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北大巴山平利一带晚三叠世粗面岩和基性岩墙群成因及其地质意义

陈涛, 陈隽璐, 李平, 朱卫红, 郝晨羽, 孙吉明, 王健, 颜玲丽

陈涛,陈隽璐,李平,等. 北大巴山平利一带晚三叠世粗面岩和基性岩墙群成因及其地质意义[J]. 西北地质,2025,58(1):93−105. doi: 10.12401/j.nwg.2023071
引用本文: 陈涛,陈隽璐,李平,等. 北大巴山平利一带晚三叠世粗面岩和基性岩墙群成因及其地质意义[J]. 西北地质,2025,58(1):93−105. doi: 10.12401/j.nwg.2023071
CHEN Tao,CHEN Junlu,LI Ping,et al. Petrogenesis of Late Triassic Trachyte and Basic Dike Swarms in Northern Dabashan and Its Geological Significance[J]. Northwestern Geology,2025,58(1):93−105. doi: 10.12401/j.nwg.2023071
Citation: CHEN Tao,CHEN Junlu,LI Ping,et al. Petrogenesis of Late Triassic Trachyte and Basic Dike Swarms in Northern Dabashan and Its Geological Significance[J]. Northwestern Geology,2025,58(1):93−105. doi: 10.12401/j.nwg.2023071

北大巴山平利一带晚三叠世粗面岩和基性岩墙群成因及其地质意义

基金项目: 中国地质调查局项目(DD20243439、DD20230228、12120114020501、DD20230215),陕西省自然科学基础研究计划(2023-JC-ZD-15、2023-JC-YB-268)和国家自然科学基金项目(40972150)联合资助。
详细信息
    作者简介:

    陈涛(1992−),男,助理工程师,长期从事基础地质研究工作。 E−mail:297041366@qq.com

    通讯作者:

    陈隽璐(1964−),男,研究员,长期从事大地构造研究工作。E−mail:chjl0116@163.com

  • 中图分类号: P581

Petrogenesis of Late Triassic Trachyte and Basic Dike Swarms in Northern Dabashan and Its Geological Significance

  • 摘要:

    北大巴山紫阳−平利−竹溪一带较为广泛地分布有一期基性岩墙与碱性火山岩,这些火山−侵入岩系多被认为形成于早古生代。通过对基性岩和粗面岩的LAICP−MS锆石UPb同位素测年工作发现,其形成时代分别为(219.5±2.2)Ma和(223.9±2.8)Ma,属于晚三叠世岩浆作用的产物。其中,基性岩墙中的辉绿岩显示出贫Si、高Ti的特征,粗面岩显示高Ti、富碱的特征,两类岩石轻、重稀土元素分馏存有一定差异。辉绿岩的Pb−Sr−Nd同位素组成上显示出OIB物质源区组成且具有EMⅡ和上地壳富集物质成分的加入,碱性系列的粗面岩在原始地幔标准化图解上则显示出大隆起的微量元素分布样式,构造环境判别图解均显示出二者与板内岩浆活动具有成因关系。结合区域地质特征,认为北大巴山地区晚三叠世的粗面岩−辉绿岩组合形成于勉−略洋闭合之后持续的板内伸展活动,为南秦岭地区深部地幔岩浆物质演化的地质记录。

    Abstract:

    An amount of basic dikes and alkaline igneous rock occurred in Ziyang−Pingli−Zhuxi regions of the North Daba Mountain, most of these rock series are believed to have been formed in Early Paleozoic magmatic activity, while the zircon U−Pb isotope dating of the basic dike swarms and trachyte in this study show them formed at (219.5 ± 2.2)Ma and (223.9 ± 2.8) Ma, respectively. The rock series can be regarded as a product of Late Triassic magmatism. The diabase from the basic dike swarms shows a characteristic of high Ti and low Si, trachyte shows a feature of high Ti and is rich in alkali, both of which have some differences for the fractionation of REE. The Pb−Sr−Nd isotopic composition of the diabase shows a source region of OIB, with some additions of enrichment material of EmⅡ and upper crust, the trachyte shows an obvious rise inthe Primitive Mantle normalized diagram. Thus, both of them are formed by the intra-plate magmatism. The Late Triassic trachyte−diabase assemblage in North Beidaba Mountain is considered to have been formed by the continuous intraplate extension after the closure of the Mian−Lue Ocean, also is a geological record of mantle derived magma in South Qinling.

  • 阿尔泰造山带位于中亚造山带的西南部,呈北西–南东向横跨中、俄、哈、蒙四国疆域,是中亚造山带的重要组成部分(Sengör et al.,1993Xiao et al.,2004)。在古亚洲洋扩张、洋壳俯冲、大洋闭合、大陆碰撞/俯冲、山脉形成和垮塌等构造演化过程中,阿尔泰造山带伴随有不同程度的岩浆活动,形成了大量的岩浆岩和与岩浆活动有关的矿产资源,并以伟晶岩型稀有金属矿产闻名于世,与之相关的岩浆作用,一直是阿尔泰造山带研究的焦点(王登红等,20012003邹天人等,2006朱永峰,2007任宝琴等,2011刘锋等,20122014周起凤等,2013彭素霞等,2015张亚峰等,20152017王星等,201620192022蔺新望等,2017201920202021)。中国阿尔泰造山带内分布着数以万条的伟晶岩脉,这些伟晶岩脉主要分布于38个伟晶岩田内,蕴藏着丰富的后碰撞–后造山花岗伟晶岩型稀有金属锂铍铌钽矿、白云母、长石和宝玉石等矿产资源(王登红等,2003邹天人等,2006计文化等,2022张照伟等,2022孔会磊等,2023)。世界著名的典型伟晶岩型稀有金属矿床–可可托海3号伟晶岩矿床,因产出巨晶矿物、清晰的矿物结构分带及稀有金属顺序矿化等特征,被国内外矿业界和地学界广泛关注(Windley et al.,2002Xiao et al.,2004Wang et al.,2006)。近年来,有学者研究认为,阿尔泰造山带伟晶岩型稀有金属矿产主要形成于印支期,稀有金属的成矿作用与同期岩浆–热液活动关系密切(朱永峰,2007任宝琴等,2011蔺新望等,2017)。

