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新疆温泉县别珍套山新元古代花岗岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及其成因

曾祥武, 赵军, 聂晓勇

曾祥武, 赵军, 聂晓勇. 2020: 新疆温泉县别珍套山新元古代花岗岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及其成因. 地质通报, 39(2-3): 177-193. DOI: 10.12097/gbc.dztb-39-2-3-177
引用本文: 曾祥武, 赵军, 聂晓勇. 2020: 新疆温泉县别珍套山新元古代花岗岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及其成因. 地质通报, 39(2-3): 177-193. DOI: 10.12097/gbc.dztb-39-2-3-177
ZENG Xiangwu, ZHAO Jun, NIE Xiaoyong. 2020: LA-ICP-MS zircon U-Pb age, geochemistry and genesis of Neoproterozoic granitoids in the Biezhentao Mountain of Wenquan County, Xinjiang. Geological Bulletin of China, 39(2-3): 177-193. DOI: 10.12097/gbc.dztb-39-2-3-177
Citation: ZENG Xiangwu, ZHAO Jun, NIE Xiaoyong. 2020: LA-ICP-MS zircon U-Pb age, geochemistry and genesis of Neoproterozoic granitoids in the Biezhentao Mountain of Wenquan County, Xinjiang. Geological Bulletin of China, 39(2-3): 177-193. DOI: 10.12097/gbc.dztb-39-2-3-177

新疆温泉县别珍套山新元古代花岗岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及其成因

基金项目: 

中国地质调查局项目《西北华北重点地区地质矿产调查评价》 12120115041301

详细信息
    作者简介:

    曾祥武(1977-), 男, 硕士, 高级工程师, 从事多金属矿产勘查工作和区矿调工作。E-mail:tzxw126@126.com

  • 中图分类号: P534.3;P588.12+1

LA-ICP-MS zircon U-Pb age, geochemistry and genesis of Neoproterozoic granitoids in the Biezhentao Mountain of Wenquan County, Xinjiang

  • 摘要:

    对新疆温泉县别珍套山新元古代花岗岩开展了相关研究。获得了3个片麻状-眼球状花岗岩4件锆石样品年龄,其中206Pb/238U年龄值一致,大多集中在910~950 Ma之间。极少量继承锆石的年龄大于1000 Ma。这些花岗岩以特有的粗粒、巨大的眼球状片麻结构为特征。岩体具有高硅(≥ 70%)、富碱(K2O+Na2O,6.5%~8.9%)且K2O>Na2O的特征,表现出从钙碱性到钾玄岩演化的变化趋势。稀土元素特征表明其与碱性花岗岩相似。样品的微量元素蛛网图几乎完全相同,均明显亏损Ba、Nb、Ta、Sr、P、Ti,富集Rb、Th、U、K等元素,显示活动大陆边缘岩石特征。全岩Sr-Nd同位素特征表明具典型壳源花岗岩(S型花岗岩)的特征。Lu-Hf同位素特征表明单阶段Hf模式年龄(tDM1)为883~1351 Ma,平均为1133 Ma;二阶段Hf模式年龄(tDM2)为891~1588 Ma,平均为1250 Ma,与锆石形成年龄较接近。新元古代早期(约9 Ga)片麻状花岗岩可能是与Rodinia超大陆会聚有关的格林维尔期造山作用、地壳增厚导致地壳物质部分熔融的产物。

    Abstract:

    The Neoproterozoic granites of the Biezhentao Mountain in Wenquan County of Xinjang were studied in this paper.Four LA-ICP-MS zircon U-Pb ages of 910~950 Ma were obtained for granitic gneisses in the Biezhentao Mountain of Wenquan County of Xinjiang.These new zircon LA-ICP MS U-Pb ages, together with previously published data, indicate that the granites were emplaced during 910~950 Ma.A few inherited old zircons U-Pb ages of >1000 Ma were found in all dated samples; they may have derived from the source rocks. These granitoids are characterized by a very coarse grained and huge augen gneiss texture. Major element data indicate that they belong to peraluminous monzogranite, with SiO2 (≥ 70%), K2O+Na2O (6.5%~8.9%), and K2O > Na2O, thus defined as calc-alkaline to shoshonitic rocks. These rocks show nearly parallel REE patterns with different abundances and distinct negative Eu anomalies. All the granitoids display similar spider diagrams with obvious negative anomalies of Ba, Nb, Ta, Sr, P and Ti, and obvious enrichment of Rb, Th, U, K. Sr-Nd data suggest that the protoliths of Neoproterozoic granitoids belong to peraluminous S-type granites. Zircon εHf (t) values range from +1.7 to +5.7, with model ages (tDM1) of 883~1351 Ma and model ages (tDM2) of 891~1588 Ma. Furthermore, with the age information on the ancient terranes of Tarim basin, the authors hold that the Tianshan ancient block probably formed a part of Rodina supercontinent during Early Neoproterozoic period and these granitoid rocks were linked to lithospheric thickening.

  • 查隆岩体位于西藏昂仁县措迈乡西北部,所处大地构造位置为冈底斯-喜马拉雅造山系(一级)中的拉达克-冈底斯-察隅弧盆系(二级),属中冈底斯北侧的岩浆带。目前普遍认为,冈底斯带中生代花岗岩为新特提斯洋壳向北俯冲和班公-怒江洋向南俯冲共同消减作用的结果[1-3]。另外,前人也对冈底斯中生代岩浆岩的构造性质、构造演化、岩浆活动及成矿作用进行了较多研究。王成善等[4]认为,冈底斯中生代花岗岩是新特提斯洋壳至少2次俯冲消亡和多次俯冲-碰撞的结果;有学者认为,冈底斯带中北部地区的岩浆作用与班公湖-怒江洋壳向南的俯冲作用有关[1-3];也有学者认为,冈底斯带中北部地区的岩浆作用与冈底斯和羌塘地块碰撞后软流圈上涌引起的地壳熔融有关[5]。区域上晚白垩世岩浆大面积出露于南冈底斯带,中冈底斯带一直缺少晚白垩世花岗岩的报道。另外,冈底斯岩浆弧带成矿地质条件优越,孕育了大量的铜、金、银、钼、富铁、铅锌等矿产资源,是青藏高原最重要的成矿区带,但对铁矿的研究明显偏少。在填绘1:5万羊他幅时发现了晚白垩世岩体和查隆磁铁矿点,在对该岩体进行详细野外调查的基础上,结合区域资料,对晚白垩世岩体的岩石成因、地球动力学背景及成矿意义进行探讨,以期对冈底斯带构造岩浆研究提供可靠的基础资料。

    查隆岩体以岩株的形式产出,主要由5个独立的侵入体组成,在研究区呈零星分布,出露面积约9km2(图 1)。在各武勒嘎一带,南部被林子宗群年波组火山岩及第四系不整合覆盖,与围岩接触带岩石有弱的变质变形;在查隆一带侵位于拉嘎组、昂杰组、下拉组,与围岩接触带附近有变质变形、硅化、角岩化现象,岩体接触带附近可见黑云母钾长变粒岩、角岩化粉砂岩、变质含砾细粒岩屑石英砂岩等热接触变质岩。岩体以中酸性岩石为主,岩石类型为黑云花岗闪长岩、花岗闪长岩(图版Ⅰ-ab)。研究区处于冈底斯成矿带中西段,主体位于冈底斯-念青唐古拉中生代、新生代铜钼金铁铬盐类成矿带西段,矿点出露地层为石炭系—二叠系碎屑岩及碳酸盐岩,构造主要表现为断裂、节理,以及与逆断层伴生的牵引褶皱。北西向断裂较常见,为主要的赋矿构造,倾向一般为40°~50°,倾角为55°~ 60°,且多为逆断层。磁铁矿化蚀变带以浸染状的形式赋存于拉嘎组(C2P1l)、昂杰组(P1a)与中细粒黑云母花岗闪长岩岩体的外接触带上。初步圈定磁铁矿体3条,拣块样全铁最高品位68.9%(图版Ⅰ-c)。矿体呈似层状、透镜状产出,围岩硅化、角岩化蚀变较强,且受断层控制明显。矿石矿物主要为磁铁矿,少量赤铁矿、黄铁矿(图版Ⅰ-d)。

