引用本文
尹继元, 陈文, 肖文交, 等 .
西准噶尔包古图Ⅰ号岩体的锆石U-Pb年代学和地球化学特征[J]. 吉林大学学报(地球科学版), 2016, 46(6): 1754-1768
Yin Jiyuan, Chen Wen, Xiao Wenjiao, et al .
Geochronology and Geochemistry in Pluton Ⅰ in Baogutu Area, West Junggar[J]. Journal of Jilin University(Earth Science Edition), 2016, 46(6): 1754-1768.
西准噶尔包古图Ⅰ号岩体的锆石U-Pb年代学和地球化学特征
1. 中国地质科学院地质研究所同位素热年代学实验室/大陆构造与动力学国家重点实验室, 北京 100037;
2. 中国科学院地质与地球物理研究所/岩石圈演化国家重点实验室, 北京 100029;
3. 南阳师范学院南阳市独山玉研究重点实验室, 河南 南阳 473061;
4. 河北省区域地质矿产调查研究所, 河北 廊坊 065000
2. 中国科学院地质与地球物理研究所/岩石圈演化国家重点实验室, 北京 100029;
3. 南阳师范学院南阳市独山玉研究重点实验室, 河南 南阳 473061;
4. 河北省区域地质矿产调查研究所, 河北 廊坊 065000
摘要:
西准噶尔包古图地区发育一些小型的闪长质岩体。前人对这些小岩体开展了岩石学、年代学和地球化学等研究，然而，其成因机制和构造背景仍然存在争议，阻碍了区域构造演化和成矿作用的认识。本文在前人研究的基础上，选择包古图Ⅰ号岩体为研究对象，有望揭示包古图岩体的岩石成因和构造背景。锆石U-Pb年代学研究显示，包古图Ⅰ号岩体形成于（313.8±1.1）Ma。包古图Ⅰ号闪长岩体以富SiO2（58.0%~59.0%）、Al2O3（16.6%~17.4%）和Sr（757×10-6~882×10-6），低的Y（14.6×10-6~15.7×10-6）和Yb（1.51×0-6~1.60×0-6）质量分数为特征，具有高的Sr/Y（50~59）值和弱的Eu异常，类似于俯冲成因的埃达克岩。另外，这些闪长岩具有较高的Mg（w（MgO）=3.46%~3.77%，Mg#=52.8~53.2），高的Cr（63.8×10-6~74.7×10-6）和Ni（45.2×10-6~49.8×10-6）质量分数，亏损HFSE（Nb，Ta和Ti）。该闪长质岩体可能由俯冲的板片熔体与上覆地幔相互作用而成。它的形成可能与西准噶尔地区晚石炭世的洋脊俯冲作用有关。
关键词:
西准噶尔
包古图Ⅰ号岩体
埃达克岩
洋脊俯冲
地球化学
Geochronology and Geochemistry in Pluton Ⅰ in Baogutu Area, West Junggar
1. Laboratory of Isotope Thermochronology, Institute of Geology, Chinese Academy of Geological Sciences/State Key Laboratory of Continental Tectonics and Dynamics, Beijing 100037, China;
2. State Key Laboratory of Lithospheric Evolution/Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;
3. Nanyang City Key Laboratory of Dushan Jade, Nanyang Normal University, Nanyang 473061, Henan China;
4. Regional Geology and Mineral Resources Survey of Hebei Province, Langfang, 065000, Hebei, China
2. State Key Laboratory of Lithospheric Evolution/Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;
3. Nanyang City Key Laboratory of Dushan Jade, Nanyang Normal University, Nanyang 473061, Henan China;
4. Regional Geology and Mineral Resources Survey of Hebei Province, Langfang, 065000, Hebei, China
Supported by Supported by the Major Basic Research Project of the Ministry of Science and Technology of China (2014CB448000), the China Geological Survey (DD20160123-02), the Outlay Research Fund of Institute of Geology, Chinese Academy of Geological Sciences (J1517) and the Rresearch Grant of State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (SKLIG-KF-13-05)
Abstract: Some small-size dioritic plutons widely occur in the Baotutu area, west Junggar. The petrology, geochronology and geochemistry of thse plutons had been researched, while their petrogenesis and tectonic setting still existed controversy, which restricts the knowledge of the tectonic evolution and mineralization. To reveal the petrogenesis and tectonic setting of Baogutu dioritic plutons during Late Caberniferious, on basis of previous researches, this paper chooses pluton Ⅰ in the Baogutu area as research subjects. The LA-ICP-MS zircon U-Pb for dioritic pluton Ⅰ yield 206Pb/238U age of (313.8±1.1) Ma. The dioritic pluton is characterized by relatively high SiO2 (58.0%-59.0%), Al2O3 (16.6%-17.4%), Sr ((757-882)×10-6), and low Y ((14.6-15.7)×10-6) and Yb ((1.51-1.60)×10-6) contents, with high Sr/Y (50-59) ratios and slight Eu anomalies, which are analogous to those of slab-derived adakites. In addition, the dioritic pluton is relatively rich in MgO (MgO=3.46%-3.77%; Mg#=52.8-53.2), Cr ((63.8-74.7)×10-6), Ni ((45.2-49.8)×10-6), with negative Nb-Ta-Ti anomalies. The dioritic pluton is generated by partial melting of a subducted oceanic slab and subsequent melt-mantle interaction. The formation of the adakitic pluton in the Baogutu area was probably associated with the ridge subduction during Late Carboniferous period.