    新疆北部可可托海地区出露的阿拉尔岩体,位于可可托海3号矿坑以北15 km处,与伟晶岩脉独特的、密切的时空伴生关系,使其成为重要的研究载体。前人运用不同的测试方法获得其年龄为210~248.8 Ma之间,并认为举世闻名的可可托海3号伟晶岩脉与阿拉尔岩体存在成因上的联系(Zhu et al.,2006邹天人等,2006Wang et al.,20072008Lü et al.,2012刘锋等,2012张亚峰等,2015);但也有学者认为两者之间并无相关性,阿拉尔岩体即不是或者不可能是3号脉的母岩,而且两者的源区也有所不同,二者并不存在演化关系(陈剑锋等,2011刘文政,2014张辉等,2014)。鉴于前人对阿拉尔岩体与周围伟晶岩脉及其相关矿化的是否存在成因关系一直存在争议,且对伟晶岩脉的研究主要集中在形成时代上,岩浆成因以及源区研究相对较少,很难给出全面解释,故笔者以阿拉尔花岗岩体西部的含绿柱石伟晶岩脉群为研究对象,详细研究伟晶岩脉的地质特征、LA–ICP–MS锆石U–Pb年龄、岩石地球化学和Lu–Hf同位素,并结合区域地质资料探讨含矿伟晶岩脉与阿拉尔岩体的关系,以期为可可托海地区伟晶岩型稀有金属矿产成矿规律研究提供有力支撑。

    阿尔泰造山带位于横跨中–俄–哈–蒙4国疆域,北邻西萨彦岭岛弧带,南以额尔齐斯断裂与准噶尔地块相接,是中亚造山带的重要组成部分(图1a)。阿尔泰造山带呈北西–南东向展布,全长约为2 000 km,中国阿尔泰位于中亚造山带的西南缘,境内的部分约为500 km,大地构造位置属西伯利亚板块南部大陆边缘增生区,属古亚洲洋域的北带(何国琦等,1990Windley et al.,2002)。以红山嘴–诺尔特断裂和阿巴宫–库尔提断裂为界,可将阿尔泰造山带由北向南依次划分为:北阿尔泰、中阿尔泰和南阿尔泰3个构造带(图1b) (Xiao et al.,2004Li et al.,2003)。北阿尔泰构造带主要由震旦系—寒武系、上泥盆统—下石炭统火山-沉积岩组成;中阿尔泰构造带主要由震旦系—下古生界深变质岩系和奥陶纪—侏罗纪侵入岩组成,花岗岩在该区最为发育;南阿尔泰构造带主要由元古宇片麻岩和泥盆纪火山–沉积岩系组成。阿拉尔岩体及其西部的含绿柱石伟晶岩脉分布区,位于红山嘴断裂的南侧,属中阿尔泰构造带的组成部分。

    图  1  阿尔泰造山带构造位置图(a)(据何国琦等,1990)和构造分区图(b)(据Windley et al.,2002
    Figure  1.  (a) Tectonic position and (b) division maps of Altay orogenic belt

    阿拉尔花岗岩体西侧发现的伟晶脉体(图2),主要产于苏普特岩群和泥盆纪侵入体中,规模普遍较大,形态较复杂,多呈简单脉状、弯曲脉状、网脉状、不规则脉状、条带状等(图3a图3f)。其中,发育于苏普特岩群中的伟晶岩脉,与围岩侵入关系清楚,或顺中深变质岩的片麻理发育(图3a图3b),或与地层产状斜交(图3c),围岩蚀变清楚;分布于侵入岩中的伟晶岩脉,多沿岩体中节理、裂隙贯入(图3d图3e),受局部拉张作用形成的张性节理控制,脉体边界不平整(图3f);尤其是侵入阿拉尔岩体中的伟晶岩脉,与岩体之间的界线较为模糊,具有渐变过渡的特征(图3g),指示两者形成时代相近。

    图  2  阿拉尔地区地质简图
    1.红山嘴组;2.苏普特岩群;3.三叠纪黑云母花岗岩;4.三叠纪二云母二长花岗岩;5.三叠纪斑状二云母正长花岗岩;6.石炭纪黑云母花岗岩;7.石炭纪二云母花岗岩;8.泥盆纪石英闪长斑岩;9.泥盆纪花岗闪长岩;10.泥盆纪花岗斑岩;11.泥盆纪英云闪长岩;12.泥盆纪辉长岩;13.奥陶纪花岗闪长岩;14.伟晶岩脉;15.伟晶岩脉群;16.地质界线;17.脉动界线;18.断层界线;19.年龄样采样位置;20.地球化学样采样位置
    Figure  2.  Simplified geological map of the Aral area
    图  3  伟晶岩脉野外宏观照片
    a. 顺地层片麻理发育的伟晶岩脉;b. 顺地层片理发育的伟晶岩脉;c. 斜切地层片理发育的伟晶岩脉;d. 沿岩体裂隙发育的伟晶岩脉;e. 沿岩体节理发育的伟晶岩脉;f. 伟晶岩脉与围岩之间的侵入接触关系;g. 伟晶岩脉与围岩之间的渐变过渡关系;h. 伟晶岩脉中发育的绿柱石等矿物
    Figure  3.  Outcrop photographs of the pegmatite vein

    该地区发育的含绿柱石伟晶岩脉,走向一般为300°~340°,其次为270°~290°,以北东倾为主,部分南倾,倾角为40°~65°。脉体一般长为50~200 m,部分长为300~400 m;一般宽约为0.5~5 m,少数宽为5~8 m,小范围内常成群出露。伟晶岩中可见白云母带、细粒伟晶岩带、文象–准文象带、细粒钠长石带、块体石英带,同一条伟晶岩脉中往往只出现其中二到三种结构带。稀有金属矿化以铍矿化为主,主要呈条带状富集,分布在石英–白云母带、细粒钠长石带中,其他零星分散产于中粗粒结构、石英核接触处和星散矿化的含铍石英脉中,少部分呈矿条状或巢状矿产于含铍花岗岩中,以含绿柱石等矿物为特征(图3h)。基岩露头中,可见六方柱状绿柱石呈杂乱分布,颜色以浅蓝色、草绿色为主,中等透明度,少部分可达水蓝等宝石级别,绿柱石,柱径为0.3~5 cm,柱长为0.5~8 cm。

    伟晶岩脉:灰白色,伟晶结构,脉状构造、块状构造。岩石主要由石英、钾长石、斜长石(钠长石)、白云母、绿柱石,及石榴子石、电气石等矿物组成,矿物颗粒大小差异较大,岩石具脉状构造。石英颗粒紧密镶嵌,变形拉长,边缘呈锯齿状镶嵌,颗粒具碎裂,表面裂纹分布;石英脉裂隙间充填钠长石细脉,钠长石表面干净,发育聚片双晶和卡钠复合双晶;钠长石为热液交代变质分异作用形成,脉状分布;白云母不均匀分布,局部见解理缝中铁质析出(图4)。

    图  4  伟晶岩脉显微岩相照片
    Figure  4.  Thin section microphotographs of the pegmatite vein

    本次在阿拉尔花岗岩体西部的阿热散一带,采集了含绿柱石伟晶岩脉测年样品,进行LA–ICP–MS锆石U–Pb同位素定年,样品编号为DP01-4-3,采集地理坐标为:N 47°31′53″、E 89°35′30″(图2)。

