Geochemical Characteristics and LA-ICP-MS Zircon U-Pb Age of the Azhalang Intrusion in Sumdo, Southern Tibet
-
摘要: 阿扎朗岩体位于冈底斯岩浆弧中东部的松多地区.岩体的锆石U-Pb定年和全岩地球化学分析结果表明,阿扎朗岩体岩性为石英二长斑岩,形成时代为中新世(17.9±0.2 Ma),地球化学上表现高Sr(1 052×10-6~1 150×10-6)、低Y(8.51×10-6~9.04×10-6)和Yb(0.85×10-6~0.94×10-6),高的Sr/Y(118~128)和La/Yb(30.9~40.8)比值,无明显的Eu异常,同时具有较高的K2O(3.17%~3.84%)含量和较低的Cr(6.46×10-6~7.78×10-6)和Ni(5.41×10-6~7.45×10-6)含量,较高的Rb/Sr比值,较高的Mg#值(43.8~49.8),大离子亲石元素的含量,如Rb、Ba、Th和U明显比LREE高.这些地球化学特征表明其岩石成因可能为增厚的下地壳部分熔融形成,形成于印度-欧亚大陆碰撞造山的后碰撞构造背景下,可能有一定的幔源物质参与.该研究为揭示冈底斯成矿带中新世埃达克岩的成因及成矿地质背景提供重要的制约.Abstract: The Azhalang pluton is located in the Sumdo area in the east-central part of the Gangdise magmatic arc. Zircon U-Pb dating and geochemical analysis of the whole rock indicate that the Azhalang intrusion is quartz monzonite porphyry and the formation period is Miocene (17.9±0.2 Ma). Geochemical characteristics show high Sr (1 052×10-6-1 150×10-6), low Y (8.51×10-6-9.04×10-6) and Yb (0.85×10-6-0.94×10-6), high Sr/Y (118-128) and La/Yb (30.9-40.8) ratios, no obvious Eu anomalies, high K2O (3.17%-3.84%) content, low Cr (6.46×10-6-7.78×10-6) and Ni (5.41×10-6-7.45×10-6) content, high Mg# value (43.8-49.8), high Rb/Sr ratio, large ion lithophile element content, such as Rb, Rb, Rb. Ba, Th and U were significantly higher than LREE.These geochemical characteristics indicate that the petrogenesis of the rocks may be formed by partial melting of the thicker lower crust and formed in the post-collisional tectonic setting of the India-Eurasia collision orogeny, and some mantle-derived materials may be involved.This study provides important constraints for revealing the genesis and metallogenic geological setting of the Miocene adakite in the Gangdise metallogenic belt.
-
Key words:
- Tibetan Plateau /
- Cenozoic /
- adakite /
- geochemistry
-
0. 引言
冈底斯-喜马拉雅成矿带是我国重要的铜矿资源基地,在该成矿带内分布着众多的中新世斑岩体及斑岩型铜钼矿床(图 1a).这些斑岩体(曲晓明等,2001;侯增谦等, 2004;Qu et al., 2004)具有典型的埃达克岩地球化学特征,与印度大陆和欧亚大陆的碰撞活动密切相关,但其岩石成因仍存在较大的争议.目前主要有以下几种观点:(1)俯冲的新特提斯洋壳的部分熔融(Qu et al., 2004;胡永斌,2015);(2)加厚或拆沉的下地壳的部分熔融(Chung et al., 2009;Li et al., 2011;孟元库等,2018);(3)被板片来源熔体所交代的上地幔的部分熔融(Gao et al., 2010);(4)俯冲的印度下陆壳部分熔融(Xu et al., 2010).前人先后对驱龙、甲玛、冲江、厅宫、岗讲、拉抗俄等斑岩型铜钼矿床的斑岩体进行了详细的研究(林武等,2004;郑有业等,2012;Chen et al., 2014;冷秋锋等,2016;杨震等,2017;孟元库等,2018),其研究主要集中在该时期含矿斑岩体及其成矿意义等方面,对非含矿斑岩体的研究相对较少.为了揭示冈底斯成矿带中新世埃达克岩的成因,为成矿地质背景提供制约,本文以冈底斯成矿带上松多地区阿扎朗岩体为研究对象,以详细的野外地质调查为基础,通过岩石学、同位素年代学和地球化学等方面的研究,探讨阿扎朗岩体岩石成因及构造背景.
图 1 西藏冈底斯东段中新世斑岩体及斑岩型矿床分布简图及研究区阿扎朗岩体地质简图据秦克章等(2008)修改;图a中:LSSZ.龙木措-双湖-澜沧江板块缝合带;BNSZ.班公湖-怒江板块缝合带;JSSZ.西金乌兰-金沙江板块缝合带,IYZSZ.印度河-雅鲁藏布江板块缝合带;图c中:1.中新世达弄多组;2.早侏罗世叶巴组;3.中新世石英二长斑岩;4.中新世二长花岗岩;5.中新世石英斑岩;6.早侏罗世二长花岗岩;7.早侏罗世花岗闪长岩;8.推测断层;9.角岩化带;10.铜钼矿床(点);11.钼矿化点;12.采样位置Fig. 1. The simplified distribution map of Miocene porphyry and porphyry deposits of eastern Gangdise and simplified geological map of Azhalang pluton in researched area, Tibet1. 地质概况
研究区位于西藏松多地区阿扎朗一带,大地构造位置位于班公湖-怒江缝合带和雅鲁藏布江缝合带之间的拉萨地块之上(图 1a).研究区出露的地层主要为下侏罗统叶巴组(J1y)和中新统达弄多组(N1d).叶巴组(J1y)火山岩岩性主要以流纹岩、英安岩以及英安质凝灰岩为主,形成时代为早侏罗世(Wei et al., 2017);中新统达弄多组(N1d)火山岩岩性主要为流纹岩、安山岩以及流纹质含角砾凝灰岩.研究区内岩浆活动剧烈,可进一步厘定出早侏罗世岩浆岩和中新世岩浆岩两期,其中早侏罗世岩浆岩分布于研究区的东南和东北两个角落,岩性以花岗闪长岩和二长花岗岩为主,中新世岩浆岩出露规模较小,以两个小岩株形式侵入于叶巴组(J1y)之中,主要分布于研究区的中部,岩性以石英二长斑岩、石英斑岩和似斑状花岗岩为主(图 1c),并伴生有多个铜钼矿床(点).本次研究的阿扎朗岩体就出露在早侏罗世叶巴组(J1y)的流纹质含角砾凝灰岩中.
2. 岩相学特征
阿扎朗岩体岩性主要为石英二长斑岩,岩体呈近北东向展布,延伸超过2 km,宽约1 km,围岩为叶巴组(J1y)的英安质晶屑凝灰岩,岩体与围岩为侵入接触关系.实验样品均采自新鲜岩体.其岩相学特征如下:新鲜面为浅灰色,风化面为灰白色,斑状结构,块状构造(图 2a,2b),斑晶主要为正长石、斜长石、石英和少量的角闪石,基质为隐晶质(图 2d).正长石:半自形板状,粒度在0.5~1.0 mm之间,可见有卡式双晶,含量约5%~10%;斜长石:半自形-自形板柱状,粒度在0.5~1.5 mm之间,可见有聚片双晶,含量约10%~20%,石英:半自形粒状,普遍具有波状消光,粒度在0.5~1.5 mm之间,含量约5%;角闪石:半自形-自形长柱状,粒度在0.3~ 1.0 mm之间,两组斜交解理明显,部分绿泥石化(图 2c),含量约2%.
3. 分析方法
3.1 LA-ICP-MS锆石U-Pb定年
本文用于锆石年龄测定样品均采自新鲜岩体露头,送至河北省廊坊市宇能岩石矿物分选技术服务有限公司粉碎并应用重选、磁选和重液分异等方法对石英二长斑岩样品进行锆石的分选,在双目镜下挑选出干净的锆石单矿物,挑选出来的锆石颗粒安装在环氧树脂盘中.样品制靶(d=2.5 cm)在北京凯德正科技有限公司进行,并打磨样品靶,然后抛光.锆石透射光和反射光的拍摄在中国地质科学院地质研究所的阴极发光设备上完成.锆石U-Pb年龄测定在国土资源部东北亚矿产资源评价重点实验室的激光等离子体质谱仪(LA-ICP-MS)完成,仪器主要由Agilent7500a型四级杆等离子体质谱仪和193 nm激光剥蚀进样系统UP 193SS构成的,以He作为载气,锆石斑束直径为36 μm,选取Nist610和91500作为标样,对测试结果进行数据处理和铅校正.数据处理应用Iso-plot3.0和Glitter(version4.4)软件,铅校正方法见Andersen(2002).