Key words:
west Junggar
pluton I of Baogutu area
Adakite
ridge subduction
geochemistry
0 引言
埃达克岩是Defant和Drummond提出的, 用来描述在阿留申群岛的埃达克岛发现的一类具有俯冲洋壳部分熔融组分的特殊岩石，其具有如下地球化学特征：高的w (SiO2)≥56%、w(Al2O3)≥15%和高的Sr/Y>40，低的w(Y)≤18×10-6和w(Yb)≤1.9×10-6[1]。该概念的提出引起了地学界广泛关注。近年来，埃达克岩成为地学研究的热点，多种成因机制被提出：如洋脊俯冲[2-4]、拆沉下地壳部分熔融[5-7]、陆壳俯冲[8]和玄武质岩浆底侵等[9-10]。
中亚造山带(Central Asian Orogenic Belt)已经成为地质研究的热点，是全球显生宙陆壳增生与改造最显著的地区[11-13]。西准噶尔位于哈萨克斯坦，阿尔泰和天山之间，是中亚造山带的重要组成部分[14-15]。该地区出露有大量的石炭-二叠纪岩浆岩，它们以巨大型的花岗质岩基(如铁厂沟、哈图、阿克巴斯套、庙尔沟和克拉玛依花岗岩等)和中小型岩株或岩墙形式产出。这些侵入岩大多侵位于下石炭统中，大量的年代学数据表明，这些岩浆活动主要发生在316~287 Ma[16-21]。一些学者对区内花岗岩研究表明，它们是未变形的、碱性的花岗岩、伴有正的εNd(t)值，可能形成于后碰撞环境[16-17, 19-20]；还有学者对该地区的斑岩研究显示，其地球化学特征类似于埃达克岩，可能形成于与洋壳俯冲作用有关的岛弧环境[22]。最近，一些学者在西准噶尔地区识别出一些高温的岩浆组合(如埃达克岩、拉斑玄武岩、富镁闪长岩、赞岐岩和紫苏花岗岩等)，认为是洋脊俯冲作用的产物[23-29]。
此外，自从西准噶尔包古图大型斑岩铜矿床发现以后，很多学者对该地区的矿床、岩体和岩墙进行了大量的岩石学、年代学、矿床学和岩石地球化学研究[30-34]。然而，对与斑岩成矿密切相关岩体的成因机制仍然存在争议。如：受交代的亏损地幔部分熔融生成的玄武质岩浆经历高度结晶分异之后的产物[33]；俯冲洋脊两侧的板片熔融而形成[24]；与洋内俯冲有关的岛弧环境[22]；洋壳和受交代的地幔部分熔融而成[34]等。这些认识上的不统一严重阻碍了西准噶尔地区区域构造演化、成矿作用、成矿模式的认识。因此，本文在前人研究的基础上，选择包古图Ⅰ号岩体为研究对象，同时结合前人在包古图地区的相关研究成果，有望揭示包古图岩体的岩石成因和构造背景，为该地区石炭-二叠纪的构造演化和铜金成矿作用提供制约。
1 地质背景和样品来源西准噶尔地区NE-NNE向的大断裂(如达拉布特断裂(图 1)、哈图断裂、安齐断裂和巴尔雷克断裂等)十分发育，表现为多组、多期次的时空分布特征，对区内地层、岩浆岩、构造形态及矿化类型起着重要的控制作用。西准噶尔地区在不断的拼贴和增生过程中，产生唐巴勒、玛依勒、达拉布特、百碱滩等多条蛇绿岩带。通过大量的年代学研究，将这些蛇绿岩至少分为三期：中奥陶世的唐巴勒-白碱滩蛇绿岩[35-38]、中晚志留世的玛依勒蛇绿岩[35, 39]和中泥盆世的达拉布特蛇绿岩[37, 40]。
西准噶尔地区，中酸性侵入岩分布非常广泛，它们既有深成相的巨大岩基和中小型岩株, 也有超浅成相的岩枝或岩脉。研究表明，这些花岗岩包括A型花岗岩、紫苏花岗岩和I型花岗岩[16-17, 19-20, 23]。年代学数据显示，西准噶尔地区岩浆活动的时限为340~275 Ma，岩浆活动的高峰发生在310~295 Ma[16-17, 19-21, 41]，但是对这些花岗岩的成因机制仍然存在着争议。一些学者认为是形成于后碰撞环境[16-17, 19-20]；另一些学者认为形成于洋脊俯冲背景[23-26]。
西准噶尔包古图地区位于达拉布特断裂以南，克拉玛依市西南部(图 1)。该区下石炭统是一套与海相火山活动有关的浊积岩层，主要沉积地层包括下石炭统的希贝库拉斯组、包古图组和太勒古拉组。然而，其地层的上下关系仍然存在着争议。一些学者认为石炭系从下到上为太勒古拉组、包古图组和希贝库拉斯组[42-43]；也有学者认为从下到上为希贝库拉斯组、包古图组、太勒古拉组[44-45]。太勒古拉组下部为一套海底喷发的玄武岩熔岩、玄武质凝灰岩、凝灰质角砾岩和硅质岩等。包古图组为灰黑色薄层凝灰质粉砂岩和灰绿色凝灰岩互层。希贝库拉斯组为灰色厚层凝灰质砂岩、含砾砂岩和凝灰岩，富含化石。包古图地区的中小型岩体和岩墙都比较发育，侵入早石炭世的地层当中。小岩体主要由闪长岩、似斑状闪长岩、似斑状石英黑云母闪长岩、闪长玢岩等组成。这些小岩体的锆石U-Pb定年结果集中在332~310 Ma[46-47]。包古图岩墙主要由闪长质岩石组成，走向以NNE向为主，年龄在316~313 Ma [48]。而包古图斑岩铜矿中辉钼矿的Re-Os定年结果在315~310 Ma[30-32]。包古图岩墙与小岩体具有相似的形成年龄、地球化学特征和成岩过程，而且小岩体或岩墙普遍受到矿化的影响；此外，部分岩墙中包含有石英硫化物脉，显示它们与铜金成矿密切相关[24, 48-49]。
本文研究样品采自包古图Ⅰ号岩体(图 2)。样品WJ1302由斜长石(50%)、石英(10%~15%)、黑云母(10%~15%)和角闪石(25%)组成, 副矿物为不透明矿物、锆石和磷灰石, 定名为黑云母石英闪长岩(图 3a，b)。斜长石呈半自形板状，杂乱分布，粒度一般为0.2~2.0 mm，部分2.0~3.2 mm，环带发育，粒内聚片双晶发育(图 3c)。石英呈他形粒状，填隙状分布，粒度一般0.1~2.0 mm，部分2.0~2.8 mm，粒内波状消光。角闪石呈半自形柱状或自形-半自形近菱形六边形，杂乱分布，粒度一般0.1~2.0 mm，少数2.0~2.8 mm，颜色不均匀。黑云母呈片状，杂乱分布，粒度一般为0.2~2.0 mm，部分2.0~2.5 mm，多被绿泥石、绿帘石交代呈假象，少残留(图 3d)。
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| Hbl.角闪石；Pl.斜长石；Bi.黑云母；Q.石英。a、b、c为正交光，d为单偏光。 图 3 包古图Ⅰ号岩体的显微镜照片 Figure 3 Microscopic photos of Pluton Ⅰ in the Baogutu area |
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LA-ICP-MS锆石U-Pb定年测试在香港大学地球科学系完成, 所用仪器为VG PQ Excell ICP-MS及与之配套的New Wave UP213激光剥蚀系统。详细的分析流程见文献[50]，测试所选的锆石颗粒多为无色或浅灰色，自形或半自形，多呈柱状、板状，长轴变化于40~250 um，长短轴变化于1:1~3:1。大多数锆石环带结构发育(图 4)。样品的LA-ICP-MS锆石U-Pb分析结果列于表 1。
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| 图 4 包古图Ⅰ号岩体代表性锆石阴极发光图像和测试点位置 Figure 4 CL images and analyzed points of representative zircons from Pluton Ⅰ in Baogutu area |
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表 1 包古图Ⅰ号岩体的锆石LA-ICP-MS U-Pb定年分析结果
Table 1 LA-ICP-MS zircon U-Pb dating results of the Pluton Ⅰ in the Baogutu area
| 分析点 | Th/U | 同位素比值 | 年龄/Ma | |||||||||||
| 207Pb/206Pb | 1σ | 207Pb/235U | 1σ | 206Pb/238U | 1σ | 207Pb/206Pb | 1σ | 207Pb/235U | 1σ | 206Pb/238U | 1σ | |||
| WJ1302-1 | 0.81 | 0.054 26 | 0.000 30 | 0.371 87 | 0.003 71 | 0.049 96 | 0.000 60 | 382 | 12 | 321 | 3 | 314 | 4 | |
| WJ1302-2 | 0.98 | 0.053 65 | 0.000 35 | 0.369 84 | 0.005 52 | 0.049 97 | 0.000 65 | 356 | 15 | 320 | 4 | 314 | 4 | |
| WJ1302-3 | 0.70 | 0.052 22 | 0.002 12 | 0.357 42 | 0.014 20 | 0.049 64 | 0.000 42 | 295 | 95 | 310 | 11 | 312 | 3 | |
| WJ1302-4 | 1.07 | 0.052 52 | 0.000 23 | 0.363 35 | 0.002 77 | 0.050 18 | 0.000 37 | 308 | 8 | 315 | 2 | 316 | 2 | |
| WJ1302-5 | 0.74 | 0.053 37 | 0.000 27 | 0.366 77 | 0.003 84 | 0.049 81 | 0.000 44 | 345 | 11 | 317 | 3 | 313 | 3 | |
| WJ1302-6 | 0.82 | 0.053 62 | 0.000 2 | 0.367 87 | 0.004 05 | 0.049 81 | 0.000 58 | 355 | 12 | 318 | 3 | 313 | 4 | |
| WJ1302-7 | 1.20 | 0.053 39 | 0.000 21 | 0.367 29 | 0.002 00 | 0.049 89 | 0.000 23 | 345 | 6 | 318 | 1 | 314 | 1 | |
| WJ1302-8 | 0.88 | 0.054 31 | 0.000 21 | 0.374 82 | 0.003 09 | 0.050 12 | 0.000 42 | 384 | 9 | 323 | 2 | 315 | 3 | |
| WJ1302-10 | 0.67 | 0.052 91 | 0.001 45 | 0.360 51 | 0.009 59 | 0.049 42 | 0.000 34 | 325 | 64 | 313 | 7 | 311 | 2 | |
