(LILE)Rb、Th、U、Pb,亏损重稀土元素(HREEs)和高场强元素(HFSE)Nb、Ta、P、Ti,且轻重稀土元素分馏较强,(La/Yb)N变化于4.77~6.35,具有弱的负铕异常,δEu为0.79~0.94。上述特征表明,该期花岗闪长岩属于准铝质钙碱性I型花岗岩,岩浆源区为下地壳,受到地幔物质的混染,形成构造背景为陆缘弧。结合邻区特征,得出红石山—百合山—蓬勃山蛇绿岩带代表的洋盆于晚石炭世可能发生了南北双向俯冲。 相似文献
2.
德乌鲁岩体位于西秦岭地区,其主体岩性为花岗闪长岩,在岩体内及其接触带发育有多处金、铜矿床。LA-ICP-MS 锆石U-Pb定年表明该岩体侵位于印支早期,年龄为(250±1.8) Ma,该岩体为准铝质,其铝饱和指数ASI为0.9~1.0。所有样品具有高的K2O含量(2.95%~3.52%)、K2O/Na2O比值(0.97~1.10)、Mg#(0.57~0.61)和相容元素含量(w(Cr)=(88~132)×10-6)。因此,我们认为德乌鲁寄主岩形成于壳幔岩浆的混合作用。在该岩体中广泛分布有镁铁质岩浆包体,这些包体即是镁铁质岩浆注入中酸性岩浆中时迅速降温形成的。德乌鲁包体具有中性的成分,其SiO2含量为56.17%~60.95%,岩性主要为辉长闪长岩和闪长岩。相对于寄主岩,包体有着更高的Mg#(0.65~0.67)和低的TiO2含量(0.57%~0.62%)。它们也有着高的钾含量(1.74%~2.43%),属于高钾钙碱性系列岩石。所有样品具有高的相容元素含量,如Cr((212~419)×10-6)和Ni((46~111)×10-6)。相对于重稀土元素,样品中轻稀土元素相对富集,并且具有中等的Eu负异常。在原始地幔标准化的微量元素蛛网图上,所有包体具有明显的Nb-Ta负异常。德乌鲁暗色包体可能形成于曾受俯冲作用改造过的富钾的岩石圈地幔源区部分熔融过程,并伴随有后期镁铁质矿物的分异。本区的印支早期岩浆作用及与其有关的矿床很可能形成于活动大陆边缘环境。 相似文献
3.
内蒙古西部阿拉善地区哈里努登花岗岩LA-ICP-MS锆石U-Pb年龄和地球化学特征 总被引：4，自引：2，他引：2
哈里努登岩体位于阿拉善地块北缘,主要由花岗闪长岩、黑云母二长花岗岩组成。锆石LA-ICP-MS U-Pb测年显示其形成时代为284.0Ma±1.8Ma,并非以往认为的志留纪。岩石SiO2含量为67%~72%,CaO为2.2%~4.4%,Na2O为3.7%~4.3%,K2O为2.1%~2.9%,具有较高的全碱含量,属钙碱性—高钾钙碱性系列,Al2O3含量为14.5%~17.2%,为准铝—弱过铝质(A/CNK=0.90~1.07),总体显示出I型花岗岩的特征。稀土元素总量较低(35.2×10-6~130.6×10-6),轻稀土元素相对富集,Eu呈正异常(δEu=1.04~1.90)。在原始地幔标准化图解中,大离子亲石元素(K、Rb、Ba、Sr)富集,亏损高场强元素(Ta、Nb、P、Yb、Y等),显示出弧花岗岩的特征。结合区域背景分析,阿拉善北缘在早二叠世时可能还存在与弧物质有关的岩浆活动。 相似文献
4.
巴仑台闪长岩反映的大洋俯冲信息为对比乌瓦门蛇绿岩与西侧长阿吾子和东侧库米什蛇绿岩的关系,探讨南天山洋的洋-陆演化过程具有重要意义。闪长岩具高碱和高铝特征,(Na2O+K2O)=4.14%~7.05%,Al2O3为14.62%~17.35%,为一套高钾钙碱性系列岩石,(La/Yb)N平均10.46,以富集轻稀土元素和大离子亲石元素(如K、Rb、Ba、Pb等)、亏损Nb、Ta、Ti等高场强元素为特征,形成于岛弧环境。闪长岩LA-ICP-MS锆石U-Pb年龄为(430.1±1.1)Ma,锆石εHf(t)=-12.7~-7.6,二阶段Hf模式年龄TDM2为1895~2219 Ma,指示巴仑台闪长岩为早志留世南天山洋北向俯冲,导致中天山古老结晶基底部分熔融形成。 相似文献
5.