3.2 岩石地球化学测试
本次用于全岩地球化学测试分析的样品共5件,为保证测试分析的准确性与实验结果的可靠性,所有用于全岩地球化学测试分析的样品均采自新鲜的岩体露头,室内进行去除风化面处理,同时剔除样品中的包体、杏仁体以及石英脉等影响实验结果可靠性的杂质.在河北省廊坊市宇能岩石矿物分选技术服务有限公司的无污染实验室先用浓度小于5%的稀硝酸处理,之后用去离子水清洗,将处理完的样品进行干燥,然后放入无污染玛瑙球磨机粉碎至200目.最后将粉碎的样品送到中国地质大学(北京)地质过程与矿产资源国家重点实验室用于全岩地球化学主微量元素分析.其中在等离子体发射光谱仪(ICP-OEC)实验里进行全岩地球化学主量元素分析,等离子体光谱仪型号为PS-950.应用ICP-MS测试方法在Agilent-7500a电感耦合等离子质谱仪上进行微量元素测试分析,实验过程中的参考样品均采用国际标准AGV-2和GSR-3进行校对,具体实验细节参见于红(2011).
4. 测试结果
4.1 锆石LA-ICP-MS U-Pb年代学
用于锆石年龄测试的石英二长斑岩样品在阴极发光图像中的锆石形态主要为短柱状,少数为长柱状,自形程度较好,长约80~120 μm,长宽比为1:1至1:2,具有明显的岩浆振荡生长环带结构,晶面发育(图 3a),符合岩浆型锆石特点.在锆石球粒陨石标准化图解中(图 3b),锆石稀土元素配分曲线呈现明显的左倾,轻、重稀土元素分异明显,具有典型的岩浆锆石稀土元素特征,锆石稀土元素测试结果见表 1.本文对S17T26样品选取10个点进行测试分析,锆石U-Pb同位素分析数据见表 2.分析测试结果显示,Th的含量为(367~1 940)×10-6,U的含量为(357~1 234)×10-6,Th/U为0.87~2.96,具有岩浆锆石特征.10个锆石测点的206Pb/238U年龄在17.6~18.0 Ma之间,年龄加权平均值为17.9± 0.2 Ma(MSWD=0.16)(图 3a),为中新世.
表 1 阿扎朗岩体石英二长岩锆石稀土元素(10-6)分析结果Table Supplementary Table Analytical results of the quartz-monzonite porphyry zircon REE elements(10-6)of Azhalang pluton点号 La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu S17T26-01 0.19 24.83 0.09 0.66 1.72 0.57 2.96 2.15 24.28 10.30 48.74 13.59 168.82 29.78 S17T26-02 0.07 60.52 0.29 5.72 10.02 4.01 20.10 9.88 97.31 32.68 134.02 30.50 340.36 52.03 S17T26-03 4.24 42.01 1.19 7.17 2.73 1.02 8.13 4.03 49.47 20.48 93.88 24.27 296.07 51.27 S17T26-04 0.09 28.21 0.07 1.21 2.00 0.60 4.60 3.01 33.18 13.02 62.77 16.49 201.88 35.98 S17T26-05 0.58 59.38 0.23 1.64 3.18 1.34 8.79 5.62 66.42 25.92 124.96 32.34 394.41 67.86 S17T26-06 4.97 64.73 1.44 8.23 4.07 1.47 12.51 5.58 63.71 24.74 114.93 29.28 351.50 61.09 S17T26-07 0.11 33.98 0.04 0.45 1.74 0.81 5.12 3.78 49.38 22.23 115.22 31.08 406.98 74.39 S17T26-08 0.08 34.19 0.04 0.89 1.72 0.71 5.31 3.37 39.92 15.99 77.89 19.96 243.98 42.01 S17T26-09 0.53 24.98 0.17 1.37 1.73 0.59 3.37 2.13 26.88 11.11 55.72 15.54 200.60 37.26 S17T26-10 0.11 28.93 0.04 0.71 2.09 0.77 4.32 2.96 35.54 14.61 76.40 20.03 249.53 45.64 表 2 阿扎朗岩体LA-ICP-MS锆石U-Pb定年结果Table Supplementary Table LA-ICP-MS zircon U-Pb dating results of Azhalang pluton样品及测点 Th(10-6) U(10-6) Th/U 207Pb/235U 1σ 206Pb/238U 1σ 207Pb/235U (Ma) 1σ (Ma) 206Pb/238U (Ma) 1σ (Ma) NEST610 450.9 457.1 0.1 25.262 0.344 59 0.204 73 0.002 85 3 318.5 13 1 201.3 15.0 91500 20.5 58.0 0.4 1.850 20 0.039 81 0.179 20 0.002 67 1 064.2 14 1 063.5 15.0 Ple 43.4 480 0.1 0.408 20 0.007 57 0.055 09 0.000 78 348.2 5.0 346.1 5.0 S17T26-01 367.4 357.1 1.0 0.017 65 0.001 62 0.002 76 0.000 05 17.8 1.6 17.8 0.3 S17T26-02 1 087.9 367.7 3.0 0.017 68 0.001 96 0.002 77 0.000 07 17.8 2.0 17.8 0.4 S17T26-03 458.9 497.23 1.0 0.017 72 0.002 25 0.002 78 0.000 05 17.8 2.3 17.9 0.3 S17T26-04 442.2 407.5 1.1 0.017 81 0.001 38 0.002 79 0.000 06 17.9 1.4 18.0 0.4 S17T26-05 1 940.2 1 230.3 1.6 0.017 94 0.001 06 0.002 80 0.000 04 18.1 1.1 18.0 0.2 NEST610 20.0 58.3 0.3 1.850 2 0.037 69 0.179 20 0.002 65 1 064.2 13.0 1 063.4 14.0 S17T26-06 1 345.3 1 034.6 1.3 0.018 54 0.001 35 0.002 78 0.000 04 18.7 1.4 17.9 0.2 S17T26-07 539.0 620.0 0.9 0.017 48 0.001 28 0.002 73 0.000 05 17.6 1.3 17.6 0.3 S17T26-08 467.3 466.9 1.0 0.017 80 0.001 37 0.002 79 0.000 05 17.9 1.4 17.9 0.3 S17T26-09 390.8 429.5 0.9 0.017 80 0.001 58 0.002 78 0.000 06 17.9 1.6 17.9 0.4 S17T26-10 396.9 375.9 1.1 0.017 53 0.003 90 0.002 74 0.000 06 17.6 3.9 17.7 0.4 NEST610 20.5 58.6 0.3 1.850 20 0.041 44 0.179 20 0.002 70 1 064.2 15.0 1 063.5 15.0 91500 450.9 457.1 1.0 25.300 0.348 08 0.201 43 0.002 81 3 320.3 13.0 1 183.4 15.0 4.2 岩石地球化学测试
4.2.1 主量元素
阿扎朗岩体5个样品的主量元素分析结果(表 3)显示SiO2含量为58.2%~63.8%,Na2O含量为5.44%~6.18%,K2O含量为3.17%~3.84%,具有较高的Al2O3含量(17.8%~21.0%)、低的MgO含量(1.35%~1.52%)和较低的Mg#值(43.8~49.8).在SiO2-(Na2O+K2O)图解中样品主要落入二长岩和石英二长岩区域(图 4a).SiO2-K2O图解中,样品分布在高钾钙碱性系列-钾玄岩系列中(图 4b).具有较低的A/CNK(0.89~0.98)值,均小于1.0,属于准铝质系列.