| WJ1302-11 | 0.70 | 0.052 77 | 0.000 38 | 0.362 97 | 0.004 06 | 0.049 87 | 0.000 42 | 319 | 12 | 314 | 3 | 314 | 3 | |
| WJ1302-12 | 0.49 | 0.054 17 | 0.000 29 | 0.373 60 | 0.003 55 | 0.049 99 | 0.000 38 | 378 | 10 | 322 | 3 | 314 | 2 | |
| WJ1302-14 | 0.67 | 0.054 69 | 0.000 54 | 0.376 94 | 0.004 59 | 0.050 01 | 0.000 39 | 400 | 14 | 325 | 3 | 315 | 2 | |
| WJ1302-15 | 0.67 | 0.054 92 | 0.001 00 | 0.378 59 | 0.008 33 | 0.049 95 | 0.000 39 | 409 | 35 | 326 | 6 | 314 | 2 | |
| WJ1302-17 | 0.68 | 0.052 45 | 0.001 73 | 0.358 99 | 0.010 97 | 0.049 64 | 0.000 62 | 305 | 77 | 311 | 8 | 312 | 4 | |
| WJ1302-19 | 0.73 | 0.053 43 | 0.001 54 | 0.364 81 | 0.010 30 | 0.049 52 | 0.000 28 | 347 | 67 | 316 | 8 | 312 | 2 | |
| WJ1302-20 | 0.68 | 0.053 28 | 0.001 82 | 0.367 36 | 0.011 84 | 0.050 01 | 0.000 56 | 341 | 79 | 318 | 9 | 315 | 3 | |
主、微量元素的分析测试均在中国科学院广州地球化学研究所同位素地球化学国家重点实验室完成。主量元素分析是用Rigaku RIX2000型荧光光谱仪(XRF)分析，其详细步骤见文献[51]。微量元素的分析则采用Perkin-ElmerSciex ELAN 6000型电感耦合等离子体质谱仪(ICP-MS)，具体的流程见文献[52]。代表性样品的主量元素和微量元素分析结果见表 2。
表 2 包古图Ⅰ号岩体的主量和微量元素化学成分
Table 2 Geochemical composition and trace element abundance of the Pluton Ⅰ in the Baogutu area
| 样品号 | SiO2 | TiO2 | Al2O3 | TFe2O3 | MnO | MgO | CaO | Na2O | K2O | P2O5 | 烧失量 | 总量 | Na2O+K2O | K2O/Na2O | Mg# | La | Ce | Pr | Nd | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | Lu | ΣREE | Sc | Ti | V | Cr | Mn | Co | Ni | Cu | Zn | Ga | Ge | Rb | Sr | Y | Zr | Nb | Cs | Ba | Hf | Ta | Pb | Th | U |
| WJ1302-1 | 58.0 | 0.76 | 17.2 | 6.29 | 0.09 | 3.55 | 6.17 | 4.30 | 1.19 | 0.18 | 1.78 | 99.5 | 5.49 | 0.28 | 52.8 | 11.3 | 26.3 | 3.86 | 16.8 | 3.64 | 1.05 | 3.21 | 0.51 | 2.95 | 0.61 | 1.64 | 0.24 | 1.56 | 0.24 | 73.8 | 14.2 | 4 641 | 142 | 65.5 | 671 | 20.5 | 46.8 | 42.0 | 52.9 | 21.5 | 2.22 | 18.8 | 857 | 15.1 | 127.0 | 2.26 | 0.92 | 560 | 3.26 | 0.15 | 2.70 | 1.62 | 0.40 |
| WJ1302-2 | 58.5 | 0.78 | 16.6 | 6.56 | 0.09 | 3.77 | 6.10 | 4.13 | 1.10 | 0.19 | 1.71 | 99.5 | 5.23 | 0.27 | 53.2 | 11.2 | 26.2 | 3.87 | 17.0 | 3.79 | 1.05 | 3.34 | 0.53 | 3.07 | 0.63 | 1.69 | 0.25 | 1.59 | 0.25 | 74.3 | 14.5 | 4 691 | 146 | 67.6 | 677 | 21.2 | 48.1 | 39.3 | 52.0 | 20.3 | 2.11 | 16.2 | 757 | 15.2 | 99.0 | 2.34 | 0.76 | 503 | 2.72 | 0.17 | 2.58 | 2.15 | 0.45 |
| WJ1302-3 | 58.4 | 0.75 | 17.3 | 6.21 | 0.09 | 3.56 | 6.04 | 4.17 | 1.19 | 0.18 | 1.59 | 99.5 | 5.36 | 0.29 | 53.2 | 11.2 | 25.9 | 3.78 | 16.6 | 3.66 | 1.05 | 3.25 | 0.51 | 2.93 | 0.61 | 1.63 | 0.24 | 1.51 | 0.23 | 73.1 | 13.4 | 4 381 | 143 | 63.8 | 636 | 19.6 | 45.2 | 36.6 | 49.7 | 20.8 | 1.97 | 18.8 | 816 | 14.6 | 72.1 | 2.21 | 0.88 | 604 | 2.12 | 0.15 | 2.45 | 1.62 | 0.35 |
| WJ1302-4 | 59.0 | 0.76 | 16.8 | 6.24 | 0.09 | 3.54 | 6.03 | 4.08 | 1.29 | 0.18 | 1.54 | 99.6 | 5.37 | 0.32 | 53.0 | 13.2 | 29.3 | 4.02 | 17.2 | 3.66 | 1.02 | 3.32 | 0.51 | 2.91 | 0.60 | 1.61 | 0.23 | 1.52 | 0.23 | 79.3 | 13.2 | 4 375 | 140 | 66.2 | 639 | 19.8 | 45.5 | 37.7 | 50.2 | 20.1 | 2.00 | 19.8 | 804 | 14.7 | 84.5 | 2.19 | 0.90 | 671 | 2.37 | 0.15 | 2.57 | 1.81 | 0.36 |
| WJ1302-5 | 58.5 | 0.74 | 17.4 | 6.06 | 0.08 | 3.46 | 6.13 | 4.35 | 1.13 | 0.18 | 1.48 | 99.5 | 5.48 | 0.26 | 53.0 | 11.0 | 25.9 | 3.72 | 16.3 | 3.60 | 1.05 | 3.12 | 0.50 | 2.91 | 0.60 | 1.61 | 0.24 | 1.53 | 0.23 | 72.3 | 41.0 | 4 707 | 139 | 66.4 | 658 | 20.1 | 45.8 | 40.5 | 53.9 | 21.8 | 2.05 | 17.3 | 882 | 14.9 | 118.0 | 2.31 | 0.94 | 579 | 3.08 | 0.17 | 2.53 | 1.66 | 0.39 |
| WJ1302-6 | 58.0 | 0.80 | 17.3 | 6.40 | 0.09 | 3.66 | 6.28 | 4.24 | 1.07 | 0.19 | 1.51 | 99.5 | 5.31 | 0.25 | 53.1 | 11.6 | 27.7 | 3.98 | 17.2 | 3.82 | 1.07 | 3.38 | 0.54 | 3.09 | 0.64 | 1.71 | 0.25 | 1.60 | 0.24 | 76.7 | 15.8 | 4 900 | 148 | 74.7 | 719 | 22.0 | 49.8 | 40.3 | 57.4 | 22.3 | 2.23 | 17.0 | 832 | 15.8 | 97.2 | 2.34 | 0.77 | 514 | 2.56 | 0.16 | 2.49 | 1.58 | 0.36 |
| 注：主量元素质量分数单位为%；微量元素质量分数单位为10-6。 | |||||||||||||||||||||||||||||||||||||||||||||||||||||
包古图Ⅰ号岩体(WJ1302)的锆石U-Pb定年分析点共20个，其Th/U值为0.49~1.20。有4个分析点的206Pb/238U表观年龄明显偏离正态分布特征, 其他16个点在谐和图上形成单一和集中的聚集束。206Pb/238U年龄为311~315 Ma，加权年龄平均为(313.8±1.1) Ma (图 5), 代表了该样品的结晶年龄。该年龄与包古图其他小岩体的形成年龄在误差范围内一致[46-47]。
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| 图 5 包古图Ⅰ号岩体的LA-ICP-MS锆石U-Pb谐和图 Figure 5 Concordia diagrams of LA-ICP-MS zircon U-Pb ages of Pluton Ⅰ in the Baogutu area |
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包古图Ⅰ号岩体的SiO2质量分数为58.0%~59.0%。该岩体显示贫碱、富钠、贫钾的特征，w(K2O+Na2O)为5.23%~5.49%，K2O/Na2O为0.25~0.32。在w(K2O)-w(SiO2)图解中，这些样品显示了中钾钙碱性的特点(图 6)。它们均含有高的w(Al2O3)(16.6%~17.4%)，w(MgO)(3.46%~3.77%)和Mg#(52.8~53.2)值(表 2)。