    图  1  查隆花岗岩地质简图及大地构造位置(据参考文献修改)
    1—断层;2—同位素采样位置;3—U-Pb年龄值;4—花岗岩体;5—热变质;6—火山岩;7—地层界线;Q—第四系;E3—渐新统;E2—始新统;P2—中二叠统;C-P—石炭系-二叠系;Ⅰ4-2—北喜马拉雅大陆边缘褶冲带北带;Ⅱ1—雅鲁藏布江缝合带;Ⅱ3—拉孜-曲松增生逆推带;Ⅲ1—日喀则弧前盆地;南冈底斯:Ⅲ2—冈底斯下察隅火山岩浆弧;中冈底斯:Ⅲ3—隆格尔-念青唐古拉火山岩浆弧,Ⅲ4—措勤-申扎火山岩浆弧;Ⅲ5—狮泉河蛇绿混杂岩带;北冈底斯:Ⅲ6—班戈-八宿岩浆弧;Ⅳ1—班公-怒江结合带; Ⅳ2—东恰错增生楔逆推带;Ⅴ1—羌南陆块
    Figure  1.  Simplified geological map of the granite in Chalong area and the division of tectonic units in adjacent areas
      图版Ⅰ 
    a.查隆岩体花岗闪长岩;b.闪长岩镜下特征;c.磁铁矿;d.磁铁矿镜下特征。Q—石英;Pl—斜长石;Kfs—钾长石;Mag—磁铁矿;Py—黄铁矿;Hm—赤铁矿
      图版Ⅰ. 

    查隆岩体的主要岩石类型为中细粒花岗闪长岩、细粒-中粒黑云花岗闪长岩。

    中细粒花岗闪长岩:呈灰白色,中细粒半自形粒状结构,块状构造,主要矿物成分为斜长石(56%~57%)、石英(20%~21%)、钾长石(12%~ 13%)、角闪石(4%~5%)和黑云母(3%~4%)。长石可分为1~1.5mm细粒级和2~2.5mm中粒级,不同颗粒相互紧密嵌接,杂乱分布。斜长石呈半自形粒状,较洁净;石英呈他形填隙粒状,洁净;钾长石呈他形粒状,较混浊,显示条纹结构;角闪石呈半自形粒状,浅绿色;黑云母呈半自形片状,红褐色。

    细粒黑云母花岗闪长岩:呈灰白色,细粒花岗结构,块状构造,主要矿物成分为斜长石(50%)、石英(25%)、钾长石(15%)及绿泥石化黑云母(8%),少量磷灰石,金红石+金属矿物含量为2%;另见副矿物为磷灰石、不透明金属矿物等。长石大部分为板柱状,一般粒径在0.90mm×1.72mm以上,个别可达1.15mm×2.25mm~1.43mm×2.80mm;斜长石泥化和绢云母化明显,较浑浊;钾长石略具泥化现象,个别可见卡氏双晶,为正长石;石英多为不规则粒状,分布于长石粒间,粒径一般小于0.70mm,个别可达1.00mm;黑云母为片状,最大片径0.71mm × 1.00mm,大部分已绿泥石化并有细针状或网状金红石,部分可见铁质析出物;副矿物见磷灰石,多为不规则状,粒径小于0.12mm;金属矿物多为较规则粒状,一般粒径小于0.25mm,部分有白钛矿化特征。

    磁铁矿石特征(图版Ⅰ-c):呈黑色,他形粒状结构,块状构造。主要金属矿物为磁铁矿(90%),另见赤铁矿(3%)和个别黄铁矿。磁铁矿一般粒径小于0.15mm,镶嵌分布,沿边部及解理裂隙可见赤铁矿交代的现象,黄铁矿仅见个别微粒,粒径小于0.005mm。脉石矿物主要为石榴子石(7%),不规则粒状,粒径一般小于0.30mm,个别可达0.63mm,裂隙较发育,部分裂隙中见少量绿泥石及个别石英,充填分布于金属矿物粒间。

    将5件新鲜花岗闪长岩样品无污染碎样至200目后,送至自然资源部西安矿产资源监督检测中心,分析其岩石化学数据。样品加工前先切掉氧化或蚀变膜。岩石化学成分用XRF光谱测定,分析精度一般优于2%。微量元素用XRF玻璃饼熔样,以保证样品中的副矿物全部溶解,然后在ICP-MS上测定,分析精度一般为2%~5%。

    锆石单矿物分离在河北廊坊区域地质调查研究所完成。将约5kg的样品破碎至60~80目,淘洗后获得重砂,再经过磁选,得到纯度较高的试样,在双目显微镜下挑选出晶形和透明度较好的锆石颗粒,制作成环氧树脂样品靶。待环氧树脂充分固化后打磨抛光至锆石颗粒中心暴露,然后拍摄反射光、透射光和阴极发光图像,最后进行LA-ICPMS U-Pb同位素测定。锆石的阴极发光(CL)图像在西北大学大陆动力学国家重点实验室扫描电镜加载阴极发光仪上完成。

    LA-ICP-MS测定在西北大学大陆动力学重点实验室完成,使用的ICP-MS为Agilient公司生产的Agilient7500a。锆石U-Pb定年及微量元素分析在同一个系统内同时完成,分析仪器为配备193nmArF-excimer激光器的Geo-Las200M型激光剥蚀系统和Elan6100DRC型四极杆质谱仪,激光束斑直径为44μm。LA-ICP-MS激光剥蚀采样采用单点剥蚀的方式, 数据分析前用NIST610进行仪器调试, 使之达到最优状态。在测试过程中每测定5个样品点后, 重复测定一次标准锆石91500和一次标准玻璃NIST610进行校正,观察仪器的状态以保证测试的精度。锆石年龄计算采用标准锆石91500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NISTSRM610为外标,29Si为内标元素进行校正。数据采集处理采用Glitter(Version4.0),并采用Anderson软件[6]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[7]完成。因样品年轻,采用206Pb/238U年龄,206Pb/238U年龄加权平均值误差具95%置信度。

    岩石化学分析结果见表 1。SiO2含量为65.32%~69.19%,平均为67.10%,在TAS分类图解上位于花岗闪长岩区(图 2),为中酸性侵入岩类。K2O/Na2O=0.86~2.00,平均为1.31,显示贫钠富钾特征;SiO2-K2O岩石系列判别图解显示为高钾钙碱性系列岩石(图 3-a)。Al2O3含量为13.75% ~ 15.38%,平均为14.63%,A/CNK=0.95~1.12,平均为1.00,均小于1.1,岩石铝饱和指数判别图解显示属于准铝质花岗岩(图 3-b)。里特曼指数σ=0.78~ 2.09,大部分大于1.8;全碱(K2O + Na2O)含量为6.04%~7.49%,平均为6.84%;AR=1.8~2.16,平均为2.05。固结指数(SI)为0.71~1.32,平均为0.94;分异指数(DI)为71.18~73.08,平均为72.18,说明岩浆结晶分异程度较高。

