华南早新元古代莲沱组地层磁倾角偏低研究及其古地理意义

    景先庆, 杨振宇, 仝亚博, 王恒, 韩志锐, 徐颖超

    景先庆, 杨振宇, 仝亚博, 王恒, 韩志锐, 徐颖超. 2016: 华南早新元古代莲沱组地层磁倾角偏低研究及其古地理意义. 地质通报, 35(11): 1797-1806.
    引用本文: 景先庆, 杨振宇, 仝亚博, 王恒, 韩志锐, 徐颖超. 2016: 华南早新元古代莲沱组地层磁倾角偏低研究及其古地理意义. 地质通报, 35(11): 1797-1806.
    JING Xianqing, YANG Zhenyu, TONG Yabo, WANG Heng, HAN Zhirui, XU Yingchao. 2016: Inclination shallowing study of the Early-Neoproterozoic Liantuo Formation in South China and its paleogeographic implications. Geological Bulletin of China, 35(11): 1797-1806.
    Citation: JING Xianqing, YANG Zhenyu, TONG Yabo, WANG Heng, HAN Zhirui, XU Yingchao. 2016: Inclination shallowing study of the Early-Neoproterozoic Liantuo Formation in South China and its paleogeographic implications. Geological Bulletin of China, 35(11): 1797-1806.

    华南早新元古代莲沱组地层磁倾角偏低研究及其古地理意义

    基金项目: 

    国家自然科学基金项目 41230208

    详细信息
      作者简介:

      景先庆(1988-), 男, 在读博士生, 从事古地磁与大地构造学研究。E-mail:jktsjisgeo@hotmail.com

      通讯作者:

      杨振宇(1963-), 男, 博士, 教授, 从事全球变化及海陆块体格局变化研究。E-mail:yangzhenyu@cags.ac.cn

    • 中图分类号: P534.3;P631.2

    Inclination shallowing study of the Early-Neoproterozoic Liantuo Formation in South China and its paleogeographic implications

    • 摘要:

      华南莲沱组最新的年龄结果表明,其时代结束于715Ma,因此,准确确定莲沱组的古纬度对“雪球地球”的研究具有重要意义。通过对莲沱组红层进行等温剩磁各向异性研究,获得其磁倾角校正因子为0.8719,校正后的磁倾角为70.4°,对比热退磁实验测得的莲沱组磁倾角为67.8°,则其磁倾角偏低量为2.6°。通过校正前后的磁倾角分别计算古纬度,获得磁倾角偏低所引起的古纬度变化为3.9°±6°。通过对比华南与澳大利亚-东南极板块的720Ma古地理位置,发现这一时期冰碛岩从中纬度到赤道广泛分布,验证了当时的“雪球地球”环境。

      Abstract:

      New dating data indicate that the Liantuo Formation ended at 715Ma, and hence the constraint of the paleolatitude of the Liantuo Formation will shed a light on the "Snowball Earth" theory. Researchers have obtained reliable paleomagnetic results from the Liantuo Formation, but the inclination shallowing has not been considered by them. In this paper, the authors obtained a corrected parameter by conducting a remnant anisotropy research on Liantuo Formation. The inclination shallowing in Liantuo Formation is 2.6°, which results in a latitude difference of 3.9°±6°. The reconstruction of the South China and Australia block at 720Ma shows the diamictite distribution from middle latitude to tropical region, which proves the "Snowball Earth" theory.

    • 阿尔金造山带位于青藏高原东北部边缘,介于塔里木板块、柴达木微板块及祁连、东昆仑造山带之间,处于古特提斯洋盆(双湖带、南羌塘、班怒带)北部大陆边缘。阿尔金构造带是中—新生代以来强烈活动的左行走滑断裂带为青藏高原北部一条重要的应力释放线[1-2]。根据校培喜等[2]的划分方案,将阿尔金造山带自北向南划分为红柳沟-拉配泉(蛇绿)构造混杂岩带、阿中地块、阿南(蛇绿)构造混杂岩带。研究区位于阿尔金造山带南缘,以阿尔金南缘主断裂为界,可进一步划分为阿中地块和阿南(蛇绿)构造混杂岩带,本次研究的中—晚奥陶世正长花岗岩出露于阿中地块(图 1)。

      图  1  阿尔金造山带地质构造图(a)及研究区地质简图(b, 据参考文献修改)
      TRB—塔里木盆地;QL—祁连山;QDB—柴达木盆地;WKL—西昆仑;EKL—东昆仑;HMLY—喜马拉雅山;INP—印度板块;Q—第四系;N2y—新近系油砂山组;J1—2dm—侏罗系大煤沟组;OMm—奥陶纪茫崖蛇绿混杂岩;QbS—青白口系索尔库里群;Pt1A—古元古代阿尔金岩群;O-S—玉苏普阿勒塔格岩体;ξγO2—3c—正长花岗岩;γδoQb—亚干布阳片麻岩;γδQb—盖里克片麻岩;OΣH—超基性岩块体;β—玄武岩块体;v—辉长岩脉;νQb—斜长角闪岩
      Figure  1.  Geological and tectonic map of Altun orogenic belt (a) and geological sketch map of the study area (b)

      阿尔金造山带南缘广泛出露早古生代岩浆岩,作为阿尔金造山带南缘构造演化过程的岩浆响应,是研究揭示阿尔金南缘陆壳深俯冲作用及折返演化过程的线索。然而,前人对早古生代花岗岩的形成环境还存在争议。阿中地块发育大规模的早古生代岩浆岩,北东东向展布,与区域主构造方向一致,岩体变形较弱,部分岩体发育片麻理,主要由钾长花岗岩、二长花岗岩、黑云母花岗岩、片麻状花岗岩等构成,大多与围岩呈侵入接触关系,局部为断层或韧性剪切带接触。其中,江尕勒萨依黑云母花岗岩主要组成矿物为钾长石(30%~40%)、斜长石(20%~30%)、石英(20%~25%)、黑云母(10%~15%);若羌河片麻状花岗岩的主要组成矿物为钾长石(35%~40%)、斜长石(20%~25%)、黑云母(15%~20%)、白云母(10%~15%)和石英(10%~15%)。锆石U-Pb定年显示,吐拉、江尕勒萨依、迪木那里克、瓦石峡、若羌河和茫崖花岗岩的年龄分别为453.4± 2.5Ma、453.1 ± 2.1Ma、452.8 ± 3.1Ma、462 ± 2Ma、454.0±1.8Ma和451±1.7Ma[3-5],反映了南阿尔金地区早古生代区域性壳源花岗质岩浆和幔源基性岩浆侵入的构造岩浆热事件。

      茫崖镇北石英闪长岩和阿卡龙山花岗岩的SHRIMP锆石U-Pb定年结果显示,其形成年龄分别为466±5Ma和469±6Ma,二者均具有岛弧火成岩的地球化学属性,其形成可能与洋壳的俯冲作用有关[6]。玉苏普阿勒克塔格岩体中花岗细晶岩和寄主花岗岩的形成时代分别为406Ma和424Ma,表明阿尔金南缘在早古生代末期存在造山后伸展背景下的幔源岩浆底侵作用[7];塔特勒克布拉克复式花岗岩体被认为形成于俯冲碰撞造山后抬升阶段,451± 1.7Ma和462±2Ma的年龄对应于区内深俯冲陆壳的折返时代[3-4];阿尔金造山带南缘在约500Ma时发生了以超高压岩石为代表的陆壳深俯冲-碰撞事件,同时在约450Ma发生了陆壳深俯冲/折返事件[5]。可见,早古生代花岗岩形成的构造环境存在争议。

      因此,本文选取帕夏拉依档岩体中新发现的肉红色正长花岗岩为研究对象,结合野外考察,基于岩相学、LA-ICP-MS锆石U-Pb定年和地球化学研究,确定其形成年代、岩石成因及构造环境,同时对比阿尔金造山带南、北缘岩浆响应,为早古生代构造演化过程提供新证据。