这些闪长岩的稀土总量w(ΣREE)为72.3×10-6~79.3×10-6，其稀土分布模式呈现出LREE ((La/Yb)N=5.03~6.24)略富集，HREE ((Gd/Yb)N=1.69~1.78)相对平坦以及弱的Eu (Eu/Eu=0.90~0.96)负异常等特征(图 7a)。在原始地幔标准化图解中，这些闪长岩富集大离子亲石元素(LILE)(如Ba、K、Rb和U)、LREE和弱的Sr正异常，相对亏损高强场元素(如Nb、Ta和Ti)(图 7b)，显示了俯冲带相关的岩浆特征。这些特征与包古图其他埃达克质岩体的地球化学特征类似(图 7，8)。这些闪长岩具有高的Sr (757×10-6~882×10-6)和Ba (503×10-6~671×10-6)和高的Sr/Y (50~59)值，亏损重稀土(w(Yb)=1.51×10-6~1.60×10-6；w(Y)=14.6×10-6~15.8×10-6)，类似于包古图埃达克岩，如高的w(Sr)(346×10-6~841×10-6)和w(Ba)(216×10-6~887×10-6)和高的Sr/Y (31~67)值，亏损重稀土(w(Yb)=0.93×10-6~1.60×10-6；w(Y)=9.18×10-6~16.5×10-6))[22, 24]，显示了埃达克岩的典型特征[1, 55]。在Sr/Y-w(Y)图解中，所有样品也都投在了埃达克岩的区域(图 8a)。
包古图Ⅰ号岩体显示高Sr和Sr/Y，低Y和Yb，弱的负Eu异常及平坦的HREE配分模式和Nb、Ta、Ti的异常，这些特征类似于典型的埃达克岩[1, 57]。目前，多种埃达克质岩浆的形成机制被提出，主要包括：1)俯冲洋壳熔融[1, 58]；2)玄武质岩浆的结晶分异[9-10]；3)增厚或拆沉下地壳熔融[5-7, 59]；4)俯冲的陆壳熔融[8]。
在图 9中，包古图Ⅰ号岩体并没有显示出高压或低压分离结晶的趋势，因此，它可能不是由玄武质岩浆的结晶分异而成。玄武质岩浆底垫，使加厚下地壳部分熔融，能形成埃达克岩，但是这种机制没有地幔楔的参与，形成的埃达克岩具有低的MgO、Cr、Ni质量分数。而包古图Ⅰ号岩体具有高的MgO (3.46%~3.77%)、Cr (63.8×10-6~74.7×10-6)、Ni (45.2×10-6~49.8×10-6)质量分数, 明显不同于增厚下地壳熔融形成的埃达克岩(图 8b)。另外，拆沉下地壳或者俯冲陆壳熔融也是可能的成因机制之一。拆沉下地壳或者俯冲陆壳熔融形成的埃达克岩通常具有高的K2O质量分数(通常大于3%)和低的εNd(t)值(通常低于3)[8]。然而，包古图埃达克岩具有低的K2O质量分数(1.07%~1.29%)和正的εNd(t)值(5.8~8.3)[24], 暗示上述机制在晚石炭世可能没有发生。
通过大量埃达克岩地球化学数据的统计，Martin等[57]将埃达克岩分成两个亚类，即高硅埃达克岩和低硅埃达克岩。1)高硅埃达克岩(wSiO2)>60%;w(MgO)=0.5%~4.0%)是指俯冲的板片熔体在上升过程中与地幔楔的产物；2)低硅埃达克岩(w(SiO2)< 60%；w(MgO)=4%~9%)是受硅质熔体交代的地幔橄榄岩的部分熔融而成。在低硅和高硅埃达克岩的分类图中，包古图Ⅰ号岩体全部投在高硅埃达克岩的范围内[57](图 10)。因此，包古图Ⅰ号岩体可能是俯冲的板片熔体与上覆地幔楔反应的产物。该结论与前人对包古图埃达克岩成因研究结论一致[24]。
目前，对于西准噶尔地区晚石炭世的构造背景仍然存在着激烈的争论，主要观点有：后碰撞环境、地幔柱、洋脊俯冲和弧后盆地等[16, 19, 23-29, 60-61]。我们对包古图Ⅰ号岩体的岩相学研究显示，这些埃达克岩含有大量角闪石和黑云母等富水矿物，其锆石饱和温度较低(629~652 ℃)，与高温的“干”的地幔岩浆明显不同。另外，由于地幔热流上涌，地壳呈三联点式张性破裂，从而形成放射状岩墙群[62]。尽管西准噶尔地区岩墙非常发育，但其主要以北西向为主，少量北东向和近南北向；此外，西准噶尔晚石炭世岩浆主要以钙碱性的花岗质岩浆为主，伴有少量的基性岩浆，与地幔柱作用产生广泛的基性岩浆不同。另外，地幔柱模式已经广泛用于解释新疆290~260 Ma基性岩墙的成因[63]。然而，包古图埃达克岩形成于(313.8±1.1) Ma，明显早于早二叠世塔里木大火成岩省活动时限。因此，西准噶尔地区晚石炭世的岩浆作用可能与地幔柱作用无关。在后碰撞背景下，增厚或拆沉下地壳熔融和俯冲的陆壳熔融都能形成埃达克岩。如岩浆成因讨论所述，上述机制可能没有发生。更重要的是，古地理研究表明, 直到290 Ma，西准噶尔部分地区仍然为浅海-次深海环境, 以细碎屑沉积为主, 夹含放射虫硅质岩、玄武岩[45]。而古地磁研究显示, 在准噶尔岛弧和伊犁板块之间的准噶尔洋在晚石炭世仍然存在[64]。因此, 在晚石炭世西准噶尔地区可能都仍处于俯冲背景。
实验岩石学研究显示，埃达克岩的形成通常需要相对高的温压条件(p=1.5~2.5 GPa，T=850~1 050 ℃)[65]。在当今的大多数俯冲体系，由于较低的地热梯度，俯冲的洋壳板片不会熔融，而只发生脱水作用，从而形成正常的岛弧安山岩[66-67]。在晚石炭世，西准噶尔地区不仅出露有埃达克岩，还有大量的碱性花岗岩(Alkali-feldspar granite)[23-24]、碱性玄武岩(Alkaline basalt)[29]、富镁闪长岩(Magnesian diorite)[25, 48]、赞岐质岩墙(Sanukitic dyke)[26, 68]和紫苏花岗岩(Charnockite)[23]等代表高温和拉张环境的特殊岩石组合。为了能够解释上述特殊岩石组合, 一个洋脊俯冲模式被提出来解释这些岩浆作用和成矿作用[23-26]。本文研究也支持这种模式。
当西准噶尔洋中脊进入俯冲区域以后，正常的俯冲作用将停止，由于俯冲的洋中脊的持续扩张作用将会使该洋中脊两侧的洋壳板片之间形成一个持续加宽的间隙，这个间隙成为板片窗[69-70]。热的软流圈上涌，促使板片窗两侧的洋壳板片发生熔融而形成埃达克质岩浆[71-72]。而高温的软流圈地幔加热下地壳，使之发生部分熔融而形成紫苏花岗岩和碱性花岗岩[23, 29, 73]。由于热的软流圈地幔通过板片窗上涌，使冷的岩石圈地幔迅速拉张和走滑，为岩浆上升提供通道，从而形成大量的中-基性岩墙。而铜是中度不相容元素，在洋壳中的质量分数一般为60×10-6~125×10-6[74]，也有的研究估计平均丰度在74×10-6[75]，远比地幔(30×10-6)[76]和陆壳的平均丰度(27×10-6)[77]高，因此，洋壳部分熔融形成的岩浆具有较高的铜含量，有利于成矿[78]。另外，在洋脊俯冲时，洋脊两侧的板片熔融形成的熔体在上升过程中与地幔楔反应，使地幔楔橄榄岩的fO2增高，硫化物不稳定，使地幔中的金属硫化物氧化而溶解于硅酸盐中，从而使Cu、Au等元素富集形成矿床[48]。而西准噶尔地区的包古图斑岩铜矿(315~310 Ma)[30-32]和包古图埃达克岩(316~313 Ma)同时同地形成[46-47]，表明它们之间可能有密切的成因关系。目前的找矿勘探显示，Ⅱ号和V号小岩体矿化比较好，Ⅰ号、Ⅲ号、Ⅳ号小岩体也有矿化，也进一步证实了这点。因此，西准噶尔洋脊俯冲显然有利于相关矿床的形成，暗示该区具有良好的成矿远景。
7 结论1) 包古图Ⅰ号闪长质岩体的锆石U-Pb年龄为(313.8±1.1) Ma，为晚石炭世。
2) 包古图Ⅰ号闪长质岩体以富SiO2、Al2O3和高Sr、低Y和Yb为特征，类似于俯冲成因的埃达克岩。
3) 这个闪长质岩体可能由俯冲的板片熔融与上覆地幔相互作用而成。它的形成可能与西准噶尔晚石炭世期间的洋脊俯冲作用有关。
致谢: 样品的锆石U-Pb定年分析和数据处理工作得到香港大学地球科学系耿红燕博士、Wong Jean博士的帮助, 主量和微量元素分析得到中国科学院广州地球化学研究所同位素年代学和地球化学国家重点实验室胡光黔老师和王鑫玉同学的帮助，在此表示衷心的感谢！
参考文献
| [1] | Defant M J, Drummond M S. Derivation of Some Mo-dern Arc Magmas by Melting of Young Subducted Lithosphere[J]. Nature, 1990, 347 : 662-665. DOI:10.1038/347662a0 |
| [2] | Aguillon-Robles A, Calmus T, Benoit M, et al. Late Miocene Adakites and Nb-Enriched Basalts from Vizcaino Peninsula, Mexico:Indicators of East Pacific Rise Subduction Below Southern Baja California?[J]. Geology, 2001, 29 : 531-534. DOI:10.1130/0091-7613(2001)029<0531:LMAANE>2.0.CO;2 |
| [3] | Sajona F G, Maury R, Bellon H, et al. High Field St-rength Element Enrichment of Pliocene-Pleistocene Island Arc Basalts, Zamboanga Peninsula, Western Mindanao (Philippines)[J]. Journal of Petrology, 1996, 37 : 693-726. DOI:10.1093/petrology/37.3.693 |
| [4] | Sajona F G, Maury R C, Bellon H, et al. Initiation of Subduction and the Generation of Slab Melts in Western and Eastern Mindanao, Philippines[J]. Geology, 1993, 21 : 1007-1010. DOI:10.1130/0091-7613(1993)021<1007:IOSATG>2.3.CO;2 |
| [5] | Gao S, Rudnick R L, Yuan H L, et al. Recycling Lo-wer Continental Crust in the North China Craton[J]. Nature, 2004, 432 : 892-897. DOI:10.1038/nature03162 |