青海东昆仑东段按纳格闪长岩地球化学及锆石U-Pb年代学研究 总被引：2，自引：0，他引：2
对产于东昆仑成矿带东段的按纳格闪长岩体进行的岩石学和地球化学研究及锆石LA-ICP-MS U-Pb法定年研究表明:该岩体的成岩年龄为(474.1±2.4)Ma,形成时代为早奥陶世,属加里东期;其w(SiO2)为52.63%~56.56%,具贫K2O(0.41%~0.73%),富CaO(7.23%~9.17%)、Na2O(2.62%~4.67%)的特点,为钙碱性-低钾(拉斑)系列准铝质岩石。岩石明显富集大离子亲石元素(如Ba)、LREE和活泼的不相容元素(如U、Th),相对亏损高场强元素(如Nb、Zr、Hf、Ti、P)。稀土元素总量变化不大(130.09×10-6~182.76×10-6),显示了轻稀土元素强烈富集的右倾式稀土元素配分型式。δEu变化范围为0.81~0.89,具有弱的负铕异常。Rb/Sr、Nb/Ta等特征反映出岩石具幔源岩浆的特点,亦显示岩浆受到地壳物质的混染。构造环境判别图解显示按纳格闪长岩形成的大地构造背景为洋壳俯冲造山阶段的岛弧环境。 相似文献
6.
东天山卡拉塔格泥盆纪岩浆岩地球化学特征及成因 总被引：1，自引：0，他引：1
文中对卡拉塔格地区泥盆纪岩浆岩进行了系统的岩相学、岩石地球化学研究,探讨其成因及形成构造背景。卡拉塔格地区泥盆纪火山岩主要为安山岩,并被同期一套成分连续的侵入体,包括辉长岩、闪长岩、石英闪长岩、二长岩等侵入。其中,辉长岩为钙碱性低钾系列准铝质岩石,具有较高的Al2O3含量(18.76%~19.06%)和Mg#(57.28~69.37),具有正Eu异常;闪长岩、石英闪长岩、二长岩和安山岩为钙碱性高钾钙碱性系列的准铝质弱过铝质岩石,也具有较高的Al2O3含量(15.02%~17.43%)和Mg#(53.67~72.91),具有较弱的Eu负异常或无Eu异常。这些岩浆岩都具有较低的初始Sr值(0.703 11~0.705 18)以及较高的εNd(t)值(5.36~7.72),均富集轻稀土和大离子亲石元素Rb、Ba、K等,亏损重稀土和高场强元素Ta、Nb、Ti等,都具有岛弧岩浆岩的特征。相似的岩石地球化学特征显示它们可能为同源岩浆活动的产物,可能是由俯冲洋壳形成的流体交代地幔楔岩石发生部分熔融而形成。泥盆纪岩浆岩形成于康古尔洋向卡拉麦里洋俯冲的岛弧背景。 相似文献
7.
别里赛北铁矿床是近几年在东昆仑成矿带上新发现的一处小型矿床,在对矿区地质背景及矿床特征分析的基础上,对与成矿关系最密切的石英闪长岩进行了LA-ICP-MS锆石U-Pb定年,岩石地球化学研究。研究结果显示石英闪长岩LA-ICP-MS锆石U-Pb年龄为(242.9±0.6)Ma,MSWD值为0.6,n=22;Si O2的含量在53.62%~63.83%,Al2O3含量在14.55%~17.57%,Na2O含量在2.95%~4.06%,K2O含量在1.60%~3.83%,为准铝质中-高钾钙碱性岩石系列;稀土元素总量中等,轻稀土元素富集,中等负铕异常;强不相容元素K、Rb、Th强烈富集,高场强元素Ta、Nb、Zr、Hf及轻稀土元素Ce、Sm中等富集,Ba、Sr富集不明显,贫P、Ti而Sm、Y、Yb元素含量高出球粒陨石值不多,反映了岩浆具有壳源为主的特点。 相似文献
8.
辽西-辽南地区新太古代花岗质岩石的锆石LA-ICP-MS U-Pb年代学和微量元素及全岩地球化学和锆石Hf同位素研究为探讨华北克拉通东北部前寒武纪地壳生长和演化提供了制约。结果表明,辽西地区钓鱼台二长花岗岩和辽南地区城子坦片麻状石英闪长岩、安波花岗质片麻岩中锆石均发育岩浆生长环带,结合相对高的Th/U比值(0.24~1.75)和锆石稀土元素特征,暗示它们均为岩浆锆石。定年结果显示,钓鱼台二长花岗岩、城子坦片麻状石英闪长岩和安波花岗质片麻岩的原岩分别形成于2519±9Ma、2505±10Ma和2519±11Ma,即它们均形成于新太古代晚期。辽西-辽南地区新太古代花岗质岩石均具有高SiO2(61.85%~73.38%)、低MgO(0.36%~2.83%)、富Na2O+K2O(7.64%~10.86%)的特征,为准铝质-弱过铝质的高钾钙碱性系列岩石;富集轻稀土元素和大离子亲石元素,亏损重稀土元素和高场强元素,发育弱的Eu负异常和Sr、P、Ti的亏损。岩浆锆石均具有正的εHf(t)值,介于0.4~5.9之间,tDM1变化于2595~2798Ma之间,峰值年龄为2740Ma,与华北克拉通最重要的一次地壳增生事件相一致。辽西-辽南地区新太古代花岗质岩石形成于板块俯冲的弧构造环境下新增生下地壳物质的部分熔融。 相似文献
9.