      帕夏拉依档岩体前人解体出二长花岗岩(ηγO2-3a)和偶含斑二长花岗岩(ηγO2-3b) 2个侵入体,本次新发现的肉红色正长花岗岩(ξγO2-3c)分布于研究区北部,出露于古—中元古代结晶基底中,多呈岩滴产出,出露面积较小。正长花岗岩的围岩有中—晚奥陶世浅灰色二长花岗岩(ηγO2-3a)、古元古界阿尔金岩群和青白口纪盖里克片麻岩(γδQb)。中—晚奥陶世浅灰色二长花岗岩形成年龄为460.1±3.9Ma,形成于挤压体制向拉张体制转换的构造环境[8];阿尔金岩群属变质结晶基底,为一套浅海相碎屑岩-火山岩-碳酸盐岩建造;盖里克片麻岩岩性主要由眼球状黑云斜长片麻岩、二云二长片麻岩组成,原岩为斜长花岗岩、黑云母花岗岩,LA-ICP-MS锆石U-Pb定年结果显示形成年龄为886.5±5Ma,形成于同碰撞构造环境,可能对应于新元古代的罗迪尼亚(Rodinia)超大陆汇聚事件[9]

      本次新发现的正长花岗岩,与中—晚奥陶世浅灰色二长花岗岩(ηγO2-3a)呈脉动接触关系(图版Ⅰ-ab),并侵入于下元古界阿尔金岩群a岩组和青白口纪盖里克片麻岩(γδQb)中,其中可见大量围岩的捕虏体(图版Ⅰ-c),在遥感影像上其与围岩的界线也非常清楚(图版Ⅰ-d)。其岩石学特征如下。

        图版Ⅰ 
      a、b、c.正长花岗岩宏观露头照片;d.正长花岗岩遥感影像特征;e.正长花岗岩中条纹长石;f.正长花岗岩中斜长石绢云母化、粘土化。Pt1A—古元古代阿尔金岩群;γδQb—盖里克片麻岩;ηγO2-3a—二长花岗岩;ξγO2-3c—正长花岗岩;Qhpal—全新统冲洪积物
        图版Ⅰ. 

      正长花岗岩,呈肉红色,具花岗结构,主要由石英(25%)、斜长石(15%)和碱性长石(56%)组成,含有少量绿泥石(3%),大部分为中粒,粒径2.00~4.00mm,少量为细粒,粒径0.50~2.00mm。石英呈他形粒状,表面干净,具波状消光,部分表面有裂纹,石英具动态重结晶,呈锯齿状镶嵌。斜长石呈他形板状,表面污浊,绢云母化、粘土化,可见聚片双晶和卡钠复合双晶。碱性长石呈他形板状和粒状,大部分为条纹长石,少量为格子双晶状的微斜长石,部分表面污浊,粘土化。绿泥石呈片状,具靛蓝和紫色异常干涉色。金属矿物呈他形粒状,散点状分布。

      在中―晚奥陶世正长花岗岩中采集锆石U-Pb定年样品1件,样品编号为PM030/25-1,岩性为正长花岗岩,测年样品采样点坐标:北纬38°27′10″、东经89°26′46″,高程3460m。采集样品约15kg,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(CL)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193nm深紫外ArF准分子激光器,激光波长为193nm,束斑直径为30μm,频率为8Hz,能量为70mJ,采样方式为单点剥蚀, 每个分析点的气体背景采集时间为30s,信号采集时间为40s;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1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NISTSRM610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Anderson软件[10]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[11]完成。详细的实验原理和流程及仪器参见Yuan等[12]

      主量、微量和稀土元素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Axios X射线光谱仪,依据标准GB/T14506.28—2010;所有稀土及微量元素中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;TFe2O3值通过计算公式TFe2O3=Fe2O3+FeO×1.1113得出。主量元素分析数据中烧失量值介于0.40%~0.66%之间,总量在99.05%~99.93%之间,满足精度标准要求;主量元素分析误差小于1%,微量和稀土元素分析精度优于5%。

      用于锆石U-Pb同位素测定的样品采自中—晚奥陶世正长花岗岩(PM030/25-1)。锆石CL图像(图 2)显示其颗粒粗大,多为浅黄色-无色透明,晶形较好,以长柱状为主,粒径为100~500μm,长宽比为1.5:1~5:1。CL图像显示,部分锆石环带特征不明显,部分具有弱的环带特征,整体发暗,可能主要是锆石的U、Th、稀土元素含量较高造成的。

      图  2  中―晚奥陶世正长花岗岩锆石阴极发光(CL)图像及U-Pb年龄
      Figure  2.  Zircon CL images and U-Pb ages of the syenogranite in Middle-Late Ordovician period

      对正长花岗岩样品PM030/25-1的18粒锆石进行了18个点的测试,分析结果见表 1。锆石的Th、U含量分别为26.49×10-6~189.53×10-6、3036.06×10-6~12768.64×10-6,除点5、7、11和18外,其余14个测点的数据明显组成一个年龄密集区(图 3表 1),206Pb/238U年龄值集中在448± 7~459±7Ma之间,年龄加权平均值为455.1± 3.6Ma(MSWD=0.13),所以455.1±3.6Ma的年龄值可以代表帕夏拉依档岩体正长花岗岩的侵位年龄。另外,测点5和7的206Pb/238U年龄值均为424±6Ma。测点11和18的206Pb/238U年龄值分别为391±6Ma和395±6Ma。打点位置均位于锆石边部,代表中—晚奥陶世正长花岗岩分别经历了晚志留世和早三叠世的热事件改造。

      表  1  正长花岗岩(PM030-25) LA-ICP-MS锆石U-Th-Pb同位素分析结果
      Table  1.  LA-ICP-MS zircon U-Th-Pb isotopic analyses of the syenogranite(PM030/25-1)
      点号 同位素比值 年龄/Ma
      207Pb/206Pb 207Pb/235U 206Pb/238U 208Pb/232Th 207Pb/206U 207Pb/235U 206Pb/238Th 208Pb/232Th
      比值 误差
      (1σ)
      比值 误差
      (1σ)
      比值 误差
      (1σ)
      比值 误差
      (1σ)
      年龄 误差
      (1σ)
      年龄 误差
      (1σ)
      年龄 误差
      (1σ)
      年龄 误差
      (1σ)
      01 0.05707 0.00171 0.57749 0.00941 0.07342 0.00112 0.05629 0.0011 494 65 463 6 457 7 1107 21
      02 0.05687 0.00168 0.57305 0.00885 0.0731 0.00111 0.07703 0.00145 486 65 460 6 455 7 1500 27
      03 0.05535 0.00164 0.55877 0.00869 0.07323 0.00112 0.02783 0.00069 426 64 451 6 456 7 555 14
      04 0.05688 0.00174 0.57085 0.00989 0.0728 0.00113 0.05736 0.00174 486 67 459 6 453 7 1127 33
      05 0.06285 0.00188 0.58845 0.00961 0.06792 0.00105 0.14796 0.00256 703 63 470 6 424 6 2789 45
      06 0.0543 0.0016 0.54623 0.00841 0.07297 0.00112 0.0405 0.00066 383 65 443 6 454 7 803 13
      07 0.07356 0.00224 0.68855 0.0118 0.0679 0.00106 0.27561 0.00532 1029 60 532 7 424 6 4920 84
      08 0.05507 0.00162 0.55805 0.00866 0.0735 0.00114 0.04739 0.00075 415 64 450 6 457 7 936 15
      09 0.0534 0.00173 0.52987 0.01078 0.07197 0.00114 0.0417 0.00171 346 72 432 7 448 7 826 33
      10 0.05618 0.00166 0.56795 0.00899 0.07332 0.00114 0.04302 0.00086 459 65 457 6 456 7 851 17
      11 0.08164 0.0024 0.70473 0.01088 0.0626 0.00098 0.37524 0.00498 1237 56 542 6 391 6 6440 73
      12 0.05635 0.00166 0.56979 0.00893 0.07332 0.00115 0.06536 0.00104 466 64 458 6 456 7 1280 20
      13 0.05457 0.00161 0.55501 0.0087 0.07375 0.00116 0.06298 0.00094 395 64 448 6 459 7 1235 18
      14 0.05535 0.00163 0.55715 0.00873 0.07298 0.00115 0.06047 0.00084 426 64 450 6 454 7 1187 16
      15 0.05469 0.00161 0.55186 0.00871 0.07316 0.00116 0.02667 0.00039 400 63 446 6 455 7 532 8
      16 0.05455 0.00161 0.55219 0.00877 0.07339 0.00117 0.03629 0.00059 394 64 446 6 457 7 721 12
      17 0.05348 0.00158 0.54063 0.00861 0.07329 0.00117 0.02897 0.00048 349 65 439 6 456 7 577 9
      18 0.0608 0.00179 0.52975 0.00842 0.06316 0.00101 0.11114 0.00152 632 62 432 6 395 6 2130 28
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      图  3  中―晚奥陶世正长花岗岩LA-ICP-MS锆石U-Pb年龄谐和图
      Figure  3.  LA-ICP-MS zircon U-Pb concordia diagram for the syenogranite in Middle-Late Ordovician period

