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坦桑尼亚乌本迪带内基性–酸性岩类的锆石U-Pb年龄、地球化学特征及地质意义

许康康, 谢薇, 刘晓阳, 赵晓博, 顾延景

许康康,谢薇,刘晓阳,等. 坦桑尼亚乌本迪带内基性–酸性岩类的锆石U-Pb年龄、地球化学特征及地质意义[J]. 西北地质,2024,57(3):209−222. doi: 10.12401/j.nwg.2023147
引用本文: 许康康,谢薇,刘晓阳,等. 坦桑尼亚乌本迪带内基性–酸性岩类的锆石U-Pb年龄、地球化学特征及地质意义[J]. 西北地质,2024,57(3):209−222. doi: 10.12401/j.nwg.2023147
XU Kangkang,XIE Wei,LIU Xiaoyang,et al. Zircon U-Pb Age, Geochemistry and Geological Significance of the Basic-Acidic Rocks in the Ubendian Belt, Tanzania[J]. Northwestern Geology,2024,57(3):209−222. doi: 10.12401/j.nwg.2023147
Citation: XU Kangkang,XIE Wei,LIU Xiaoyang,et al. Zircon U-Pb Age, Geochemistry and Geological Significance of the Basic-Acidic Rocks in the Ubendian Belt, Tanzania[J]. Northwestern Geology,2024,57(3):209−222. doi: 10.12401/j.nwg.2023147

坦桑尼亚乌本迪带内基性–酸性岩类的锆石U-Pb年龄、地球化学特征及地质意义

基金项目: 国家重点研发计划课题“辽东/胶东矿集区深部矿产勘查与增储示范”(2018YFC0603805)和中国地质调查局项目(DD20160108;DD20190439;DD20551801)联合资助。
详细信息
    作者简介:

    许康康(1986–),男,高级工程师,主要从事地质矿产勘查与研究工作。E–mail:xukang06@163.com

    通讯作者:

    谢薇(1987–),女,高级工程师,主要从事环境地球化学研究。E–mail:Chinav2012@163.com

  • 中图分类号: P584;P597

Zircon U-Pb Age, Geochemistry and Geological Significance of the Basic-Acidic Rocks in the Ubendian Belt, Tanzania

  • 摘要:

    乌本迪带位于坦桑尼亚西南缘,具有多阶段的构造演化历史。相比其他演化阶段,有关中元古代的岩浆作用研究相对较少,从而制约了乌本迪带中元古代构造演化历史的研究。基于此,笔者选择坦桑尼亚姆贝亚(Mbeya)地区发现的中元古代辉长岩和正长花岗岩进行岩石学、地质年代学和地球化学研究。结果表明,辉长岩和正长花岗岩的锆石结晶年龄分别为(1433±9)Ma和(1428±11)Ma,为中元古代岩浆活动的产物。辉长岩具有高的TiO2含量(最高可达2.6%)和Ti/Y值(最高可达601),轻稀土元素(LREE)富集,(La/Yb)N值为4.85;Eu具轻微正异常,δEu值为1.02;富集大离子亲石元素(LILEs,如Rb、Ba、Sr、K),亏损高场强元素(HFSEs,如Nb、Ta、Zr),其微量元素组成与大陆溢流玄武岩(CFB)类似,推测为富集大陆岩石圈地幔发生低程度部分熔融的产物。正长花岗岩具高的SiO2含量(71.59%~75.08%)和Ga/Al值(Ga/Al×104值为2.98~3.11),Zr+Nb+Ce+Y远大于350×10−6;LREE富集,(La/Yb)N值为22.86~28.51;Eu具明显负异常,δEu值为0.12~0.34,显示A型花岗岩特征,较低的Mg#值(6~10)和Sr/Y值(0.17~0.65),表明其可能为中–下地壳基性岩石部分熔融的产物。辉长岩和正长花岗岩的构造环境研究显示,两者均形成于板内拉张环境,与全球该时期构造演化体制相吻合,为Columbia超大陆裂解事件的岩浆产物。

    Abstract:

    The Ubendian Belt, which is situated on Tanzania’s southwest border, has undergone a multi-stage tectonic evolution history. Compared with other stages, there has been comparatively little research on the Mesoproterozoic Mag Matism, which restricts the study on the Mesoproterozoic tectonic evolution history of Ubendian Belt. Based on this, the Mesoproterozoic gabbro and syenite are selected for petrological, geochronology and geochemistry studies. The results show that the crystallization ages of the gabbro and syenogranite are (1433±9) Ma and (1428±11) Ma, respectively, indicating they are Mesoproterozoic. The gabbro is characterized by high content of TiO2(2.6%) and Ti/Y ratio (601), enriched in LREE with (La/Yb)N of 4.85, and slightly positive Eu ano Malies (δEu=1.02). The LILEs (Rb, Ba, Sr, K) are enriched and HFSEs (Nb, Ta, Zr) are depleted, the geochemical features of the gabbro are consistent with continental flood basalts (CFB), indicating that it May be the production of a low degree partial melting of the enriched continental lithospheric Mantle. The syenites have high contents of SiO2 (71.59%~75.08%), they are characterized by enrichment in LREE with (La/Yb)N of 22.86~28.51, significant negative Eu ano Malies (δEu=0.12~0.34). Their values of Ga/Al are high (Ga/Al×104=2.98~3.11) and the content of Zr+Nb+Ce+Y is much larger than 350×10−6, indicating that they are A-type granites. The lower Mg# values (6~10) and Sr/Y ratios (0.17~0.65), indicating that they are the production of partial melting of basaltic rocks in the middle-lower crust. Both of the gabbro and syenite originated within an intra-plate rifting enviroment, which is consistent with the global tectonic regime of the Columbia Supercontinent rifting event.

  • 中亚造山带横亘于西伯利亚板块和华北–塔里木板块之间,其形成与古亚洲洋及其陆缘的演化密切相关(Şengör et al.,1993Badarch et al.,2002Xiao et al.,20032018Windley et al.,2007付超等,2023张永玲等,2024)。关于古亚洲洋或其分支洋闭合时限存在泥盆纪—早石炭世(Charvet et al.,2007Xu et al.,2013邵济安等,2014刘桂萍等,2021)和二叠纪至早—中三叠世不同认识(Xiao et al.,20032018Li,2006Windley et al.,2007Jian et al.,2008Zheng et al.,20202021),究其原因,可能与古亚洲洋自西向东剪刀式闭合有关或多期造山有关(Wang et al.,2022Li et al.,2022),且西伯利亚板块与华北–塔里木板块之间存在不同时期的微陆块和岛弧,不同地体碰撞拼贴的时间也存在差异(陈井胜等,2022董玉等,2022)。中亚造山带各个部分地质演化记录的研究能够丰富对其构造演化过程的精细认识。

    内蒙古阿拉善盟额济纳旗位于中亚造山带中段南缘,是连接造山带东、西两段的关键部位,区域出露有大量岩浆岩,记录了深部壳幔相互作用的信息,是研究中亚造山带构造演化过程的关键。埃达克岩被认为形成于“高压”构造环境(张旗等,20022003,2020),有学者将埃达克岩的产出作为中亚造山带处于俯冲/碰撞期的标志(谢春林等,2009Li et al.,201220132017Liu et al.,2012Liu et al.,2019Lu et al.,2020Wang et al.,2020Zheng et al.,20202021Luan et al.,2022)。A型花岗岩被认为形成于伸展的构造环境(Eby,1992),A型花岗岩的侵位时代可限定其造山后伸展作用的时限(Wu et al.,2002Shi et al.,2004Li et al.,2012Shi et al.,2016Zheng et al.,2016Du et al.,2018Eizenhöfer et al.,2018Lu et al.,2020Song et al.,2020),这些包括埃达克岩和A型花岗岩在内的典型岩浆作用可为理解中亚造山带洋陆演化过程提供关键约束(王元元等,2023舍建忠等,2023)。

    区域地质调查工作过程中在内蒙古阿拉善盟额济纳旗达伦乌苏地区新识别出了两期岩浆岩,利用岩石学、同位素地质年代学和岩石地球化学研究方法,确定了其活动时代,探讨了其成因和构造背景,为该区域典型岩浆作用和构造演化史的研究提供了新证据。

    研究区南侧恩格尔乌苏蛇绿混杂岩带内见有超镁铁岩、辉长岩、枕状和块状玄武岩、硅质岩、细碧岩等,其中辉长岩锆石U-Pb年龄为380 Ma(王廷印等,1993),枕状玄武岩显示正常型大洋中脊玄武岩特征,其SHRIMP 锆石U-Pb年龄为(302±14)Ma(Zheng et al.,2014),多被认为是古亚洲洋在本段的最终闭合位置,向东与索伦蛇绿岩带相连,该蛇绿混杂岩带以北属中亚造山带的中段。研究区北侧蒙古境内Gurvan Sayhan- Zoolen 蛇绿岩带的蛇绿岩组分形成于520~511 Ma ,被(494±6)Ma的闪长岩脉截切侵入,代表了北侧Zoolen洋和对接带(Jian et al., 2014)。雅干断裂带近EW向横穿研究区,两侧古生代地层、火山岩和侵入岩特征存在明显差异,长期以来被视为一条重要的地质界线,北侧主体为奥陶纪—石炭纪岛弧,南侧为珠斯楞-杭乌拉大陆边缘(吴泰然等,1993王廷印等,1993Windley et al.,2007郑荣国等,2013Liu et al.,201620172018)。研究区向西与北山造山带隔巴丹吉林沙漠相望,向东雅干断裂带所分隔的两地体分别与Badarch等(2002)在蒙古境内划分具岛弧性质的Hashaat地体和具克拉通性质的南戈壁微陆块相连(图1a)。达伦乌苏二长花岗岩、花岗斑岩紧邻雅干断裂带,位于其北侧,侵入石炭系地层和更早期的岩体中(图1a、图1b)。