表 3 阿扎朗岩体主量元素(%)和微量元素(10-6)分析结果Table Supplementary Table Analytical results of major (%) and trace elements (10-6) for Azhalang pluton样品 S17T26H1 S17T26H2 S17T26H3 S17T26H4 S17T26H5 R1 AGV-2 GSR-1 GSR-3 SiO2 59.4 62.9 57.3 59.2 62.7 73.5 TiO2 0.5 0.5 0.5 0.5 0.4 0.3 Al2O3 19.9 17.6 20.7 19.9 18.5 12.6 TFe2O3 3.6 3.4 4.5 3.5 3.2 2.1 MnO 0.1 0.1 0.1 0.1 0.1 0.1 MgO 1.5 1.4 1.5 1.5 1.3 0.4 CaO 3.7 4.0 4.0 3.7 3.6 1.5 Na2O 6.1 5.5 6.1 5.7 5.4 3.0 K2O 3.3 3.3 3.7 3.8 3.1 5.3 P2O5 0.3 0.2 0.3 0.3 0.2 0.1 LOI 1.2 0.8 1.0 1.4 0.9 0.70 Total 99.5 99.4 99.5 99.5 99.4 TFeO 3.3 3.1 4.1 3.2 2.9 Mg# 49.3 48.6 43.8 49.8 49.3 A/CNK 1.0 0.9 1.0 1.0 1.0 Li 32.7 29.7 36.3 37.7 24.0 10.7 130.0 10.4 P 1 009.8 811.2 1 114.0 997.2 677.2 2 162.0 400.8 4 290.0 K 22 920.0 22 140.0 25 240.0 25 900.0 20 700.0 24 160.0 41 200.0 19 766.0 Sc 3.8 3.6 4.0 4.1 3.5 12.1 6.0 14.1 Ti 2 624.0 2 478.0 2 536.0 2 602.0 2 270.0 6 252.0 1 752.8 14 858.0 V 62.5 55.7 62.5 60.5 50.9 125.8 24.5 187.6 Cr 7.2 6.5 7.8 6.7 6.5 17.0 3.8 133.5 Mn 527.6 468.2 553.4 520.2 416.6 757.2 467.4 1 426.4 Co 7.7 6.8 8.1 7.4 6.0 16.4 3.1 45.1 Ni 6.8 6.3 7.4 6.6 5.4 19.4 2.3 147.0 Cu 20.8 13.8 14.3 17.1 23.5 52.9 3.0 50.0 Zn 57.0 57.1 56.0 56.7 50.6 91.5 30.6 154.2 Ga 23.0 20.7 23.0 22.3 20.0 20.4 19.8 25.0 Rb 96.2 87.8 105.0 112.8 94.5 74.4 489.6 37.4 Sr 1 125.0 1 060.7 1 052.1 1 149.8 1 070.8 686.4 106.7 1 122.0 Y 9.0 9.0 8.7 9.0 8.5 19.0 63.9 21.6 Zr 143.6 132.7 158.2 160.8 120.2 234.4 171.7 295.0 Nb 7.8 7.7 7.6 7.8 6.9 15.6 42.6 90.8 Cs 3.2 2.8 3.3 3.9 3.0 1.1 41.6 0.7 Ba 1 127.5 1 223.0 1 112.5 1 210.0 1 163.4 1 044.8 351.4 531.6 La 36.7 29.1 26.3 30.8 29.4 38.5 53.5 57.4 Ce 71.6 57.3 54.9 63.0 58.3 73.5 108.3 108.0 Pr 7.5 6.7 6.1 6.8 6.7 8.5 12.5 12.8 Nd 25.7 24.5 21.5 23.9 24.2 31.7 44.5 51.3 Sm 4.0 4.0 3.5 3.9 4.0 5.8 9.8 10.3 Eu 0.9 1.0 0.9 0.9 1.0 1.6 0.8 3.2 Gd 2.8 2.9 2.5 2.7 2.8 5.0 9.2 9.1 Tb 0.3 0.3 0.3 0.3 0.3 0.6 1.5 1.1 Dy 1.8 1.8 1.6 1.7 1.8 3.6 10.1 5.6 Ho 0.3 0.3 0.3 0.3 0.3 0.7 2.1 0.9 Er 0.9 0.9 0.8 0.9 0.9 1.8 6.4 1.9 Tm 0.1 0.1 0.1 0.1 0.1 0.3 1.1 0.3 Yb 0.9 0.9 0.9 0.9 0.9 1.7 7.5 1.4 Lu 0.1 0.1 0.1 0.1 0.1 0.3 1.2 0.2 Hf 3.5 3.2 3.7 3.6 2.9 4.7 6.1 6.4 Ta 0.4 0.4 0.5 0.5 0.5 0.9 7.3 4.3 Pb 42.0 43.1 39.2 43.2 43.5 12.5 35.7 6.5 Th 17.9 17.1 15.0 17.0 17.6 6.0 54.8 5.9 U 3.6 3.8 2.7 3.8 3.1 1.9 19.1 1.4 Eu/Eu* 0.9 0.9 0.9 0.9 0.9 Sr/Y 124.0 118.0 122.0 128.0 126.0 图 4 阿扎朗岩浆岩主微量判别图解a. (Na2O+K2O)-SiO2图解,据Middlemost(1994);b. SiO2-K2O图解,据Peccerillo and Taylor(1976);c. (La/Yb)N-(Yb);d. Sr/Y-Y图解,据Drummond and Defant(1990)Fig. 4. Distinction diagrams of primary and trace elements of Azhalang magmatite4.2.2 微量元素
微量元素分析结果(表 3)显示稀土元素含量(ΣREE)较高,变化范围为(400~505)×10-6,Eu/Eu*=0.86~0.89,无明显的Eu异常,轻稀土元素富集,轻、重稀土元素之间分馏明显,总体呈右倾的稀土配分模式(图 5a).在原始地幔标准化蛛网图上,岩石相对富集Rb、Th、U、K、Pb等大离子亲石元素(LILE),亏损Nb、Ta、P、Ti等高场强元素(HFSE)(图 5b).
5. 讨论
5.1 岩石成因
岩石地球化学特征表明,阿扎朗岩体石英二长斑岩具有富SiO2(58.2%~63.8%)、高Al2O3(17.8%~21.0%)、高Sr(1 052×10-6~1 150×10-6),低Y(8.51×10-6~9.04×10-6)、Yb(0.85×10-6~0.94×10-6),高的Sr/Y(118~128)和La/Yb(30.9~40.8)比值,Eu/Eu*=0.86~0.89,无明显的Eu异常.与典型的埃达克岩特征(Drummond and Defant, 1990)一致,同时在埃达克岩判别图解中,样品全部落在埃达克岩区域内(图 4c,4d).
研究初始,埃达克岩被认为是年轻的洋壳俯冲部分熔融形成的,随着研究的不断深入,研究者提出埃达克岩的岩石成因模式主要有以下3种:(1)俯冲的玄武质洋壳部分熔融形成(Drummond and Defant, 1990;Wu et al., 2015);(2)高压下玄武质岩浆结晶分异和同化混染作用(AFC)(Castillo et al., 1999;Kadioglu and Dilek, 2010);(3)高温下镁铁质下地壳部分熔融(拆沉或加厚的下地壳部分熔融)(Atherton and Petford, 1993;Kadioglu and Dilek, 2010;Long et al., 2015).
一般起源于地幔的埃达克岩多为中性岩,但往往伴随着大面积出露的基性-超基性岩石(Whalen,1985),而研究区在同时期基本未见基性岩如玄武岩等出露.Rapp et al.(1999)认为高压下玄武质岩浆结晶分异和同化混染形成的埃达克岩多为高镁安山岩,其Mg#值一般大于60(Yogodzinski et al., 1994;Zhang et al., 2010),而阿扎朗石英二长斑岩Mg# < 50,同时较低的Cr、Ni含量也不同于幔源成因的埃达克岩(Rapp and Watson, 1995;Wu et al., 2015).高压下基性岩浆通过角闪石和石榴子石分离结晶也会产生埃达克岩,这种埃达克岩一般具有较高的Sr/Y和Dy/Yb值,同时具有明显的随着SiO2的增加Sr/Y、Dy/Yb值逐渐增大的趋势(Tang et al., 2010),而本文阿扎朗岩体埃达克质岩虽然具有高的Sr/Y和Dy/Yb值,但与SiO2无明显的线性关系(图 6a,6b).所以无论从地化特征还是岩性来看研究区的中新世阿扎朗岩体的埃达克质岩石不同于地幔成因的埃达克岩.因此首先排除高压下玄武质岩浆结晶分异和同化混染作用成因模式的可能性.
图 6 中新世埃达克岩判别图解a. SiO2-Sr/Y;b. SiO2-Dy/Yb图解(Castillo et al., 1999);c. La/Ce-Rb/Sr;d. Nb/U-Rb/Sr图解,据侯增谦等(2004),Cook岛弧埃达克岩数据引自Stern and Kilian(1996),新生代埃达克岩(n=140)、埃达克岩和高铝TTG(n=394)和太古宙高铝TTG(n=174)数据引自Drummond et al.(1996)Fig. 6. Distinction diagrams of Miocene adakite排除了其是高压下玄武质岩浆结晶分异和同化混染作用成因模式的可能性,那么该岩体究竟为俯冲的玄武质洋壳部分熔融形成还是高温下镁铁质下地壳部分熔融(拆沉或加厚的下地壳部分熔融)?依据如下几点,笔者认为阿扎朗岩体的埃达克质岩成因为加厚的下地壳部分熔融.(1)阿扎朗岩体的石英二长斑岩具有较高K2O(3.17%~3.84%)含量,在K2O-SiO2图解中样品位于高钾钙碱性-钾玄岩系列中(图 4b),与起源地壳的高钾-钙碱性系列埃达克岩相似.同时强不相容元素的含量,如Rb、Ba、Th和U明显比LREE高(图 5b),具有高的Th/La和Th含量,明显不同于洋壳板片部分熔融形成的埃达克岩(一般具有较低的K2O含量,较高的Cr和Ni含量,强不相容元素低于或相近于LREE,较低的Th/La比值和Th含量)(Wang et al., 2006;Ma et al., 2013);(2)阿扎朗岩体样品的Rb/Sr比值在埃达克岩和高铝TTG岩石组合与太古宙高铝TTG岩石组合之间,在La/Ce-Rb/Sr和Nb/U-Rb/Sr两类图解中更加倾向于下地壳成因的埃达克岩(图 6c,6d);(3)由俯冲洋壳形成的埃达克岩在上升过程中有地幔物质的加入会导致岩石Cr和Ni的含量升高.阿扎朗岩体的Cr(6.46×10-6~7.78×10-6)和Ni(5.41×10-6~7.45×10-6)含量远小于洋壳衍生的埃达克质岩石(Wang et al., 2006),与下地壳形成的埃达克岩相似;(4)在SiO2-主微量元素图解中,本文样品均落入增厚下地壳成因埃达克岩区域内(图 7),与区域内同时期增厚新生下地壳熔融的埃达克岩显示了相似的特点(夏抱本等,2007).同时在Mg#-SiO2图解中也位于增厚下地壳部分熔融形成的埃达克岩区域内(图 8b).