      中―晚奥陶世正长花岗岩的主量、微量及稀土元素测试结果见表 2

      表  2  中―晚奥陶世正长花岗岩主量、微量和稀土元素分析结果
      Table  2.  Major, trace and rare earth elements analyses of the syenogranite in Middle-Late Ordovician period
      样号 PM030/25-1 PM030/25-2 PM030/27-1 PM030/27-2
      SiO2 73.53 73.49 72.15 72.21
      TiO2 0.14 0.15 0.11 0.13
      Al2O3 13.96 13.68 14.49 14.52
      Fe2O3 0.68 0.70 0.65 0.65
      FeO 0.76 0.72 0.86 0.85
      MnO 0.02 0.02 0.02 0.02
      MgO 0.32 0.30 0.29 0.29
      CaO 0.52 0.51 0.55 0.50
      Na2O 2.36 2.18 1.99 2.01
      K2O 6.68 6.59 8.20 8.17
      P2O5 0.06 0.05 0.06 0.06
      烧失量 0.54 0.66 0.40 0.52
      总计 99.57 99.05 99.77 99.93
      σ 2.68 2.52 3.56 3.55
      K2O/Na2O 2.83 3.02 4.12 4.06
      AR 1.97 1.89 1.72 1.73
      SI 2.96 2.86 2.42 2.42
      FL 94.56 94.50 94.88 95.32
      MF 81.77 82.56 83.93 83.84
      R1 2455.31 2537.80 2138.28 2141.96
      R2 345.35 337.79 357.47 352.70
      AIK 0.80 0.78 0.84 0.84
      A/CNK 1.16 1.17 1.10 1.11
      K2O+Na2O 9.04 8.77 10.19 10.18
      Na2O/K2O 0.35 0.33 0.24 0.25
      m/f 0.41 0.39 0.35 0.35
      La 25.4 23.66 15.1 18.23
      Ce 54.6 50.38 32.3 36.66
      Pr 7.23 7.42 4.22 5.64
      Nd 25.8 23.66 15.1 17.23
      Sm 7.17 6.98 4.24 4.67
      Eu 0.598 0.61 0.635 0.63
      Gd 6.66 5.99 4 4.26
      Tb 1.08 1.02 0.665 0.85
      Dy 5.77 4.99 3.68 3.95
      Ho 0.966 0.95 0.632 0.72
      Er 2.33 2.16 1.53 1.73
      Tm 0.318 0.29 0.208 0.26
      Yb 1.78 1.78 1.14 1.28
      Lu 0.264 0.2 0.164 0.19
      Y 30.2 28.76 19.1 21.93
      ∑REE 170.17 158.85 102.71 118.23
      LREE 120.80 112.71 71.60 83.06
      HREE 49.37 46.14 31.12 35.17
      LREE/HREE 2.45 2.44 2.30 2.36
      δEu 0.26 0.28 0.46 0.42
      δCe 0.94 0.89 0.94 0.84
      (La/Yb)N 9.64 8.98 8.95 9.62
      (La/Sm)N 2.23 2.13 2.24 2.46
      (Gd/Yb)N 3.03 2.73 2.84 2.70
      Cu 14.10 13.99 13.50 13.65
      Pb 66.90 66.40 65.80 66.10
      Zn 35.50 34.60 26.00 28.20
      Co 1.88 1.94 2.59 2.42
      Ni 2.13 2.45 3.57 3.31
      Cr 17.10 16.96 15.30 16.10
      V 6.60 8.20 11.90 10.30
      Ga 17.20 17.10 16.20 16.80
      Sr 86.10 88.20 92.30 91.40
      Ba 255.70 266.00 295.80 289.00
      Rb 319.20 327.00 339.50 338.00
      Nb 28.70 26.80 11.10 13.70
      Ta 3.42 3.32 0.94 1.45
      Zr 67.80 65.90 26.40 27.10
      Hf 7.46 7.32 1.77 1.89
      U 7.23 7.13 6.40 6.41
      Th 16.70 15.10 9.24 10.30
      Ag 0.03 0.03 0.04 0.04
      Au/10-9 3.17 3.16 3.12 3.16
      Cs 7.47 7.58 7.87 7.79
      Mg# 29.43 28.37 26.30 26.43
      Rb/Sr 3.71 3.71 3.68 3.70
      K/Rb 173.65 167.23 200.42 200.57
      Ba/Sr 2.97 3.02 3.20 3.16
      Th/Ta 4.88 4.55 9.82 7.10
      K 55429.79 54682.98 68042.55 67793.62
      注:主量元素含量单位为%,微量和稀土元素含量为10-6
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      正长花岗岩SiO2含量较高(平均72.85%),变化范围不大(72.15%~73.53%),属于酸性岩浆岩;富钾(K2O=6.59%~8.20%,平均7.41%;K2O/Na2O= 2.83~4.12);富碱(K2O+Na2O=8.77%~10.19%,平均9.55%);低P2O5(0.05%~0.06%,平均0.06%)、Na2O (1.99%~2.36%,平均2.14%)、MgO(0.29%~0.32%,平均0.30%);贫钙CaO(0.50%~0.55%,平均0.52%)和低钛TiO2(0.11%~0.15%,平均0.13%)含量的特征。TFeO含量在1.35% ~1.45%之间,平均为1.40%;岩石铝含量较高(Al2O3=13.68%~14.52%,平均14.16%),铝饱和指数(A/CNK)介于1.10~1.17之间,均大于1.1,A/NK>1,在A/CNK- A/NK图解上样品全部落入过铝质花岗岩区域(图 4-a),为强过铝质系列;岩石的碱度率指数AR为4.24~5.21,具有富铝的特点;里特曼指数σ为2.52~3.56,平均为3.08,小于3.3,属钙碱性。岩石中K2O含量较高,在SiO2-K2O图解(图 4-b)上,表现出钾玄岩系列岩石特征,暗示原始岩浆富钾,花岗岩源岩具有壳源的特点,说明岩石属铝和硅过饱和类型。上述特征表明,阿尔金帕夏拉依档岩体具有富硅、铝、钾,贫铁、镁的特点,总体显示偏过铝钾(碱)质花岗岩的特征。

      图  4  中―晚奥陶世正长花岗岩A/CNK-A/NK (a)和SiO2-K2O图解(b) [13-14]
      Figure  4.  A/CNK-A/NK (a) and SiO2-K2O diagrams (b) of the syenogranite in Middle-Late Ordovician period