    图  1  内蒙古西部大地构造简图(a)及研究区地质简图(b)
    Figure  1.  (a) Tectonic map of the western Inner Mongolia and (b) sketch geological map of the study area

    达伦乌苏早三叠世二长花岗岩体北东向展布,出露面积约为3.2 km2,侵入石炭系白山组和早期角闪辉长岩中,局部被下白垩统巴音戈壁组和第四系冲洪积物不整合覆盖(图1b)。岩石多为似斑状花岗结构。斑晶主要为钾长石,大者可达3 cm,含量约为5%~10%。基质为中粗粒花岗结构,矿物大小多为3~10 mm,主要由斜长石(35%~40%)、钾长石(20%~25%)、石英(30%)和少量黑云母组成(图2a、图2b)。

    图  2  达伦乌苏早三叠世二长花岗岩(a、b)和中三叠世花岗斑岩岩体(c、d)野外及镜下特征
    Pl. 斜长石;Kfs. 钾长石;Bt. 黑云母;Qtz. 石英
    Figure  2.  (a, b) Representative photomicrographs of the Dalunwusu early- middle Triassic monzogranite and (c, d) granite porphyry

    达伦乌苏中三叠世花岗斑岩呈一小岩株产出,出露面积约0.5 km2,侵入早二叠世正长花岗岩和晚石炭世花岗闪长岩中,局部被第四系冲洪积物覆盖(图1b)。岩石呈斑状–似斑状结构,多由斑晶和基质组成。斑晶见斜长石、钾长石及石英,粒径0.2~2.5 mm不等。斜长石呈半自形板状,镜下隐约可见聚片双晶,部分可见环带构造。钾长石为(正)条纹长石,呈半自形板状,部分粒内嵌布板条状斜长石。石英呈他形粒状,多聚集在一起分布。基质由微细粒的长石、石英及少量白云母组成(图2c、图2d)。岩体整体钼含量较高,其中曾发现了多条钼矿体。

    本次研究在额济纳旗达伦乌苏北早三叠世二长花岗和中三叠世花岗斑岩内各采集了一件锆石U-Pb同位素测年样品,具体采样位置见图1b。样品采自新鲜的岩石露头,粗碎清洗剔除风成砂和风化面。锆石分选、制靶、阴极发光(CL)照相和LA-ICP-MS锆石U-Pb同位素分析均在中国冶金地质总局山东局测试中心完成。锆石U-Pb同位素测试使用美国Coherent 公司生产的193nmArF准分子系统,ICP-MS为美国热电Thermo iCAP Q,激光束斑直径为30 μm,激光脉冲10 Hz。测试采用标准锆石91500作为外部标准物质,元素含量采用NIST610作为外标,29Si作为内标元素,具体实验测试方法与李凤春等(2016)相同。样品的同位素比值及元素含量计算采用ICPMSDATACAL程序,普通铅校正采用ComPbCorr#3.17校正程序,U-Pb谐和图和年龄权重平均计算采用Isoplot程序(Ludwing,2003)完成。

    在岩体的不同位置采集了主、微量和稀土元素测试样品。其中二长花岗岩4件(GS5215-1、GS5137-1、GS5107-1、TW5127-1),花岗斑岩3件(PM54TW7、GS5312-1、GS5312-2),具体采样位置见图1b。样品主量元素测试工作采用X射线荧光法进行分析(XRF),在中国地质调查局呼和浩特自然资源综合调查中心实验室Axios MaxX-荧光光谱仪上完成。稀土、微量元素分析测试工作在中国冶金地质总局山东局测试中心完成,其中Cs、Ba、Nb、Rb、Zr元素分析采用X荧光光谱法分析,其他元素在X Series2电感耦合等离子体质谱仪(YQ006)上完成,具体分析流程与Yan等(2019)相同。

    TW5127-1样品锆石多为自形短柱状晶体,其长轴多为130~220 µm,长宽比在1.5~2.5之间,阴极发光图像显示锆石显示有清晰的震荡环带,具岩浆锆石特征(图3a)。除去部分锆石普通铅过高和和未获有效的平坦的波谱段外,样品中的23个测点具相近的单颗粒锆石年龄,详细分析结果见表1。锆石Th含量为240.0×10−6~935.0×10−6,U含量为545.8×10−6~1250.5×10−6,Th/U值为0.39~0.91(均>0.1),锆石206Pb/ 238U年龄为240~257 Ma,23个点测试结果均位于谐和线附近,其206Pb/ 238U加权平均年龄为(249.0±2.3)Ma(MSWD = 3.4,n=23)(图4a、图4b),代表了该二长花岗岩的结晶年龄。