图 7 SiO2-主微量元素埃达克岩判别图解a.SiO2-Ni;b.SiO2-Cr;c.SiO2-MgO;d.SiO2-TFeO/MgO图解,据Wang et al.(2006)Fig. 7. Distinction diagrams of SiO2-primary and trace elements of adakite图 8 中新世埃达克岩源区判别图解a. Th/Yb-Th/Sm,据Zhu et al.(2009);b. SiO2-Mg#图解,据Wang et al.(2006)Fig. 8. Distinction diagrams of Miocene adakite source region5.2 源区性质
阿扎朗岩体埃达克质岩在原始地幔标准化蛛网图上亏损Nb、Ta和Ti等高场强元素,表明基性下地壳部分熔融过程中,残留大量金红石等含钛矿物(侯增谦等, 2004);无明显的Eu异常,说明源区基本无斜长石残留.岩石具有较低的HREE、Y和Yb,较高的Sr,暗示源区有角闪石和石榴子石残留,而残留的石榴子石只有在1 GPa条件以上才会出现在熔体中,大于1.2 GPa(相当于地壳40~50 km深度)条件下才可以和熔体处于平衡状态(Rapp and Waston, 1995).同时地球物理研究表明,冈底斯板块在中新世时期的地壳厚度大约在70~80 km(Atherton and Petford, 1993),表明阿扎朗岩体埃达克质岩的岩浆源区深度大于40 km.
侯增谦等(2006)发现藏南冈底斯中新世埃达克质斑岩由来自深部亏损地幔物质与下地壳物质发生交换作用,导致冈底斯地壳加厚、下地壳熔融形成.而由加厚下地壳熔融形成的熔体一般Mg# < 40(Rapp and Waston, 1995),地幔物质的加入会导致埃达克岩Mg#值增大(Martin, 1999),而本文研究样品具有较高的Mg#值(43.8~49.8),说明可能存在一定的幔源物质参与,具有壳幔混源特征.
5.3 构造背景
本文通过锆石CL图像分析和锆石U-Pb定年发现,阿扎朗岩体中的石英二长斑岩成岩年龄为17.87±0.19 Ma,形成时代为中新世.阿扎朗岩体的形成年龄与冈底斯成矿带的驱龙矿床斑岩体(LA-ICP-MS锆石U-Pb年龄17.21±0.52 Ma、15.7± 0.2 Ma;郑有业等,2012;Lu et al., 2017)、吉如矿床二长花岗斑岩(SHRIMP锆石U-Pb年龄16.0± 0.4 Ma;Zheng et al., 2014)、马攸木花岗闪长斑岩(Ar-Ar黑云母年龄17.68±0.15 Ma;江思宏等,2006)、知不拉花岗闪长岩(SHRIMP锆石U-Pb年龄16.9±0.3 Ma;Xu et al., 2016)和二长花岗岩(SHRIMP锆石U-Pb年龄17.0±0.2 Ma;Xu et al., 2016)、甲玛矿床花岗斑岩(LA-ICP-MS锆石U-Pb年龄16.7±0.3 Ma;孟元库等,2018)年龄基本一致.同时冈底斯成矿带上的中新世侵入岩多为含矿斑岩体,这些斑岩体与斑岩型铜钼矿床的形成密切相关,少部分为不含矿岩体,形成时代主要集中在12~ 20 Ma(表 4),可能为同一岩浆活动事件的产物.
表 4 冈底斯成矿带中新世岩浆岩形成时代Table Supplementary Table Age of Miocene magmatic rocks of Gangdise metallogenic belt地区 岩性 测试方法 测试对象 年龄(Ma) 资料来源 驱龙 斑状花岗闪长岩 LA-ICP-MS U-Pb 锆石 17.2±0.5 郑有业等,2012 驱龙 高镁闪长斑岩 LA-ICP-MS U-Pb 锆石 15.7±0.2 Lu et al., 2017 冲江 花岗闪长斑岩 SHRIMP U-Pb 锆石 12.9±0.3 林武等,2004 吉如 二长花岗斑岩 SHRIMP U-Pb 锆石 16.0±0.4 Zheng et al., 2014 厅宫 二长斑岩 LA-ICP-MS U-Pb 锆石 15.5±0.3 Chen et al., 2014 厅宫 闪长斑岩 LA-ICP-MS U-Pb 锆石 15.0±0.2 Chen et al., 2014 马攸木 花岗闪长斑岩 Ar- Ar 黑云母 17.7±0.15 江思宏等,2006 知不拉 花岗闪长岩 SHRIMP U-Pb 锆石 16.9±0.3 Xu et al., 2016 知不拉 二长花岗岩 SHRIMP U-Pb 锆石 17.0±0.2 Xu et al., 2016 岗讲 花岗闪长斑岩 LA-ICP-MS U-Pb 锆石 16.6±0.3 杨震等,2017 甲玛 花岗斑岩 LA-ICP-MS U-Pb 锆石 16.7±0.3 孟元库等,2018 甲玛 花岗闪长斑岩 LA-ICP-MS U-Pb 锆石 14.4±0.3 孟元库等,2018 达布 花岗闪长斑岩 LA-ICP-MS U-Pb 锆石 16.5±0.3 李世杰等,2018 拉抗俄 花岗闪长斑岩 LA-ICP-MS U-Pb 锆石 13.6±0.4 冷秋锋等,2016 汤不拉 花岗斑岩 LA-ICP-MS U-Pb 锆石 19.7±0.2 王保弟等,2010 朱诺 黑云母花岗闪长岩 LA-ICP-MS U-Pb 锆石 14.1±0.3 黄勇等,2015 阿扎朗 石英二长斑岩 LA-ICP-MS U-Pb 锆石 17.9±0.2 本文 关于这期岩浆岩的成因,目前争议较大,研究者提出以下4种成因模式:(1)俯冲的新特提斯洋壳的部分熔融(Qu et al., 2004;胡永斌,2015);(2)加厚或拆沉的下地壳的部分熔融(Chung et al., 2009;Li et al., 2011;孟元库等,2018);(3)被板片来源熔体所交代的上地幔的部分熔融(Gao et al., 2010);(4)俯冲的印度下陆壳部分熔融(Xu et al., 2010).笔者结合本文的研究及区域上的相关资料,认为该期岩浆为印度大陆与欧亚大陆碰撞造山活动的产物.
冈底斯成矿带内发育着大面积、小体积的钾质-超钾质岩,其东西长约1 000 km,断续分布,形成时代集中在10~25 Ma(侯增谦等, 2004).同时根据侯增谦等(2006)对碰撞造山过程的划分标志,在25 Ma左右,印度大陆与欧亚大陆碰撞造山过程已经进入了后碰撞阶段.阿扎朗埃达克质岩在Th/Ce-Th图解和Th/Yb-Th/Sm图解中,样品投点均落在后碰撞埃达克岩区域内(图 8a,9a);在Pearce et al.(1984)提出的Rb-Y+Nb图解中样品投点落在后碰撞花岗岩中(图 9b);在R1-R2构造判别图解中,样品投点主要落在造山晚期花岗岩中(图 10).综上所述,笔者认为阿扎朗岩体可能形成于印度大陆与欧亚大陆碰撞的后碰撞阶段.
图 9 中新世埃达克质岩构造环境判别图解a. Th-Th/Ce图解,据Wang et al.(2006);b. Rb-Y+Nb图解,据Pearce et al.(1984);ORG.大洋脊花岗岩;WPG.板内花岗岩;VAG.火山弧花岗岩;syn-COLG.同碰撞花岗岩;post-COLG.后碰撞花岗岩Fig. 9. Distinction diagrams of Miocene adakite tectonic setting图 10 中酸性侵入岩的R1-R2构造判别图解R1=4Si-11(Na+K)-2(Fe+Ti), R2=6Ca+2Mg+Al; 据Batchelor and Bowden (1985)Fig. 10. R1-R2 diagram intermediate-acid intrusive rocks6. 结论
(1)阿扎朗岩体岩性为石英二长斑岩,锆石U-Pb年龄为17.9±0.2 Ma,为中新世.
(2)阿扎朗岩体具有典型的埃达克质岩地球化学特征,为增厚的下地壳部分熔融成因,源区可能有一定幔源物质的加入.
(3)结合冈底斯成矿带的钾质-超钾质岩浆活动、地球化学特征综合研究,笔者认为阿扎朗岩体可能形成于印度大陆与欧亚大陆碰撞的后碰撞阶段.
致谢: 岩石地球化学测试得到了中国地质大学(北京)地质过程与矿产资源国家重点实验室相关工作人员的热心帮助;野外工作和文章撰写得到吉林大学范建军副教授、曾孝文、王斌、罗安波硕士的帮助,同时两位审稿人对本文提出了宝贵意见,在此一并致谢!