    表  1  查隆花岗岩主量、微量和稀土元素分析结果
    Table  1.  Major, trace and rare earth element compositions of granite in Chalong area
    样品号 D1641-1 D1658-1 D1660-1 D1573-1 D1574-2
    岩石名称 中细粒花岗闪长岩 细粒黑云母花岗闪长岩 中粒黑云花岗闪长岩
    SiO2 66.5 69.19 67.74 65.32 66.74
    Al2O3 14.3 14.34 13.75 15.37 15.38
    MgO 2.05 1.41 1.89 1.97 1.65
    CaO 2.68 2.13 2.55 3.93 3.1
    Na2O 3.21 2.36 3.05 3.25 3.23
    K2O 4.13 4.71 4.44 2.79 3.01
    P2O5 0.2 0.14 0.19 0.18 0.15
    MnO 0.14 0.06 0.07 0.11 0.1
    TiO2 0.66 0.54 0.61 0.59 0.51
    TFe2O3 4.86 3.86 4.47 5.11 4.48
    烧失量 2.18 1.7 1.83 0.62 0.97
    总计 100.91 100.44 100.59 99.24 99.32
    A/NK 1.47 1.6 1.4 1.84 1.79
    A/CNK 0.98 1.12 0.95 0.99 1.08
    R1 2220 2598 2299 2443 2518
    R2 680 588 646 834 729
    Y 21.3 21.8 19.7 19.4 16
    La 64.2 38.8 60.1 43.7 30
    Ce 134 79 122 80 58.2
    Pr 13.6 8.54 12.7 8.14 5.96
    Nd 47.3 30.1 44.9 29.8 22.3
    Sm 6.96 5.67 7.19 5.1 4.06
    Eu 1.33 0.99 1.22 1.22 1.1
    Gd 6.99 5.64 6.51 4.88 3.71
    Tb 0.74 0.66 0.6 0.52 0.46
    Dy 3.79 3.96 3.57 3.37 2.75
    Ho 0.63 0.65 0.6 0.54 0.47
    Er 1.93 2.05 1.89 1.83 1.58
    Tm 0.24 0.27 0.28 0.22 0.21
    Yb 1.75 2.08 1.77 1.82 1.47
    Lu 0.22 0.29 0.24 0.25 0.2
    ΣREE 283.38 178.7 263.47 181.39 132.47
    LREE 267.09 163.1 248.01 167.96 121.62
    HREE 16.29 15.6 15.46 13.43 10.85
    LREE/ 16.4 10.46 16.04 12.51 11.21
    HREE 26.31 13.38 24.36 17.22 14.64
    (La/Yb)N 2.03 4.1 1.72 3.07 4.17
    (La/Sm)N 3.82 1.82 1.62 1.61 1.91
    (Gd/Lu)N 0.58 0.53 0.53 0.74 0.85
    δEu 34287.26 39102.42 36860.88 23162.58 24989.02
    K 3956.7 3237.3 3656.95 3537.05 3057.45
    Ti 981.9 600.2 662.9 828 626
    P 707.9 607.8 506.8 506 517
    Ba 33.4 24.7 43 26.8 22.7
    Th 3.17 2.26 6.24 2.38 1.64
    U 1.06 1.28 3.61 2.39 1.78
    Ta 7.41 15.8 25.1 13.7 14.2
    Nb 173 200 190.8 115 127
    Rb 225.4 211.5 210.1 163 126
    注:元素分析由自然资源部西安矿产资源监督检测中心完成;主量元素含量单位为%,微量和稀土元素为10-6
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    图  2  查隆花岗岩SiO2-(Na2O +K2O)图解(底图据参考文献[8])
    Figure  2.  SiO2-(Na2O +K2O)diagram of granite in Chalong area
    图  3  查隆花岗岩SiO2-K2O图解(a, 底图据参考文献[9])和A/CNK-A/NK图解(b, 底图据参考文献[10])
    Figure  3.  SiO2 versus K2O diagram (a) and A/CNK versus A/NK diagram (b) of granite in Chalong area

    稀土元素分析结果见表 1。稀土元素总量(ΣREE)变化较大,ΣREE为132×10-6~283×10-6,LREE/HREE值为10.46~16.40,平均为12.98,(La/Yb)N值为13.38~26.31,平均为18.39,表明轻稀土元素较富集且分馏程度较高。稀土元素球粒陨石标准化配分曲线呈右倾特征,轻稀土元素富集,重稀土元素亏损,表明该岩浆经过一定程度的分异(图 4-a)。δEu值为0.53~0.85,显示中等的负Eu异常,配分曲线在Eu处的沟谷不明显,反映该岩体虽有微弱的亏损,但分异程度不明显。

    图  4  查隆花岗岩稀土元素球粒陨石标准化配分型式图(a)和微量元素原始地幔标准化蛛网图(b)(底图据参考文献[11])
    Figure  4.  Chondrite-normalized REE patterns (a) and trace element spider diagrams (b) for granite in Chalong area

    微量元素分析结果见表 1。原始地幔标准化微量元素蛛网图(图 4-b)显示,Th、Rb、K元素含量偏高,显示正异常;Ba、Nb、P、Ti元素显示负异常;比值蛛网图呈“W”型,大离子亲石元素Rb、K相对富集,Ba、Sr相对亏损;高场强元素Th、La、Nd相对富集,Ti、Nb、P相对亏损,P和Ti亏损一般与俯冲有关,这种特点与火山弧环境的花岗岩类似。

    测年样品均采于查隆岩体中部。其中, 样品RZ1641-1为中细粒花岗闪长岩,锆石晶形较完好,多呈长柱状,长宽比为2~3,发育明显的振荡环带,为典型的岩浆成因锆石。测得24粒锆石24个数据的206Pb/238U年龄介于88.5~91.3Ma之间(表 2图 5),其年龄加权平均值为89.88±0.55Ma(95%置信度),MSWD=0.43(图 5)。