    图  3  达伦乌苏二长花岗岩(a)和紫红色花岗斑岩体(b)代表性锆石阴极发光图像
    Figure  3.  (a) The cathodoluminescence (CL) images of typical zircon grains of the Dalunwusu early- middle Triassic monzogranite and (b) granite porphyry
    表  1  达伦乌苏早三叠世二长花岗岩和中三叠世花岗斑岩LA-ICP-MS锆石U-Pb 测年结果
    Table  1.  LA-ICP-MS zircon U-Pb dating results for the Dalunwusu early-middle triassic monzogranite and granite porphyry
    样品号含量(10−6Th/U同位素比值年龄(Ma)
    PbThU207Pb/206Pb207Pb/235U206Pb/238U208Pb/232Th207Pb/206Pb207Pb/235U206Pb/238U
    TW5127-1,二长花岗岩
    spot-01 32.8 326.9 674.0 0.49 0.05049 0.00147 0.28031 0.00805 0.04026 0.00048 0.01271 0.00033 217 67 251 6 254 3
    spot-02 45.2 455.1 918.5 0.50 0.05321 0.00132 0.29573 0.00716 0.04026 0.00044 0.01333 0.00032 345 57 263 6 254 3
    spot-03 28.3 258.8 604.2 0.43 0.04913 0.00141 0.26853 0.00759 0.03961 0.00044 0.01198 0.00027 154 67 242 6 250 3
    spot-04 53.0 553.6 1104.3 0.50 0.05191 0.00116 0.28680 0.00654 0.03992 0.00045 0.01226 0.00028 280 52 256 5 252 3
    spot-06 36.8 315.5 771.4 0.41 0.05038 0.00249 0.28842 0.00889 0.04069 0.00050 0.01441 0.00045 213 115 257 7 257 3
    spot-07 52.9 653.7 1115.6 0.59 0.05049 0.00128 0.26964 0.00651 0.03867 0.00044 0.01216 0.00026 217 55 242 5 245 3
    spot-08 53.5 681.0 1150.5 0.59 0.05180 0.00184 0.27615 0.00703 0.03824 0.00042 0.01142 0.00027 276 86 248 6 242 3
    spot-09 59.7 588.7 1247.8 0.47 0.05236 0.00134 0.29155 0.00711 0.04018 0.00047 0.01260 0.00030 302 62 260 6 254 3
    spot-10 26.7 259.7 576.7 0.45 0.05159 0.00165 0.27715 0.00837 0.03891 0.00049 0.01281 0.00035 333 74 248 7 246 3
    spot-11 32.9 282.6 723.8 0.39 0.05188 0.00138 0.27909 0.00744 0.03876 0.00043 0.01279 0.00035 280 61 250 6 245 3
    spot-12 61.6 743.3 1250.5 0.59 0.05035 0.00115 0.28021 0.00614 0.04020 0.00044 0.01272 0.00025 209 49 251 5 254 3
    spot-13 58.5 935.0 1168.0 0.80 0.05662 0.00127 0.30055 0.00718 0.03820 0.00042 0.01236 0.00024 476 48 267 6 242 3
    spot-14 33.1 398.4 699.9 0.57 0.05294 0.00130 0.28662 0.00766 0.03900 0.00053 0.01247 0.00031 328 28 256 6 247 3
    spot-16 50.1 789.2 954.3 0.83 0.05336 0.00124 0.29522 0.00668 0.04002 0.00049 0.01279 0.00029 343 47 263 5 253 3
    spot-18 32.2 366.7 644.9 0.57 0.05154 0.00161 0.28431 0.00892 0.03999 0.00056 0.01268 0.00033 265 77 254 7 253 3
    spot-22 43.9 763.0 844.2 0.90 0.04963 0.00120 0.26183 0.00619 0.03795 0.00037 0.01184 0.00022 176 56 236 5 240 2
    spot-24 25.9 240.0 545.8 0.44 0.05098 0.00152 0.28251 0.00887 0.03984 0.00065 0.01215 0.00041 239 70 253 7 252 4
    spot-25 34.6 491.3 697.3 0.70 0.04986 0.00133 0.26655 0.00691 0.03842 0.00049 0.01198 0.00030 187 63 240 6 243 3
    spot-27 35.5 383.4 718.5 0.53 0.05046 0.00134 0.28351 0.00710 0.04058 0.00052 0.01273 0.00031 217 61 253 6 256 3
    spot-29 37.2 350.4 796.3 0.44 0.04926 0.00147 0.26735 0.00737 0.03925 0.00050 0.01164 0.00028 167 70 241 6 248 3
    spot-30 39.0 658.3 726.7 0.91 0.05058 0.00132 0.28010 0.00692 0.03998 0.00046 0.01233 0.00027 220 59 251 5 253 3
    spot-31 51.3 747.0 1026.8 0.73 0.05171 0.00134 0.27898 0.00669 0.03889 0.00040 0.01207 0.00026 272 59 250 5 246 3
    spot-32 45.1 528.0 924.9 0.57 0.05077 0.00151 0.27851 0.00752 0.03980 0.00056 0.01234 0.00031 232 66 249 6 252 3
    PM54TW7,花岗斑岩
    spot-01 28.7 427.2 572.8 0.75 0.05527 0.00186 0.29714 0.00979 0.03869 0.00065 0.01221 0.00040 433 76 264 8 245 4
    spot-02 48.7 619.9 1002.1 0.62 0.05177 0.00152 0.27438 0.00762 0.03805 0.00054 0.01167 0.00033 276 69 246 6 241 3
    spot-03 33.9 406.8 725.1 0.56 0.05418 0.00204 0.27645 0.00792 0.03671 0.00053 0.01233 0.00037 389 81 248 6 232 3
    spot-05 42.4 786.6 831.7 0.95 0.05388 0.00157 0.28522 0.00820 0.03811 0.00058 0.01118 0.00030 365 67 255 6 241 4
    spot-09 24.3 284.9 523.6 0.54 0.05405 0.00210 0.28162 0.01030 0.03766 0.00058 0.01145 0.00037 372 87 252 8 238 4
    spot-10 55.3 781.8 1085.9 0.72 0.05242 0.00438 0.27090 0.01148 0.03757 0.00062 0.01364 0.00049 306 191 243 9 238 4
    spot-13 38.0 550.1 770.3 0.71 0.05064 0.00156 0.26967 0.00809 0.03845 0.00051 0.01204 0.00035 233 72 242 6 243 3
    spot-14 36.8 470.6 743.6 0.63 0.05036 0.00182 0.27417 0.00974 0.03923 0.00053 0.01244 0.00038 213 88 246 8 248 3
    spot-15 34.4 538.8 723.4 0.74 0.05096 0.00156 0.26393 0.00810 0.03735 0.00051 0.01168 0.00031 239 72 238 7 236 3
    spot-16 25.8 435.0 524.3 0.83 0.05166 0.00184 0.26403 0.00885 0.03711 0.00056 0.01228 0.00033 333 81 238 7 235 3
    spot-21 27.5 373.2 569.7 0.66 0.05394 0.00206 0.28668 0.01036 0.03826 0.00059 0.01193 0.00044 369 87 256 8 242 4
    spot-22 39.5 549.3 782.3 0.70 0.05610 0.00259 0.30074 0.00964 0.03877 0.00057 0.01394 0.00045 457 102 267 8 245 4
    spot-23 33.4 588.1 646.7 0.91 0.04870 0.00181 0.26388 0.00917 0.03937 0.00071 0.01205 0.00040 132 87 238 7 249 4
    spot-27 33.8 463.5 682.4 0.68 0.05041 0.00173 0.26837 0.00914 0.03865 0.00059 0.01287 0.00044 213 84 241 7 244 4
    下载: 导出CSV 
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    图  4  达伦乌苏二长花岗岩(a、b)和紫红色花岗斑岩体(c、d)锆石U-Pb年龄谐和图
    Figure  4.  (a, b) LA-ICP-MS U-Pb zircon concordia diagram of the Dalunwusu early-middle Triassic monzogranite and (c, d) granite porphyry

    PM54TW7样品锆石多为自形长柱状晶体,其长轴为250~500 µm,长宽比为2.5~5.5,阴极发光图像显示锆石具有清晰的震荡环带,为岩浆锆石(图3b)。除去部分测点普通铅过高和未获有效的平坦的波谱段外,样品中的14个锆石获得了较谐和的单颗粒锆石年龄,详细分析结果见表1。其Th含量为284.9×10−6~786.6×10−6,U含量为523.6×10−6~1085.9×10−6,Th/U值为0.54~0.95(均>0.1),显示岩浆成因锆石特征。锆石206Pb/ 238U年龄为232~249Ma,14个点测试结果均位于谐和线附近,其206Pb/ 238U加权平均年龄为(241.0±2.8) Ma (MSWD = 1.9,n=14),代表了该花岗斑岩的结晶年龄(图4c、图4d)。

    达伦乌苏早三叠世浅肉红色二长花岗岩和中三叠世紫红色花岗斑岩主、微量分析结果见表2

    表  2  达伦乌苏早三叠世二长花岗岩和中三叠世花岗斑岩主、微量分析测试结果
    Table  2.  Major (%) and trace element (10−6) analysis results for the Dalunwusu early- middle Triassic monzogranite and granite porphyry
    GS5215-1GS5137-1GS5107-1TW5127-1PM54TW7GS5312-1GS5312-2
    岩体早三叠世二长花岗岩中三叠世紫红色花岗斑岩
    SiO271.8071.2171.7472.7177.0077.2578.08
    TiO20.300.320.290.260.080.100.10
    Al2O315.1215.0514.8414.9812.2711.6211.35
    Fe2O31.401.161.121.361.010.941.02
    FeO0.901.471.310.320.491.130.80
    CaO1.852.071.721.390.720.600.54
    MgO0.690.840.660.600.140.190.15
    K2O3.663.254.164.505.115.895.71
    Na2O4.144.474.053.793.152.232.22
    MnO0.040.040.030.020.020.030.02
    P2O50.090.110.080.070.010.020.02
    LOI1.280.600.820.910.330.250.27
    TOTAL99.7099.6699.69100.1399.8899.7899.81
    K2O/Na2O0.890.731.031.191.622.642.58
    FeOT2.162.522.331.551.401.971.72
    A/CNK1.071.031.041.101.021.041.05
    A/NK1.401.381.331.351.141.161.15
    Mg#40.2441.2237.4744.7517.6917.1915.34
    R12388231622952392277129183027
    R2529558508472324302287
    Ga19.619.419.819.721.51816.8
    Rb95.5107126168383388403
    Sr39574840248724.865.465.2
    Y4.15.334.544.684.477.425.43
    Zr16115314611881.77672.5
    Nb3.633.783.463.2514.318.415.2
    Ba579727901105652.9127132
    La14.723.320.418.711119.16
    Ce28.542.537.838.917.319.617.6
    Pr3.314.84.13.781.541.811.42
    Nd11.917.214.513.94.135.654.19
    Sm2.022.752.342.470.640.90.66
    Eu0.590.790.70.490.0840.170.15
    Gd1.722.352.041.990.710.970.78
    Tb0.210.270.230.220.10.170.12
    Dy0.781.080.91.010.5310.7
    Ho0.140.190.160.160.110.230.17
    Er0.440.540.480.430.460.830.63
    Tm0.0490.0720.0610.0620.0820.150.1
    Yb0.360.470.410.380.691.150.78
    Lu0.0590.0740.0580.0590.130.20.13
    Hf4.464.193.933.574.153.683.21
    Ta0.120.140.0990.410.971.671.29
    Pb23.727.222.826.451.231.731.9
    Th15.717.419.313.339.44938
    U1.451.540.921.298.677.066.72
    δEu0.970.950.980.680.380.560.64
    ΣREE64.7896.3984.1882.5537.5143.8336.59
    (La/Yb)N29.3035.5835.7135.3111.446.868.43
    (La/Sm)N4.705.485.634.8911.117.908.97
    10000×Ga/Al2.452.432.522.483.312.932.80
    下载: 导出CSV 
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    达伦乌苏早二叠世二长花岗岩样品SiO2含量为71.21%~72.71%,平均含量为71.87%,在TAS分类图解中样品落入花岗岩区(图5a)。样品全碱含量高(K2O+Na2O=7.72%~8.29%),Na2O/K2O=0.73~1.19,平均为0.96,属高钾钙碱性系列(图5b、图5c)。其Al2O3含量为14.84%~15.12%,平均为15%,A/CNK值均>1且<1.1(1.03~1.10),在A/NK-A/CNK图解中样品全部落入过铝质区域内(图5c)。样品Sr含量较高,在395×10−6~748×10−6之间,平均含量为508×10−6 (>400×10−6)。具有较低的Y(4.10×10−6~5.33×10−6,平均<18×10−6)和Yb(0.36×10−6~0.47×10−6,平均<1.9×10−6)含量。具较高的Sr/Y 值(88.55~140.34,>20~40)。在球粒陨石标准化图解中稀土配分曲线呈右倾型,富集轻稀土元素而亏损重稀土元素,样品无明显Eu异常,δEu值为0.68~0.98,平均为0.89(图6a)。在微量元素蛛网图中,岩体明显富集Sr、K、Th、Rb,相对亏损Nb、Ta、P、Ti(图6b)。