      正长花岗岩稀土元素总量∑REE=102.71×10-6~170.17×10-6,平均为137.49×10-6,轻、重稀土元素比值较高(∑LREE/∑HREE=2.30~2.45,平均值为2.39)。轻稀土元素相对富集且分异较弱[(La/Sm)N= 2.13~2.46],重稀土元素相对亏损且发生分异[(Ga/Yb)N=2.69~3.02],轻、重稀土元素分异明显[(La/Yb)N= 8.93~9.62];δEu=0.26~0.46,平均值为0.36,显示明显的负Eu异常,暗示岩浆在形成过程中可能存在斜长石的分离结晶作用或部分熔融过程中源区有斜长石的残留。稀土元素球粒陨石标准化分布型式图显示轻稀土元素富集、重稀土元素亏损的右倾型分布模式(图 5-a),指示其为壳源型花岗岩。

      图  5  中―晚奥陶世正长花岗岩球粒陨石标准化稀土元素分布型式(a)和原始地幔标准化微量元素蛛网图(b) [15]
      Figure  5.  Chondrite-normalized REE patterns(a) and primitive mantle-normalized trace element patterns (b) of the syenogranite in Middle-Late Ordovician period

      在微量元素原始地幔标准化蛛网图(图 5-b)上,正长花岗岩富集Rb、Th、K等大离子亲石元素(LILE)和La、Ce、Nd等轻稀土元素,Ba、Sr、Ti明显亏损;具有明显的Ba和Sr负异常,Zr和Hf无明显分异,Ba、Sr、P亏损和负Eu异常,充分指示成岩过程中存在斜长石、磷灰石、钛铁矿等的分离结晶作用。

      研究区缺乏与中―晚奥陶世正长花岗岩同时代大面积的基性岩浆的出露,且岩石的Nb/Ta值为8.07~11.80,平均值为9.43,接近于地壳平均值(12~13),Nb、Ta的亏损反映了岩浆源区具有壳源物质成分。Cr、Ni含量很低,分别为15.3×10-6~17.10×10-6(平均为16.37×10-6)和2.13×10-6~3.57×10-6(平均为2.87×10-6),说明其由富集的幔源岩浆受到地壳混染形成的可能性很小。Mg#指数为26.30~29.43 (平均值为27.63),明显小于玄武岩熔融实验熔体成分的Mg#[16],地壳部分熔融形成的熔体不管熔融程度如何,形成的岩石均具有较低的Mg#值(<40)。以上特征也说明,中―晚奥陶世正长花岗岩与地壳物质部分熔融有关。在(Na2O + K2O)- 10000Ga/Al和Nb- 10000Ga/Al图解[17-18](图 6)中,样品点都投在I & S型花岗岩范围。在ACF图解(图 7)中,样品点全部投影在S型花岗岩区域。S型花岗岩岩浆起源于大陆地壳中沉积的源岩,Rb/Sr值能灵敏地记录源区物质的性质,当Rb/Sr<0.9时,为I型花岗岩;Rb/Sr>0.9时,为S型花岗岩。正长花岗岩Rb/Sr=3.68~3.71,显示S型花岗岩特征。岩石的10000Ga/Al值(2.11~2.36,平均值为2.25),接近S型花岗岩的平均值(2.28) [17]。因此,中―晚奥陶世正长花岗岩属于S型花岗岩,是地壳物质熔融的产物[19]

      图  6  中―晚奥陶世正长花岗岩10000Ga/Al-FeO/MgO(a)和10000Ga/Al-Y图解(b)
      Figure  6.  Diagrams of 10000Ga/Al-FeO/MgO (a) and 10000Ga/Al-Y (b) of the syenogranite in Middle-Late Ordovician period
      图  7  中―晚奥陶世正长花岗岩ACF图解
      Figure  7.  ACF diagram of the syenogranite in Middle-Late Ordovician period

      中―晚奥陶世正长花岗岩具有铝过饱和(A/CNK=1.10~1.17)且富钾(K2O=6.59%~8.20%,平均7.41%)的特点。正长花岗岩的CaO/Na2O值介于0.22~0.28之间(平均值为0.24),暗示源区为泥质岩。在Rb/Sr-Rb/Ba图解(图 8)中,样品点全部分布在粘土岩源区,表明其源岩主要为地壳泥质岩沉积物。

      图  8  中―晚奥陶世正长花岗岩Rb/Sr-Rb/Ba图解
      Figure  8.  Rb/Sr-Rb/Ba diagram of the syenogranite in Middle-Late Ordovician period

      在阿尔金造山带南缘,早古生代岩浆岩以高温低压岩浆活动为特征,并发育花岗岩,这与板片拆离后同折返阶段的岩浆岩组合和岩石成因一致[20]。在板片拆离和地壳折返过程中,下地壳岩石往往不发生抬升折返,这是因为地壳主要由密度较小的长英质岩石组成,而下地壳主要由密度较大的镁铁质岩石组成所致[21-23],造成阿尔金南缘在该阶段发生以上地壳物质为主的减压熔融作用。因此,中―晚奥陶世肉红色正长花岗岩是上地壳变质泥质岩系部分熔融的产物。

      中―晚奥陶世肉红色正长花岗岩变形变质较弱,其时代与高压麻粒岩相的退变质年代455Ma吻合,说明在此阶段俯冲板片可能已经拆离,导致物质折返[5]

      正长花岗岩铝饱和指数(A/CNK)介于1.10~1.17之间,稀土元素总量高,轻稀土元素富集,Eu强烈负异常,反映其岩浆来源于地壳增厚重熔作用,高钾钙碱性和钾玄岩系列被认为是大陆碰撞造山带的典型组合。在构造环境判别(Y+Nb) -Rb图解(图 9-a)中,2个样品点落入同碰撞花岗岩区域,2个样品点落入同碰撞花岗岩和板内花岗岩相交区域;在(Yb+Ta) -Rb图解(图 9-b)中,样品点全部落入同碰撞花岗岩区;在Yb-Ta图解(图 9-c)和Y-Nb图解(图 9-d)中,也分别有1个和2个样品点投在同碰撞花岗岩和板内花岗岩相交区域。在R1-R2图解中,样品点落入同碰撞花岗岩且靠近造山后花岗岩区域(图 10-a);在Hf-Rb/30-Ta×3三角判别图解中,2个样品点落入同碰撞花岗岩区,2个样品点投到碰撞后花岗岩区域(图 10-b)。

      图  9  中―晚奥陶世正长花岗岩微量元素构造环境判别图解[24-25]
      ORG—洋中脊花岗岩;VAG—火山弧花岗岩;WPG—板内花岗岩;syn-COLG—同碰撞花岗岩
      Figure  9.  Diagrams of the tectonic setting of major elements for the syenogranite in Middle-Late Ordovician period
      图  10  中―晚奥陶世正长花岗岩R1-R2构造环境判别图解(a) [26]和Hf-Rb/30-Ta×3三角判别图解(b) [27]
      Figure  10.  R1-R2(a) and Hf-Rb/30-Ta×3 (b)discrimination diagrams for the syenogranite in Middle-Late Ordovician period

      花岗岩类的微量和稀土元素表现为富集大离子亲石元素(LILE)和La、Ce、Nd等轻稀土元素,亏损Nb、Ta、Ti等高场强元素,也具备碰撞花岗岩的特征。

      区域上,杨文强等[28]认为,南阿尔金俯冲碰撞杂岩带中早古生代花岗质岩浆活动第二期时代为466~451Ma,形成于深俯冲陆壳断离后的伸展背景。刘良等[5]认为,462~451Ma花岗岩形成于陆壳俯冲碰撞挤压向伸展抬升转换阶段。本文正长花岗岩形成时代(455.1±3.6Ma)不仅与阿尔金南缘地区代表板片拆离的高压-超高压岩石的退变质时代(445Ma)吻合,还与杨文强等[28]和刘良等[5]研究的早古生代花岗岩时代一致,应具有相同的地质构造背景,均形成于初始后碰撞伸展环境。