    表  2  查隆岩体花岗闪长岩(RZ1641-1)和黑云花岗闪长岩(RZ1573-1)LA-ICP-MS锆石U-Th-Pb同位素数据
    Table  2.  LA-ICP-MS zircon U-Th-Pb data of granodiorite (RZ1641-1) and biotite granodiorite(RZ1573-1)in Chalong area
    测点号 同位素比值 年龄/Ma
    207Pb/206Pb 207Pb/235U 206Pb/238U 208Pb/232Th 207Pb/206Pb 207Pb/235U 206Pb/238U 208Pb/232Th
    花岗闪长岩
    1 0.0479 0.0034 0.0936 0.0063 0.0142 0.0002 0.0043 0.0001 95 160 91 6 91 2 87 2
    2 0.0475 0.0022 0.0921 0.0039 0.0141 0.0002 0.0045 0.0001 73 108 90 4 90 1 91 1
    3 0.0477 0.0024 0.093 0.0043 0.0141 0.0002 0.0044 0.0001 83 116 90 4 91 1 89 2
    4 0.0473 0.0061 0.0925 0.0116 0.0142 0.0004 0.0047 0.0002 65 283 90 11 91 3 94 4
    5 0.0484 0.0026 0.0923 0.0045 0.0138 0.0002 0.0042 0.0001 119 120 90 4 89 1 84 2
    6 0.0476 0.0021 0.0931 0.0037 0.0142 0.0002 0.0045 0.0001 76 103 90 3 91 1 91 1
    7 0.0473 0.0042 0.0926 0.0079 0.0142 0.0003 0.0045 0.0001 63 199 90 7 91 2 92 3
    8 0.0482 0.0071 0.0922 0.0132 0.0139 0.0004 0.0048 0.0002 107 315 90 12 89 3 97 4
    9 0.0476 0.0024 0.093 0.0043 0.0142 0.0002 0.0044 0.0001 78 117 90 4 91 1 88 2
    10 0.0471 0.0025 0.0927 0.0045 0.0143 0.0002 0.0047 0.0001 55 120 90 4 91 1 94 2
    11 0.0481 0.0064 0.0929 0.0121 0.014 0.0004 0.0049 0.0002 106 289 90 11 90 2 98 4
    12 0.0478 0.0027 0.0911 0.0047 0.0138 0.0002 0.0047 0.0001 89 128 89 4 89 1 96 2
    13 0.047 0.0051 0.0916 0.0097 0.0141 0.0003 0.0048 0.0002 50 242 89 9 91 2 97 4
    14 0.0479 0.004 0.0923 0.0073 0.014 0.0003 0.0045 0.0001 95 185 90 7 90 2 90 2
    15 0.047 0.0023 0.0917 0.0041 0.0142 0.0002 0.0043 0.0001 49 112 89 4 91 1 86 2
    16 0.0469 0.0025 0.0906 0.0045 0.014 0.0002 0.0043 0.0001 45 125 88 4 90 1 87 1
    17 0.0483 0.0034 0.0933 0.0063 0.014 0.0002 0.0046 0.0001 112 160 91 6 90 1 92 2
    18 0.0481 0.0029 0.0922 0.0051 0.0139 0.0002 0.0046 0.0001 102 134 90 5 89 1 92 2
    19 0.0482 0.0026 0.0924 0.0046 0.0139 0.0002 0.0043 0.0001 109 122 90 4 89 1 87 2
    20 0.0477 0.0036 0.0909 0.0065 0.0138 0.0002 0.0041 0.0001 85 171 88 6 89 2 83 2
    21 0.0481 0.0031 0.0925 0.0056 0.014 0.0002 0.0045 0.0001 103 144 90 5 89 1 90 2
    22 0.0482 0.0065 0.0936 0.0123 0.0141 0.0004 0.0046 0.0002 107 292 91 11 90 2 93 4
    23 0.048 0.0065 0.0916 0.0122 0.0138 0.0004 0.0048 0.0002 97 295 89 11 89 2 97 4
    24 0.0489 0.0039 0.0942 0.0071 0.014 0.0002 0.0043 0.0001 145 176 91 7 89 2 87 2
    黑云花岗闪长岩
    1 0.0469 0.0065 0.0885 0.0117 0.0137 0.0004 0.004 0.0003 41 301 86 11 88 3 82 6
    2 0.0482 0.0052 0.0895 0.0091 0.0135 0.0004 0.0039 0.0002 111 235 87 8 86 2 78 4
    3 0.0481 0.0025 0.0904 0.0039 0.0136 0.0002 0.0042 0.0001 104 117 88 4 87 1 85 2
    4 0.0478 0.0029 0.0921 0.0049 0.014 0.0002 0.0045 0.0001 86 137 90 5 90 2 90 3
    5 0.0477 0.0061 0.0917 0.0112 0.014 0.0004 0.0047 0.0003 82 279 89 10 89 3 95 6
    6 0.048 0.0026 0.0848 0.004 0.0128 0.0002 0.0039 0.0001 97 125 83 4 82 1 79 2
    7 0.0481 0.0032 0.0904 0.0053 0.0136 0.0002 0.0042 0.0001 105 148 88 5 87 2 85 2
    8 0.0473 0.008 0.0853 0.014 0.0131 0.0005 0.0043 0.0004 65 360 83 13 84 3 87 7
    9 0.0477 0.004 0.0901 0.0071 0.0137 0.0003 0.0041 0.0002 81 190 88 7 88 2 82 3
    10 0.0477 0.0039 0.0862 0.0066 0.0131 0.0003 0.004 0.0002 85 185 84 6 84 2 80 3
    11 0.0478 0.0027 0.087 0.0042 0.0132 0.0002 0.0038 0.0001 86 127 85 4 85 1 77 2
    12 0.0473 0.0043 0.0863 0.0073 0.0132 0.0003 0.004 0.0002 63 202 84 7 85 2 81 3
    13 0.0475 0.0028 0.0908 0.0047 0.0139 0.0002 0.004 0.0001 76 135 88 4 89 1 81 2
    14 0.0478 0.004 0.0885 0.007 0.0134 0.0003 0.0041 0.0002 86 190 86 7 86 2 82 3
    15 0.049 0.0166 0.0913 0.0303 0.0135 0.0009 0.0043 0.0004 146 646 89 28 87 6 86 8
    16 0.0479 0.0036 0.0922 0.0064 0.014 0.0003 0.0043 0.0001 93 171 90 6 89 2 88 3
    17 0.0477 0.0038 0.0924 0.0069 0.014 0.0003 0.0044 0.0002 84 181 90 6 90 2 88 3
    18 0.0477 0.0028 0.0892 0.0047 0.0136 0.0002 0.0042 0.0001 81 136 87 4 87 1 84 2
    19 0.0477 0.003 0.0877 0.0049 0.0133 0.0002 0.004 0.0001 85 142 85 5 85 2 81 2
    20 0.0485 0.0031 0.0912 0.0053 0.0137 0.0002 0.0041 0.0001 121 146 89 5 87 2 83 2
    21 0.0477 0.0028 0.0869 0.0044 0.0132 0.0002 0.0042 0.0001 81 133 85 4 85 1 85 3
    22 0.0483 0.0028 0.0904 0.0045 0.0136 0.0002 0.0041 0.0001 115 129 88 4 87 1 82 3
    23 0.0477 0.0032 0.0933 0.0057 0.0142 0.0003 0.0042 0.0001 85 155 91 5 91 2 85 3
    24 0.0479 0.0028 0.0933 0.0047 0.0141 0.0002 0.0045 0.0001 91 132 91 4 91 2 90 2
    25 0.0473 0.0029 0.0855 0.0047 0.0131 0.0002 0.004 0.0001 62 142 83 4 84 1 81 2
    26 0.0482 0.0086 0.0846 0.0146 0.0127 0.0005 0.0042 0.0003 109 372 83 14 82 3 84 7
    27 0.0468 0.0027 0.0877 0.0043 0.0136 0.0002 0.0041 0.0001 41 130 85 4 87 1 82 2
    28 0.0482 0.0031 0.0921 0.0053 0.0139 0.0003 0.0042 0.0001 109 144 89 5 89 2 85 3
    29 0.0473 0.0053 0.0865 0.0092 0.0133 0.0004 0.0043 0.0002 63 247 84 9 85 2 86 4
    30 0.0478 0.0032 0.0889 0.0053 0.0135 0.0003 0.004 0.0001 89 151 87 5 86 2 81 2
    下载: 导出CSV 
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    图  5  查隆花岗岩(RZ1641-1)锆石阴极发光(CL)图像(a)和U-Pb年龄谐和图(b、c)
    Figure  5.  CL images (a) and U-Pb concordia diagrams (b, c) of zircon from granite (sample RZ1641-1) in Chalong area

    样品RZ1573-1为黑云花岗闪长岩,锆石晶形较完好,多呈长柱状,长宽比为2~4,发育明显的振荡环带,为典型的岩浆成因锆石。测得29粒锆石的30个数据的206Pb/238U年龄介于82.1~90.8Ma之间,其年龄加权平均值为86.6±1.0Ma(95%置信度),MSWD=0.43(表 3;图 6)。