    图  5  达伦乌苏早三叠世二长花岗岩和花岗斑岩TAS图解(a)(据Middemost, 1994)、SiO2-(Na2O+ K2O- CaO)(b)、SiO2- K2O(c)和A/NK-A/CNK图解(d)(据Miniar et al., 1989
    Figure  5.  (a) TAS diagram, (b) SiO2 vs. (Na2O+ K2O-CaO) , (c) SiO2 vs. K2O and (d) A/CNK vs. A/NK diagram for the Dalunwusuearly Triassic monzogranite and granite porphyry
    图  6  达伦乌苏早三叠世二长花岗岩和中三叠世花岗斑岩稀土元素球粒陨石标准化配分模式图(a)及微量元素蛛网图(b)
    球粒陨石标准化值据Boynton (1984);原始地幔标准化值据Sun等(1989)
    Figure  6.  (a) Chondrite-normalized REE patterns and (b) Primitive mantle-normalized multiple trace element diagrams of the Dalunwusu early-middle Triassic monzogranite and granite porphyry

    达伦乌苏中三叠世花岗斑岩样品SiO2含量为77.00%~78.08%,平均为77.44%,在TAS分类图解中样品落入花岗岩区(图4a)。岩石富碱,(Na2O+K2O)含量为7.93%~8.27%,平均为8.10%;K2O/Na2O为0.38~0.62,属高钾钙碱性系列(图4b图4c)。样品具有较低的CaO含量为0.54%~0.72%和Al2O3含量为11.35%~12.27%,平均为11.74%,其A/CNK值接近1(1.02~1.05),属过铝质岩石(图4d)。样品MgO含量较低0.14%~0.19%,Mg#值亦较低,介于15.34~17.69(表2)。稀土总量较低36.59×10−6~43.83×10−6,轻重稀土分馏明显(LREE/HREE=8.33~12.34,(La/Yb)N=6.86~11.44),轻稀土内部分馏亦明显(La/Sm)N=7.90~11.11,重稀土元素相对平坦,具中等Eu负异常(δEu= 0.38~0.64),稀土元素球粒陨石标准化图解中配分曲线呈“右倾海鸥型” (图6a)。在微量元素蛛网图中,样品明显富集高场强元素Th、U、 Rb 、K,相对亏损Ba、Sr、P、Ti(图6b)。样品10 000×Ga/Al值为2.80~3.31(均大于2.6)。

    笔者获得的锆石U-Pb年龄显示达伦乌苏二长花岗岩、花岗斑岩岩体分别形成于(249.0±2.3)Ma、(241.0±2.8)Ma,侵位于早—中三叠世。该年龄修正了雅干幅1∶20万区域地质矿产调查中在达伦乌苏二长花岗岩体的长石中获得的K-Ar年龄为193.5 Ma。区域三叠系分布较少,目前已知的仅在苏亥特高勒南东、拐子湖附近零星出露上三叠统珊瑚井组。前人在研究区西具低Sr/Y值的乔伦恩格次岩体获得了(236.8±2.1) Ma的锆石U-Pb年龄(王丕军,2018刘基等,2020),望湖山岩体获得了230 Ma的锆石U-Pb年龄(Liu et al., 2018)。达伦乌苏两期岩体是区域三叠纪岩浆作用和区域地质演化研究的新载体。

    达伦乌苏早三叠世二长花岗岩样品Sr含量较高(平均为508×10−6),Y含量和Yb含量较低,具较高的Sr/Y值(88.55~140.34)和La/Yb值(40.83~49.76),弱的Eu负异常(δEu平均值为0.89)。这些特征暗示熔融时斜长石在源区是不稳定的,源区熔体与榴辉岩处于平衡,对应于高压环境(张旗等,2020),这种与榴辉岩平衡的熔体形成的岩浆岩多具埃达克岩特征。样品SiO2平均含量71.87%,MgO含量为0.60%~0.84%,稀土配分曲线呈右倾型,微量元素相对亏损Nb、Ta、Ce、P等高场强元素,与典型埃达克岩高硅(SiO2≥56%)、高铝(Al2O3≥15%)、低MgO(<3%)、低Y(<18×10−6)、低Yb(<1.9×10−6)和高Sr含量(极少<400×10−6)等地球化学特征一致,在微量元素判别图解中也均落入埃达克岩区域内(图7a)(Defant et al.,1990)。埃达克岩形成于高压环境,可分为与板块的消减作用有关的O型埃达克岩和与板块的消减作用无关的C型埃达克岩(张旗等,2002,2020熊万宇康等,2023)。达伦乌苏早三叠世二长花岗岩属高钾钙碱性系列,相对O型埃达克岩更富钾,Al2O3含量和Mg#值相对更低,其Y/Yb值主要变化于8~15之间,与C型埃达克岩地球化学特征相一致。该埃达克岩体根据Wang等(2006)的分类也属与加厚下地壳相关的埃达克岩(图7b)。样品Mg#值较低,为37.5~44.7,与加厚下地壳部分熔融的熔体相符(一般小于45,Rapp et al.,1995)。实验岩石学研究表明埃达克岩的原岩需满足基性、含水条件,残留相要有石榴子石存在(张旗等,2002)。综上所述,达伦乌苏早三叠世二长花岗岩属C型埃达克岩,形成于高压环境,可能为地壳加厚区底部的下地壳中基性麻粒岩部分熔融形成的。

    图  7  达伦乌苏早三叠世二长花岗岩岩石类型(a)及构造环境判别图解(b)
    Figure  7.  (a) Geochemical classification discrimination and (b) tectonic setting diagrams for Dalunwusu early Triassic mozogranite pluton

    达伦乌苏中三叠世花岗斑岩呈小岩株产出,出露面积小,与A型花岗岩侵位高、规模小的特征相符(杨玉柱等,1993)。岩石呈斑状-似斑状结构,在冷凝过程中仅部分矿物形成了斑晶,暗示岩浆快速上升降温,可能对应于伸展构造环境。化学成分上,样品富SiO2、富碱、富K,贫CaO、MgO和Al2O3,微量元素强烈亏损Ba、Sr、P、Ti,表明源区发生了长石、磷灰石和榍石或金红石的结晶分离作用,与A型花岗岩特征一致(Whalen et al., 1987Eby, 1992)。因其10 000×Ga/Al值均大于2.6,在Whalen等(1987)的以10 000×Ga/Al值为坐标轴的判别图解中均落入A型花岗岩区域(图8a)。样品具高的FeOT/MgO值(9.76~11.58),属铁质花岗岩,高于长英质I型和S型花岗岩,在Forst 等(2001)的主量元素判别图解中也均落入A型花岗岩区域(图8b)。达伦乌苏花岗斑岩具极低的P2O5含量(0.01%~0.02%),与高分异S型花岗岩(均值为0.14%)不同,具较高的FeOT含量(1.40%~1.97%)可与高分异I型花岗岩(一般小于1%)区分(贾小辉等,2009)。样品相对典型A型花岗岩具低的稀土元素含量,δEu值略高(0.38~0.64,一般小于0.3;张旗等,2012),但其稀土配分模式图与典型A型花岗岩一致,为“右倾海鸥型”(图6a),原因可能与源区的稀土元素含量较低有关。本次研究认为达伦乌苏花岗斑岩属A型花岗岩,是低压条件下源岩脱水熔融的产物,形成于伸展构造环境。

    图  8  达伦乌苏中三叠世花岗斑岩岩石类型及构造环境判别图解(a据Whalen et al., 1987; b据Forst et al., 2001
    Figure  8.  (a) Geochemical classification and (b) discrimination diagrams of the tectonic setting for Dalunwusu middle Triassic granite porphyry pluton

    珠斯楞-杭乌拉活动大陆边缘近年来发现了较多元古宙地质信息(Wang et al., 2001Zhang et al., 2016宋博等,2021马军等,2021王振义等,2022),表明该构造带具前寒武基底,应为蒙古境内划分的南戈壁微陆块的自然延伸。地块北侧圆包山岩浆弧发育有中—下奥陶统咸水湖组和石炭系白山组弧火山岩,分别以为基性火山岩和酸性火山岩为主,反映了奥陶纪—石炭纪火山弧逐渐成熟的过程(吴泰然等,1993雷聪聪等,2023)。Liu等(2018)根据岩浆岩锆石Hf同位素和全岩Nd同位素研究成果认为298~277 Ma区域处于俯冲构造环境,~230 Ma花岗岩为后碰撞构造环境。查干桃勒盖地区发育一套浅海相沉积碎屑岩,含有海百合化石和繁盛于早—中二叠世海相腕足类化石,可能代表了区域最晚闭合的残余海盆或弧后盆地。微陆块南侧恩格尔乌苏和查干础鲁蛇绿岩带代表的古亚洲洋分支洋的闭合发生在早二叠世后(Zheng et al., 2014)。区域地质发育情况表明,奥陶纪—二叠纪,南戈壁微陆块处于南北两侧古亚洲洋分支洋的俯冲作用下,而其后由造山到造山后的伸展的时代未能精确限定。