      综上所述,中―晚奥陶世肉红色细粒正长花岗岩具有同碰撞挤压-后碰撞伸展转折环境的特征,形成于挤压体制向拉张体制转换的构造环境,属后碰撞花岗岩类。

      阿尔金造山带南缘具有典型碰撞造山的特征,其主要标志为与大陆深俯冲有关的高压-超高压变质作用、中酸性侵入岩广泛发育、碰撞后伸展、垮塌作用等[29]。阿尔金南缘超高压岩石的峰期变质时代(504~486Ma) [30]与该阶段花岗岩的侵位时代(501~496Ma)基本一致。该阶段发生了碰撞造山作用,导致“南阿尔金洋盆”闭合,一直持续到茫崖二长花岗岩(472.1±1.1Ma),依旧显示阿尔金南缘为碰撞造山,伴随地壳物质发生深俯冲作用[31]。在约450Ma发生了陆壳深俯冲/折返事件,俯冲陆壳发生板片断离并开始折返,构造由碰撞挤压转换为伸展体制,导致高压-超高压变质岩石在462~451Ma发生退变质作用,并产生同折返或后碰撞花岗岩。

      笔者于2016年对中—晚奥陶世二长花岗岩的研究表明,其形成时代为460.1±3.9Ma,属早古生代中—晚奥陶世,构造环境反映其具有同碰撞向后碰撞环境过渡的特征,形成于挤压体制向拉张体制转换的构造环境,属后碰撞花岗岩类[8]。本次新发现的正长花岗岩的形成时代为455.1±3.6Ma,与其具有类似的构造环境。前人在邻区也发现了大量后碰撞花岗岩的物质记录,塔特勒克布拉克二长花岗岩形成年龄为462±2Ma,形成于碰撞造山后抬升初期,即俯冲碰撞造山后应力释放的初级阶段,陆壳物质由于压力释放而部分熔融[3];塔特勒克布拉克复式花岗质岩体形成年龄为451±1.7Ma,与超高压岩石高压麻粒岩相退变质时代基本一致,该岩体形成可能是陆壳深俯冲/折返构造过程的岩浆作用响应,构造背景为碰撞造山后应力释放的伸展[4]。该时段岩浆岩的岩性较复杂,区域内,超基性-基性岩浆岩主要由辉橄岩、角闪辉长岩、辉长岩和辉绿岩组成,识别出长沙沟-清水泉镁铁-超镁铁质侵入体、长沙沟杂岩体、柴水沟辉绿岩、茫崖角闪辉长岩和长沙沟辉长岩,形成时代分别为467.4±1.4Ma[32]、458.7 ± 1.8Ma[33]、453.5 ± 3.5Ma[6]、444.9 ± 1.3Ma[34]和444.9±3.4Ma[35],上述基性-超基性岩大多与围岩呈侵入接触关系,并非蛇绿构造混杂岩带组分,岩石属于碱性岩石。前人研究成果表明,该阶段为后碰撞伸展阶段,但局部仍存在高压部分熔融特征的岩浆活动,因此该阶段应属于碰撞后伸展的初始阶段。

      碰撞后伸展阶段,高压-超高压变质岩石进一步发生角闪岩相退变质作用,并产生426~385Ma的花岗质岩浆作用[5]。在本次锆石U-Pb年龄中出现了424~391Ma的年龄,反映了晚志留世和早三叠世的热事件改造。在该阶段岩浆岩发育规模较大,前人测得玉苏普阿勒克塔格岩体形成年龄为424Ma[7],吐拉花岗岩形成时间为385.2Ma[36],总体属高钾钙碱性系列,具类似“海鸥”式的A型花岗岩稀土元素配分曲线特征,结合岩浆活动以高温低压为特征,426~385Ma阶段构造环境应为后碰撞伸展拉张环境。

      结合本文和前人研究成果,将阿尔金造山带南缘早古生代俯冲碰撞杂岩带的构造演化过程至少划分为3个阶段:①504~472Ma,碰撞造山的陆-陆深俯冲阶段;②462~451Ma,具板片拆离后同折返岩浆岩特征,属于初始后碰撞伸展的地壳折返阶段,本文正长花岗岩即在该阶段侵位;③424~385Ma,后碰撞伸展阶段。

      (1) 阿尔金造山带南缘肉红色正长花岗岩LA-ICP-MS锆石U-Pb测年结果表明,其形成年龄为455.1±3.6Ma,属中—晚奥陶世。

      (2) 地球化学特征表明,阿尔金造山带南缘肉红色正长花岗岩主量元素具有富硅、高铝、富碱、富钾,低钛、贫钙、贫镁的特点,为过铝质花岗岩系列,具典型的高钾钙碱性特征。稀土元素总量较高,轻稀土元素相对富集、重稀土元素亏损,有右倾型特征和明显的负Eu异常。Ba、Sr、Ti等具负异常,Rb、Th、K等大离子亲石元素具正异常,显示S型花岗岩特征。推断其源区物质主要来源于上地壳变泥质沉积岩类。

      (3) 结合区域资料,认为正长花岗岩形成于挤压体制向拉张体制转换的构造环境,对应于深俯冲陆壳的折返和超高压岩石高压麻粒岩相退变质阶段。进一步表明,在中—晚奥陶世阿尔金造山带南缘已由碰撞挤压阶段转为后碰撞伸展阶段。

      致谢: 审稿专家对本文进行了认真细致的审阅,并提出了宝贵的修改意见,在此表示衷心的感谢。
    • 图  1   采样区区域地质简图

      (图中蓝色正方形为本次采样点位置)

      Figure  1.   Tectonic framework of South China, and geological map of the sampling area

      图  2   本次研究获取的采点(下划线标注TLS编号)在地层上的分布

      (TL编号为Jing等[29]采点)

      Figure  2.   Stratigraphic column of the Liantuo Formation and detailed sampling layer positions of three sub-sections at Yichang

      图  3   代表性样品的热退磁Z氏图(所有结果都为地理坐标系下投影)

      Figure  3.   Orthogonal vector projection of NRM thermal demagnetization for Liantuo Formation in geographical coordinate, at three Gorges profiles

      图  4   45°方向加场后平行于层面方向(IRMx)和垂直于层面方向(IRMz)等温剩磁获得曲线图(a, d),IRMz/IRMx关系图(b, e)和IRMz/IRMx的热退磁结果(c, f)

      Figure  4.   Plots of IRMx (parallel to bedding) and IRMz (perpendicular to bedding) acquisitions produced by applying magnetic field at 45° to bedding as function of increasing field (a, d), plots of IRMZ/IRMX(b, e), the thermal demagnetization results of IRMZ/IRMX(c, f)

      图  5   代表性样品磁化率随温度变化曲线

      Figure  5.   Thermomagnetic curves of susceptibility (K-T) of representative specimens

      图  6   中新元古代华南现有古地磁极与澳大利亚古地磁极对比及古地理位置重建

      LT-莲沱组古地磁极[29];Nantuo-南沱组古地磁极[38];LT-corr-经过磁倾角偏低校正后的莲沱组古地磁极;MDS、YF及EF分别为澳大利亚755Ma、640Ma和635Ma的古地磁极[22, 47-48]

      Figure  6.   The 720Ma reconstruction of South China and Australia and their Mid-Neoproterozoic poles

      表  1   宜昌地区剖面莲沱组样品等温热剩磁各向异性及磁倾角偏低值

      Table  1   Anisotropy of isothermal remnant magnetization for Liantuo Formation red beds in Yichang area