    图  6  查隆黑云花岗闪长岩(RZ1573-1)锆石阴极发光(CL)图像(a)和U-Pb年龄谐和图(b、c)
    Figure  6.  CL images (a) and U-Pb concordia diagrams (b, c) of zircon from biotite granodiorite (sample RZ1573-1) in Chalong area

    晚白垩世花岗岩多分布于南冈底斯中东段,中冈底斯和北冈底斯零星出露。其中南冈底斯带门巴地区金达北部的花岗闪长岩年龄为68.8± 1.6Ma(U-Pb年龄)[12],朗县—米林地区的花岗岩年龄介于84~78Ma之间(U-Pb年龄)[13],雪拉岩体的花岗闪长岩年龄为70.4±2.2Ma(U-Pb年龄)[14],谢通门地区的花岗岩年龄介于110~90Ma之间(U-Pb年龄)[15];而冈底斯带西北缘的扎隆琼娃石英二长岩年龄为85.6±0.48Ma(U-Pb年龄)[16],中冈底斯带岩体的花岗闪长岩年龄为74.8±1.6Ma(U-Pb年龄)[17],扎布耶茶卡的第二期闪长岩年龄为100.2±0.75Ma[18]。可见区域上既有晚白垩世早期的岩体也有晚白垩世末期的岩体,岩性以花岗闪长岩为主,多为俯冲型的Ⅰ型花岗岩。本文中2个年龄样品采自中冈底斯,年龄介于89.88~ 86.6Ma之间,岩性、地球化学特征及构造环境与区域上高度一致。结合目前冈底斯带晚白垩世岩体的特点,纵向上具有从北向南年龄变老的趋势,反映从俯冲到碰撞造山岩浆活动的中心总体从南向北发生迁移的过程。

    岩相学上没有发现堇青石、石榴子石、白云母等传统意义上S型花岗岩判别标志的富铝矿物。岩石CIPW标准矿物计算显示,刚玉分子3个样品均小于1%,Na2O含量多接近或大于3.2%,反映Ⅰ型花岗岩的特点。综上所述,查隆岩体应为高钾钙碱性的准铝质Ⅰ型花岗岩。

    研究表明,微量元素是岩浆混合作用和成岩过程的最好记录,壳、幔两类岩浆混合及成岩过程中,有显著的元素迁移和成分交换,并形成独特的扩散作用[19]。根据微量元素地球化学性质,Rb为强不相容元素,Ti为高场强元素,来自不同岩浆房成岩后,Rb/Ti值变化较大[20]。查隆岩体的Rb/Ti值为0.03~0.06,说明幔源基性岩浆和壳源酸性岩浆已经发生混合岩浆作用。Nb、Ta为强不相容元素,在侵蚀和变质作用过程中较稳定, Nb/Ta值可以示踪原始岩浆源区的特征[21-22]。查隆花岗闪长岩的Nb/ Ta值为5.73~12.34,其特征介于原始地幔(17.39)[23]和大陆地壳(Nb/Ta=11~12)[24]之间,暗示岩浆源区可能由地幔熔体和地壳熔体的混合形成。另外,熔融实验研究表明,陆壳熔融通常富钠,不能形成具高钾钙碱性特征的花岗质岩浆[25-27]。Panino等[27]根据陆壳岩石熔融结果,提出高钾钙碱性花岗岩通常是壳幔混合的结果。综上所述,查隆岩体岩浆来源显示了壳幔岩浆混合起源的特征。

    研究认为,新特提斯洋大致在晚三叠世或更早的时间打开,同时形成班公湖-怒江洋(北支)及雅鲁藏布洋(南支)[28]。大致于中侏罗世扩张到最大规模,然后开始消减缩小。北支班公湖-怒江洋大致在早白垩世末(100Ma左右)完全闭合,完成了拉萨地块与羌塘地块的碰撞拼合,南支雅鲁藏布洋闭合较晚。在古近纪印度大陆开始与拉萨地块碰撞[29]。而弧背断隆带和中冈底斯的形成时代分别为105~ 135Ma和95~145Ma,说明至少在早侏罗世,冈底斯带还受到班公湖怒江洋向南、雅鲁藏布江洋向北的双向俯冲作用影响,直到晚白垩世竟柱山组(位于岩体西北部)在93.9~100.5Ma沉积时,冈底斯中北部的俯冲作用才基本停止[30]。雅鲁藏布洋板块自中侏罗世开始向北俯冲于拉萨地块之下,65~70Ma前,雅鲁藏布洋开始闭合,印度-亚洲大陆开始碰撞[3]

    本次获得的年龄无疑属于新特提斯洋板块俯冲阶段,是俯冲成因的花岗闪长岩,表明在冈底斯带中部晚白垩世早期(约90Ma)至少存在一期由俯冲作用诱导的岩浆混合作用。到晚白垩世时,班公-怒江洋盆已经闭合,雅鲁藏布江洋盆向北单向强烈俯冲,由于洋壳俯冲速度不断加快,沿俯冲带产生的摩擦力持续增强,重熔速度加快,使地壳深部物质熔融。岩体的岩浆源区来自于上地幔和下地壳物质不断熔融,由于幔源岩浆在上侵过程中与下地壳物质发生不同程度的混溶作用,形成晚白垩世花岗闪长岩及同时期的磁铁矿。双向剪刀式俯冲作用只能解释早侏罗世―早白垩世的花岗岩特点,到晚白垩世已经变成单向俯冲,区域上晚白垩世岩体集中发育在南冈底斯带,该岩体的发现及认识对研究中冈底斯带晚白垩世岩浆作用的深部动力学过程具有重要意义。

    查隆地区的磁铁矿与燕山末期的中酸性岩浆侵入活动有关,岩浆演化晚期分离出成矿热液,沿层间裂隙、构造破碎带等部位与围岩发生接触交代反应,形成磁铁矿体。区内石炭系―二叠系沉积地层,燕山末期的侵入岩及近北西向大断裂控制的次级断裂和褶皱的发育构成了最有利的成矿岩性组合及控矿条件。中酸性花岗闪长岩直接侵入到有较强变形的石炭系―二叠系沉积地层,矿区构造复杂,具备良好的围岩条件,发现的磁铁矿石品位较富,说明该区是寻找与接触交代作用有关的富铁矿产地的有利区域,有望在区内找到中等以上规模的富磁铁矿产地。

    磁铁矿石普遍石榴子石化、少量绿泥石化,矿点的东侧及南侧均有中二叠统下拉组灰岩发育,具有矽卡岩型磁铁矿特征;脉状和浸染状磁铁矿的出现,表明矿床后期具有热液叠加特征。综上所述,该矿床早期为矽卡岩型成矿,后期叠加热液改造,其中矽卡岩期是磁铁矿形成的主要阶段,矿床成因类型应为矽卡岩-热液叠加改造型磁铁矿床。

    冈底斯带中北部晚白垩世可能发生过金属成矿大爆发,目前在冈底斯中北部已发现日阿铜矿床、尕尔穷铜矿床、拔拉扎铜钼矿床等,这些矿床的成矿环境、成矿条件、控矿构造、岩体地球化学特征等都具有相似性,可能属于同一成矿系统。该磁铁矿点的发现对开展西藏冈底斯中北部地区中生代矽卡岩型铁铜矿典型矿床的成矿作用、找矿方向具有重要意义。

    (1)查隆花岗闪长岩和黑云花岗闪长岩锆石U-Pb年龄分别为86.6±1.0Ma和89.88±0.55Ma,为雅江洋壳向北俯冲作用延续到晚白垩世的年代学证据,该岩体的发现为中冈底斯带存在晚白垩世岩浆活动提供了证据。