-
图 1 西藏冈底斯东段中新世斑岩体及斑岩型矿床分布简图及研究区阿扎朗岩体地质简图
据秦克章等(2008)修改;图a中:LSSZ.龙木措-双湖-澜沧江板块缝合带;BNSZ.班公湖-怒江板块缝合带;JSSZ.西金乌兰-金沙江板块缝合带,IYZSZ.印度河-雅鲁藏布江板块缝合带;图c中:1.中新世达弄多组;2.早侏罗世叶巴组;3.中新世石英二长斑岩;4.中新世二长花岗岩;5.中新世石英斑岩;6.早侏罗世二长花岗岩;7.早侏罗世花岗闪长岩;8.推测断层;9.角岩化带;10.铜钼矿床(点);11.钼矿化点;12.采样位置
Fig. 1. The simplified distribution map of Miocene porphyry and porphyry deposits of eastern Gangdise and simplified geological map of Azhalang pluton in researched area, Tibet
图 4 阿扎朗岩浆岩主微量判别图解
a. (Na2O+K2O)-SiO2图解,据Middlemost(1994);b. SiO2-K2O图解,据Peccerillo and Taylor(1976);c. (La/Yb)N-(Yb);d. Sr/Y-Y图解,据Drummond and Defant(1990)
Fig. 4. Distinction diagrams of primary and trace elements of Azhalang magmatite
图 5 石英二长斑岩球粒陨石标准化稀土配分曲线及原始地幔标准化微量元素蛛网图
标准化数据引自Sun and McDonough(1989);冈底斯带不含矿埃达克岩数据胡永斌(2015);冈底斯成矿带中东部埃达克岩数据曲晓明等(2010)
Fig. 5. Chondrite-normalized REE patterns and primitive mantle-normalized trace element spidergrams for the quartz-monzonite porphyry
图 6 中新世埃达克岩判别图解
a. SiO2-Sr/Y;b. SiO2-Dy/Yb图解(Castillo et al., 1999);c. La/Ce-Rb/Sr;d. Nb/U-Rb/Sr图解,据侯增谦等(2004),Cook岛弧埃达克岩数据引自Stern and Kilian(1996),新生代埃达克岩(n=140)、埃达克岩和高铝TTG(n=394)和太古宙高铝TTG(n=174)数据引自Drummond et al.(1996)
Fig. 6. Distinction diagrams of Miocene adakite
图 7 SiO2-主微量元素埃达克岩判别图解
a.SiO2-Ni;b.SiO2-Cr;c.SiO2-MgO;d.SiO2-TFeO/MgO图解,据Wang et al.(2006)
Fig. 7. Distinction diagrams of SiO2-primary and trace elements of adakite
图 8 中新世埃达克岩源区判别图解
a. Th/Yb-Th/Sm,据Zhu et al.(2009);b. SiO2-Mg#图解,据Wang et al.(2006)
Fig. 8. Distinction diagrams of Miocene adakite source region
图 9 中新世埃达克质岩构造环境判别图解
a. Th-Th/Ce图解,据Wang et al.(2006);b. Rb-Y+Nb图解,据Pearce et al.(1984);ORG.大洋脊花岗岩;WPG.板内花岗岩;VAG.火山弧花岗岩;syn-COLG.同碰撞花岗岩;post-COLG.后碰撞花岗岩
Fig. 9. Distinction diagrams of Miocene adakite tectonic setting
图 10 中酸性侵入岩的R1-R2构造判别图解
R1=4Si-11(Na+K)-2(Fe+Ti), R2=6Ca+2Mg+Al; 据Batchelor and Bowden (1985)
Fig. 10. R1-R2 diagram intermediate-acid intrusive rocks
表 1 阿扎朗岩体石英二长岩锆石稀土元素(10-6)分析结果
Table 1. Analytical results of the quartz-monzonite porphyry zircon REE elements(10-6)of Azhalang pluton
点号 La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu S17T26-01 0.19 24.83 0.09 0.66 1.72 0.57 2.96 2.15 24.28 10.30 48.74 13.59 168.82 29.78 S17T26-02 0.07 60.52 0.29 5.72 10.02 4.01 20.10 9.88 97.31 32.68 134.02 30.50 340.36 52.03 S17T26-03 4.24 42.01 1.19 7.17 2.73 1.02 8.13 4.03 49.47 20.48 93.88 24.27 296.07 51.27 S17T26-04 0.09 28.21 0.07 1.21 2.00 0.60 4.60 3.01 33.18 13.02 62.77 16.49 201.88 35.98 S17T26-05 0.58 59.38 0.23 1.64 3.18 1.34 8.79 5.62 66.42 25.92 124.96 32.34 394.41 67.86 S17T26-06 4.97 64.73 1.44 8.23 4.07 1.47 12.51 5.58 63.71 24.74 114.93 29.28 351.50 61.09 S17T26-07 0.11 33.98 0.04 0.45 1.74 0.81 5.12 3.78 49.38 22.23 115.22 31.08 406.98 74.39 S17T26-08 0.08 34.19 0.04 0.89 1.72 0.71 5.31 3.37 39.92 15.99 77.89 19.96 243.98 42.01 S17T26-09 0.53 24.98 0.17 1.37 1.73 0.59 3.37 2.13 26.88 11.11 55.72 15.54 200.60 37.26 S17T26-10 0.11 28.93 0.04 0.71 2.09 0.77 4.32 2.96 35.54 14.61 76.40 20.03 249.53 45.64 表 2 阿扎朗岩体LA-ICP-MS锆石U-Pb定年结果
Table 2. LA-ICP-MS zircon U-Pb dating results of Azhalang pluton
样品及测点 Th(10-6) U(10-6) Th/U 207Pb/235U 1σ 206Pb/238U 1σ 207Pb/235U (Ma) 1σ (Ma) 206Pb/238U (Ma) 1σ (Ma) NEST610 450.9 457.1 0.1 25.262 0.344 59 0.204 73 0.002 85 3 318.5 13 1 201.3 15.0 91500 20.5 58.0 0.4 1.850 20 0.039 81 0.179 20 0.002 67 1 064.2 14 1 063.5 15.0 Ple 43.4 480 0.1 0.408 20 0.007 57 0.055 09 0.000 78 348.2 5.0 346.1 5.0 S17T26-01 367.4 357.1 1.0 0.017 65 0.001 62 0.002 76 0.000 05 17.8 1.6 17.8 0.3 S17T26-02 1 087.9 367.7 3.0 0.017 68 0.001 96 0.002 77 0.000 07 17.8 2.0 17.8 0.4 S17T26-03 458.9 497.23 1.0 0.017 72 0.002 25 0.002 78 0.000 05 17.8 2.3 17.9 0.3 S17T26-04 442.2 407.5 1.1 0.017 81 0.001 38 0.002 79 0.000 06 17.9 1.4 18.0 0.4 S17T26-05 1 940.2 1 230.3 1.6 0.017 94 0.001 06 0.002 80 0.000 04 18.1 1.1 18.0 0.2 NEST610 20.0 58.3 0.3 1.850 2 0.037 69 0.179 20 0.002 65 1 064.2 13.0 1 063.4 14.0 S17T26-06 1 345.3 1 034.6 1.3 0.018 54 0.001 35 0.002 78 0.000 04 18.7 1.4 17.9 0.2 S17T26-07 539.0 620.0 0.9 0.017 48 0.001 28 0.002 73 0.000 05 17.6 1.3 17.6 0.3 S17T26-08 467.3 466.9 1.0 0.017 80 0.001 37 0.002 79 0.000 05 17.9 1.4 17.9 0.3 S17T26-09 390.8 429.5 0.9 0.017 80 0.001 58 0.002 78 0.000 06 17.9 1.6 17.9 0.4 S17T26-10 396.9 375.9 1.1 0.017 53 0.003 90 0.002 74 0.000 06 17.6 3.9 17.7 0.4 NEST610 20.5 58.6 0.3 1.850 20 0.041 44 0.179 20 0.002 70 1 064.2 15.0 1 063.5 15.0 91500 450.9 457.1 1.0 25.300 0.348 08 0.201 43 0.002 81 3 320.3 13.0 1 183.4 15.0 表 3 阿扎朗岩体主量元素(%)和微量元素(10-6)分析结果
Table 3. Analytical results of major (%) and trace elements (10-6) for Azhalang pluton
样品 S17T26H1 S17T26H2 S17T26H3 S17T26H4 S17T26H5 R1 AGV-2 GSR-1 GSR-3 SiO2 59.4 62.9 57.3 59.2 62.7 73.5 TiO2 0.5 0.5 0.5 0.5 0.4 0.3 Al2O3 19.9 17.6 20.7 19.9 18.5 12.6 TFe2O3 3.6 3.4 4.5 3.5 3.2 2.1 MnO 0.1 0.1 0.1 0.1 0.1 0.1 MgO 1.5 1.4 1.5 1.5 1.3 0.4 CaO 3.7 4.0 4.0 3.7 3.6 1.5 Na2O 6.1 5.5 6.1 5.7 5.4 3.0 K2O 3.3 3.3 3.7 3.8 3.1 5.3 P2O5 0.3 0.2 0.3 0.3 0.2 0.1 LOI 1.2 0.8 1.0 1.4 0.9 0.70 Total 99.5 99.4 99.5 99.5 99.4 TFeO 3.3 3.1 4.1 3.2 2.9 Mg# 49.3 48.6 43.8 49.8 49.3 A/CNK 1.0 0.9 1.0 1.0 1.0 Li 32.7 29.7 36.3 37.7 24.0 10.7 130.0 10.4 P 1 009.8 811.2 1 114.0 997.2 677.2 2 162.0 400.8 4 290.0 K 22 920.0 22 140.0 25 240.0 25 900.0 20 700.0 24 160.0 41 200.0 19 766.0 Sc 3.8 3.6 4.0 4.1 3.5 12.1 6.0 14.1 Ti 2 624.0 2 478.0 2 536.0 2 602.0 2 270.0 6 252.0 1 752.8 14 858.0 V 62.5 55.7 62.5 60.5 50.9 125.8 24.5 187.6 Cr 7.2 6.5 7.8 6.7 6.5 17.0 3.8 133.5 Mn 527.6 468.2 553.4 520.2 416.6 757.2 467.4 1 426.4 Co 7.7 6.8 8.1 7.4 6.0 16.4 3.1 45.1 Ni 6.8 6.3 7.4 6.6 5.4 19.4 2.3 147.0 Cu 20.8 13.8 14.3 17.1 23.5 52.9 3.0 50.0 Zn 57.0 57.1 56.0 56.7 50.6 91.5 30.6 154.2 Ga 23.0 20.7 23.0 22.3 20.0 20.4 19.8 25.0 Rb 96.2 87.8 105.0 112.8 94.5 74.4 489.6 37.4 Sr 1 125.0 1 060.7 1 052.1 1 149.8 1 070.8 686.4 106.7 1 122.0 Y 9.0 9.0 8.7 9.0 8.5 19.0 63.9 21.6 Zr 143.6 132.7 158.2 160.8 120.2 234.4 171.7 295.0 