    采集样品约15 kg,在核工业二〇三研究所采用常规方法进行粉碎,并用浮选和电磁选方法进行分选,然后在西北大学大陆动力学国家重点实验室双目镜下挑选出晶形和透明度较好的锆石颗粒,将它们粘贴在环氧树脂表面,待环氧树脂充分固化后,再对其进行抛光至锆石内部暴露。在西北大学大陆动力学国家重点实验室进行反射光、透射光和阴极发光显微照相,锆石的CL图像分析在装有英国Gatan公司生产的Mono CL3+阴极发光装置系统的电子显微扫描电镜上完成。通过对反射光、透射光和阴极发光图像分析,选择吸收程度均匀和形态明显不同的区域进行分析。锆石微量元素分析在西北大学大陆动力学国家重点实验室的LA-ICP-MS仪器上用标准测定程序进行。分析仪器为美国Agilent公司生产的Agilent7500a型四极杆质谱仪和德国Microlas公司生产的Geolas200M型激光剥蚀系统,激光器为193 nm 深紫外ArF准分子激光器,激光波长为193 nm,束斑为30 μm,频率为8 Hz,能量为70 mJ,采样方式为单点剥蚀,每个分析点的气体背景采集时间为30 s,信号采集时间为40 s;用美国国家标准人工合成硅酸盐玻璃标准参考物质NIST SRM 610 进行仪器最佳化调试,数据采集选用质量峰采点的跳峰方式,每完成6个待测样品测定,插入测标样一次。锆石年龄计算采用标准锆石91500作为外标,元素含量采用美国国家标准物质局人工合成硅酸盐玻璃NIST SRM 610作为外标,29Si作为内标元素进行校正。数据采集处理采用GLITTER(Version4.0,Mcquaire University),并采用Andersen软件对测试数据进行普通铅校正,年龄计算及谐和图绘制采用ISOPLOT(3.0版)软件(Ludwig,2001)完成。详细的实验原理和流程及仪器参见Yuan等(2004)

    本次挑选的锆石颗粒相对均一,粒径约为100 um,自形四方双锥或四方柱状,长宽比近似1:1。阴极发光图像显示:大部分锆石阴极发光较弱,内部环带退化显著,局部发育有裂隙,呈斑杂结构,表明锆石发生了一定程度的蜕晶化;边部不同程度的保留有蜕化前的韵律环带,有些锆石可见明显的岩浆振荡环带,显示典型岩浆锆石的特征(图5)(吴元保等,2004)。高的U、Th含量造成了锆石内部显著的蜕晶化和不同程度的重结晶作用,Th含量为62.57×10−6~1711.35×10−6,平均值为220.17×10−6;U含量为2417.34×10−6~54382.46×10−6,平均值为10925.76×10−6,Th/U值为0.01~0.09,平均值为0.02。

    图  5  伟晶岩脉锆石阴极发光图像及年龄值
    Figure  5.  Representative zircon cathodoluminescence (CL) images and U–Pb ages of the pegmatite vein

    本次对含绿柱石伟晶岩脉(DP01-4-3)进行LA–ICP–MS锆石U–Pb同位素年龄测试。所测24个测点中14、15号测点的谐和度较低,分别为75%和64%,故不参与年龄计算;19号测点所获得的年龄值,与其余21个测点年龄值存在较大差异,可能代表了早期的岩浆结晶作用;剩下的21个测点206Pb/238U年龄值较为集中(表1),且206Pb/238U和207Pb/235U比较和谐,其206Pb/238U加权平均年龄为(203.9±2.2)Ma(图6),时代为晚三叠世晚期。测试样品锆石阴极发光图像(图5)显示其为岩浆成因,所测年龄值代表了岩浆的结晶年龄,即该期伟晶岩脉的形成时间为晚三叠世晚期,属印支晚期岩浆活动的产物。

    表  1  含绿柱石伟晶岩脉(DP01-4-3)锆石LA–ICP–MS U–Th–Pb同位素分析结果表
    Table  1.  Analysis result of LA–ICP–MS zircon U–Th–Pb of the beryl bearing pegmatite vein (DP01-4-3)

    含量Th/U同位素比值年龄(Ma)谐和
    Pb*ThU207Pb/206Pb207Pb/235U206Pb/238U208Pb/232Th207Pb/206Pb207Pb/235U206Pb/238U208Pb/232Th
    (10−6比值比值比值年龄年龄年龄年龄
    1147.5881.005177.080.020.048030.001340.211990.006050.031860.000550.009330.00089102671955202318818 96%
    2230.80134.088150.140.020.047780.001330.205330.005340.031080.000460.010360.000918767190419732081896%
    3281.72162.169703.230.020.050090.001660.223620.007240.032470.000690.016190.0012819878205620643252599%
    41607.211711.3554382.460.030.052490.004270.213520.007030.031560.001020.007720.0004430618719762006155998%
    5180.82109.456092.360.020.052370.001530.239880.009400.033070.000950.020870.0014530267218821064172996%
    6401.66329.5414053.460.020.050970.001650.226310.009410.031850.000680.015190.0013623981207820243052797%
    7508.57271.9616891.520.020.055840.001570.249980.012090.032340.001250.048050.00316456582271020589496190%
    8180.6362.576148.720.010.048370.001260.222700.008670.033140.000810.011530.0010611761204721052322197%
    9181.2878.136152.340.010.049050.001500.222880.007670.033100.000790.011900.0011715072204621052392397%
    10164.12112.775558.500.020.049050.001770.216160.008300.032190.001120.024270.0017515083199720474853597%
    11312.28127.7210286.260.010.046130.001310.208490.007340.032720.000720.010590.00094400−322192620842131992%
    12202.0985.536761.020.010.049140.001530.225500.008440.033360.000850.019070.0012115477206721253822497%
    13210.77136.646979.740.020.048620.001270.219350.005820.033050.000800.012480.0009312856201521052511995%
    14177.49228.275389.960.040.066800.003480.311750.024460.033900.002040.038230.00520831108276192151375810175%
    15105.18224.502417.340.090.078670.003430.452120.022230.042050.001320.048780.004311165863791626689638364%
    16142.4877.864704.980.020.052420.005160.231930.022870.032260.001610.019570.0042230223121219205103928496%
    17338.51178.5511435.530.020.049140.001530.215850.010200.031800.000970.013480.0009415477198920262711998%
    18207.78129.636852.780.020.046920.002010.210380.011420.032700.001300.014130.0011256911941020782842293%
    19780.17343.2421577.300.020.047670.001410.250850.008080.038330.000850.012340.000828370227724252481693%
    20589.57291.5020100.950.010.049960.001180.214270.006050.031260.000640.010380.0007719528197519842091599%
    21290.04130.879612.800.010.049510.001630.219280.008870.032300.001010.016870.0020717278201720563384198%
    22268.29101.808934.030.010.048490.001730.213080.009630.031960.000990.010720.0012812485196820362152696%
    23192.6370.956418.380.010.051010.001610.224460.008520.032090.000910.008970.0010324377206720461812199%
    24251.08103.948437.390.010.049020.001570.214600.008520.031910.000950.009870.0009615074197720361991997%
     注:Pb*=0.241×206Pb+0.221×207Pb+0.524×208Pb。
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    图  6  伟晶岩脉锆石U–Pb年龄谐和图(a)和加权平均图(b)
    Figure  6.  (a) LA–ICP–MS zircon U–Pb concordia diagrams and (b) weighted average diagrams of the pegmatite vein