| [6] | Wang Q, Wyman D A, Xu J F, et al. Early Creta-ceous Adakitic Granites in the Northern Dabie Complex, Central China:Implications for Partial Melting and Delamination of Thickened Lower Crust[J]. Geochimica et Cosmochimica Acta, 2007, 71 : 2609-2636. DOI:10.1016/j.gca.2007.03.008 |
| [7] | Wang Q, Wyman D A, Xu J F, et al. Partial Melting of Thickened or Delaminated Lower Crust in the Middle of Eastern China:Implications for Cu-Au Mineralization[J]. The Journal of Geology, 2007, 115 : 149-161. DOI:10.1086/510643 |
| [8] | Wang Q, Wyman D A, Xu J F, et al. Eocene Melting of Subducting Continental Crust and Early Uplifting of Central Tibet:Evidence from Central-Western Qiangtang High-K Calc-Alkaline Andesites, Dacites and Rhyolites[J]. Earth and Planetary Science Letters, 2008, 272 : 158-171. DOI:10.1016/j.epsl.2008.04.034 |
| [9] | Castillo P R, Janney P E, Solidum R. Petrology and Geochemistry of Camiguin Island, Southern Philippines:Insights into the Source of Adakite and Other Lavas in a Complex Arc Tectonic Setting[J]. Contributions to Mineralogy and Petrology, 1999, 134 : 33-51. DOI:10.1007/s004100050467 |
| [10] | Macpherson C G, Dreher S T, Thirlwall M F. Adaki-tes Without Slab Melting:High Pressure Differentiation of Island Arc Magma, Mindanao, the Philippines[J]. Earth and Planetary Science Letters, 2006, 243 : 581-593. DOI:10.1016/j.epsl.2005.12.034 |
| [11] | Buslov M M, Fujiwara Y, Iwata K, et al. Late Pa-leozoic-Early Mesozoic Geodynamics of Central Asia[J]. Gondwana Research, 2004, 7 : 791-808. DOI:10.1016/S1342-937X(05)71064-9 |
| [12] | Jahn B M, Capdevila R, Liu D, et al. Sources of Phanerozoic Granitoids in the Transect Bayanhongor-Ulaan Baatar, Mongolia:Geochemical and Nd Isotopic Evidence, and Implications for Phanerozoic Crustal Growth[J]. Journal of Asian Earth Sciences, 2004, 23 : 629-653. DOI:10.1016/S1367-9120(03)00125-1 |
| [13] | Xiao W J, Santosh M. The Western Central Asian Orogenic Belt:A Window to Accretionary Orogenesis and Continental Growth[J]. Gondwana Research, 2014, 25 : 1429-1444. DOI:10.1016/j.gr.2014.01.008 |
| [14] | Xiao W J, Han C M, Yuan C, et al. Middle Cam-brian to Permian Subduction-Related Accretionary Orogenesis of North Xinjiang, NW China:Implications for the Tectonic Evolution of Central Asia[J]. Journal of Asian Earth Sciences, 2008, 32 : 102-117. DOI:10.1016/j.jseaes.2007.10.008 |
| [15] | Windley B F, Alexeiev D, Xiao W J, et al. Tectonic Models for Accretion of the Central Asian Orogenic Belt[J]. Journal of the Geological Society, 2007, 164 : 31-47. DOI:10.1144/0016-76492006-022 |
| [16] | 韩宝福, 季建清, 宋彪, 等. 新疆准噶尔晚古生代陆壳垂向生长(Ⅰ):后碰撞深成岩浆活动的时限[J]. 岩石学报, 2006, 22 (5) : 1077-1086. Han Baofu, Ji Jianqing, Song Biao, et al. Late Paleozoic Vertical Growth of Continental Crust Around the Junggar Basin, Xinjiang, China (Part Ⅰ):Timing of Postcollisional Plutonism[J]. Acta Petrologica Sinica, 2006, 22 (5) : 1077-1086. |
| [17] | 苏玉平, 唐红峰, 侯广顺, 等. 新疆西准噶尔达拉布特构造带铝质A型花岗岩的地球化学研究[J]. 地球化学, 2006, 35 (1) : 55-67. Su Yuping, Tang Hongfeng, Hou Guangshun, et al. Geochemistry of Aluminous A-Type Granites Along Darabut Tectonic Belt in West Junggar, Xinjiang[J]. Geochemica, 2006, 35 (1) : 55-67. |
| [18] | 尹继元, 陈文, 袁超, 等. 新疆西准噶尔晚古生代侵入岩的年龄和构造意义:来自锆石LA-ICP-MS定年的证据[J]. 地球化学, 2013, 42 (5) : 415-430. Yin Jiyuan, Chen Wen, Yuan Chao, et al. Ages and Tectonic Implication of Late Paleozoic Plutons in the West Junggar, North Xinjiang:Evidence from LA-ICPMS Zircon Geochronology[J]. Geochimica, 2013, 42 (5) : 415-430. |
| [19] | Chen B, Arakawa Y. Elemental and Nd-Sr Isotopic Geochemistry of Granitoids from the West Junggar Fold-Belt (NW China), with Implications for Phanerozoic Continental Growth[J]. Geochimica et Cosmochimica Acta, 2005, 69 : 1307-1320. DOI:10.1016/j.gca.2004.09.019 |
| [20] | Chen B, Jahn B M. Genesis of Post-Collisional Gran-itoids and Basement Nature of the Junggar Terrane, NW China:Nd-Sr Isotope and Trace Element Evidence[J]. Journal of Asian Earth Sciences, 2004, 23 : 691-703. DOI:10.1016/S1367-9120(03)00118-4 |
| [21] | Chen J F, Han B F, Ji J Q, et al. Zircon U-Pb Ages and Tectonic Implications of Paleozoic Plutons in Northern West Junggar, North Xinjiang, China[J]. Lithos, 2010, 115 : 137-152. DOI:10.1016/j.lithos.2009.11.014 |
| [22] | 张连昌, 万博, 焦学军, 等. 西准包古图含铜斑岩的埃达克岩特征及其地质意义[J]. 中国地质, 2006, 33 (3) : 626-631. Zhang Lianchang, Wan Bo, Jiao Xuejun, et al. Characteristics and Geological Significance of Adakitic Rocks in Copper-Bearing Porphyry in Baogutu, Western Junggar[J]. Geology in China, 2006, 33 (3) : 626-631. |