Nb 7.8 7.7 7.6 7.8 6.9 15.6 42.6 90.8 Cs 3.2 2.8 3.3 3.9 3.0 1.1 41.6 0.7 Ba 1 127.5 1 223.0 1 112.5 1 210.0 1 163.4 1 044.8 351.4 531.6 La 36.7 29.1 26.3 30.8 29.4 38.5 53.5 57.4 Ce 71.6 57.3 54.9 63.0 58.3 73.5 108.3 108.0 Pr 7.5 6.7 6.1 6.8 6.7 8.5 12.5 12.8 Nd 25.7 24.5 21.5 23.9 24.2 31.7 44.5 51.3 Sm 4.0 4.0 3.5 3.9 4.0 5.8 9.8 10.3 Eu 0.9 1.0 0.9 0.9 1.0 1.6 0.8 3.2 Gd 2.8 2.9 2.5 2.7 2.8 5.0 9.2 9.1 Tb 0.3 0.3 0.3 0.3 0.3 0.6 1.5 1.1 Dy 1.8 1.8 1.6 1.7 1.8 3.6 10.1 5.6 Ho 0.3 0.3 0.3 0.3 0.3 0.7 2.1 0.9 Er 0.9 0.9 0.8 0.9 0.9 1.8 6.4 1.9 Tm 0.1 0.1 0.1 0.1 0.1 0.3 1.1 0.3 Yb 0.9 0.9 0.9 0.9 0.9 1.7 7.5 1.4 Lu 0.1 0.1 0.1 0.1 0.1 0.3 1.2 0.2 Hf 3.5 3.2 3.7 3.6 2.9 4.7 6.1 6.4 Ta 0.4 0.4 0.5 0.5 0.5 0.9 7.3 4.3 Pb 42.0 43.1 39.2 43.2 43.5 12.5 35.7 6.5 Th 17.9 17.1 15.0 17.0 17.6 6.0 54.8 5.9 U 3.6 3.8 2.7 3.8 3.1 1.9 19.1 1.4 Eu/Eu* 0.9 0.9 0.9 0.9 0.9 Sr/Y 124.0 118.0 122.0 128.0 126.0 表 4 冈底斯成矿带中新世岩浆岩形成时代
Table 4. Age of Miocene magmatic rocks of Gangdise metallogenic belt
地区 岩性 测试方法 测试对象 年龄(Ma) 资料来源 驱龙 斑状花岗闪长岩 LA-ICP-MS U-Pb 锆石 17.2±0.5 郑有业等,2012 驱龙 高镁闪长斑岩 LA-ICP-MS U-Pb 锆石 15.7±0.2 Lu et al., 2017 冲江 花岗闪长斑岩 SHRIMP U-Pb 锆石 12.9±0.3 林武等,2004 吉如 二长花岗斑岩 SHRIMP U-Pb 锆石 16.0±0.4 Zheng et al., 2014 厅宫 二长斑岩 LA-ICP-MS U-Pb 锆石 15.5±0.3 Chen et al., 2014 厅宫 闪长斑岩 LA-ICP-MS U-Pb 锆石 15.0±0.2 Chen et al., 2014 马攸木 花岗闪长斑岩 Ar- Ar 黑云母 17.7±0.15 江思宏等,2006 知不拉 花岗闪长岩 SHRIMP U-Pb 锆石 16.9±0.3 Xu et al., 2016 知不拉 二长花岗岩 SHRIMP U-Pb 锆石 17.0±0.2 Xu et al., 2016 岗讲 花岗闪长斑岩 LA-ICP-MS U-Pb 锆石 16.6±0.3 杨震等,2017 甲玛 花岗斑岩 LA-ICP-MS U-Pb 锆石 16.7±0.3 孟元库等,2018 甲玛 花岗闪长斑岩 LA-ICP-MS U-Pb 锆石 14.4±0.3 孟元库等,2018 达布 花岗闪长斑岩 LA-ICP-MS U-Pb 锆石 16.5±0.3 李世杰等,2018 拉抗俄 花岗闪长斑岩 LA-ICP-MS U-Pb 锆石 13.6±0.4 冷秋锋等,2016 汤不拉 花岗斑岩 LA-ICP-MS U-Pb 锆石 19.7±0.2 王保弟等,2010 朱诺 黑云母花岗闪长岩 LA-ICP-MS U-Pb 锆石 14.1±0.3 黄勇等,2015 阿扎朗 石英二长斑岩 LA-ICP-MS U-Pb 锆石 17.9±0.2 本文 -
Andersen, T., 2002. Correction of Common Lead in U-Pb Analyses that do not Report 204Pb. Chemical Geology, 192(1-2): 59-79. https://doi.org/10.1016/s0009-2541(02)00195-x Atherton, M. P., Petford, N., 1993. Generation of Sodium-Rich Magmas from Newly Underplated Basaltic Crust. Nature, 362(6416): 144-146. https://doi.org/10.1038/362144a0 Batchelor, R. A., Bowden, P., 1985. Petrogenetic Interpretation of Granitoid Rock Series Using Multicationic Parameters. Chemical Geology, 48(1-4): 43-55. https://doi.org/10.1016/0009-2541(85)90034-8 Castillo, P. R., Janney, P. E., Solidum, R. U., 1999. Petrology and Geochemistry of Camiguin Island, Southern Philippines: Insights to the Source of Adakites and Other Lavas in a Complex Arc Setting. Contributions to Mineralogy and Petrology, 134(1): 33-51. https://doi.org/10.1007/s004100050467 Chen, R., Liu, Y. L., Guo, L. S., et al., 2014. Geochronology and Geochemistry of the Tinggong Porphyry Copper Ore Deposit, Tibet. Acta Geologica Sinica (English Edition), 88(3): 780-800. https://doi.org/10.1111/1755-6724.12238 Chung, S. L., Chu, M. F., Ji, J. Q., et al., 2009. The Nature and Timing of Crustal Thickening in Southern Tibet: Geochemical and Zircon Hf Isotopic Constraints from Postcollisional Adakites. Tectonophysics, 477(1-2): 36-48. https://doi.org/10.1016/j.tecto.2009.08.008 Drummond, M. S., Defant, M. J., 1990. A Model for Trondhjemite-Tonalite-Dacite Genesis and Crustal Growth Via Slab Melting: Archean to Modern Comparisons. Journal of Geophysical Research, 95(B13): 21503. https://doi.org/10.1029/jb095ib13p21503 Drummond, M. S., Defant, M. J., Kepezhinskas, P. K., 1996. Petrogenesis of Slab-Derived Trondhjemite-Tonalite- Dacite/Adakite Magmas. Transactions of the Royal Society of Edinburgh: Earth Sciences, 87(1-2): 205-215. https://doi.org/10.1017/s0263593300006611 Gao, Y. F., Yang, Z. S., Santosh, M., et al., 2010. Adakitic Rocks from Slab Melt-Modified Mantle Sources in the Continental Collision Zone of Southern Tibet. Lithos, 119(3-4): 651-663. https://doi.org/10.1016/j.lithos.2010.08.018 Hou, Z. Q., Gao, Y. F., Meng, X. J., et al., 2004. Genesis of Adakitic Porphyry and Tectonic Controls on the Gangdese Miocene Porphyry Copper Belt in the Tibetan Orogen. Acta Petrologica Sinica, 20(2):239-248 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ysxb98200402006 Hou, Z. Q., Zhao, Z. D., Gao, Y. F., et al., 2006. Tearing and Dischronal Subduction of the Indian Continental Slab: Evidence from Cenozoic Gangdese Volcano-Magmatic Rocks in South Tibet. Acta Petrologica Sinica, 22(4):761-774 (in Chinese with English abstract). http://cn.bing.com/academic/profile?id=239e9e4351186a4fced2935b590008e6&encoded=0&v=paper_preview&mkt=zh-cn Hu, Y. B., 2015. Petrogenesis and Metallogenetic Implications of Aadakites in the Gangdese Porphyry Copper Belt (Dissertation). Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou (in Chinese with English abstract). Huang, Y., Ding, J., Li, G. M., et al., 2015. U-Pb Dating, Hf Isotopic Characteristics of Zircons from Intrusions in the Zhuluo Porphyry Cu-Mo-Au Deposit and Its Mineralization Significance. Acta Geologica Sinica, 89(1):99-108 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dizhixb201501008 Jiang, S. H., Nie, F. J., Hu, P., et al., 2006.40Ar-39Ar Age and Geochemical Features of the Mayum Adakitic Porphyry in Tibet. Acta Petrologica Sinica, 22(3):603-611 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ysxb98200603009 Kadioglu, Y. K., Dilek, Y., 2010. Structure and Geochemistry of the Adakitic Horoz Granitoid, Bolkar Mountains, South-Central Turkey, and Its Tectonomagmatic Evolution. International Geology Review, 52(4-6): 505-535. https://doi.org/10.1080/09507110902954847 Leng, Q. F., Tang, J. X., Zheng, W. B., et al., 2016. Geochronology, Petrogeochemistry and Petrogenesis of Ore-Bearing Rock Massif in Dabu Mining Area, Tibet. Earth Science, 41(6): 999-1015 (in Chinese with English abstract). https://doi.org/10.3799/dqkx.2016.083 Li, J. X., Qin, K. Z., Li, G. M., et al., 2011. Post-Collisional Ore-Bearing