    地球化学数据检测分析由核工业二〇三研究所分析测试中心完成。FeO采用容量法分析,依据标准GB/T14506.14-2010;其余主量元素、TFe2O3和微量元素中P、Ba、V、Cr、Rb、Sr、Zr、Sc均采用XRF法分析,使用仪器为荷兰帕纳科公司制造的AxiosX射线光谱仪,依据标准GB/T14506.28-2010;所有稀土元素及微量元素中Co、Ni、Nb、Hf、Ta、Th、U采用ICP-MS法分析,使用仪器为Thermo Fisher Scientific公司制造的XSERIES2型ICP-MS,依据标准GB/T14506.30-2010;Fe2O3*值通过计算得出,计算公式为Fe2O3*=TFe2O3-FeO×1.1113。岩石主量、稀土、微量元素化学成分及特征值见表2

    表  2  含绿柱石伟晶岩脉(DP01-4-3)主量元素(%)、稀土元素(10−6)和微量元素(10−6)分析结果表
    Table  2.  Major element (%), REE (10−6) and trace element (10−6) dataes of the beryl bearing pegmatite vein (DP01-4-3)
    元素TC03/H3TC03/H10TC03-1/H3TC03-2/H3TC05/H4TC05-1/H2TC05-1/H6
    SiO273.7775.0779.1177.4575.5776.7673.01
    TiO20.020.020.020.020.020.020.02
    Al2O314.613.8211.6512.2213.3912.9514.91
    T Fe2O31.570.740.81.030.430.861.03
    FeO0.790.340.370.420.190.340.49
    Fe2O3*0.70.360.390.560.220.480.49
    MnO0.590.030.160.040.030.110.09
    MgO0.20.20.20.20.20.20.2
    CaO0.60.40.360.10.10.440.59
    Na2O6.544.664.422.682.715.987.88
    K2O1.484.72.775.617.532.282.29
    P2O50.10.160.110.080.10.170.16
    LOI0.580.370.460.520.090.390.18
    Total99.97100.13100.0299.9100.15100.12100.31
    A/CNK1.091.031.071.151.050.990.9
    A/NK1.181.081.131.171.061.050.97
    Mg#20.0534.8733.1327.7847.9631.5427.78
    SI2.061.952.452.111.842.151.76
    La2.82.823.50.890.61.061.44
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    续表2
    元素TC03/H3TC03/H10TC03-1/H3TC03-2/H3TC05/H4TC05-1/H2TC05-1/H6
    Ce5.165.136.641.31.262.452.94
    Pr0.60.630.760.190.120.260.31
    Nd2.142.22.510.720.430.921.19
    Sm0.470.560.640.180.0820.30.33
    Eu0.0590.0610.0530.0610.0740.0640.12
    Gd0.440.490.420.150.0750.30.32
    Tb0.130.120.0960.0270.0150.0860.068
    Dy10.620.490.130.0740.410.35
    Ho0.250.110.0980.0260.0130.0710.055
    Er0.850.280.320.0770.0390.160.13
    Tm0.20.0510.0690.0110.0050.0250.018
    Yb1.720.350.550.0710.030.140.13
    Lu0.270.0480.0870.0120.0050.0190.018
    Y9.454.263.680.920.482.852.04
    Ti119.9119.9119.9119.9119.9119.9119.9
    K12286.23901722995.146571.362510.218927.419010.4
    P436698480349436742698
    Sr15.619.11115.721.121.221.8
    Ba30.3361813718743.691.1
    Cr6.184.373.674.634.727.45.32
    Co0.760.540.490.650.440.810.73
    Ni2.892.331.72.131.912.053.29
    Ga27.220.220.526.217.522.420.7
    Th3.662.611.640.490.30.821.42
    U1.841.013.121.590.194.043.66
    Zr83.839.62828.125.436.927.7
    Hf6.381.561.771.611.141.552.45
    Ge4.32.923.283.433.24.274.09
    B14.411.728.714.94.758.3322.5
    Sn1.81.911.72.230.481.550.76
    F757463636519266826412
    Li78.363.973.977.224.1100.945.8
    Be104.5107.1149.1342.8131.2193125
    Nb34.714.62331.88.527.415.9
    Cs18.240.824.6120.467.846.733.6
    Ta7.732.752.786.941.432.721.56
    W3.881.912.122.710.892.570.85
    Sc3.35.41.42.53.91.53.1
    Rb253.2478.2353.4604.4749.3378317.6
     注:Fe2O3*值通过实测得TFe2O3和FeO含量计算得出,计算公式为Fe2O3*=TFe2O3-FeO×1.1113。
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    岩石中SiO2含量为73.01%~79.11%,平均值为75.82%;TiO2含量≤0.2%,Al2O3含量为11.65%~14.91%,平均值为13.36%,Na2O含量为2.68%~7.88%,平均值为4.98%,K2O含量为1.48%~7.53%,平均值为3.81%。岩石具有高Si、低Ti、富Al、富碱的特征。在K2O–SiO2图解(图7)中,样品主要落入中钾钙碱性、高钾钙碱性系列。样品A/CNK值为0.95~1.24,平均值为1.08,介于准铝质和过铝质之间,在A/CNK–A/NK图解中(图8),样品集中投影在偏铝质–过铝质岩石系列过渡区域。镁值(Mg#)在22.05~47.96,平均值为31.87,固结指数(SI)值为1.76~2.45,平均值为2.05,反映出岩浆结晶分异程度较高的特征。

    图  7  SiO2–K2O图(据Peccerillo et al.,1976
    Figure  7.  SiO2–K2O diagram
    图  8  A/CNK–A/NK图(据Rickwood,1989
    Figure  8.  A/CNK–A/NK diagram

    稀土总量较低,∑REE值为2.82×10−6~16.23×10−6,均值为9.45×10−6,(La/Yb)N值为1.10~13.51,均值为6.49,(La/Sm)N值为2.22~4.61,(Gd/Yb)N值为0.21~2.03,表明轻稀土元素富集和轻、重稀土元素分馏明显。稀土元素球粒陨石标准化配分曲线图(图9),显示轻稀土元素富集规律一致,重稀土元素分布特征各异。岩石样品δEu值变化较大,为0.31~2.88,可能与斜长石的分离结晶作用导致的局部富集有关。

    图  9  球粒陨石标准稀土配分图(标准化值据Taylor et al.,1985
    Figure  9.  Chondrite–normalized REE patterns