      ID Iobs IRMz/IRMx
      (610~1200mT)
      IF1 ΔI1(=IF1-Iobs) IRMz/IRMx
      (600°C以上)
      IF2 ΔI2(=IF2-Iobs)
      15 64.4 0.7796 69.518 5.118 0.8542 67.7425 3.3425
      15-2c 71.5 0.8414 74.277 2.777 0.8513 74.1009 2.6009
      15-5b 65 0.899 67.256 2.256 0.8757 67.7876 2.7876
      17-1 72.1 0.831 74.976 2.876 0.8118 75.3075 3.2075
      3-1 73 0.87 75.105 2.105 0.8859 74.8452 1.8452
      4-2b 66.3 0.6147 74.899 8.599 0.901 68.4206 2.1206
      5-2b 64.2 0.8472 67.728 3.528 0.9117 66.2153 2.0153
      5-4b 66 0.7989 70.420 4.420 0.872 68.7818 2.7818
      7-1 61.9 0.8579 65.389 3.489 0.8731 65.0054 3.1054
      8-3 70 0.8737 72.359 2.359 0.856 72.6951 2.6951
      8-4 66.8 0.8701 69.548 2.748 0.8977 68.9555 2.1555
      平均值 67.8 0.8258 71.377 3.577 0.8719 70.4146 2.6146
      注:ID为样品号,Iobs为热退磁实验所得样品磁倾角,IRMz/IRMx(610~1200mT)为610~1200mT之间垂直层面方向和平行层面方向等温剩磁大小的比值,IRMz/IRMx(600°C以上)为600 °C以上垂直层面方向和平行层面方向等温剩磁大小的比值,IF为校正后磁倾角,ΔI为校正值
      下载: 导出CSV
    • Cawood P A, Hawkesworth C J. Earth's middle age[J]. Geology, 2014, 42(6):503-506. doi: 10.1130/G35402.1

      Cawood P A, Hawkesworth C J. Earth's middle age[J]. Geology, 2014, 42(6):503-506. doi: 10.1130/G35402.1

      Kirschvink J L. Late Proterozoic low-latitude global glaciation:the snowball Earth[C]//The Proterozoic biosphere:a multidisciplinary study. Cambridge University Press, New York, 1992:51-52.

      Kirschvink J L. Late Proterozoic low-latitude global glaciation:the snowball Earth[C]//The Proterozoic biosphere:a multidisciplinary study. Cambridge University Press, New York, 1992:51-52.

      Hoffman P F, Kaufman A J, Halverson G P, et al. A Neoproterozoic snowball earth[J]. Science, 1998, 281(5381):1342-1346. doi: 10.1126/science.281.5381.1342

      Hoffman P F, Kaufman A J, Halverson G P, et al. A Neoproterozoic snowball earth[J]. Science, 1998, 281(5381):1342-1346. doi: 10.1126/science.281.5381.1342

      Hyde W T, Crowley T J, Baum S K, et al. Neoproterozoic ‘snowball Earth’ simulations with a coupled climate/ice-sheet model[J]. Nature, 2000, 405(6785):425-429. doi: 10.1038/35013005

      Hyde W T, Crowley T J, Baum S K, et al. Neoproterozoic 'snowball Earth' simulations with a coupled climate/ice-sheet model[J]. Nature, 2000, 405(6785):425-429. doi: 10.1038/35013005

      Eyles N. Earth's glacial record and its tectonic setting[J]. Earth-Science Reviews, 1993, 35(1/2):1-248.

      Eyles N. Earth's glacial record and its tectonic setting[J]. Earth-Science Reviews, 1993, 35(1/2):1-248.

      Harland W B. Critical evidence for a great infra-Cambrian glaciation[J]. Geologische Rundschau, 1964, 54(1):45-61. doi: 10.1007/BF01821169

      Harland W B. Critical evidence for a great infra-Cambrian glaciation[J]. Geologische Rundschau, 1964, 54(1):45-61. doi: 10.1007/BF01821169

      Cox G M, Halverson G P, Stevenson R K, et al. Continental flood basalt weathering as a trigger for Neoproterozoic Snowball Earth[J]. Earth and Planetary Science Letters, 2016, 446:89-99. doi: 10.1016/j.epsl.2016.04.016

      Cox G M, Halverson G P, Stevenson R K, et al. Continental flood basalt weathering as a trigger for Neoproterozoic Snowball Earth[J]. Earth and Planetary Science Letters, 2016, 446:89-99. doi: 10.1016/j.epsl.2016.04.016

      Klein C, Beukes N J. Sedimentology and geochemistry of the glaciogenic late Proterozoic Rapitan iron-formation in Canada[J]. Economic Geology, 1993, 88(3):542-565. doi: 10.2113/gsecongeo.88.3.542

      Klein C, Beukes N J. Sedimentology and geochemistry of the glaciogenic late Proterozoic Rapitan iron-formation in Canada[J]. Economic Geology, 1993, 88(3):542-565. doi: 10.2113/gsecongeo.88.3.542

      Canfield D E, Poulton S W, Narbonne G M. Late-Neoproterozoic deep-ocean oxygenation and the rise of animal life[J]. Science, 2007, 315(5808):92-95. doi: 10.1126/science.1135013

      Canfield D E, Poulton S W, Narbonne G M. Late-Neoproterozoic deep-ocean oxygenation and the rise of animal life[J]. Science, 2007, 315(5808):92-95. doi: 10.1126/science.1135013

      Scott C, Lyons T W, Bekker A, et al. Tracing the stepwise oxygenation of the Proterozoic ocean[J]. Nature, 2008, 452(7186):456-459. doi: 10.1038/nature06811

      Scott C, Lyons T W, Bekker A, et al. Tracing the stepwise oxygenation of the Proterozoic ocean[J]. Nature, 2008, 452(7186):456-459. doi: 10.1038/nature06811

      Chen X, Ling H F, Vance D, et al. Rise to modern levels of ocean oxygenation coincided with the Cambrian radiation of animals[J]. Nature Communications, 2015, 6:7142-7148. doi: 10.1038/ncomms8142

      Chen X, Ling H F, Vance D, et al. Rise to modern levels of ocean oxygenation coincided with the Cambrian radiation of animals[J]. Nature Communications, 2015, 6:7142-7148. doi: 10.1038/ncomms8142

      Moores E M. Southwest US-East Antarctic (SWEAT) connection:a hypothesis[J]. Geology, 1991, 19(5):425-428. doi: 10.1130/0091-7613(1991)019<0425:SUSEAS>2.3.CO;2

      Moores E M. Southwest US-East Antarctic (SWEAT) connection:a hypothesis[J]. Geology, 1991, 19(5):425-428. doi: 10.1130/0091-7613(1991)019<0425:SUSEAS>2.3.CO;2

      Dalziel I W D. Pacific margins of Laurentia and East AntarcticaAustralia as a conjugate rift pair:Evidence and implications for an Eocambrian supercontinent[J]. Geology, 1991, 19(6):598-601. doi: 10.1130/0091-7613(1991)019<0598:PMOLAE>2.3.CO;2

      Dalziel I W D. Pacific margins of Laurentia and East AntarcticaAustralia as a conjugate rift pair:Evidence and implications for an Eocambrian supercontinent[J]. Geology, 1991, 19(6):598-601. doi: 10.1130/0091-7613(1991)019<0598:PMOLAE>2.3.CO;2

      Hoffman P F. Did the breakout of Laurentia turn Gondwanaland inside-out[J]. Science, 1991, 252(5011):1409-1412. doi: 10.1126/science.252.5011.1409

      Hoffman P F. Did the breakout of Laurentia turn Gondwanaland inside-out[J]. Science, 1991, 252(5011):1409-1412. doi: 10.1126/science.252.5011.1409

      Li Z X, Zhang L, Powell C M A. South China in Rodinia:part of the missing link between Australia-East Antarctica and Laurentia?[J]. Geology, 1995, 23(5):407-410. doi: 10.1130/0091-7613(1995)023<0407:SCIRPO>2.3.CO;2

      Li Z X, Zhang L, Powell C M A. South China in Rodinia:part of the missing link between Australia-East Antarctica and Laurentia?[J]. Geology, 1995, 23(5):407-410. doi: 10.1130/0091-7613(1995)023<0407:SCIRPO>2.3.CO;2

      Li Z X, Bogdanova S V, Collins A S, et al. Assembly, configuration, and break-up history of Rodinia:a synthesis[J]. Precambrian Research, 2008, 160(1):179-210.