    (2)岩石学、岩石地球化学特征显示,查隆岩体为高钾钙碱性Ⅰ型花岗岩,为壳幔混合的产物。

    (3)查隆磁铁矿的成因类型为矽卡岩型-热液叠加改造型,对研究西藏冈底斯中北部地区中生代矽卡岩型铁铜矿典型矿床的成矿作用和找矿方向具有重要意义。

  • 图  1   西天山温泉地区侵入岩分布简图(据参考文献修改)

    Figure  1.   Simplified intrusive rock map of the Wenquan area in West Tianshan

    图  2   温泉县别珍套山地质简图(据参考文献修改)

    Figure  2.   Simplified geological map for the Biezhentao Mountain of Wenquan County

    图  3   新元古代片麻状-眼球状花岗岩野外特征剖面图

    a—托克赛附近岩体特征示意图;b—夏尔依西根附近岩体特征示意图

    Figure  3.   Simplified geological map for theBiezhentao Mountain of Wenquan County

    图  4   锆石阴极发光(CL)图像、U-Pb年龄分析点(实线圈)及Lu-Hf同位素分析点(虚线圈)和206Pb/238U年龄

    Figure  4.   CL images, analytical points for U-Pb(solid circles), analytical points for Lu-Hf isotope(dashed circles)and 206Pb/238U ages of zircons

    图  5   花岗岩锆石U-Pb谐和图和206Pb/238U年龄加权平均值图

    Figure  5.   U-Pb concordia diagrams and weighted average 206Pb/238U ages of zircons for the granitic gneiss

    图  6   SiO2-K2O图解(a)和铝质判别图解(b)

    Figure  6.   The K2O versus SiO2 diagram(a) and Shand's index Al/(Na + K) versus Al/(Ca + Na + K)plots(b)

    图  7   稀土元素配分曲线(a)和微量元素蛛网图(b)

    Figure  7.   Chondrite-normalized REE patterns(a)and multi-element variation diagrams(b)

    图  8   (87Sr/86Sr)iNd(t)(a)和锆石年龄-εHf(t)关系图(b)

    MORB—洋中脊玄武岩;OIB—洋岛玄武岩;DM—亏损地幔;CHUR—球粒陨石均一库

    Figure  8.   Diagrams of (87Sr/86Sr)iNd(t)(a)and age-εHf(t)(b)for the granitic gneiss

    图  9   新元古代片麻状花岗岩R1-R2(a)和Rb/30-Hf-3Ta(b)构造环境判别图

    Figure  9.   Tectonic implications for granite R1-R2(a)and Rb/30-Hf-3Ta(b) diagrams

    表  1   新元古代片麻状花岗岩锆石U-Th-Pb年龄测试结果

    Table  1   Zircon U-Th-Pb dating results of Neoproterozoic granitoids

    测点Pb
    (总量)
    232Th238UTh/U同位素比值同位素年龄/Ma谐和
    度/%
    /10-6207Pb/206Pb207Pb/235U206Pb/238U207Pb/206Pb207Pb/235U206Pb/238U
    PM16-2-TW1
    1122786880.110.06810.00171.5240.0390.16240.002487050940169701396.9
    21722539480.270.06660.00141.5040.0340.16380.002382644932149781395.3
    317815910660.150.06740.00141.4190.0310.15270.002284942897139161297.9
    4216138710261.350.06690.00141.3560.0300.14710.002183443870138851298.3
    51271576620.240.07260.00171.6700.0400.16680.00241003469971599513100.2
    650761932330.190.06910.00101.3750.0230.14440.0020901298791087011101.0
    747381029450.280.06930.00101.4090.0240.14750.0020908308931088711100.7
    823318013890.130.06710.00131.4190.0290.15350.002283939897129211297.4
    91601009480.110.06620.00151.4170.0330.15530.002281246896149311296.2
    1017318410400.180.06850.00151.4370.0320.15210.002288443904139131299.0
    1220461713160.470.07160.00141.3920.0300.14110.0020973408851385111104.0
    1318713511090.120.06640.00141.4250.0320.15560.002282044899139321296.5
    141391937490.260.06690.00161.5260.0380.16550.002483449941159871395.3
    15621203510.340.06750.00241.4320.0510.15400.002585372903219231497.8
    1618213511240.120.06730.00141.3910.0310.15000.002284642885139011298.2
    171361147950.140.06790.00151.4590.0350.15600.002386546914149341397.9
    1832719219850.100.06730.00111.4200.0260.15320.002184634897119191297.6
    19234113514360.790.06910.00131.4270.0280.14980.0021902379001290012100.0
    201491098720.130.06750.00141.4800.0330.15920.002385243922139521396.8
    PM18-61-TW1
    122234613370.260.06790.00141.4070.0320.15040.002386642892139031398.8
    220647411710.400.07250.00171.4990.0380.15020.0024999479301590213103.1
    332034418890.180.06960.00141.4980.0330.15610.002491841929149351399.4
    429333816940.200.06990.00151.5210.0360.15800.002492544939149451499.4
    527636914710.250.07210.00181.6520.0430.16640.002698749990179921599.8
    6598105032530.320.07170.00131.5880.0330.16090.0025977389661396214100.4
    723790713130.690.07440.00231.5930.0500.15560.00261051609682093214103.9
    824424014080.170.07030.00181.5460.0420.15960.002593752949179551499.4
    9836212843860.490.08450.00161.7700.0370.15200.002313053510351391213113.5
    1039651121180.240.07370.00191.6770.0460.16510.002610345110001798515101.5
    1139269123480.290.07130.00151.4670.0350.14940.0023966439171489813102.1
    1219534410400.330.07690.00221.7240.0510.16280.002711185610181997215104.7
    1322144212310.360.07070.00191.5180.0420.15580.0025949539381793414100.4
    1429641316190.260.06960.00151.5700.0370.16370.002591744958159771498.1
    1519521210650.200.07160.00191.6560.0460.16780.0027975539921810001599.2
    1628452215940.330.07280.00161.5730.0380.15680.00241010449601593914102.2
    1719133110640.310.06830.00191.4810.0430.15730.002787755923189421598.0
    1841654423990.230.07010.00141.5060.0340.15570.0026931409331493314100.0
    1919437610910.340.06890.00201.4740.0450.15510.002789659920199301598.9
    2029646016560.280.06880.00171.4960.0400.15760.002789351929169441598.4
    2131450316210.310.07700.00201.7810.0500.16770.002911215210391899916104.0
    2224436813290.280.06940.00191.5620.0460.16320.002891156955189741698.0
    2323136712170.300.06890.00191.5870.0470.16710.002989557965199961696.9
    2426948514340.340.06840.00181.5450.0440.16370.002888255949189771697.1
    2519420910630.200.06940.00211.5850.0490.16560.002991060964199881697.6
    PM11-30-TW1
    120938011790.320.07140.00151.4330.0320.14550.0021969429031387612103.1
    218629010810.270.06890.00151.3520.0310.14240.0020896458691385811101.3
    457973020.320.06840.00281.4510.0590.15400.002687982910249231498.6
    51202586090.420.06850.00201.4760.0450.15630.002488460921189361398.4
    6891954710.410.07020.00251.4300.0500.14780.0023933709022188913101.5
    8621433210.440.08270.00341.6620.0670.14580.00251262789942687714113.3
    91352676930.390.06900.00191.5060.0430.15820.002490057933189471398.5
    10531232660.460.07490.00321.5910.0680.15410.00271066849672692415104.7
    11351201810.670.06640.00391.3450.0770.14700.0028818117865348841697.9
    12521392740.510.07120.00311.4540.0630.14810.0026963869112689014102.4
    13971875000.370.07010.00221.5060.0470.15590.002493162933199341399.9
    14381141910.600.06930.00351.4470.0730.15160.0028907101909309101599.9
    151082235510.400.06790.00201.4570.0430.15570.002386659913189331397.9
    16661693540.480.07040.00251.3920.0500.14350.0023939718852186413102.4
    17561112810.390.06990.00261.5360.0570.15950.002692475945239541499.1
    18812024140.490.07000.00221.4550.0460.15070.0023929639121990513100.8
    19661613400.470.06730.00241.4120.0500.15220.002484871894219131397.9
    21411132110.540.07180.00321.4550.0630.14710.0025979879122688514103.1
    22801903990.480.06910.00231.4790.0500.15540.002490167922209311399.0
    PM16-11-TW3
    1721863950.470.0630.00331.3370.0700.15410.0029708108862319241693.3
    21545348070.660.07150.00221.5350.0480.15580.0026970619441993414101.1
    31102736050.450.07130.00261.5370.0560.15650.0027965729452393715100.9
    4961855160.360.06950.00271.5490.0610.16160.002991478950249661698.3
    51232587120.360.07060.00251.4640.0530.15040.0026947719162290315101.4
    6691663750.440.07230.00381.5550.0820.1560.00329951049523293418101.9
    735731750.420.07470.00571.6870.1260.16390.004106014610044897822102.7
    8401232180.570.06980.0051.4720.1040.15310.00359221409194391820100.1
    9561543190.480.06840.00421.3630.0830.14470.00318801238733687117100.2
    10782074180.490.06960.00331.5060.0700.1570.00391793933299401799.3
    11971635430.30.07120.00281.5240.0600.15530.0028963789402493115101.0
    12471342720.490.06860.00331.3820.0660.14620.0028885968812888016100.1
    1320754412160.450.06890.00161.3820.0350.14540.0023897478811587513100.7
    15882294930.460.0720.00251.4960.0530.15070.0026985709292290515102.7
    16591543320.460.06450.00331.3350.0670.15010.0028758103861299021695.5
    17611023790.270.06870.0031.3800.0610.14560.0027890888802687615100.5
    181192127170.290.06940.00221.3970.0460.14610.0025909658881987914101.0
    19451182500.470.07110.00371.5080.0770.15380.00319601029343192217101.3
    20611513360.450.07030.00311.4800.0650.15270.0028937889222791616100.7
    注:谐和度=100×(207Pb/235U年龄)/(206Pb/238U年龄)
    下载: 导出CSV