| [23] | Geng H Y, Sun M, Yuan C, et al. Geochemical, Sr-Nd and Zircon U-Pb-Hf Isotopic Studies of Late Carboniferous Magmatism in the West Junggar, Xinjiang:Implications for Ridge Subduction?[J]. Chemical Geology, 2009, 266 (3/4) : 373-398. |
| [24] | Tang G J, Wang Q, Wyman D A, et al. Ridge Sub-duction and Crustal Growth in the Central Asian Orogenic Belt:Evidence from Late Carboniferous Adakites and High-Mg Diorites in the Western Junggar Region, Northern Xinjiang (West China)[J]. Chemical Geology, 2010, 277 : 281-300. DOI:10.1016/j.chemgeo.2010.08.012 |
| [25] | Yin J Y, Long X P, Yuan C, et al. A Late Carbo-niferous Slab Window:Geochronological and Geochemical Evidence from Mafic to Intermediate Dykes in West Junggar, NW China[J]. Lithos, 2013 (175/176) : 146-162. |
| [26] | Yin J Y, Yuan C, Sun M, et al. Late Carboniferous High-Mg Dioritic Dykes in Western Junggar, NW China:Geochemical Features, Petrogenesis and Tectonic Implications[J]. Gondwana Research, 2010, 17 : 145-152. DOI:10.1016/j.gr.2009.05.011 |
| [27] | Yang G X, Li Y J, Gu P Y, et al. Geochronological and Geochemical Study of the Darbut Ophiolitic Complex in the West Junggar (NW China):Implications for Petrogenesis and Tectonic Evolution[J]. Gondwana Research, 2012, 21 : 1037-1049. DOI:10.1016/j.gr.2011.07.029 |
| [28] | Yang G X, Li Y J, Santosh M, et al. Geochronology and Geochemistry of Basaltic Rocks from the Sartuohai Ophiolitic Mélange, NW China:Implications for a Devonian Mantle Plume Within the Junggar Ocean[J]. Journal of Asian Earth Sciences, 2012, 59 : 141-155. DOI:10.1016/j.jseaes.2012.07.020 |
| [29] | Yang G X, Li Y J, Yan J, et al. Geochronological and Geochemical Constraints on the Origin of the 304±5 Ma Karamay A-Type Granites from West Junggar, Northwest China:Implications for Understanding the Central Asian Orogenic Belt[J]. International Geology Review, 2014, 56 : 393-407. DOI:10.1080/00206814.2013.847608 |
| [30] | Liu Y L, Guo L S, Liu Y D. Geochronology of Bao-gutu Porphyry Copper Deposit in Western Junggar Area, Xinjiang of China[J]. Science in China:Series D:Earth Science, 2009, 52 (10) : 1543-1549. DOI:10.1007/s11430-009-0127-7 |
| [31] | 宋会侠, 刘玉琳, 屈文俊, 等. 新疆包古图斑岩铜矿矿床地质特征[J]. 岩石学报, 2007, 23 (8) : 1981-1988. Song Huixia, Liu Yulin, Qu Wenjun, et al. Geological Characters of Baogutu Porphyry Copper Deposit in Xinjiang, NW China[J]. Acta Petrologica Sinica, 2007, 23 (8) : 1981-1988. |
| [32] | Shen P, Shen Y C, Pan H D, et al. Geochronology and Isotope Geochemistry of the Baogutu Porphyry Copper Deposit in the West Junggar Region, Xinjiang, China[J]. Journal of Asian Earth Sciences, 2012, 49 (30) : 99-115. |
| [33] | 魏少妮, 朱永峰. 新疆西准噶尔包古图地区中酸性侵入体的岩石学、年代学和地球化学研究[J]. 岩石学报, 2015, 31 (1) : 143-160. Wei Shaoni, Zhu Yongfeng. Petrology, Geochronology and Geochemistry of Intermediate-Acidic Intrusions in Baogutu Area, West Junggar, Xinjiang[J]. Acta Petrologica Sinica, 2015, 31 (1) : 143-160. |
| [34] | Shen P, Shen Y C, Liu T B, et al. Geochemical Signature of Porphyries in the Baogutu Porphyry Copper Belt, Western Junggar, NW China[J]. Gondwana Research, 2009, 16 (2) : 227-242. DOI:10.1016/j.gr.2009.04.004 |
| [35] | 何国琦, 刘建波, 张越迁, 等. 准噶尔盆地西缘克拉玛依早古生代蛇绿混杂岩带的厘定[J]. 岩石学报, 2007, 23 (7) : 1573-1576. He Guoqi, Liu Jianbo, Zhang Yueqian, et al. Keramay Ophiolitic Mélange Formed During Early Paleozoic in West Junggar Basin[J]. Acta Petrologica Sinica, 2007, 23 (7) : 1573-1576. |
| [36] | 肖序常, 汤耀庆, 冯益民. 新疆北部及其邻区大地构造 [M]. 北京: 地质出版社, 1992 : 1-171. Xiao Xuchang, Tang Yaoqing, Feng Yimin. Tectonic Evolution of Northern Xinjiang and Its Adjacent Regions [M]. Beijing: Geological Publishing House, 1992 : 1-171. |
| [37] | Zhang C, Zhai M G, Allen M B, et al. Implications of Palaeozoic Ophiolites from West Junggar, NW China, for the Tectonics of Central Asia[J]. Journal of the Geological Society of London, 1993, 150 : 551-561. DOI:10.1144/gsjgs.150.3.0551 |
| [38] | Kwon S T, Tilton G R, Coleman R G, et al. Isotopic Studies Bearing on the Tectonics of the West Junggar Region, Xinjiang, China[J]. Tectonics, 1989, 8 (4) : 719-727. DOI:10.1029/TC008i004p00719 |
| [39] | 魏荣珠. 西准噶尔玛依勒山枕状熔岩地质特征及大地构造意义[J]. 新疆地质, 2010, 28 (3) : 229-235. Wei Rongzhu. The Mayileshang Pillow Lavas (Western Junggar, Xinjiang) and Their Tectonic Implications:Constraints from the Geological and Geochemical Characteristics and Rb-Sr Isochron Ages[J]. Xinjiang Geology, 2010, 28 (3) : 229-235. |
| [40] | 辜平阳, 李永军, 张兵, 等. 西准达尔布特蛇绿岩中辉长岩LA-ICP-MS锆石U-Pb测年[J]. 岩石学报, 2009, 25 (6) : 1364-1372. Gu Pingyang, Li Yongjun, Zhang Bing, et al. LA-ICP-MS Zircon U-Pb Dating of Gabbro in the Darbut Ophiolite, West Junggar, China[J]. Acta Petrologica Silica, 2009, 25 (6) : 1364-1372. |