    研究显示,达伦乌苏早三叠世二长花岗岩属C埃达克岩,其形成构造背景大致有3种:活动陆缘地壳加厚地区,板块碰撞导致的地壳加厚地区和高原底部,与高压背景有关(张旗等,20022003,2020)。该期岩体与中亚造山带东西两段报道的埃达克岩的形成时代相近(谢春林等,2009Li et al., 201220132017Wang et al., 2020Zheng et al., 20202021Luan et al., 2022)。达伦乌苏中三叠世花岗斑岩属A型花岗岩,可形成于大陆裂谷或板内的非造山环境和与陆-陆碰撞或岛弧岩浆作用有关的后造山环境,均与伸展的构造背景有关(Eby, 1992)。两期构造环境截然不同的岩浆活动共同限定中亚造山带中段南缘由挤压-伸展的转换时代应在249~241 Ma之间。结合其位于南戈壁微陆块和圆包山岩浆弧之间的活动陆缘区,埃达克岩可能形成于造山晚期的地壳增厚阶段,而A型花岗斑岩应形成于造山后的伸展阶段。这一过程与张旗等(2002)提出的中国东部埃达克岩及其后的拆沉作用模型类似,随着埃达克岩从下地壳大量熔出,下地壳密度增加,导致拆沉作用,形成了A型花岗岩。

    (1)达伦乌苏二长花岗岩、花岗斑岩岩体分别形成于(249.0±2.3) Ma和(241.0±2.8) Ma,为早—中三叠世岩体。

    (2)达伦乌苏早三叠世二长花岗岩具C型埃达克岩地球化学特征,中三叠世花岗斑岩具A型花岗岩地球化学特征。

    (3)达伦乌苏早三叠世二长花岗岩具埃达克特征,指示了古亚洲洋闭合后陆壳碰撞加厚的背景,而达伦乌苏中三叠世A型花岗岩指示了造山后伸展构造背景。两期岩浆作用标志着中亚造山带中段南缘在早—中三叠世发生了由增生造山到造山后伸展的构造环境转换。

    致谢:匿名审稿人专业的意见建议极大地提高了本文的质量,在此致以诚挚的感谢。

  • 图  1   坦桑尼亚姆贝亚地区地质简图(a)及乌本迪带地质简图(b)(据Boniface et al., 2014

    Figure  1.   (a) Simplified geological maps of Mbeya, Tanzania and (b) the Ubendian Belt

    图  2   乌本迪带内辉长岩(a)和正长花岗岩(b)显微照片

    Pl.斜长石;Di.透辉石;Kf.钾长石;Q.石英

    Figure  2.   (a) Microscope photographs of the gabbro and (b) syenogranite in Ubendian Belt

    图  3   辉长岩和正长花岗岩代表性锆石CL图像(a, c)和锆石U-Pb年龄谐和图(b, d)

    Figure  3.   (a, c) Cathodoluminescence (CL) images and (b, d) U-Pb concordia diagrams for representative zircons from gabbro and syenogranite

    图  4   乌本迪带内不同岩体的TAS图解(据Wilson, 1989

    Figure  4.   TAS classification diagram for the different rocks in the Ubendian Belt

    图  5   乌本迪带内不同岩体的球粒陨石标准化稀土元素配分图(a)和原始地幔标准化微量元素蛛网图(b)

    OIB数据引自Sun等(1989);大陆溢流玄武岩数据引自Elburg等(2000)Kampunzu等(2003)

    Figure  5.   (a) Chondrite-normalized REE patterns and (b) primitive mantle-normalized trace element spider diagram for different rocks in the Ubendian Belt

    图  6   乌本迪带内基性岩Nb/Yb-Th/Yb (a)和Zr/Y-(La/Sm)N (b)图解(据Pearce, 2014

    库鲁克塔格地区基性岩数据引自Wang等(2018)张健等(2018)

    Figure  6.   (a) Nb/Yb vs. Th/Yb and (b) Zr/Y vs. (La/Sm)N diagrams for the mafic rocks in the Ubendian Belt

    图  7   乌本迪带辉长岩和正长花岗岩的Ti/100-Zr-3Y(a)、2Nb-Zr/4-Y(b)、Yb/Ta-Y/Nb(c)和Sc/Nb-Y/Nb(d)构造判别图解(据Eby, 1992; Chusi et al., 2015

    图(a)中:A.岛弧拉板玄武岩;B.MORB、岛弧拉板玄武岩和钙碱性玄武岩;C.岛弧钙碱性玄武岩;D.板内玄武岩;图(b)中:AⅠ.板内碱性玄武岩;AⅡ.板内碱性玄武岩和板内拉板玄武岩;B.E-MORB;C.板内拉板玄武岩和火山弧玄武岩;D.火山弧玄武岩和 N-MORB;图(c、d)中:A1.非造山A型花岗岩;A2.造山后A型花岗岩;库鲁克塔格地区基性岩数据引自张健等(2018);大陆溢流玄武岩(CFB)数据引自Elburg等(2000)Kampunzu等(2003)Wang等(2018)

    Figure  7.   (a) Ti/100-Zr-3Y, (b) 2Nb-Zr/4-Y , (c) Yb/Ta-Y/Nb and (d) Sc/Nb-Y/Nb tectonic discrimination diagrams for the gabbro and syenogranites in the Ubendian Belt

    表  1   乌本迪带地质体特征(据Daly, 1988; Boniface et al., 2017

    Table  1   Geological characteristics of the Ubendian terranes

    地体
    名称
    地质年龄(Ma)岩性线理
    走向
    岩浆作用变质作用
    Ubende 1890~1860 Ma(榴辉岩U-Pb锆石) 角闪岩、榴辉岩、片麻岩和变质基性岩 ENE—WSW
    1170 Ma (变质泥岩U-Th-Pb独居石)
    600 Ma (变质泥岩U-Th-Pb独居石)
    Wakole 1170~1000 Ma (变质泥岩U-Pb 锆石) 富铝硅酸岩质片岩 NW—SE
    Katuma 2650 Ma (变质基性岩U-Pb锆石) 1960 Ma (变质泥岩U-Th-Pb独居石) 变质基性岩 NW—SE
    1940 Ma (变质泥岩U-Th-Pb独居石)
    Ufipa (1847 ± 37) Ma(花岗岩U-Pb 锆石) 590~520 Ma (榴辉岩U-Pb锆石) 花岗质片麻岩 NW—SE
    (1864 ± 32) Ma (花岗岩U-Pb 锆石)
    Mbozi (2084 ± 8) Ma (片麻岩U-Pb锆石) 片麻岩、混合岩、石英岩±麻粒岩±变质基性岩 NW—SE
    Lupa 2760 Ma (花岗岩U-Pb金红石) 变质火山岩、花岗岩和花岗质片麻岩 NW—-SE
    (1943 ± 32) Ma
    (玄武质安山岩U-Pb锆石)
    (1878 ± 15) Ma (花岗岩U-Pb 锆石)
    Upangwa (2084 ± 86) Ma (花岗岩U-Pb 锆石) (1045 ± 25) Ma (片麻岩U-Pb锆石) 变质斜长岩 NW—SE
    1880~1850 Ma
    (石英闪长岩U-Pb 锆石)
    (724 ± 6) Ma (花岗岩U-Pb 锆石)
    Nyika 1990~1930 Ma (花岗岩U-Pb 锆石) (1813 ± 13) Ma; (947 ± 7) Ma; (560 ± 6) Ma(变质泥岩U-Th-Pb独居石) 堇青石麻粒岩 E—W
    (1010 ± 22) Ma (榴辉岩U-Pb锆石) 1930~1969 Ma(变质泥岩Pb-Pb锆石)
    下载: 导出CSV

    表  2   乌本迪带内不同岩体的LA-MC-ICP-MS锆石U-Pb测年数据

    Table  2   LA-MC-ICP-MS Zircons U-Pb isotopic data from different rocks in the Ubendian Belt