      Li Z X, Bogdanova S V, Collins A S, et al. Assembly, configuration, and break-up history of Rodinia:a synthesis[J]. Precambrian Research, 2008, 160(1):179-210.

      Karlstrom K E, Williams M L, McLelland J, et al. Refining Rodinia:geologic evidence for the Australia-Western US connection in the Proterozoic[J]. GSA Today, 1999, 9(10):1-7.

      Karlstrom K E, Williams M L, McLelland J, et al. Refining Rodinia:geologic evidence for the Australia-Western US connection in the Proterozoic[J]. GSA Today, 1999, 9(10):1-7.

      Burrett C, Berry R. Proterozoic Australia-Western United States (AUSWUS) fit between Laurentia and Australia[J]. Geology, 2000, 28(2):103-106. doi: 10.1130/0091-7613(2000)28<103:PAUSAF>2.0.CO;2

      Burrett C, Berry R. Proterozoic Australia-Western United States (AUSWUS) fit between Laurentia and Australia[J]. Geology, 2000, 28(2):103-106. doi: 10.1130/0091-7613(2000)28<103:PAUSAF>2.0.CO;2

      Wingate M T D, Pisarevsky S A, Evans D A D. Rodinia connections between Australia and Laurentia:no SWEAT, no AUSWUS?[J]. Terra Nova, 2002, 14(2):121-128. doi: 10.1046/j.1365-3121.2002.00401.x

      Wingate M T D, Pisarevsky S A, Evans D A D. Rodinia connections between Australia and Laurentia:no SWEAT, no AUSWUS?[J]. Terra Nova, 2002, 14(2):121-128. doi: 10.1046/j.1365-3121.2002.00401.x

      Evans D A D. The palaeomagnetically viable, long-lived and allinclusive Rodinia supercontinent reconstruction[J]. Geological Society, London, Special Publications, 2009, 327(1):371-404. doi: 10.1144/SP327.16

      Evans D A D. The palaeomagnetically viable, long-lived and allinclusive Rodinia supercontinent reconstruction[J]. Geological Society, London, Special Publications, 2009, 327(1):371-404. doi: 10.1144/SP327.16

      Abrajevitch A, Van der Voo R. Incompatible Ediacaran paleomagnetic directions suggest an equatorial geomagnetic dipole hypothesis[J]. Earth and Planetary Science Letters, 2010, 293(1):164-170.

      Abrajevitch A, Van der Voo R. Incompatible Ediacaran paleomagnetic directions suggest an equatorial geomagnetic dipole hypothesis[J]. Earth and Planetary Science Letters, 2010, 293(1):164-170.

      Schmidt P W, Williams G E, McWilliams M O. Palaeomagnetism and magnetic anisotropy of late Neoproterozoic strata, South Australia:Implications for the palaeolatitude of late Cryogenian glaciation, cap carbonate and the Ediacaran System[J]. Precambrian Research, 2009, 174(1):35-52.

      Schmidt P W, Williams G E, McWilliams M O. Palaeomagnetism and magnetic anisotropy of late Neoproterozoic strata, South Australia:Implications for the palaeolatitude of late Cryogenian glaciation, cap carbonate and the Ediacaran System[J]. Precambrian Research, 2009, 174(1):35-52.

      Hodych J P, Buchan K L. Early Silurian palaeolatitude of the Springdale Group redbeds of central Newfoundland:a palaeomagnetic determination with a remanence anisotropy test for inclination error[J]. Geophysical Journal International, 1994, 117(3):640-652. doi: 10.1111/gji.1994.117.issue-3

      Hodych J P, Buchan K L. Early Silurian palaeolatitude of the Springdale Group redbeds of central Newfoundland:a palaeomagnetic determination with a remanence anisotropy test for inclination error[J]. Geophysical Journal International, 1994, 117(3):640-652. doi: 10.1111/gji.1994.117.issue-3

      Tauxe L, Kent D V. A simplified statistical model for the geomagnetic field and the detection of shallow bias in paleomagnetic inclinations:was the ancient magnetic field dipolar?[J]. Timescales of the Paleomagnetic Field, 2004:101-115.

      Tauxe L, Kent D V. A simplified statistical model for the geomagnetic field and the detection of shallow bias in paleomagnetic inclinations:was the ancient magnetic field dipolar?[J]. Timescales of the Paleomagnetic Field, 2004:101-115.

      Wang B, Yang Z. Late Cretaceous paleomagnetic results from southeastern China, and their geological implication[J]. Earth and Planetary Science Letters, 2007, 258(1):315-333.

      Wang B, Yang Z. Late Cretaceous paleomagnetic results from southeastern China, and their geological implication[J]. Earth and Planetary Science Letters, 2007, 258(1):315-333.

      方大钧, 谈晓冬.等温剩磁各向异性及其在磁倾角校正中的应用[J].地球物理学报, 2000, 43(5):719-724. http://www.cnki.com.cn/Article/CJFDTOTAL-DQWX200005015.htm
      王恒, 仝亚博, 高亮, 等.青藏高原东南缘川滇地块古近纪沉积地层古地磁分析及其构造意义[J].地质通报, 2015, 34(1):45-57. http://dzhtb.cgs.cn/ch/reader/view_abstract.aspx?file_no=20150107&flag=1
      Gilder S, Chen Y, Cogné J P, et al. Paleomagnetism of Upper Jurassic to Lower Cretaceous volcanic and sedimentary rocks from the western Tarim Basin and implications for inclination shallowing and absolute dating of the M-0(ISEA?) chron[J]. Earth and Planetary Science Letters, 2003, 206(3):587-600.

      Gilder S, Chen Y, Cogné J P, et al. Paleomagnetism of Upper Jurassic to Lower Cretaceous volcanic and sedimentary rocks from the western Tarim Basin and implications for inclination shallowing and absolute dating of the M-0(ISEA?) chron[J]. Earth and Planetary Science Letters, 2003, 206(3):587-600.

      Jing X, Yang Z, Tong Y, et al. A revised paleomagnetic pole from the mid-Neoproterozoic Liantuo Formation in the Yangtze block and its paleogeographic implications[J]. Precambrian Research, 2015, 268:194-211. doi: 10.1016/j.precamres.2015.07.007

      Jing X, Yang Z, Tong Y, et al. A revised paleomagnetic pole from the mid-Neoproterozoic Liantuo Formation in the Yangtze block and its paleogeographic implications[J]. Precambrian Research, 2015, 268:194-211. doi: 10.1016/j.precamres.2015.07.007

      Lan Z, Li X H, Zhu M, et al. Revisiting the Liantuo Formation in Yangtze Block, South China:SIMS U-Pb zircon age constraints and regional and global significance[J]. Precambrian Research, 2015, 263:123-141. doi: 10.1016/j.precamres.2015.03.012

      Lan Z, Li X H, Zhu M, et al. Revisiting the Liantuo Formation in Yangtze Block, South China:SIMS U-Pb zircon age constraints and regional and global significance[J]. Precambrian Research, 2015, 263:123-141. doi: 10.1016/j.precamres.2015.03.012

      Van der Voo R. The reliability of paleomagnetic data[J]. Tectonophysics, 1990, 184(1):1-9. doi: 10.1016/0040-1951(90)90116-P

      Van der Voo R. The reliability of paleomagnetic data[J]. Tectonophysics, 1990, 184(1):1-9. doi: 10.1016/0040-1951(90)90116-P

      安志辉, 童金南, 叶琴, 等.峡东青林口地区新元古代地层序列及沉积演变[J].地球科学(中国地质大学学报), 2014, 39(7):795-806. http://www.cnki.com.cn/Article/CJFDTOTAL-DQKX201407003.htm
      Liu P, Li X, Chen S, et al. New SIMS U-Pb zircon age and its constraint on the beginning of the Nantuo glaciation[J]. Science Bulletin, 2015, 60(10):958-963. doi: 10.1007/s11434-015-0790-3

      Liu P, Li X, Chen S, et al. New SIMS U-Pb zircon age and its constraint on the beginning of the Nantuo glaciation[J]. Science Bulletin, 2015, 60(10):958-963. doi: 10.1007/s11434-015-0790-3

      Peters K E, Cunningham A E, Walters C C, et al. Petroleum systems in the Jiangling-Dangyang area, Jianghan basin, China[J]. Organic Geochemistry, 1996, 24(10):1035-1060.