    微量元素含量及微量元素原始地幔标准化蛛网图(图10)表明,岩体富集大离子亲石元素Cs、Rb、U和高场强元素Nb、Ta、Zr、Hf,亏损Ba、Th、Sr、Ti,具有低Ba、Sr的特征,表明其可能是壳源物质低程度部分熔融的产物。Nb、Ta、Zr、Hf的富集可能与稀有元素在后期岩浆中的富集有关,Ba、Sr、Ti的亏损可能与斜长石、钛铁矿的分离结晶作用有关。

    图  10  原始地幔标准化蛛网图(标准化值据Sun et al.,1989
    Figure  10.  Primitive mantle–normalized trace element spidergrams

    为了更好地分析研究该含矿伟晶岩脉的成因与源区特征,笔者对Be矿化伟晶岩脉进行锆石Hf同位素测试。锆石176Hf/177Hf值为0.282714~0.282749,εHft)值为+2.56~+3.65,tDMC模式年龄为852~912 Ma(表3)。阿拉尔岩体中似斑状黑云母正长花岗岩176Hf/177Hf值为0.282675~0.282763,εHft)值为+1.03~+4.37,tDMC模式年龄为827~993 Ma;斑状正长花岗岩176Hf/177Hf值为0.282642~0.282800,εHft)值为−0.02~+5.73,tDMC模式年龄为759~1 052 Ma。两者具有基本一致的Hf同位素特征及模式年龄数据。

    表  3  阿拉尔岩体西部含绿柱石伟晶岩脉(DP01-4-3)锆石Hf同位素结果表
    Table  3.  Zircon Hf isotope results of the beryl bearing pegmatite vein (DP01-4-3)
    点号年龄(Ma)1s176Yb/177Hf2SE176Lu/177Hf2SE176Hf/177Hf2SEεHf(0)εHftTDM1TDM2fLu/Hf
    DP01-4-3205.994.320.000.000.0000890.0000000.2827230.000006−1.731.052.781.05732897−1.00
    DP01-4-4200.316.400.000.000.0000930.0000010.2827320.000006−1.411.052.981.06719883−1.00
    DP01-4-5209.765.940.000.000.0000660.0000000.2827290.000007−1.531.053.071.06723886−1.00
    DP01-4-6202.154.240.010.000.0002240.0000030.2827190.000007−1.871.052.541.06740907−0.99
    DP01-4-9210.205.050.000.000.0001170.0000050.2827210.000007−1.811.052.791.06735901−1.00
    DP01-4-10209.944.920.000.000.0000300.0000000.2827140.000007−2.041.052.561.06743912−1.00
    DP01-4-11204.267.020.000.000.0000380.0000000.2827300.000006−1.501.052.981.06722886−1.00
    DP01-4-13211.525.320.000.000.0000670.0000000.2827160.000006−1.991.052.651.06741909−1.00
    DP01-4-17204.6810.070.000.000.0000930.0000000.2827390.000006−1.171.053.311.07710869−1.00
    DP01-4-18201.836.070.000.000.0000580.0000010.2827220.000005−1.761.042.661.05732900−1.00
    DP01-4-21198.404.000.000.000.0000480.0000010.2827330.000007−1.381.052.971.06717882−1.00
    DP01-4-22204.936.330.010.000.0001880.0000060.2827490.000006−0.831.053.651.06698852−0.99
    DP01-4-24202.796.170.000.000.0000640.0000010.2827390.000007−1.161.053.291.06709869−1.00
    DP01-4-25203.615.660.000.000.0000830.0000000.2827180.000009−1.901.072.561.08738907−1.00
    DP01-4-26202.505.930.010.000.0004690.0000040.2827340.000010−1.331.093.051.09723881−0.99
     注:该表中的点号与表1中的点号对应。
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    伟晶岩脉锆石U–Pb年龄与其他同位素定年体系获得的年龄值相结合,能够限定伟晶岩形成时代和演化时限。以阿尔泰地区研究程度最高的可可托海3号矿脉为例,获得不同相带的锆石U–Pb年龄、白云母及全岩Rb–Sr年龄、辉钼矿Re–Os年龄分别为212~220 Ma、(218.4±5.8)Ma、(209.9±1.3)Ma(Zhu et al.,2006Wang et al.,2007陈剑锋,2011刘文政等,2014),表明各相带的形成时间为209~220 Ma,演化时限约为10 Myr。Lü等(2012)获得3号伟晶岩脉中锆石εHft)值为+1.25~+2.39间,TDM值为1 102~1 174 Ma,阿拉尔花岗岩体中锆石εHf(t)值为+1~+4,TDM值为1 007~1 196 Ma。这与本次获得的晚三叠世Be矿化伟晶岩脉及其成矿母岩,即阿拉尔复式岩体Hf同位素特征基本一致,指示中生代岩浆活动产生的岩体及矿体起源于相同的源区,均为前寒武纪微陆块的壳源物质部分熔融的产物。

    中国阿尔泰造山带内分布有数以万条的伟晶岩脉,蕴藏丰富的稀有金属、白云母、长石和宝玉石矿床,其形成时代与成矿作用一直是前人研究的焦点问题。王登红等(2000)研究证实阿尔泰地区伟晶岩具有多样性,既有变质成因伟晶岩脉,也有岩浆结晶分异伟晶岩脉;既可以形成于加里东期,也可以形成于华力西期,还可以形成于燕山期。根据阿尔泰西部的也拉曼大型含绿柱石白云母矿床(426±13)Ma、阿尔泰中部的那森恰大型含绿柱石白云母矿床(477±4)Ma及阿尔泰东部的青河拜兴白云母伟晶岩脉(436±5)Ma中获得了可靠的加里东期成矿的同位素资料,从根本上打破了阿尔泰地区伟晶岩型矿床只形成于华力西期的传统看法(王登红等,2001)。近年来,随着高精度LA–ICP–MS锆石U–Pb同位素定年方法的广泛应用,区域上已积累了大量的伟晶岩脉锆石U–Pb同位素年龄资料。任宝琴等(2011)通过对阿尔泰造山带19 条伟晶岩脉进行锆石U–Pb 年代学研究,认为阿尔泰伟晶岩可划分为4 个主要形成时期:加里东期(约476 Ma)、华力西晚期(约260~280 Ma)、印支期(205~250Ma)、燕山期(180~200 Ma)。杨富全等(2018)则将伟晶岩脉的形成时代划分为奥陶纪—早志留世(476~436 Ma)、晚泥盆世(~370 Ma)、二叠纪(296~258 Ma)和三叠纪—侏罗纪(250~151 Ma),并认为三叠纪—侏罗纪为主要成矿期。最新研究表明,三叠纪时期是新疆阿尔泰地区稀有金属成矿的重要时期,已识别出的三叠纪稀有金属矿床(秦克章等,2013张辉等,20142019Che et al.,2015王春龙等,2015杨富全等,2018),包括可可托海、阿斯喀尔特等超大型、大型矿床,构成阿尔泰一条重要的三叠纪成矿带(杨富全等,2020)。笔者在新疆北部可可托海地区阿拉尔花岗岩体西部阿热散一带获得一组精度较高的含绿柱石伟晶岩脉LA–ICP–MS锆石U–Pb年龄数据,其206Pb/238U加权平均年龄为(203.9±2.2)Ma,时代为晚三叠世晚期。该年龄值代表了岩浆的结晶年龄,指示该Be矿化伟晶岩脉的形成时间为晚三叠世晚期,属印支晚期岩浆活动的产物,证实三叠纪是阿尔泰地区重要的稀有金属成矿期。