Adakitic Porphyries from Gangdese Porphyry Copper Belt, Southern Tibet: Melting of Thickened Juvenile Arc Lower Crust. Lithos, 126(3-4): 265-277. https://doi.org/10.1016/j.lithos.2011.07.018 Li, S. J., Wei, Q. R., Ci, Q., et al., 2018. Geochronology, Petrogeochemistry and Petrogenesis of Ore-Bearing Rock Massif in Dabu Mining Area, Tibet. Earth Science, 43(9):3218-3233 (in Chinese with English abstract). https://doi.org/10.3799/dqkx.2018.231 Lin, W., Liang, H. Y., Zhang, Y. Q., et al., 2004. Petrochemistry and SHRIMP U-Pb Zircon Age of the Chongjiang Ore-Bearing Porphyry in the Gangdese Porphyry Copper Belt. Geochimica, 33(6):585-592 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dqhx200406006 Long, X. P., Wilde, S. A., Wang, Q., et al., 2015. Partial Melting of Thickened Continental Crust in Central Tibet: Evidence from Geochemistry and Geochronology of Eocene Adakitic Rhyolites in the Northern Qiangtang Terrane. Earth and Planetary Science Letters, 414: 30-44. https://doi.org/10.1016/j.epsl.2015.01.007 Lu, Y. J., Hou, Z. Q., Yang, Z. M., et al., 2017. Porphyry Cu Fertility in the Lhasa Terrane, Southern Tibet: Insights from Terrane-Scale Whole-Rock Geochemistry and Zircon Trace Element and Hf-O Isotopes. SEG 2017: Ore Deposits of Asia: China and Beyond, Beijing. Ma, L., Wang, Q., Wyman, D. A., et al., 2013. Late Cretaceous (100-89 Ma) Magnesian Charnockites with Adakitic Affinities in the Milin Area, Eastern Gangdese: Partial Melting of Subducted Oceanic Crust and Implications for Crustal Growth in Southern Tibet. Lithos, 175-176: 315-332. https://doi.org/10.1016/j.lithos.2013.04.006 Martin, H., 1999. Adakitic Magmas: Modern Analogues of Archaean Granitoids. Lithos, 46(3): 411-429. https://doi.org/10.1016/s0024-4937(98)00076-0 Meng, Y. K., Ma, S. W., Xu, Z. Q., et al., 2018. Geochronology, Geochemistry and Petrogenesis of the Granitoid Porphyries from Jiama Ore Deposit in Gangdese Belt. Earth Science, 43(4):1142-1163 (in Chinese with English abstract). https://doi.org/10.3799/dqkx.2018.713 Middlemost, E. A. K., 1994. Naming Materials in the Magma/Igneous Rock System. Earth-Science Reviews, 37(3-4): 215-224. https://doi.org/10.1016/0012-8252(94)90029-9 Pearce, J. A., Harris, N. B. W., Tindle, A. G., 1984. Trace Element Discrimination Diagrams for the Tectonic Interpretation of Granitic Rocks. Journal of Petrology, 25(4): 956-983. https://doi.org/10.1093/petrology/25.4.956 Peccerillo, A., Taylor, S. R., 1976. Geochemistry of Eocene Calc-Alkaline Volcanic Rocks from the Kastamonu Area, Northern Turkey. Contributions to Mineralogy and Petrology, 58(1): 63-81. https://doi.org/10.1007/bf00384745 Qin, K. Z., Li, G. M., Zhao, J. X., 2008. Discovery of Sharang Large-Scale Porphyry Molybdenum Deposit, the First Single Mo Deposit in Tibet and Its Significance. Geology in China, 35(6):1101-1112 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=zgdizhi200806007 Qu, X. M., Hou, Z. Q., Huang, W., 2001. Is Gangdese Porphyry Copper Belt the Second "Yulong" Copper Belt?. Mineral Deposits, 20(4):355-366 (in Chinese with English abstract). https://www.researchgate.net/publication/284665935_Is_Gangdese_porphyry_copper_belt_the_second_Yulong_copper_belt Qu, X. M., Hou, Z. Q., Li, Y., 2004. Melt Components Derived from a Subducted Slab in Late Orogenic Ore-Bearing Porphyries in the Gangdese Copper Belt, Southern Tibetan Plateau. Lithos, 74(3-4): 131-148. https://doi.org/10.1016/s0024-4937(04)00027-1 Qu, X. M., Jiang, J. H., Xin, H. B., et al., 2010. A Study of Two Groups of Adakite almost Simulteneously Formed in Gangdese Collisional Orogen, Tibet: Why does One Group Contain Copper Mineralization and the Other not?. Mineral Deposits, 29(3):381-394 (in Chinese with English abstract). http://cn.bing.com/academic/profile?id=b3572a8516e1edf7f1174a01d257964b&encoded=0&v=paper_preview&mkt=zh-cn Rapp, R. P., Shimizu, N., Norman, M. D., et al., 1999. Reaction between Slab-Derived Melts and Peridotite in the Mantle Wedge: Experimental Constraints at 3.8 GPa. Chemical Geology, 160(4): 335-356. https://doi.org/10.1016/S0009-2541(99)00106-0 Rapp, R. P., Watson, E. B., 1995. Dehydration Melting of Metabasalt at 8-32 kbar: Implications for Continental Growth and Crust-Mantle Recycling. Journal of Petrology, 36(4): 891-931. https://doi.org/10.1093/petrology/36.4.891 Stern, C. R., Kilian, R., 1996. Role of the Subducted Slab, Mantle Wedge and Continental Crust in the Generation of Adakites from the Andean Austral Volcanic Zone. Contributions to Mineralogy and Petrology, 123(3): 263-281. https://doi.org/10.1007/s004100050155 Sun, S. S., McDonough, W. F., 1989. Chemical and Isotopic Systematics of Oceanic Basalts: Implications for Mantle Composition and Processes. Geological Society, London, Special Publications, 42(1): 313-345. https://doi.org/10.1144/gsl.sp.1989.042.01.19 Tang, G. J., Wang, Q., Wyman, D. A., et al., 2010. Ridge Subduction 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). Chemical Geology, 277(3-4): 281-300. https://doi.org/10.1016/j.chemgeo.2010.08.012 Wang, B. D., Xu, J. F., Chen, J. L., et al., 2010. Petrogenesis and Geochronology of the Ore-Beating Porphyritic Rocks in Tangbula Porphyry Molybdenum-Copper Deposit in the Eastern Segment of the Gangdese Metalloganic Belt. Acta Petrologica Sinica, 26(6):1820-1832(in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ysxb98201006016 Wang, L. L., Mo, X. X., Li, B., et al., 2006. Geochronology and Geochemistry of the Ore-Bearing Porphyry in Qulong Cu(Mo) Ore Deposit, Tibet. Acta Petrologica Sinica, 22(4):1001-1008 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ysxb98200604023 Wang, Q., Xu, J. F., Jian, P., et al., 2006. Petrogenesis of Adakitic Porphyries in an Extensional Tectonic Setting, Dexing, South China: Implications for the Genesis of Porphyry Copper Mineralization. Journal of Petrology, 47(1): 119-144. https://doi.org/10.1093/petrology/egi070 