    样品
    编号
    元素含量(10−6Th/U同位素比值年龄(Ma)
    PbUTh206Pb/238U207Pb/235U207Pb/206Pb206Pb/238U207Pb/235U207Pb/206Pb
    变质辉长岩(D6214)
    1 81 256 311 1.21 0.2449 0.0028 3.1028 0.0439 0.0919 0.0010 1412 16 1433 20 1465 21
    2 33 98 146 1.49 0.2452 0.0026 3.1168 0.0436 0.0922 0.0011 1414 15 1437 20 1471 23
    3 27 85 95 1.11 0.2471 0.0028 3.0677 0.0451 0.0900 0.0011 1423 16 1425 21 1426 23
    4 51 155 237 1.53 0.2434 0.0026 3.0831 0.0433 0.0919 0.0011 1404 15 1429 20 1465 22
    5 60 191 225 1.18 0.2459 0.0026 3.0710 0.0419 0.0906 0.0010 1417 15 1425 19 1438 22
    6 55 190 163 0.86 0.2446 0.0026 3.0973 0.0433 0.0919 0.0011 1410 15 1432 20 1464 22
    7 66 212 250 1.18 0.2462 0.0026 3.0653 0.0412 0.0903 0.0010 1419 15 1424 19 1432 22
    8 28 92 117 1.27 0.2444 0.0024 3.0474 0.0489 0.0904 0.0014 1409 14 1420 23 1435 29
    9 81 262 337 1.29 0.2445 0.0024 3.0482 0.0394 0.0904 0.0010 1410 14 1420 18 1434 21
    10 45 158 136 0.86 0.2439 0.0025 3.0336 0.0413 0.0902 0.0011 1407 14 1416 19 1430 22
    11 57 193 204 1.06 0.2483 0.0025 3.0826 0.0406 0.0900 0.0010 1430 14 1428 19 1426 22
    12 38 116 167 1.44 0.2470 0.0026 3.0634 0.0418 0.0900 0.0010 1423 15 1424 19 1424 22
    13 41 120 205 1.71 0.2475 0.0024 3.0561 0.0408 0.0895 0.0010 1426 14 1422 19 1416 22
    14 33 119 84 0.71 0.2478 0.0025 3.0698 0.0417 0.0898 0.0010 1427 15 1425 19 1422 22
    15 19 76 88 1.15 0.1984 0.0021 2.4408 0.0416 0.0892 0.0014 1167 12 1255 21 1409 31
    16 8 31 30 0.97 0.2078 0.0021 2.5473 0.0514 0.0889 0.0017 1217 12 1286 26 1402 36
    17 37 113 178 1.57 0.2478 0.0026 3.0450 0.0417 0.0891 0.0010 1427 15 1419 19 1407 22
    18 49 154 238 1.54 0.2461 0.0024 3.0114 0.0395 0.0888 0.0010 1418 14 1411 18 1399 22
    19 62 196 280 1.43 0.2452 0.0026 3.0551 0.0415 0.0904 0.0010 1414 15 1422 19 1433 22
    20 32 178 82 0.46 0.1688 0.0017 2.0587 0.0277 0.0885 0.0010 1005 10 1135 15 1392 23
    21 42 145 208 1.44 0.2175 0.0023 2.7131 0.0363 0.0905 0.0010 1269 13 1332 18 1435 22
    22 170 518 792 1.53 0.2464 0.0027 3.0674 0.0420 0.0903 0.0010 1420 16 1425 20 1432 21
    23 54 199 123 0.62 0.2448 0.0024 3.0399 0.0397 0.0901 0.0010 1411 14 1418 19 1427 21
    24 43 146 155 1.06 0.2447 0.0025 3.0466 0.0415 0.0903 0.0010 1411 14 1419 19 1432 22
    25 30 100 123 1.23 0.2451 0.0026 3.0616 0.0424 0.0906 0.0011 1413 15 1423 20 1438 22
    26 30 92 144 1.56 0.2439 0.0025 3.0525 0.0426 0.0908 0.0011 1407 14 1421 20 1442 23
    27 28 84 136 1.63 0.2449 0.0025 3.0651 0.0425 0.0908 0.0011 1412 15 1424 20 1442 23
    28 55 164 282 1.72 0.2426 0.0026 3.0312 0.0409 0.0906 0.0010 1400 15 1416 19 1438 22
    29 50 156 238 1.53 0.2445 0.0024 3.0347 0.0399 0.0900 0.0010 1410 14 1416 19 1426 22
    30 32 102 143 1.4 0.2450 0.0026 3.0167 0.0442 0.0893 0.0011 1413 15 1412 21 1411 24
    31 41 150 149 1 0.2293 0.0023 2.8626 0.0382 0.0906 0.0010 1331 13 1372 18 1437 22
    正长花岗岩(D6218)
    1 21 70 80 1.14 0.2447 0.0024 3.0566 0.0440 0.0906 0.0012 1411 14 1422 20 1438 25
    2 48 171 138 0.8 0.2455 0.0025 3.0741 0.0403 0.0908 0.0010 1415 14 1426 19 1443 22
    3 48 181 152 0.84 0.2469 0.0025 3.0251 0.0403 0.0889 0.0010 1422 14 1414 19 1401 22
    4 16 56 50 0.89 0.2369 0.0023 3.7693 0.0582 0.1154 0.0016 1371 14 1586 24 1886 24
    5 19 71 97 1.36 0.2093 0.0022 2.5915 0.0502 0.0898 0.0016 1225 13 1298 25 1421 34
    6 11 47 47 1 0.1944 0.0024 2.3910 0.0522 0.0892 0.0019 1145 14 1240 27 1408 42
    7 13 41 66 1.61 0.2443 0.0026 3.0670 0.0549 0.0911 0.0015 1409 15 1424 26 1448 31
    8 38 141 104 0.74 0.2453 0.0024 3.0311 0.0414 0.0896 0.0011 1414 14 1415 19 1417 23
    9 46 154 164 1.06 0.2465 0.0026 3.0549 0.0419 0.0899 0.0010 1420 15 1421 19 1423 22
    10 18 58 57 0.98 0.2466 0.0026 3.6642 0.0586 0.1078 0.0015 1421 15 1564 25 1762 25
    11 40 133 154 1.16 0.2451 0.0025 3.0328 0.0407 0.0898 0.0010 1413 15 1416 19 1420 22
    12 52 185 152 0.82 0.2449 0.0026 3.0415 0.0413 0.0901 0.0010 1412 15 1418 19 1427 22
    13 46 140 224 1.6 0.2453 0.0026 3.0277 0.0397 0.0895 0.0010 1414 15 1415 19 1416 22
    14 69 256 148 0.58 0.2453 0.0025 3.0404 0.0395 0.0899 0.0010 1414 14 1418 18 1424 21
    15 44 135 231 1.71 0.2437 0.0025 3.0466 0.0456 0.0907 0.0012 1406 15 1419 21 1440 25
    16 104 392 206 0.52 0.2461 0.0026 3.0597 0.0409 0.0902 0.0010 1418 15 1423 19 1429 21
    17 48 176 163 0.93 0.2216 0.0023 2.7455 0.0402 0.0899 0.0011 1290 14 1341 20 1422 24
    18 14 45 53 1.17 0.2445 0.0025 3.0407 0.0560 0.0902 0.0015 1410 14 1418 26 1430 32
    19 24 80 96 1.2 0.2284 0.0023 3.3401 0.0513 0.1061 0.0014 1326 14 1490 23 1733 25
    20 29 89 133 1.5 0.2432 0.0024 3.0648 0.0434 0.0914 0.0011 1404 14 1424 20 1455 23
    21 18 55 88 1.61 0.2460 0.0028 3.0551 0.0505 0.0901 0.0013 1418 16 1422 24 1427 28
    22 30 124 53 0.42 0.2305 0.0022 2.9343 0.0382 0.0923 0.0011 1337 13 1391 18 1474 22
    23 33 116 102 0.87 0.2447 0.0024 3.0376 0.0412 0.0900 0.0011 1411 14 1417 19 1426 22
    下载: 导出CSV

    表  3   乌本迪带不同岩体的主量元素(%)和微量元素(10−6)分析结果

    Table  3   Major element (%) and trace element compositions (10−6) for different rocks in the Ubendian Belt

    样品号SiO2Al2O3Fe2O3FeOCaOMgOK2ONa2OTiO2P2O5MnO灼失Cu
    D620575.0812.331.011.370.460.145.283.280.250.0190.030.612.16
    D621871.5913.132.221.40.780.135.793.750.380.0340.090.544.14
    D621447.2715.784.328.739.224.411.673.052.60.230.191.55109
    样品号PbZnCrNiCoRbSrBaVScNbTaZr
    D62059.7438.732.921.40.8421211.52890.941.5471.34.22463
    D621831.11334.052.260.641474910301.292.5150.52.4864
    D62143.5312169.235.842.254.750059546242.59.540.65143
    样品号HfBeGaUThLaCePrNdSmEuGdTb
    D620515.44.420.33.3546.825538645.115924.90.9621.43.05
    D621823.42.2120.72.229.725937045.416125.12.722.33.25
    D62144.110.8223.70.291.8218.431.85.61255.711.945.850.94
    样品号DyHoErTmYbLuY∑REE(La/Yb)NδEuMF指数
    D6205152.717.050.966.030.8967.3928.0528.510.1294.44
    D621816.93.28.531.177.631.2475.9927.4222.890.3496.53
    D62145.391.022.720.392.560.3825.9107.714.851.0274.74
     注:MF=100*(FeO+Fe2O3)/(FeO+ Fe2O3+MgO)
    下载: 导出CSV
  • 陈雪峰, 刘希军, 许继峰, 等. 桂西那坡基性岩地球化学: 峨眉山地幔柱与古特提斯俯冲相互作用的证据[J]. 大地构造与成矿学, 2016, 40(3): 545-562

    CHEN Xuefeng, LIU Xijun, XU Jifeng, et al. Geochemistry of Mafic Rocks in the Napo Area, Western Guangxi, South China: Evidence for Interaction Between the Emeishan Mantle Plume and Paleotethyan Subduction[J]. Geotectonica et Metallogenia, 2016, 40(3): 545-562.