    前人研究表明,阿尔泰地区在中生代早期进入后造山板内演化阶段(Yakubchuk,2004Glorie et al.,2012),区内缺失沉积地层,只发育少量板内岩浆侵入活动,加厚地壳熔融形成的过铝质花岗岩与相关稀有金属伟晶岩存在一定的成因关系。三叠纪作为阿尔泰造山带稀有金属矿主要成矿期,花岗伟晶岩型稀有矿产主要分布于中阿尔泰和南阿尔泰,成矿元素组合既有简单的Be 矿和Li 矿,也有复杂的Be–Nb–Mo 矿、Be–Nb–Ta 矿、Li–Be–Nb–Ta 矿和Li–Be–Nb–Ta–Rb–Cs–Hf 矿。在俄罗斯山区阿尔泰南部与中、哈、蒙等国接壤的地区已发现十多个早中生代花岗岩体都与稀有金属矿有关,典型矿床如卡尔古特Mo–W–稀有金属矿床,与成矿有关的淡色花岗岩、花岗斑岩脉年龄为218~228 Ma,Ⅰ阶段成矿年龄为218~220 Ma;Ⅱ阶段成矿与花岗斑岩和细粒花岗岩(213~215 Ma)有关,形成网脉状Cu–Mo–W 云英岩型矿化,年龄为213~214 Ma;Ⅲ阶段Mo–W–Bi–Be矿化与岩脉有关,其时代为200~204 Ma(Berzina et al.,2003Annikova et al.,2006)。Dobretsov等(1995)Potseluev等(2006)研究认为俄罗斯阿尔泰三叠纪花岗岩类和与西伯利亚超级地幔柱有关的幔源含矿岩浆活动的时限基本一致,三叠纪花岗岩类及伟晶岩脉是地幔柱岩浆活动演化最后阶段的产物。王登红等(2001)杨富全等(2018)研究证实中国阿尔泰地区多数稀有金属伟晶岩的围岩为花岗岩类,但含矿伟晶岩和赋矿花岗岩年代学揭示出稀有金属伟晶岩成矿与赋矿花岗岩之间的成因联系比较复杂。近年的研究已经证实,在中国阿尔泰山确实存在着中生代花岗岩及相关的稀有金属矿床(韩宝福,2008)。王春龙等(2015)研究表明阿斯喀尔特Be–Nb–Mo 矿床赋存于白云母钠长花岗岩中,发育稀有金属伟晶岩型和花岗岩型Be 矿化,后者产于白云母钠长花岗岩株顶部。获得的辉钼矿成矿年龄(215~229 Ma)与伟晶岩(218~221 Ma)和白云母钠长花岗(219~231 Ma)在误差范围内一致,从而认为白云母钠长花岗岩是稀有金属伟晶岩的成矿母岩,Be–Nb–Mo 矿的形成与白云母钠长花岗岩的演化有关。大喀拉苏Be–Nb–Ta矿床的成矿年龄为232~273 Ma,与赋矿黑云母花岗岩形成时间一致,两者也存在显著的成因联系。但关于三叠纪形成的可可托海稀有金属矿床与时空关系密切的阿拉尔花岗岩是否存在成因联系,目前还存在很大争议:有学者研究认为阿拉尔岩体中黑云母花岗岩、二云母花岗岩、黑云二长花岗岩和黑云钾长花岗岩年龄为210~233 Ma,与可可托海稀有金属成矿时间较一致(180~220 Ma),两者之间存在时间、空间上的密切关系,即可可托海稀有金属矿的形成与阿拉尔花岗岩体代表的岩浆活动有关(Zhu et al.,2006邹天人等,2006Wang et al.,2007刘锋等,2012刘文政等,2015张亚峰等,2015);也有学者认为阿拉尔花岗岩不属于稀有金属花岗岩,不可能是形成稀有金属伟晶岩脉的母岩,与可可托海稀有金属矿的形成没有直接关系(陈剑锋等,2018刘宏,2013刘文政,2014张辉等,2014)。

    杨富全等(2018)利用辉钼矿Re–Os 年龄和LA–ICP–MS铌钽矿U–Pb 年龄测定,限定可可托海稀有金属矿床形成于209~218 Ma,本次调查研究证实阿拉尔岩体中粗粒似斑状黑云母正长花岗岩、中细粒二云母正长花岗岩与其西部发育的Be矿化伟晶岩脉LA–ICP–MS锆石U–Pb同位素年龄分别为(217.3±3.8)Ma和(216.5±6.3)Ma、(203.9±2.2)Ma,认为阿拉尔岩体与伟晶岩脉以及Be矿化的形成时间在误差范围内一致。阿拉尔岩体与伟晶岩脉主量元素均表现为高Si、低Ti、富Al、富碱的特征,A/CNK值均介于准铝质、过铝质之间;微量元素富集大离子亲石元素Rb、Th、U和稀土元素La、Ce、Nd、Sm,亏损Ba、Nb、Ta、Zr、Hf、Sr、P、Ti,属于典型的低Ba、Sr岩石,表明两者均为壳源物质低程度部分熔融的产物,两者在成因上具有明显的相关性。Be矿化伟晶岩锆石同位素176Hf/177Hf值为0.282714~0.282749,εHft)值为+2.56~+3.65,tDMC模式年龄为852~912 Ma。这与阿拉尔岩体中粗粒似斑状黑云母正长花岗岩、中细粒二云母正长花岗岩,在误差范围内,具有十分相似的特征(另文发表)。因此,笔者认为伟晶岩脉以及Be矿化的形成与阿拉尔岩体代表的晚三叠纪晚期岩浆活动具有成因上的密切联系。

    Lü等(2012)获得3号伟晶岩脉中锆石εHft)值为+1.25~+2.39,tDMC=1102~1174 Ma,阿拉尔花岗岩中锆石εHf(t)值为+1~+4,tDMC= 1 007~1 196 Ma,与本次获得的有关中生代Be矿化伟晶岩脉Hf同位素特征基本一致。邹天人等(1986)通过Sr、Pb同位素研究,认为3号伟晶岩脉物质来源为壳源物质的重熔,且具有明显的分异特征。王春龙等(2015)通过MC–ICP MS获得阿斯喀尔特矿区白云母钠长花岗岩、Be矿化白云母钠长花岗岩及伟晶岩锆石εHft)值和tDMC模式年龄十分相近,分别为−0.72~+1.33、−0.36~+1.99、−0.45~+0.38和1 169~1 298 Ma、1 130~1 279 Ma、1 229~1 282 Ma,与3号矿脉的Hf同位素特征相近。因此,阿尔泰造山带发育的中生代稀有金属伟晶岩脉可能与阿拉尔岩体具有类似的源区。