Wei, Y. Q., Zhao, Z. D., Niu, Y. L., et al., 2017. Geochronology and Geochemistry of the Early Jurassic Yeba Formation Volcanic Rocks in Southern Tibet: Initiation of Back-Arc Rifting and Crustal Accretion in the Southern Lhasa Terrane. Lithos, 278-281: 477-490. https://doi.org/10.1016/j.lithos.2017.02.013 Whalen, J. B., 1985. Geochemistry of an Island-Arc Plutonic Suite: The Uasilau-Yau Yau Intrusive Complex, New Britain, P.N.G. Journal of Petrology, 26(3): 603-632. https://doi.org/10.1093/petrology/26.3.603 Wu, H., Li, C., Hu, P. Y., et al., 2015. Early Cretaceous (100-105 Ma) Adakitic Magmatism in the Dachagou Area, Northern Lhasa Terrane, Tibet: Implications for the Bangong–Nujiang Ocean Subduction and Slab Break-Off. International Geology Review, 57(9-10): 1172-1188. https://doi.org/10.1080/00206814.2014.886152 Xia, B. B., Xia, B., Wang, B. D., et al., 2007. Ore-Bearing Adakitic Porphyry in the Middle of Gangdese: Thickened Lower Crustal Melting and the Genesis of Porphyry Cu-Mo Deposit. Geological Science and Technology Intelligence, 26(4):19-26 (in Chinese with English abstract). http://cn.bing.com/academic/profile?id=db9f87d1b8676bef7770caec0005334e&encoded=0&v=paper_preview&mkt=zh-cn Xu, J., Zheng, Y. Y., Sun, X., et al., 2016. Geochronology and Petrogenesis of Miocene Granitic Intrusions Related to the Zhibula Cu Skarn Deposit in the Gangdese Belt, Southern Tibet. Journal of Asian Earth Sciences, 120: 100-116. https://doi.org/10.1016/j.jseaes.2016.01.026 Xu, W. C., Zhang, H. F., Guo, L., et al., 2010. Miocene High Sr/Y Magmatism, South Tibet: Product of Partial Melting of Subducted Indian Continental Crust and Its Tectonic Implication. Lithos, 114(3-4): 293-306. https://doi.org/10.1016/j.lithos.2009.09.005 Yang, Z., Jiang, H., Yang, M. G., et al., 2017. Zircon U-Pb and Molybdenite Re-Os Dating of the Gangjiang Porphyry Cu-Mo Deposit in Central Gangdese and Its Geological Significance. Earth Science, 42(3): 339-356 (in Chinese with English abstract). https://doi.org/10.3799/dqkx.2017.026 Yogodzinski, G. M., Volynets, O. N., Koloskov, A. V., et al., 1994. Magnesian Andesites and the Subduction Component in a Strongly Calc-Alkaline Series at Piip Volcano, far Western Aleutians. Journal of Petrology, 35(1): 163-204. https://doi.org/10.1093/petrology/35.1.163 Yu, H., 2011. Mineral Geochemical Characteristics and Genetic Mechanism of Olivine Rocks in Shangnan, Shanxi (Dissertation). China University of Geosciences, Beijing, 22-25 (in Chinese with English abstract). Zhang, Z. M., Zhao, G. C., Santosh, M., et al., 2010. Late Cretaceous Charnockite with Adakitic Affinities from the Gangdese Batholith, Southeastern Tibet: Evidence for Neo-Tethyan Mid-Ocean Ridge Subduction?. Gondwana Research, 17(4): 615-631. https://doi.org/10.1016/j.gr.2009.10.007 Zheng, Y. Y., Sun, X., Gao, S. B., et al., 2014. Multiple Mineralization Events at the Jiru Porphyry Copper Deposit, Southern Tibet: Implications for Eocene and Miocene Magma Sources and Resource Potential. Journal of Asian Earth Sciences, 79, B42-B57. https://doi.org/10.1016/j.jseaes.2013.03.029 Zheng, Y. Y., Sun, X., Zheng, H. T., et al., 2012. Magma Evolution of Small Intrusion and Mineralization in Gangdese, Tibet. Northwestern Geology, 45(4):165-174 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=xbdz201204015 Zhu, D. C., Zhao, Z. D., Pan, G. T., et al., 2009. Early Cretaceous Subduction-Related Adakite-Like Rocks of the Gangdese Belt, Southern Tibet: Products of Slab Melting and Subsequent Melt–peridotite Interaction?. Journal of Asian Earth Sciences, 34(3): 298-309. https://doi.org/10.1016/j.jseaes.2008.05.003 侯增谦, 高永丰, 孟祥金, 等, 2004.西藏冈底斯中新世斑岩铜矿带:埃达克质斑岩成因与构造控制.岩石学报, 20(2):239-248. http://d.old.wanfangdata.com.cn/Periodical/ysxb98200402006 侯增谦, 赵志丹, 高永丰, 等, 2006.印度大陆板片前缘撕裂与分段俯冲:来自冈底斯新生代火山-岩浆作用证据.岩石学报, 22(4):761-774. http://d.old.wanfangdata.com.cn/Periodical/ysxb98200604001 胡永斌, 2015.冈底斯斑岩铜矿带埃达克岩成因及成矿启示(博士学位论文).广州: 中国科学院广州地球化学研究所. http://cdmd.cnki.com.cn/Article/CDMD-80165-1015361478.htm 黄勇, 丁俊, 李光明, 等, 2015.西藏朱诺斑岩铜-钼-金矿区侵入岩锆石U-Pb年龄、Hf同位素组成及其成矿意义.地质学报, 89(1):99-108. doi: 10.3969/j.issn.1006-0995.2015.01.022 江思宏, 聂凤军, 胡朋, 等, 2006.西藏马莜木埃达克质斑岩的40Ar-39Ar年龄与地球化学特征.岩石学报, 22(3), 603-611. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ysxb98200603009 冷秋锋, 唐菊兴, 郑文宝, 等, 2016.西藏拉抗俄斑岩Cu-Mo矿床含矿斑岩地球化学、锆石U-Pb年代学及Hf同位素组成.地球科学, 41(6):999-1015. http://earth-science.net/WebPage/Article.aspx?id=3312 李世杰, 魏启荣, 次琼, 等, 2018.西藏达布矿区含矿岩体的时代、岩石地球化学特征及岩石成因.地球科学, 43(9):3218-3233. http://earth-science.net/WebPage/Article.aspx?id=3934 林武, 梁华英, 张玉泉, 等, 2004.冈底斯铜矿带冲江含矿斑岩的岩石化学及锆石SHRIMP年龄特征.地球化学, 33(6):585-592. doi: 10.3321/j.issn:0379-1726.2004.06.006 孟元库, 马士委, 许志琴, 等, 2018.冈底斯带甲玛矿区花岗斑岩类年代学、地球化学及岩石成因.地球科学, 43(4):1142-1163. http://earth-science.net/WebPage/Article.aspx?id=3787 秦克章, 李光明, 赵俊兴, 等, 2008.西藏首例独立钼矿-冈底斯沙让大型斑岩钼矿的发现及其意义.中国地质, 35(6):1101-1112. doi: 10.3969/j.issn.1000-3657.2008.06.007 曲晓明, 侯增谦, 黄卫, 2001.冈底斯斑岩铜矿(化)带:西藏第二条"玉龙"铜矿带?.矿床地质, 20(4):355-366. doi: 10.3969/j.issn.0258-7106.2001.04.009 曲晓明, 江军华, 辛洪波, 等, 2010.西藏冈底斯造山带几乎同时形成的两套埃达克岩为什么一套含矿一套不含矿?.矿床地质, 29(3):381-394. doi: 10.3969/j.issn.0258-7106.2010.03.001 王保弟, 许继峰, 陈建林, 等, 2010.冈底斯东段汤不拉斑岩Mo-Cu矿床成岩成矿时代与成因研究.岩石学报, 26(6):1820-1832. http://d.old.wanfangdata.com.cn/Periodical/ysxb98201006016 王亮亮, 莫宣学, 李冰, 等, 2006.西藏驱龙斑岩铜矿含矿斑岩的年代学与地球化学.岩石学报, 22(4):1001-1008. http://d.old.wanfangdata.com.cn/Periodical/ysxb98200604023 夏抱本, 夏斌, 王保弟, 等, 2007.冈底斯中段达布埃达克质含矿斑岩:增厚下地壳熔融与斑岩铜钼矿成因.地质科技情报, 26(4):19-26. doi: 10.3969/j.issn.1000-7849.2007.04.005 杨震, 姜华, 杨明国, 等, 2017.冈底斯中段岗讲斑岩铜钼矿床锆石U-Pb和辉钼矿Re-Os年代学及其地质意义.地球科学, 42(3):339-356. http://earth-science.net/WebPage/Article.aspx?id=3545 于红, 2011.陕西商南松树沟橄榄岩矿物地球化学特征及成因机理示踪(硕士学位论文).北京: 中国地质大学, 22-25. http://cdmd.cnki.com.cn/Article/CDMD-11415-1011078082.htm 郑有业, 孙祥, 郑海涛, 等, 2012.西藏冈底斯小斑岩体演化与成矿.西北地质, 45(4):165-174. doi: 10.3969/j.issn.1009-6248.2012.04.015 期刊类型引用(0)
其他类型引用(1)
-