    孙凯, 刘晓阳, 何胜飞, 等.坦桑尼亚水系沉积物地球化学特征及金资源前景[J]. 地质通报, 2023, 42(8): 1258−1275.

    SUN Kai, LIU Xiaoyang, HE Shengfei, et al. Geochemical characteristics of stream sediment in Tanzania and prospective analysis of gold resources[J]. Geological Bulletin of China, 2023, 42(8): 1258−1275.

    王杰, 刘晓阳, 任军平, 等. 坦桑尼亚前寒武纪成矿作用[J]. 华北地质, 2022, 45(1): 101-110

    WANG Jie, LIU Xiaoyang, REN Junping, et al. Precambrian mineralization in Tanzania[J]. North China Geology, 2022, 45(1): 101-110.

    吴元保, 郑永飞. 锆石成因矿物学研究及其对 U-Pb 年龄解释的制约[J]. 科学通报, 2004, 49(16): 1589-1604 doi: 10.3321/j.issn:0023-074X.2004.16.002

    WU Yuanbao, ZHENG Yongfei. Genetic mineralogy of zircons and its constraints to the age of U-Pb geochronology[J]. Chinese Science Bulletin, 2004, 49(16): 1589-1604. doi: 10.3321/j.issn:0023-074X.2004.16.002

    徐义刚, 王焰, 位荀, 等. 与地幔柱有关的成矿作用及其主控因素[J]. 岩石学报, 2013, 29(10): 3307-3322

    XU Yigang, WANG Yan, WEI Xun, et al. Mantle plume-related mineralization and their principal controlling factors[J]. Acta Petrologica Sinica, 2013, 29(10): 3307-3322.

    张健, 李怀坤, 张传林, 等. 塔里木克拉通东北缘 Columbia 超大陆裂解事件: 库鲁克塔格地区辉绿岩床的地球化学, 锆石 U-Pb 年代学和 Hf-O 同位素证据[J]. 地学前缘, 2018, 25(6): 106-123

    ZHANG Jian, LI Huaikun, ZHANG Chuanlin, et al. New evidence for the breakup of the Columbia supercontinent from the northeastern margin of Tarim Craton: rock geochemistry, zircon U-Pb geochronology and Hf-O isotopic compositions of the ca. 1.55 Ga diabase sills in the Kuruktag area[J]. Earth Science Frontier, 2018, 25(6): 106-123.

    张招崇, 王福生, 范蔚茗, 等. 峨眉山玄武岩研究中的一些问题的讨论[J]. 岩石矿物学杂志, 2001, 20(3): 239-246 doi: 10.3969/j.issn.1000-6524.2001.03.005

    ZHANG Zhaochong, WANG Fusheng, FAN Weiming, et al. A Discussion on Some Problems Concerning the Study of the Emeishan Basalts[J]. Acta Petrologica ET Mineralogica, 2001, 20(3): 239-246. doi: 10.3969/j.issn.1000-6524.2001.03.005

    周佐民, 李勇, 刘晓阳, 等. 苏丹红海州新元古代A型花岗岩的地球化学特征及构造意义[J]. 华北地质, 2023, 46(1): 71-86

    ZHOU Zuomin, LI Yong, LIU Xiaoyang, et al. Geochemical characteristics and tectonic implications of the Neoproterozoic A-type granites in Red Sea State, Sudan[J]. North China Geology, 2023, 46(1): 71-86.

    Barnes S J, Naldrett A J, Gorton M P. The origin of the fractionation of platinum-group elements in terrestrial magmas[J]. Chemical Geology, 1985, 53(3-4): 303-323. doi: 10.1016/0009-2541(85)90076-2

    Belousova E, Griffin W L, O'Reilly S Y, et al. Igneous zircon: trace element composition as an indicator of source rock type[J]. Contributions to mineralogy and petrology, 2002, 143(5): 602-622. doi: 10.1007/s00410-002-0364-7

    Biyashev M, Pentelkov V, Emelyanov S, et al. Sitalike: Geological Map Quarter Degree Sheet 170[M]. Geological Survey of Tanzania, Dodoma, 1977.

    Boniface N, Schenk V, Appel P. Paleoproterozoic eclogites of MORB-type chemistry and three Proterozoic orogenic cycles in the Ubendian Belt (Tanzania): Evidence from monazite and zircon geochronology, and geochemistry[J]. Precambrian Research, 2012, 192: 16-33.

    Boniface N, Schenk V. Neoproterozoic eclogites in the PaleoproterozoicUbendian Belt of Tanzania: evidence for a Pan-African suture between the Bang-weulu Block and the Tanzania Craton[J]. Precambrian Research, 2012, 208: 72-89.

    Boniface N, Schenk V, Appel P. Mesoproterozoic high-grade metamorphism in pelitic rocks of the northwestern Ubendian Belt: Implication for the extension of the Kibaran intra-continental basins to Tanzania[J]. Precambrian Research, 2014, 249: 215-228. doi: 10.1016/j.precamres.2014.05.010

    Boniface N, Appel P. Stenian-Tonian and Ediacaran metamorphic imprints in the southern Paleoproterozoic Ubendian Belt, Tanzania: Constraints from in situ monazite ages[J]. Journal of African Earth Sciences, 2017, 133: 25-35. doi: 10.1016/j.jafrearsci.2017.05.005

    Boven A, Theunissen K, Skylarov E, et al. Timing of exhumation of a high-pressure mafic granulite terrane of the Paleoproterozoic Ubende belt (West Tanzania)[J]. Precambrian Research, 1999, 93: 119-137. doi: 10.1016/S0301-9268(98)00101-6

    Cai Y, Wang Y, Cawood P A, et al. Neoproterozoic crustal growth of the Southern Yangtze Block: Geochemical and zircon U-Pb geochronological and Lu-Hf isotopic evidence of Neoproterozoic diorite from the Ailaoshan zone[J]. Precambrian Research, 2015, 266: 137-149. doi: 10.1016/j.precamres.2015.05.008

    Chusi L, Nicholas T A, Tang Q Y, et al. Trace element indiscrimination diagrams[J]. Lithos, 2015, 232: 76-83. doi: 10.1016/j.lithos.2015.06.022

    Daly M C, Klerkx J, Nanyaro J T. Early Proterozoic terranes and strike-slip accretion in the Ubendian Belt of southwest Tanzania[J]. Terra Cognita, 1985, 5: 257.

    Daly M C. Crustal shear zones in Central Africa: a kinematic approach toProterozoic Tectonics[J]. Episodes, 1988, 11(1): 5-11. doi: 10.18814/epiiugs/1988/v11i1/003

    DePaolo D J, Daley E E. Neodymium isotopes in basalts of the southwest basin and range and lithospheric thinning during continental extension[J]. Chemical Geology, 2000, 169(1-2): 157-185. doi: 10.1016/S0009-2541(00)00261-8

    Dilek Y, Furnes H. Ophiolite genesis and global tectonics: Geochemical and tectonic fingerprinting of ancient oceanic lithosphere[J]. Bulletin, 2011, 123(3-4): 387-411.

    Eby G N. Chemical subdivision of the A-type granitoids: petrogenetic and tectonic implications[J]. Geology, 1992, 20, 641–644.

    Elburg M, Goldberg A. Age and geochemistry of Karoo dolerite dykes from northeast Botswana[J]. Journal of African Earth Sciences, 2000, 31(3-4): 539-554. doi: 10.1016/S0899-5362(00)80006-8

    Frost B R, Barnes C G, Collins W J, et al. A geochemical classification for granitic rocks[J]. Journal of petrology, 2001, 42(11): 2033-2048. doi: 10.1093/petrology/42.11.2033

    Griffiths R W, Campbell I H. Stirring and structure in mantle starting plumes[J]. Earth and Planetary Science Letters, 1990, 99(1-2): 66-78. doi: 10.1016/0012-821X(90)90071-5

    Hoffman P F. United plates of America, the birth of a craton: Early Proterozoic assembly and growth of Laurentia. Annual Review of Earth and Planetary Sciences, 1988, 16(1): 543-603.

    Huppert H E, Sparks R S J. The generation of granitic magmas by intrusion of basalt into continental crust[J]. Jour Petrol, 1988, 29(3): 599-624. doi: 10.1093/petrology/29.3.599

    Kampunzu A B, Tombale A R, Zhai M, et al. Major and trace element geochemistry of plutonic rocks from Francistown, NE Botswana: evidence for a Neoarchaean continental active margin in the Zimbabwe craton[J]. Lithos, 2003, 71(2-4): 431-460. doi: 10.1016/S0024-4937(03)00125-7

    Kazimoto E O, Schenk V, Berndt J. Neoarchean and Paleoproterozoic crust formation in the Ubendian Belt of Tanzania: Insights from zircon geochronology and geochemistry[J]. Precambrian Research, 2014, 252: 119-144. doi: 10.1016/j.precamres.2014.06.020

    King P L, White A J R, Chappell B W, et al. Characterization and origin of aluminous A-type granites from the Lachlan Fold Belt, southeastern Australia[J]. Journal of Petrology. 1997, 38, 371–391.