      Peters K E, Cunningham A E, Walters C C, et al. Petroleum systems in the Jiangling-Dangyang area, Jianghan basin, China[J]. Organic Geochemistry, 1996, 24(10):1035-1060.

      Vernhet E, Reijmer J J G. Sedimentary evolution of the Ediacaran Yangtze platform shelf (Hubei and Hunan provinces, Central China)[J]. Sedimentary Geology, 2010, 225(3):99-115.

      Vernhet E, Reijmer J J G. Sedimentary evolution of the Ediacaran Yangtze platform shelf (Hubei and Hunan provinces, Central China)[J]. Sedimentary Geology, 2010, 225(3):99-115.

      Zhu G, Wang T, Xie Z, et al. Giant gas discovery in the Precambrian deeply buried reservoirs in the Sichuan Basin, China:implications for gas exploration in old cratonic basins[J]. Precambrian Research, 2015, 262:45-66. doi: 10.1016/j.precamres.2015.02.023

      Zhu G, Wang T, Xie Z, et al. Giant gas discovery in the Precambrian deeply buried reservoirs in the Sichuan Basin, China:implications for gas exploration in old cratonic basins[J]. Precambrian Research, 2015, 262:45-66. doi: 10.1016/j.precamres.2015.02.023

      Kirschvink J L. The least-squares line and plane and the analysis of palaeomagnetic data[J]. Geophysical Journal International, 1980, 62(3):699-718. doi: 10.1111/gji.1980.62.issue-3

      Kirschvink J L. The least-squares line and plane and the analysis of palaeomagnetic data[J]. Geophysical Journal International, 1980, 62(3):699-718. doi: 10.1111/gji.1980.62.issue-3

      Zhang S, Evans D A D, Li H, et al. Paleomagnetism of the late Cryogenian Nantuo Formation and paleogeographic implications for the South China Block[J]. Journal of Asian Earth Sciences, 2013, 72:164-177. doi: 10.1016/j.jseaes.2012.11.022

      Zhang S, Evans D A D, Li H, et al. Paleomagnetism of the late Cryogenian Nantuo Formation and paleogeographic implications for the South China Block[J]. Journal of Asian Earth Sciences, 2013, 72:164-177. doi: 10.1016/j.jseaes.2012.11.022

      Evans D A D, Li Z X, Kirschvink J L, et al. A high-quality midNeoproterozoic paleomagnetic pole from South China, with implications for ice ages and the breakup configuration of Rodinia[J]. Precambrian Research, 2000, 100(1):313-334.

      Evans D A D, Li Z X, Kirschvink J L, et al. A high-quality midNeoproterozoic paleomagnetic pole from South China, with implications for ice ages and the breakup configuration of Rodinia[J]. Precambrian Research, 2000, 100(1):313-334.

      Li Z X, Evans D A D, Halverson G P. Neoproterozoic glaciations in a revised global palaeogeography from the breakup of Rodinia to the assembly of Gondwanaland[J]. Sedimentary Geology, 2013, 294:219-232. doi: 10.1016/j.sedgeo.2013.05.016

      Li Z X, Evans D A D, Halverson G P. Neoproterozoic glaciations in a revised global palaeogeography from the breakup of Rodinia to the assembly of Gondwanaland[J]. Sedimentary Geology, 2013, 294:219-232. doi: 10.1016/j.sedgeo.2013.05.016

      Liu X, Gao S, Diwu C, et al. Precambrian crustal growth of Yangtze Craton as revealed by detrital zircon studies[J]. American Journal of Science, 2008, 308(4):421-468. doi: 10.2475/04.2008.02

      Liu X, Gao S, Diwu C, et al. Precambrian crustal growth of Yangtze Craton as revealed by detrital zircon studies[J]. American Journal of Science, 2008, 308(4):421-468. doi: 10.2475/04.2008.02

      马国干, 李华芹, 张自超.华南地区震旦纪时限范围的研究[J].中国地质科学院宜昌地质矿产研究所所刊, 1984, 8(1):1-29. http://cpfd.cnki.com.cn/Article/CPFDTOTAL-ZGDJ198412001003.htm
      Cui X, Zhu W B, Ge R F. Provenance and Crustal Evolution of the Northern Yangtze Block Revealed by Detrital Zircons from Neoproterozoic-Early Paleozoic Sedimentary Rocks in the Yangtze Gorges Area, South China[J]. The Journal of Geology, 2014, 122(2):217-235. doi: 10.1086/674801

      Cui X, Zhu W B, Ge R F. Provenance and Crustal Evolution of the Northern Yangtze Block Revealed by Detrital Zircons from Neoproterozoic-Early Paleozoic Sedimentary Rocks in the Yangtze Gorges Area, South China[J]. The Journal of Geology, 2014, 122(2):217-235. doi: 10.1086/674801

      高维, 张传恒.长江三峡黄陵花岗岩与莲沱组凝灰岩的锆石SHRIMP U-Pb年龄及其构造地层意义[J].地质通报, 2009, 28:45-50. http://dzhtb.cgs.cn/ch/reader/view_abstract.aspx?flag=1&file_no=20090106&journal_id=gbc
      Hofmann M, Linnemann U, Rai V, et al. The India and South China cratons at the margin of Rodinia-Synchronous Neoproterozoic magmatism revealed by LA-ICP-MS zircon analyses[J]. Lithos, 2011, 123(1):176-187.

      Hofmann M, Linnemann U, Rai V, et al. The India and South China cratons at the margin of Rodinia-Synchronous Neoproterozoic magmatism revealed by LA-ICP-MS zircon analyses[J]. Lithos, 2011, 123(1):176-187.

      Yang Z, Sun Z, Yang T, et al. A long connection (750-380Ma) between South China and Australia:paleomagnetic constraints[J]. Earth and Planetary Science Letters, 2004, 220(3):423-434.

      Yang Z, Sun Z, Yang T, et al. A long connection (750-380Ma) between South China and Australia:paleomagnetic constraints[J]. Earth and Planetary Science Letters, 2004, 220(3):423-434.

      Wingate M T D, Giddings J W. Age and palaeomagnetism of the Mundine Well dyke swarm, Western Australia:implications for an Australia-Laurentia connection at 755Ma[J]. Precambrian Research, 2000, 100(1):335-357.

      Wingate M T D, Giddings J W. Age and palaeomagnetism of the Mundine Well dyke swarm, Western Australia:implications for an Australia-Laurentia connection at 755Ma[J]. Precambrian Research, 2000, 100(1):335-357.

      Sohl L E, Christie-Blick N, Kent D V. Paleomagnetic polarity reversals in Marinoan (ca. 600Ma) glacial deposits of Australia:implications for the duration of low-latitude glaciation in Neoproterozoic time[J]. Geological Society of America Bulletin, 1999, 111(8):1120-1139. doi: 10.1130/0016-7606(1999)111<1120:PPRIMC>2.3.CO;2

      Sohl L E, Christie-Blick N, Kent D V. Paleomagnetic polarity reversals in Marinoan (ca. 600Ma) glacial deposits of Australia:implications for the duration of low-latitude glaciation in Neoproterozoic time[J]. Geological Society of America Bulletin, 1999, 111(8):1120-1139. doi: 10.1130/0016-7606(1999)111<1120:PPRIMC>2.3.CO;2

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    出版历程
    • 收稿日期:  2016-07-05
    • 修回日期:  2016-08-11
    • 网络出版日期:  2023-08-16
    • 刊出日期:  2016-10-31

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