    邹天人等(2006)研究了3号矿脉和阿斯喀尔特伟晶岩脉的氧、锶同位素组成,伟晶岩高的δ18O表明,这些伟晶岩脉皆为高度分异的岩浆在不同深度地质环境中结晶结晶形成,而较高的87Sr/86Sr初始值则表明中生代伟晶岩脉主要为壳源物质重熔岩浆分异形成。阿尔泰造山带发育的中生代伟晶岩脉与相关的花岗岩,可能起源于前寒武纪变质砂岩及变质泥岩等地壳物质部分熔融,并发生了显著地结晶分异作用,岩浆活动具有明显的继承性。

    (1)新疆北部可可托海地区阿拉尔花岗岩体西部发育的Be矿化伟晶岩脉,LA–ICP–MS锆石206Pb/238U加权平均年龄为(203.9±2.2)Ma,代表了岩浆的结晶年龄,指示该Be矿化伟晶岩脉的形成时间为晚三叠世晚期,属印支晚期岩浆活动的产物,证实三叠纪是阿尔泰地区重要稀有金属成矿期。

    (2)可可托海地区Be矿化伟晶岩脉与阿拉尔岩体具有LA–ICP–MS锆石U–Pb年龄、铌钽矿U–Pb年龄和辉钼矿Re–Os 年龄的一致性,地球化学特征的相关性,锆石同位素176Hf/177Hf值与εHft)值的相似性,表明两者具有密切的成因关系。中生代稀有金属伟晶岩脉与阿拉尔岩体所代表的岩浆活动可能均起源于前寒武纪变质砂岩及变质泥岩等地壳物质部分熔融,并发生了显著地结晶分异作用。

    致谢:评审专家对文稿提出了建设性的修改意见,在此表示衷心的感谢!

  • 图  1   北大巴山地区地质图及采样位置图(据徐学义等,2014

    Figure  1.   Geological map of north Daba mountain and sampling location

    图  2   平利地区辉绿岩(a)和粗面岩(b)显微照片(正交偏光)

    Kfs. 钾长石;Cpx. 单斜辉石;Hbl. 角闪石;Chl. 绿泥石;Ep. 绿帘石

    Figure  2.   Micrographs of (a) diabase and (b) trachyte in Pingli (cross–polar light)

    图  3   平利地区粗面岩(a)和辉绿岩(b)锆石CL图像

    Figure  3.   CL images of zircon for (a) trachyte and (b) diabase in Pingli

    图  4   锆石U–Pb谐和图及加权平均年龄图

    a、b. 粗面岩;c、d. 辉绿岩

    Figure  4.   Zircon U–Pb concordance diagram and weighted average age diagram

    图  5   平利地区粗面岩和辉绿岩岩石类型判别图

    a. Nb/Y–Zr/TiO2图(Winchester,1977);b. SiO2–(K2O+Na2O)图(Miyashiro, 1974

    Figure  5.   Rock types of trachyte and diabase in Pingli

    图  6   稀土元素球粒陨石标准化图(a)和微量元素原始地幔标准化图(b)

    标准化数据自Taylor 等(1985)Sun等(1989)

    Figure  6.   (a) Chondrite–normalized REE distribution patternss and (b) primitive mantle–normalized trace elements spider diagram

    图  7   平利地区辉绿岩Pb–Sr–Nd物质组成特征图

    Figure  7.   Pb–Sr–Nd composition of diabase in Pingli

    图  8   平利地区辉绿岩和粗面岩构造环境判别图 (据Pearce, 1983

    Figure  8.   Discriminant diagram of tectonic settingfor diabase and trachyte in Pingli

    表  1   平利地区粗面岩和辉绿岩锆石U–Pb同位素物质成分组成表

    Table  1   Zircon LA–ICP–MS U–Pb analytical data for the trachyteand diabase in Pingli

    样品比值年龄(Ma)组成 (10–6U/Th
    207Pb/206Pb±%207Pb/235U±%206Pb/238U±%208Pb/232Th±%207Pb/206Pb±1σ207Pb/235U±1σ206Pb/238U±1σ208Pb/232Th±1σ204Pb206Pb207Pb208Pb232Th238U
    粗面岩(08-66Tw),n=16
    10.050690.001270.24980.006390.035720.000490.00780.00018227342265226315743.4323613.674.67224.6917337.71
    20.051420.001460.246920.007070.034870.000490.005870.00017260402246221311833.5716215.224.86276.3311874.30
    30.051330.001440.261410.007360.037090.000520.010040.00021256392366235320247.3618312.0211.8460.7313552.94
    40.0540.001390.261660.006790.035340.000490.009020.00021371342365224318143.5119713.796.02275.5314615.30
    50.048930.00130.242220.006460.036150.000510.009140.0002114437220522931844<2.1417010.164.97213.8112335.77
    60.054070.00140.26380.006850.035680.00050.011030.00026374342386226322256.621489.854.76174.1611056.35
    70.050880.001550.23790.007190.034240.00050.00960.000252354321762173193583.823092.1892.7231.6910044.33
    80.048390.00130.239920.006420.036430.000520.011350.00027118372185231322856.1721812.847.07263.1414985.69
    90.048090.00140.234010.006750.03580.000520.010650.00029104412146227321464.17208125.32219.6915226.93
    100.048230.00130.230910.006170.035260.00050.008870.00024111372115223317853.9926316.497.03312.2519316.18
    110.049030.001320.229490.006080.034540.00050.00490.0001614936210521939934.311368.885.13443.4610222.31
    120.05180.001350.242330.00620.034630.00050.011810.00031277332205219323763.4622517.799.56307.6817155.58
    130.05630.001510.250470.006560.032960.000480.010750.00029464332275209321663.7620816.9810.2420.1916663.96
    140.051150.002820.252540.013360.035810.000560.011270.0001724812822911227322737.6710311.699.1186.457313.92
    150.050290.001550.223220.006620.033130.000510.01720.0005920841205521033451215.224813.1111.3326.1618385.64
    160.055810.001750.276520.008290.037070.000590.001540.00042445392487235431821.217826.2516.2251.7711874.72
    辉长岩(08-72Tw),n=16
    10.054950.002280.267360.011030.035280.000530.012340.00031410652419224324866.6447.136.78320.28350.41.09
    20.05520.001510.503070.013910.066080.000910.020020.000514203741494126401106.1324815.045.86159.88956.55.98
    30.051050.001550.249550.007610.035450.00050.005860.0002243442266225311843.6478.64.453.23296.43596.92.01
    40.052020.001870.250590.009010.034930.000510.0120.0003286552277221324162.3243.72.5043.46164.02337.92.06
    50.051410.001580.244660.007550.034510.000490.011160.00026259452226219322453.0967.13.874.91246.6520.52.11
    60.054340.001640.259080.007870.034570.000490.010980.00024385432346219322155.581166.8221.41070.3879.80.82
    70.048620.00150.226840.007050.033830.000480.010750.00026130472086214321653.0397.85.7410.1531.6794.81.50
    80.049870.002820.238870.0130.034740.000520.010970.0001318913021711220322133.9796.66.398.71417.06754.41.81
    90.051610.001840.241860.008630.033990.000510.011770.00032268542207215323764.6164.13.937.89353.71496.91.40
    100.05130.002160.242420.010170.034280.000550.011490.00036254672208217323174.7854.93.275.75276.96432.41.56
    110.048610.00450.233740.021320.034870.000560.011050.0002812921021318221322268.5413115.5822.8673.9959.71.42
    120.049710.001890.244410.009290.035660.000550.00970.0003118160222822631956<1.8166.83.756.52372.82506.51.36
    130.055140.002560.258820.011940.034050.000570.011030.000364187323410216422272.9438.42.94.25189.61256.81.35
    140.054660.002040.262820.009840.034880.000550.011190.00037398562378221322574.211228.676.81296.95912.43.07
    150.052360.002120.250410.010120.034690.000560.011650.00039301632278220323482.8152.93.295.29244.19412.81.69
    160.051280.002310.236950.010610.033520.000560.011290.00041253722169213322783.1434.82.0833.2147.24261.91.78
    下载: 导出CSV