    表  2   新元古代早期片麻状-眼球状花岗岩主量元素分析结果

    Table  2   Abundances of major elements of Neoproterozoic granitoids %

    样号岩性SiO2Al2O3Fe2O3FeOCaOMgOK2ONa2OTiO2P2O5MnO烧失量H2O+CO2总量Na2O+K2OA/CNKA/NK
    PM11-30-HQ1片麻状-眼球
    状花岗岩
    66.1813.262.115.352.770.515.3120.790.190.121.210.540.096100.447.310.941.47
    PM11-30-HQ269.0412.962.033.751.980.445.432.190.610.140.11.170.680.032100.557.620.991.37
    PM11-30-HQ369.5313.271.283.521.470.455.942.260.550.130.091.320.560.033100.48.21.031.31
    PM11-30-HQ469.9612.851.73.421.640.555.582.310.60.130.080.990.580.082100.477.891.001.31
    PM11-42-HQ167.8713.991.254.52.280.864.232.940.730.230.090.840.240.012100.067.171.031.49
    PM11-42-HQ269.1613.881.453.482.040.624.582.850.540.180.080.950.44< 0.01100.257.431.041.44
    PM16-2-HQ173.6912.451.061.741.640.625.062.210.390.110.040.80.320.13100.267.271.031.37
    PM16-2-HQ469.5513.321.662.51.950.495.852.650.550.130.061.120.340.362100.538.50.941.25
    PM16-11-HQ1糜棱岩化眼
    球状花岗岩
    70.2814.211.012.081.861.044.073.410.480.10.041.250.550.33100.717.481.061.42
    PM16-11-HQ370.1514.70.992.652.190.712.754.020.450.120.060.980.40.094100.266.771.081.53
    PM16-18-HQ2片麻状-眼球
    状花岗岩
    66.1313.52.014.82.690.595.472.080.790.190.121.430.480.407100.697.550.951.44
    PM16-101-HQ268.3513.911.473.421.841.583.373.10.690.170.071.83<0.010.276100.086.471.151.59
    PM16-101-HQ367.8314.371.672.921.851.394.942.450.630.150.071.520.960.078100.837.391.131.53
    PM18-61-YQ1糜棱岩化眼
    球状花岗岩
    71.3513.740.81.421.310.766.682.180.320.10.041.10.720.081100.68.861.041.27
    PM18-61-YQ267.514.361.832.482.421.344.332.780.590.140.061.971.320.033101.157.111.051.55
    PM18-61-YQ368.5113.921.762.721.681.543.932.910.620.140.0621.480.117101.396.841.151.54
    下载: 导出CSV

    表  3   新元古代早期片麻状-眼球状花岗岩稀土元素分析结果

    Table  3   Abundances of rare earth elements of Neoproterozoic granitoids 10-6

    样号岩性LaCePrNdSmEuGdTbDyHoErTmYbLuYΣREELREEHREELREE/
    HREE
    LaN/
    YbN
    δEu
    PM11-30-HQ1片麻状-眼球
    状花岗岩
    12425929.611322.54.2724.33.8824.2513.72.1313.82.02122641.40552.3789.036.206.450.55
    PM11-30-HQ215231934.912824.83.3125.44.0125.35.3815.22.2814.52.16136756.24662.0194.237.037.520.40
    PM11-30-HQ31362743110820.13.0620.33.1219.2411.51.7110.81.7103644.49572.1672.337.919.030.46
    PM11-30-HQ416032135.212723.53.0924.34.0123.84.9914.12.0612.71.95123757.70669.7987.917.629.040.39
    PM11-42-HQ192.61942280.515.72.5416.12.414.22.87.691.176.921.0572.5459.67407.3452.337.789.600.48
    PM11-42-HQ286.417118.965.212.72.5313.32.112.82.637.171.116.911.0665403.81356.7347.087.588.970.59
    PM16-2-HQ149.810611.843.58.841.278.171.267.261.454.060.634.060.6237.4248.72221.2127.518.048.800.45
    PM16-2-HQ411220624.289.216.21.8116.52.6615.93.39.361.459.311.3882.8509.27449.4159.867.518.630.34
    PM16-11-HQ1糜棱岩化眼
    球状花岗岩
    73.21361551.28.891.078.121.257.281.484.280.634.280.6242.2313.30285.3627.9410.2112.270.38
    PM16-11-HQ362.111412.844.77.680.836.40.94.70.882.410.362.320.3525.9260.43242.1118.3213.2219.200.35
    PM16-18-HQ2片麻状-眼球
    状花岗岩
    10120925.198203.6619.93.12183.69.871.529.861.5291.6524.15456.7667.396.787.350.55
    PM16-101-HQ269.113115.555.79.951.339.221.277.161.440.623.960.6139.9310.82282.5828.2410.0112.520.42
    PM16-101-HQ351.610111.742.68.231.167.61.156.811.363.780.583.710.5737241.85216.2925.568.469.980.44
    PM18-61-YQ1糜棱岩化眼
    球状花岗岩
    4792.410.638.47.381.286.771.066.321.243.520.533.490.5234.7220.51197.0623.458.409.660.54
    PM18-61-YQ257.811212.545.38.521.427.771.237.171.454.020.613.920.639.6264.31237.5426.778.8710.580.52
    PM18-61-YQ371.314416.157.610.51.289.421.47.971.554.160.613.960.5941.6330.44300.7829.6610.1412.920.39
    下载: 导出CSV