| [41] | Zhou T F, Yuan F, Fan Y, et al. Granites in the Sawuer Region of the West Junggar, Xinjiang, China:Geochronological and Geochemical Characteristics and Their Geodynamic Significance[J]. Lithos, 2008, 106 : 191-206. DOI:10.1016/j.lithos.2008.06.014 |
| [42] | 郭丽爽, 刘玉琳, 王政华, 等. 西准噶尔包古图地区地层火山岩锆石LA-ICP-MS U-Pb年代学研究[J]. 岩石学报, 2010, 26 (2) : 471-477. Guo Lishuang, Liu Yulin, Wang Zhenghua, et al. The Zircon U-Pb LA-ICP-MS Geochronology of Volcanic Rocks in Baogutu Areas, Western Junggar[J]. Acta Petrologica Sinica, 2010, 26 (2) : 471-477. |
| [43] | 安芳, 朱永峰. 新疆西准噶尔包古图组凝灰岩锆石SHRIMP年龄及其地质意义[J]. 岩石学报, 2009, 25 (6) : 1437-1445. An Fang, Zhu Yongfeng. SHRIMP U-Pb Zircon Ages of Tuff in Baogutu Formation and Their Geological Significances[J]. Acta Petrologica Sinica, 2009, 25 (6) : 1437-1445. |
| [44] | 王福同. 新疆维吾尔自治区古地理及地质生态图集 [M]. 北京: 中国地图出版社, 2006 . Wang Futong. The Paleogeographic and Geoecological Atlas of Xinjiang Uygur Autonomous Region [M]. Beijing: Sinomaps Press, 2006 . |
| [45] | 申萍, 沈远超, 潘成泽. 新疆哈图-包古图金铜矿集区锆石年龄及成矿特点[J]. 岩石学报, 2010, 26 (10) : 2875-2893. Shen Ping, Shen Yuanchao, Pan Chengze. Zircon Age and Metallogenic Characteristics of the Hatu-Baogutu Au-Cu Metallogenic Concentric Region in Xinjiang[J]. Acta Petrologica Sinica, 2010, 26 (10) : 2875-2893. |
| [46] | 唐功建, 王强, 赵振华, 等. 西准噶尔包古图成矿斑岩年代学与地球化学:岩石成因与构造、铜金成矿意义[J]. 地球科学:中国地质大学学报, 2009, 34 (1) : 56-74. Tang Gongjian, Wang Qiang, Zhao Zhenhua, et al. Geochronology and Geochemistry of the Ore-Bearing Porphyries in the Baogutu Area (Western Junggar):Petrogenesis and Their Implications for Tectonics and Cu-Au Mineralization[J]. Earth Science:Journal of China University of Geosciences, 2009, 34 (1) : 56-74. DOI:10.3799/dqkx.2009.007 |
| [47] | 魏少妮, 程军峰, 喻达兵, 等. 新疆包古图Ⅲ号岩体岩石学和锆石SHRIMP年代学研究[J]. 地学前缘, 2011, 18 (2) : 212-222. Wei Shaoni, Cheng Junfeng, Yu Dabing, et al. Petrology and SHRIMP Zircon Ages of Intrusive Body Ⅲ in Baogutu Area, Xinjiang[J]. Earth Science Frontiers, 2011, 18 (2) : 212-222. |
| [48] | 尹继元, 陈文, 喻顺, 等. 西准噶尔包古图富镁闪长质岩墙的时代, 地球化学特征以及铜金成矿意义[J]. 中国地质, 2013, 40 (4) : 1030-1043. Yin Jiyuan, Chen Wen, Yu Shun, et al. Age, Geochemical Features and Implications for Cu-Au Mineralization of the Magnesian Dioritic Dykes Baogutu Region of West Junggar[J]. Geology in China, 2013, 40 (4) : 1030-1043. |
| [49] | An F, Zhu Y. Native Antimony in the Baogutu Gold Deposit (West Junggar, NW China):Its Occurrence and Origin[J]. Ore Geology Reviews, 2010, 37 (3) : 214-223. |
| [50] | Xia X P, Sun M, Zhao G C, et al. Spot Zircon U-Pb Isotope Analysis by ICP-MS Coupled with a Frequency Quintupled (213 nm) Nd-YAG Laser System[J]. Geochemical Journal, 2004, 38 : 191-200. DOI:10.2343/geochemj.38.191 |
| [51] | Yuan C, Sun M, Wilde S, et al. Post-Collisional Plu-tons in the Balikun Area, East Chinese Tianshan:Evolving Magmatism in Response to Extension and Slab Break-off[J]. Lithos, 2010, 119 : 269-288. DOI:10.1016/j.lithos.2010.07.004 |
| [52] | Li X H, Li Z X, Zhou H W, et al. U-Pb Zircon Geochronology, Geochemistry and Nd Isotopic Study of Neoproterozoic Bimodal Volcanic Rocks in the Kangdian Rift of South China:Implications for the Initial Rifting of Rodinia[J]. Precambrian Research, 2002, 113 : 135-154. DOI:10.1016/S0301-9268(01)00207-8 |
| [53] | Gill T B. Orogenic Andesite and Plate Tectonics [M]. Berlin: Springer-Verlag, 1981 : 390. |
| [54] | Sun S S, McDonough W F. Chemical and Isotopic Systematics of Oceanic Basalt:Implications for Mantle Compositions and Processes[J]. Geological Society London Special Publications, 1989, 42 : 313-345. DOI:10.1144/GSL.SP.1989.042.01.19 |
| [55] | Defant M J, Drummond M S, Mount St. Helens:Po-tential Example of the Partial Melting of the Subducted Lithosphere in a Volcanic Arc[J]. Geology, 1993, 21 : 541-550. |
| [56] | Wang Q, Xu J F, Jian P, et al. Petrogenesis of Ada-kitic Porphyries in an Extensional Tectonic Setting, Dexing, South China:Implications for the Genesis of Porphyry Copper Mineralization[J]. Journal of Petrology, 2006, 47 (1) : 119-144. |
| [57] | Martin H, Smithies R H, Rapp R, et al. An Over-view of Adakite, Tonalite-Trondhjemite-Granodiorite (TTG), and Sanukitoid:Relationships and some Implications for Crustal Evolution[J]. Lithos, 2005, 79 : 1-24. DOI:10.1016/j.lithos.2004.04.048 |
| [58] | Kay R W. Aleutian Magnesian Andesites:Melts from Subducted Pacific Ocean Crust[J]. Journal of Volcanology and Geothermal Research, 1978, 4 : 117-132. DOI:10.1016/0377-0273(78)90032-X |