    表  2   平利地区粗面岩和辉绿岩主量元素(%)和微量元素(10−6)地球化学数据表

    Table  2   Major elements (%) and trace elements (10−6) compositions for the trachyte and diabase in Pingli

    样品粗面岩辉绿岩
    08-65h08-67h08-68-1h08-68-2h08-69h08-70h08-71h08-72h08-75h
    SiO261.1663.9466.1866.7850.4450.4749.1949.9348.4
    Al2O318.2316.9215.7915.5413.3312.6713.5613.6812.53
    Fe2O31.010.952.301.553.353.373.312.612.96
    FeO2.563.261.462.069.759.9110.089.6210.56
    CaO1.470.4250.480.568.179.658.757.649
    MgO1.610.9250.640.615.945.466.226.966.66
    K2O4.356.024.194.240.480.460.740.770.72
    Na2O6.665.456.836.312.792.062.643.082.08
    TiO21.090.90.840.812.012.132.031.692.78
    P2O50.20.090.090.080.220.230.220.170.32
    MnO0.20.250.250.260.20.20.210.190.19
    LOLI0.890.490.30.552.311.912.22.552.53
    Total99.4399.61599.3599.353.43.013.323.623.71
    TFeO3.464.103.513.4412.7312.9113.0311.9413.19
    MgO#41.9125.9022.0521.5646.0343.5546.3550.3246.89
    Ritman6.686.285.244.68 1.440.851.852.141.45
    La16422321322213.113.712.910.316.8
    Ce30241539341229.230.328.722.938.3
    Pr32.744.442.144.04.074.243.963.155.42
    Nd11615314414918.819.618.614.826.1
    Sm19.826.924.725.45.335.605.324.237.02
    Eu4.574.564.194.221.491.541.471.251.95
    Gd13.619.518.218.75.495.785.424.507.08
    Tb2.213.383.123.170.981.040.970.781.22
    Dy11.7018.617.218.36.386.606.155.077.15
    Ho2.133.523.273.341.251.321.261.011.34
    Er5.529.278.458.963.023.293.172.503.23
    Tm0.801.411.281.360.470.490.460.370.47
    Yb5.008.988.519.053.063.233.002.472.92
    Lu0.711.261.181.270.450.450.440.350.42
    Y58.197.196.996.533.935.532.927.334.8
    Li15.241.445.369.617.413.919.719.525.1
    Sc2.036.395.765.9438.938.237.836.433.0
    V70.834.831.331.7334336324293286
    Cr2.072.551.942.2750.335.154.189.9194
    Co18.022.847.449.351.053.552.952.257.1
    Ni0.280.630.280.2848.736.649.268.6105
    下载: 导出CSV
    续表2
    样品粗面岩辉绿岩
    08-65h08-67h08-68-1h08-68-2h08-69h08-70h08-71h08-72h08-75h
    Cu5.344.794.724.58126121124118159
    Zn172238221164119114117104146
    Ga34.045.042.641.917.418.819.116.720.1
    Rb1251451381353.273.618.217.9219.20
    Sr40818146.566.7268308402221302
    Zr811157314731593146153143114200
    Nb22934032333610.811.210.78.4419.9
    Cs0.611.280.070.260.210.210.360.140.25
    Ba56449642.780.8278198258276232
    Hf17.035.732.735.33.904.183.923.225.23
    Ta13.722.019.019.60.750.710.730.531.28
    Pb10.517.918.920.34.612.762.622.436.35
    Th19.833.230.733.41.581.641.581.231.70
    U5.408.988.058.550.430.420.410.320.48
    REE680.74932.78882.20920.77 93.0997.1891.8273.68119.42
    LREE/HREE15.4913.3413.6113.56 3.413.383.403.324.00
    (La/Sm)N5.355.365.575.65 1.591.581.571.571.55
    (La/Yb)N23.5417.8217.9617.60 3.073.043.092.994.13
    (Gd/Yb)N2.251.801.771.71 1.481.481.491.512.01
    δEu0.850.610.610.59 0.840.830.840.880.85
    下载: 导出CSV

    表  3   平利辉绿岩Sr–Nd 同位素组成

    Table  3   Sr–Nd composition for diabase in Pingli

    样品87Rb/86Sr87Sr/86Sr±2σIsr147Sm/144Nd143Nd/144Nd±2σεNd(tTDM(Ga)
    08-70h0.0340.705259110.705150.1730.51260540.032.02
    08-71h0.0590.70650060.706320.1740.5126013−0.092.10
    08-72h0.1040.7062160.705890.1740.51261730.232.04
    08-75h0.1840.70552440.704950.1640.51269432.021.39
    下载: 导出CSV

    表  4   平利辉绿岩Pb 同位素组成

    Table  4   Pb composition for diabase in Pingli

    样品206Pb/204Pb±2σ207Pb/204Pb±2σ208Pb/204Pb±2σ238U/204Pb232Th/204Pb206Pb/204Pb)t207Pb/204Pb)t208Pb/204Pb)t
    08-70h18.0351615.5011438.455490.1542.4418.03015.48237.991
    08-71h18.0151715.5081538.396440.1643.0818.00915.48837.926
    08-72h18.1451715.5241338.560380.1336.1618.14015.50838.165
    08-75h17.8912415.5272138.052490.0819.1217.88915.51737.843
    下载: 导出CSV
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  • 收稿日期:  2023-02-07
  • 修回日期:  2023-08-15
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