    表  4   新元古代早期片麻状-眼球状花岗岩微量元素分析结果

    Table  4   Abundances of trace elements of Neoproterozoic granitoids 10-6

    样号岩性PbCrNiCoRbCsSrBaVNbTaZrHfGeUTh
    PM11-30-HQ1片麻状-眼球
    状花岗岩
    373.813.423.561622.7215314101573.25.02111027.71.753.7328.5
    PM11-30-HQ241.22.732.072.71801.56126108010.862.44.3881621.51.794.3643.8
    PM11-30-HQ343.53.452.252.952042.0215612001253.83.7877120.31.53.7238.2
    PM11-30-HQ439.63.43.33.132172.82142101013.358.54.1885422.91.544.5547.7
    PM11-42-HQ126.520.18.175.392269.9714264738.333.72.259616.31.823.750.9
    PM11-42-HQ229.37.024.433.072357.9513366126.427.51.8849113.91.81550.5
    PM16-2-HQ14211.45.634.062044.718572928.310.70.672758.061.451.9422.6
    PM16-2-HQ437.74.392.763.712283.2490.368018.743.42.9161016.31.843.433.4
    PM16-11-HQ1糜棱岩化眼
    球状花岗岩
    53166.666.331903.3828889034.2141.362396.641.224.1231.2
    PM16-11-HQ331.27.543.824.72115.7520638327.119.61.522646.971.474.9231.1
    PM16-18-HQ2片麻状-眼球
    状花岗岩
    38.84.613.024.441993.13180137019.465.14.25114026.41.663.2618
    PM16-101-HQ225.822.38.989.042029.0118553457.215.81.32788.121.523.0932
    PM16-101-HQ348.319.57.948.432418.0115276952.814.81.162487.361.433.4225.9
    PM18-61-YQ1糜棱岩化眼
    球状花岗岩
    54.611.25.494.12892.8913093622.67.680.681715.421.664.0532.4
    PM18-61-YQ241.824.18.488.522112.7711383651.413.51.12467.121.643.7429.7
    PM18-61-YQ336.922.48.69.422093.311267325114.51.22517.361.423.9637.8
    下载: 导出CSV

    表  5   新元古代片麻状花岗岩Sr-Nd同位素测试结果

    Table  5   Abundances of Sr-Nd of Neoproterozoic granitoids

    样号PM11-30
    -HQ1
    PM11-30
    -HQ2
    PM16-2
    -HQ1
    PM16-2
    -HQ4
    PM11-42
    -HQ1
    PM11-42
    -HQ2
    PM16-101
    -HQ2
    PM16-101
    -HQ3
    PM18-61
    -YQ3
    87Rb/86Sr2.9230553.3898362.7733186.5287004.0653004.5727002.7965004.0239004.511800
    87Sr/86Sr0.7550710.7619950.7456290.7876130.7558980.7642900.7459110.7649200.766481
    0.0000150.0000150.0000130.0000170.0000160.0000150.0000110.0000210.000017
    ISr0.7172230.7181020.7091610.7017630.7024400.7041600.7086950.7113700.705204
    147Sm/144Nd0.1223630.1171790.1225890.1131000.1212000.1163000.1129000.1174000.113800
    143Nd/144Nd0.5121400.5121200.5120340.5120430.5121830.5121350.5119070.5118840.511856
    0.0000080.0000080.0000110.0000100.0000070.0000100.0000110.0000100.000006
    锆石年龄/
    Ma
    906906920920920920931931950
    εNd(0)-9.71-10.10-11.79-11.61-8.88-9.81-14.26-14.71-15.25
    εNd(t)-1.10-0.88-3.07-1.770.01-0.35-4.29-5.27-5.19
    fSm/Nd-0.38-0.40-0.38-0.43-0.38-0.41-0.43-0.40-0.42
    tDM1/Ma168516261866167715941588187720011971
    tDM2/Ma165016321820171515711600192820072016
    下载: 导出CSV

    表  6   新元古代片麻状花岗岩锆石Lu-Hf同位素测试结果

    Table  6   Abundances of Lu-Hf of zircons for the Neoproterozoic granitoids

    测点176Yb/177Hf176Lu/177Hf176Hf/177HfU年龄/MaεHf(0)εHftDM1/MatDM2/MatcDM/MafLu/Hf
    PM16-101-TW3
    10.0782670.0017280.2825190.000022934-8.9510.620.77989105911291135-0.95
    20.0295760.0006100.2822860.000022960-17.193.640.75455135115881603-0.98
    30.0532450.0011140.2823900.0000211005-13.507.990.74790122213501360-0.97
    40.0593850.0012840.2824260.0000231080-12.2310.760.79838117712331239-0.96
    50.0618040.0013980.2824320.000023895-12.046.900.82005117313331344-0.96
    60.0496620.0011640.2823760.000019942-14.016.080.66361124414211433-0.96
    70.0573770.0012720.2824480.0000241003-11.479.880.82656114612291236-0.96
    80.0487730.0011240.2823970.000020911-13.276.170.68598121413911403-0.97
    90.0565920.0012970.2824250.000021965-12.298.210.72471118013041314-0.96
    100.0521200.0011920.2823930.000020930-13.396.430.69463122013901401-0.96
    PM11-30-TW1
    10.0395810.0008610.2825030.000023876-9.519.350.78829105611641172-0.97
    20.0653580.0014410.2825090.000025858-9.298.840.87680106411821191-0.96
    40.0248600.0005310.2823890.000025923-13.546.540.88984120513781389-0.98
    50.0417210.0008890.2824370.000025936-11.858.300.86826115012771286-0.97
    60.0365870.0007910.2824280.000029889-12.186.991.02444116013231333-0.98
    80.0344720.0007400.2823610.000028877-14.534.420.97299125114761489-0.98
    90.0380830.0008200.2824130.000025947-12.687.730.88871118113211331-0.98
    100.0298210.0006560.2823510.000028924-14.905.110.99569126314681481-0.98
    PM16-2-TW1
    10.0711210.0015910.2824750.000023970-10.499.950.81897111711991207-0.95
    20.0787920.0017210.2825390.000022978-8.2412.270.77492103010591063-0.95
    30.0825490.0018160.2824960.000021916-9.759.400.72463109311921200-0.95
    50.0648210.0014270.2824900.000022995-9.9611.100.75681109111461151-0.96
    60.0998520.0019170.2826440.000026870-4.5313.590.89546883891894-0.94
    70.1049050.0021590.2826010.000024887-6.0612.270.85205952988992-0.93
    80.1031840.0022040.2825680.000026921-7.2211.780.92709100110451050-0.93
    90.0736350.0016360.2825030.000026931-9.5210.050.89375107911621169-0.95
    100.0804790.0017280.2825350.000027913-8.3910.740.94546103611051111-0.95
    注:PM16-101-TW3锆石Lu-Hf同位素数据据参考文献
    下载: 导出CSV
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  • 收稿日期:  2018-05-02
  • 修回日期:  2018-06-30
  • 网络出版日期:  2023-08-15
  • 刊出日期:  2020-03-14

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