《西北地质》2016,(4)
青海省治多县宗可曲地区火山岩岩性以安山岩、英安岩、流纹岩、玄武岩及火山熔岩等为主。其SiO_2含量为33.48%~74.39%,Al_2O_3含量为12.51%~20.10%,Na_2O+K_2O含量为2.21%~7.77%,由于受后期岩浆活动,该套火山岩具有硅化蚀变等特征,导致SiO_2含量增加,Al_2O_3、Na_2O+K_2O含量减少。岩石属于造山带钙碱性系列,中基性火山岩属于拉斑玄武岩系,钾含量中偏高。稀土元素总量(∑REE)为63.4%~332.9%,轻稀土元素总量(∑LREE)大于重稀土元素总量(∑HREE),轻重稀土元素分馏明显,中基性火山岩Eu异常不明显,酸性火山岩Eu负异常明显。富集Th、K、La、Zr等微量元素,亏损Nb、Sr、P、Ti元素。主量、稀土、微量元素相关判别图解均指示其为典型的钙碱性系列岩石组合,属于与板块俯冲作用有关的岩浆岛弧带的产物,从而为多彩蛇绿构造混杂岩带的俯冲极性和构造环境的进一步确定提供了新的佐证。本次在安山岩中获取锆石U-Pb年龄为(226.6±4.9)Ma,时代为三叠世晚期。 相似文献
10.
《地质通报》2020,(9)
对内蒙古白山岩浆弧内百合山石英闪长岩进行了LA-ICP-MS锆石U-Pb测年、Hf同位素及岩石地球化学分析。结果显示,该岩体的形成年龄为350.8±1.5 Ma,岩浆锆石的ε_(Hf)(t)值在5.28～9.88之间,模式年龄为724～1018 Ma。地球化学数据显示,百合山石英闪长岩为一套I型钙碱性系列岩石,富碱(Na_2O+K_2O=6.03%～6.96%),富钠(Na_2O/K_2O2),较低的Mg~#(35.48～39.78)、Ni(2.06×10~(-6)～5.54×10~(-6))和Cr(2.11×10~(-6)～7.93×10~(-6))含量。相对富集轻稀土元素,重稀土分馏不明显,较低的(La/Yb)_N值(4.28～5.60),无明显Eu异常,相对富集Rb、K、U等大离子亲石元素,亏损Nb、Ta、P、Ti等高场强元素等,地球化学成分表明,石英闪长岩具有俯冲带成因的特征。石英闪长岩的锆石U-Pb年龄和岩石成因证明了350 Ma石英闪长岩是晚古生代白山岩浆弧内首次发现的可以明确与红石山-百合山洋俯冲消减作用有关的最早的弧岩浆记录。表明红石山-百合山洋于约350 Ma之前就已经开始发生俯冲消减,比前人一般认为的俯冲开始的时间提前了22 Ma。 相似文献
11.
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
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.
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
14.
《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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S. M. Moosavirad J. Rasouli M. R. Janardhana M. R. Moghadam M. Shankara 《Arabian Journal of Geosciences》2013,6(10):3623-3634
This paper discusses the result of the detailed investigations carried out on the coal characteristics, including coal petrography and its geochemistry of the Pabedana region. A total of 16 samples were collected from four coal seams d2, d4, d5, and d6 of the Pabedana underground mine which is located in the central part of the Central-East Iranian Microcontinent. These samples were reduced to four samples through composite sampling of each seam and were analyzed for their petrographic, mineralogical, and geochemical compositions. Proximate analysis data of the Pabedana coals indicate no major variations in the moisture, ash, volatile matter, and fixed carbon contents in the coals of different seams. Based on sulfur content, the Pabedana coals may be classified as low-sulfur coals. The low-sulfur contents in the Pabedana coal and relatively low proportion of pyritic sulfur suggest a possible fresh water environment during the deposition of the peat of the Pabedana coal. X-ray diffraction and petrographic analyses indicate the presence of pyrite in coal samples. The Pabedana coals have been classified as a high volatile, bituminous coal in accordance with the vitrinite reflectance values (58.75–74.32 %) and other rank parameters (carbon, calorific value, and volatile matter content). The maceral analysis and reflectance study suggest that the coals in all the four seams are of good quality with low maceral matter association. Mineralogical investigations indicate that the inorganic fraction in the Pabedana coal samples is dominated by carbonates; thus, constituting the major inorganic fraction of the coal samples. Illite, kaolinite, muscovite, quartz, feldspar, apatite, and hematite occur as minor or trace phases. The variation in major elements content is relatively narrow between different coal seams. Elements Sc,, Zr, Ga, Ge, La, As, W, Ce, Sb, Nb, Th, Pb, Se, Tl, Bi, Hg, Re, Li, Zn, Mo, and Ba show varying negative correlation with ash yield. These elements possibly have an organic affinity and may be present as primary biological concentrations either with tissues in living condition and/or through sorption and formation of organometallic compounds. 相似文献
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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