| [59] | Chung S L, Liu D Y, Ji J Q, et al. Adakites from Continental Collision Zones:Melting of Thickened Lower Crust Beneath Southern Tibet[J]. Geology, 2003, 31 : 1021-1024. DOI:10.1130/G19796.1 |
| [60] | Gao R, Xiao L, Franco P, et al. Carboniferous-Per-mian Extensive Magmatism in the West Junggar, Xinjiang, Northwestern China:Its Geochemistry, Geochronology, and Petrogenesis[J]. Lithos, 2014, 204 : 125-143. DOI:10.1016/j.lithos.2014.05.028 |
| [61] | 田陟贤, 李永军, 田猛, 等. 西准噶尔恰达地区哈尔加乌组火山岩锆石U-Pb年代学、地球化学及地质意义[J]. 吉林大学学报(地球科学版), 2016, 46 (1) : 135-145. Tian Zhixian, Li Yongjun, Tian Meng, et al. Zircon U-Pb Geochronogy, Geochemical Characteristics and Geological Significance of Volcanic Rocks of Haerjiawu Formation in Qiada, West Junggar[J]. Journal of Jilin University (Earth Science Edition), 2016, 46 (1) : 135-145. |
| [62] | 周鼎武, 张成立, 刘颖宇. 大陆造山带基底岩块中的基性岩墙群研究:以南秦岭武当地块为例[J]. 地球科学进展, 1998, 13 (2) : 151-156. Zhou Dingwu, Zhang Chengli, Liu Yingyu. Study on Basic Dyke Swarms Developed in the Basement in the Continental Orogeny:An Example from Wudang Block in Southern Qinling[J]. Advance in Earth Sciences, 1998, 13 (2) : 151-156. |
| [63] | Zhang C L, Zou H B. Comparison Between the Per-mian Mafic Dykes in Tarim and the Western Part of Central Asian Orogenic Belt (CAOB), NW China:Implications for Two Mantle Domains of the Permian Tarim Large Igneous Province[J]. Lithos, 2013, 174 : 15-27. DOI:10.1016/j.lithos.2012.11.010 |
| [64] | Wang B, Chen Y, Zhang S, et al. Primary Carboni-ferous and Permian Paleomagnetic Results from the Yili Block (NW China) and Their Implications on the Geodynamic Evolution of Chinese Tianshan Belt[J]. Earth and Planetary Science Letters, 2007, 263 : 288-308. DOI:10.1016/j.epsl.2007.08.037 |
| [65] | Xiong X L. Trace Element Evidence for Growth of Early Continental Crust by Melting of Rutile-Bearing Hydrous Eclogite[J]. Geology, 2006, 34 : 945-948. DOI:10.1130/G22711A.1 |
| [66] | Schmidta M W, Polib S. Experimentally Based Water Budgets for Dehydrating Slabs and Consequences for Arc Magma Generation[J]. Earth and Planetary Science Letters, 1998, 163 : 361-379. DOI:10.1016/S0012-821X(98)00142-3 |
| [67] | Tatsumi Y. Making Continental Crust:The Sanuki-toid Connection[J]. Chinese Science Bulletin, 2008, 53 (11) : 1620-1633. |
| [68] | 尹继元, 袁超, 孙敏, 等. 新疆哈图早二叠世富镁闪长岩的Ar-Ar年代学, 地球化学特征, 及其与铜金矿化的关系[J]. 岩石学报, 2012, 28 (7) : 2171-2184. Yin Jiyuan, Yuan Chao, Sun Min, et al. Age, Geochemical Features and Possible Petrogenesis Mechanism of Early Permian Magnesian Diorite in Hatu, Xinjiang[J]. Acta Petrologica Sinica, 2012, 28 (7) : 2171-2184. |
| [69] | Cole R B, Stewart B W. Continental Margin Volca-nism at Sites of Spreading Ridge Subduction:Examples from Southern Alaska and Western California[J]. Tectonophysics, 2009, 464 (1/2/3/4) : 118-136. |
| [70] | Thorkelson D J. Subduction of Diverging Plates and the Principles of Slab Window Formation[J]. Tectonophysics, 1996, 255 : 47-63. DOI:10.1016/0040-1951(95)00106-9 |
| [71] | Kay S M, Ramos V A, Marquez M. Evidence in Cerro Pampa Volcanic Rocks for Slab-Melting Prior to Ridge-Trench Collision in Southern South America[J]. Journal of Geology, 1993, 101 : 703-714. DOI:10.1086/648269 |
| [72] | Yogodzinski G M, Lees J M, Churikova T G, et al. Geochemical Evidence for the Melting of Subducting Oceanic Lithosphere at Plate Edges[J]. Nature, 2001, 409 : 500-504. DOI:10.1038/35054039 |
| [73] | Viruete J E, Contreras F, Stein G, et al. Magmatic Relationships and Ages Between Adakites, Magnesian Andesites and Nb-Enriched Basalt-Andesites from Hispaniola:Record of a Major Change in the Caribbean Island Arc Magma Sources[J]. Lithos, 2007, 99 : 151-177. DOI:10.1016/j.lithos.2007.01.008 |
| [74] | Sun W D, Bennett V C, Eggins S M, et al. Rhenium Systematics in Submarine MORB and Back-Arc Basin Glasses:Laser Ablation ICP-MS Results[J]. Chemical Geology, 2003, 196 : 259-281. DOI:10.1016/S0009-2541(02)00416-3 |
| [75] | Hofmann A W. Chemcial Differentiation of the Ear-th:The Relationship Between Mantle, Oceanic Crust and Continental Crust[J]. Earth and Planetary Science Letters, 1988, 90 : 297-314. DOI:10.1016/0012-821X(88)90132-X |
| [76] | McDonough W F, Sun S S. The Composition of the Earth[J]. Chemical Geology, 1995, 120 : 223-253. DOI:10.1016/0009-2541(94)00140-4 |
| [77] | Rudnick R L, Gao S.Composition of the Continental Crust[C]//Heinrich D H, Turekian K K.Treatise on Geochemistry.Oxford:Pergamon, 2003:1-64. |
| [78] | Sun W D, Ling M X, Chung S L, et al. The Genetic Association of Adakites and Cu-Au Ore Deposits[J]. International Geology Review, 2011, 53 (5/6) : 691-703. |