    Klerkx J, Liégeois J P, Lavreau J, et al. Crustal evolution of the northern Kibaran Belt, eastern and central Africa. Proterozic Lithospheric Evolution, 1987, 17: 217-233.

    Kokonyangi J, Kampunzu, A B, Poujol M, et al. Petrology and geochronology of Mesoproterozoic mafic-intermediate plutonic rocks from Mitwaba (DR Congo): implications for the evolution of the Kibaran Belt in central Africa[J]. Geological Magazine, 2005, 142(1): 109~130. doi: 10.1017/S0016756804009951

    Lawley C J M, Selby D, Condon D J, et al. Lithogeochemistry, geochronology and geodynamic setting of the Lupa Terrane, Tanzania: implications for the extent of the Archean Tanzanian Craton[J]. Precambrian Research, 2013, 231: 174-193. doi: 10.1016/j.precamres.2013.02.012

    Lenoir J L, Liégeois J P, Theunissen K, et al. The Palaeoproterozoic Ubendian shear belt in Tanzania: geochronology and structure[J]. Journal of African Earth Sciences, 1994, 19(3): 169-184. doi: 10.1016/0899-5362(94)90059-0

    Liu S, Hu R Z, Gao S, et al. U-Pb zircon age, geochemical and Sr-Nd-Pb-Hf isotopic constraints on age and origin of alkaline intrusions and associated mafic dikes from Sulu orogenic belt, Eastern China[J]. Lithos, 2008, 106, 365-379. doi: 10.1016/j.lithos.2008.09.004

    Loiselle M C, Wones D R. Characteristics and origin of anorogenic granites[J]. Geological Society of America Abstracts with Programs, 1979, 11(7): 468.

    Ludwig K R. User's Manual for Isoplot 3.00, a Geochronological Toolkit for Microsoft Excel[M]. Geochronological Center, Special Publication No. 4, Berkeley, 2003, 25-32.

    Manya S, Kobayashi K, Maboko M A H, et al. Ion microprobe zircon U–Pb dating of the late Archaean metavolcanics and associated granites of the Musoma-Mara Greenstone Belt, Northeast Tanzania: Implications for the geological evolution of the Tanzania Craton[J]. Journal of African Earth Sciences, 2006, 45(3): 355-366. doi: 10.1016/j.jafrearsci.2006.03.004

    Mcconnell R B. Outline of the geology of Ufipa and Ubende[M]. Tanganyika Geological Survey, Dodoma, 1950, 1-62.

    Morgan W J. Convection plumes in the lower mantle[J]. Nature, 1971, 230(5288): 42-43. doi: 10.1038/230042a0

    Niu Y, O'Hara M J. Origin of ocean island basalts: A new perspective from petrology, geochemistry, and mineral physics considerations[J]. Journal of Geophysical Research, 2003, 108(B4): 1-18.

    Niu Y L. The origin of alkaline lavas[J]. Science, 2008, 320(5878): 883-884. doi: 10.1126/science.1158378

    Patiño Douce A E, Beard J S. Dehydration-melting of Biotite Gneiss and Quartz Amphibolite from 3 to 15 kbar. Journal of Petrology, 1995, 36, 707-738.

    Pearce J A. Immobile element fingerprinting of ophiolites[J]. Elements, 2014, 10(2): 101-108. doi: 10.2113/gselements.10.2.101

    Rapp R P, Watson E B. Dehydration melting of metabasalt at 8-32 kbar: implications for continental growth and crust-mantle recycling[J]. Journal of Petrology, 1995, 36(4): 891-931. doi: 10.1093/petrology/36.4.891

    Ring U, Kröner A, Toulkeridis T. Palaeoproterozoic granulite-facies metamorphism and granitoid intrusions in the Ubendian-Usagaran Orogen of northern Malawi, east-central Africa[J]. Precambrian Research, 1997, 85(1-2): 27-51. doi: 10.1016/S0301-9268(97)00028-4

    Rogers J J W, Santosh M, Yoshida A M. Mesoproterozoic Supercontinent (Call f or papers)[J]. Gondwana Research, 2000, (4): 590~591.

    Smirnov V, Pentelkov V, Tolochko V, et al. Geology and Minerals of the Central Part of the Wstern Resource Division, Dodoma, Tanzania[R]. Unpublished report of the geological mapping, 1973, 1-333.

    Stendal H, Frei R, Muhongo S, et al. Gold potential of the Mpanda Mineral Field, SW Tanzania: evaluation based on geological, lead isotopic and aeromagnetic data[J]. Journal of African Earth Sciences, 2004, 38(5): 437-447. doi: 10.1016/j.jafrearsci.2004.04.005

    Sun S S, McDonough W F. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes[J]. Geological Society, London, Special Publications, 1989, 42(1): 313-345. doi: 10.1144/GSL.SP.1989.042.01.19

    Sutton J, Watson J, James T C. A study of the metamorphic rocks of Karema and Kungwe Bay, Western Tanganyika[M]. Tanganyika Geological Survey , Bulletin, 1954, 22.

    Sylvester P J. Post-collisional alkaline granites[J]. The Journal of Geology, 1989, 97, 261-280. doi: 10.1086/629302

    Tack L, Wingate M T D, De Waele B, et al. The 1375Ma “Kibaran event” in Central Africa: Prominent emplacement of bimodal magmatism under extensional regime. Precambrian Research, 2010, 180(1-2): 63-84.

    Theunissen K, Lenoir J L, Liégois J P, et al. Major Pan-African imprint in the Ubendian Belt of SW Tanzania: U-Pb zircon geochronology and structural context[J]. Comptes-rendus del Académie des Sciences de Paris, 1992, 314, 1355-1362.

    Thomas R, Jacobs J, Aelburg M, et al. New U-Pb-Hf zircon isotope data for the Paleoproterozoic Ubendian belt in the Chimala area, SW Tanzania[J]. Geoscience Frontiers, 2019, 10(6), 1993-2006. doi: 10.1016/j.gsf.2018.05.010

    Tulibonywa T, Manya S, Torssander P, et al. Geochemistry of the Palaeoproterozoic volcanic and associated potassic granitic rocks of the Ngualla area of the Ubendian Belt, SW Tanzania[J]. Journal of African Earth Sciences, 2017, 129: 291-306. doi: 10.1016/j.jafrearsci.2017.01.022

    Wang X, Lv X, Cao X, et al. Palaeo-Mesoproterozoic magmatic and metamorphic events from the Kuluketage block, northeast Tarim Craton: geochronology, geochemistry and implications for evolution of Columbia[J]. Geological Journal, 2018, 53(1): 120-138. doi: 10.1002/gj.2881

    Wang Y J, Zhang A M, Fan W M, et al. Origin of paleosubduction-modifified mantle for Silurian gabbro in the Cathaysia block: geochronological and geochemical evidence[J]. Lithos, 2013, 160, 37-54.

    Watkins J, Clemens J, Treloar P. Archaean TTGs as sources of younger granitic magmas: melting of sodic metatonalites at 0.6-1.2 GPa. Contributions to Mineralogy and Petrology, 2007, 154, 91-110.

    Whalen J B, Currie K L, Chappell B W. A-type granites: geochemical characteristics, discrimination and petrogenesis[J]. Contributions to mineralogy and petrology, 1987, 95(4): 407-419. doi: 10.1007/BF00402202

    Wilson M. Igneous Petrogenesis[M]. Springer Netherlands, London, 1989, 22.

    Wu C Z, Santosh M, Chen Y J, et al. Geochronology and geochemistry of Early Mesoproterozoic meta-diabase sills from Quruqtagh in the northeastern Tarim Craton: implications for breakup of the Columbia supercontinent[J]. Precambrian Research, 2014, 241: 29-43. doi: 10.1016/j.precamres.2013.11.007

    Wu F Y, Sun D Y, Li H M, et al. A-type granites in northeastern China: age and geochemical constraints on their petrogenesis[J]. Chemical Geology, 2002, 187, 143–173. doi: 10.1016/S0009-2541(02)00018-9

    Xu Y, Chung S L, Jahn B, M, et al. Petrologic and geochemical constraints on the petrogenesis of Permian-Triassic Emeishan flood basalts in southwestern China[J]. Lithos, 2001, 58(3-4): 145-168.

    Zhou M F, Zhao J H, Qi L, et al. Zircon U-Pb geochronology and elemental and Sr–Nd isotope geochemistry of Permian mafic rocks in the Funing area, SW China[J]. Contributions to Mineralogy and Petrology, 2006, 151(1): 1-19. doi: 10.1007/s00410-005-0030-y

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  • 收稿日期:  2023-04-02
  • 修回日期:  2023-07-23
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