Petrogenesis and Geological Significance of Late Jurassic Volcanic Rocks in Mami Area, Central Tibetan Plateau
-
摘要: 在青藏高原中部中拉萨地块之上新识别了一套晚侏罗世-早白垩世早期岩浆岩，本次对其中麻米地区出露的火山岩进行了锆石U-Pb定年与全岩主微量元素分析研究工作.测年结果显示麻米火山岩形成于晚侏罗世（152~150 Ma），岩石地球化学具有高SiO2、高全碱含量（Na2O+K2O）、低MgO、低P2O5的特征，并显示明显的Eu、Sr、Ba等元素的亏损，具有高分异I型花岗质岩石的特征.结合区域上报道的同期中酸性侵入岩资料，麻米酸性火山岩起源于古老地壳物质重熔并经历了广泛的结晶分异作用.本文研究表明中拉萨地块上晚侏罗世-早白垩世早期岩浆作用形成于洋壳俯冲背景，应该是新特提斯洋北向俯冲过程中引发的弧型岩浆事件.Abstract: A new Late Jurassic-Early Cretaceous magmatic belt has been identified in the central Tibetan Plateau. This paper reports two zircon U-Pb ages and also new whole-rock major and trace element data of the newly discovered volcanic rocks in Mami area. These volcanic rocks were dated as Late Jurassic (152-150 Ma). The studied samples are characterized by high SiO2 content, high alkali, low MgO, and low P2O5 abundances, with significant depletion in Eu, Sr, and Ba, suggesting a geochemical affinity with highly fractionated I-type granites. It is concluded that the volcanic rocks were derived by partial melting of ancient mafic lower crust, followed by fractional crystallization. Our research propose that Late Jurassic-Early Cretaceous magmatic magmatism occurred in an oceanic subduction setting, likely related to the northward subduction of the Neo-Tethys oceanic lithosphere.
-
Key words:
- central Tibetan Plateau /
- Late Jurassic /
- volcanics /
- zircon U-Pb dating /
- geochemistry
-
图 1 青藏高原构造单元划分图（a）；研究区地质图及本文采样位置（b）；凝灰岩野外露头照片（c）；凝灰岩镜下照片（d）
引用年龄数据引自：姜昕等（2010）、杜德道等（2011）、张璋等（2011）、Li et al.(2014a, 2014b)、Liu et al.（2014）、Cao et al.（2016）、Wu et al.（2016）、闫晶晶等（2017）、尼玛次仁等（2017）、叶春林等（2018）
Fig. 1. Tectonic subdivision of the Tibetan Plateau(a); simplified geological map of the Mami area, Tibet(b); field photograph(c); petrographic photograph(d)
图 2 锆石CL图像、锆石U-Pb谐和图和年龄分布
Fig. 2. Cathodoluminescence (CL) images, U-Pb concordia plots and age distribution for zircons
图 3 岩石地球化学分类图解
a.TAS图解；b.K2O-SiO2图解；c.Th-Co图解；d.A/NK-A/CNK图解；引用数据引自：杜德道等（2011）、Cao et al.（2016）、尼玛次仁等（2017）、闫晶晶等（2017）
Fig. 3. Geochemical classifcation diagrams
图 5 岩石球粒陨石标准化稀土元素模式（a）；原始地幔标准化微量元素蛛网图（b）
标准化值引自Sun and McDonough（1989）
Fig. 5. Chondrite-normalized rare earth element(a); primitive-mantle-normalized trace element patterns(b)
图 6 岩石微量元素与元素比值变化图解
Fig. 6. Geochemical composition variation diagrams of trace elements and element ratios
图 7 南羌塘板块与中拉萨地块晚侏罗世-早白垩世早期岩浆岩年龄分布频谱图
Fig. 7. Frequency distribution of magmatic age data of southern Qiangtang and central Lhasa terranes
图 8 岩石地球化学分类图解
a.(FeO*/MgO)-Zr+Ce+Nb+Y图解，据Whalen et al.（1987）；b.P2O5-SiO2图解；c.Th-Rb图解，据Li et al.（2007）
Fig. 8. Geochemical classification diagrams
图 9 岩石地球化学判别图解
a.Rb/Sr-Sr图解；b.Ba-Sr图解，据Rollinson（1993）；Pl.斜长石；Kfs.钾长石；Bi.黑云母；Amp.角闪石
Fig. 9. Geochemical discrimination diagrams
图 10 构造环境判别图解
a.Nb-Y图解；b.Rb-Y+Nb图解，据Pearce et al.（1984）；syn-COLG.同碰撞花岗岩；VAG.火山弧花岗岩；WPG.板内花岗岩；ORG.洋脊花岗岩
Fig. 10. Tectonic setting distinguish diagram
-
[1] Cao, M. J., Qin, K. Z., Li, G. M., et al., 2016. Tectono-Magmatic Evolution of Late Jurassic to Early Cretaceous Granitoids in the West Central Lhasa Subterrane, Tibet. Gondwana Research, 39: 386-400. https://doi.org/10.1016/j.gr.2016.01.006 [2] Chappell, B. W., White, A. J. R., 1992. I- and S-Type Granites in the Lachlan Fold Belt. Transactions of the Royal Society of Edinburgh: Earth Sciences, 83(1-2): 1-26. https://doi.org/10.1017/s0263593300007720 [3] Chen, S. H., Wang, B., Zhang, J. R., et al., 2014. Lithogeochemical Characteristics and Chronology of Fuye Granitic Pluton from the Western Bangong-Nujiang Metallogenic Belt in China. Journal of East China Institute of Technology (Natural Science), 37(1):37-44 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=hddzxyxb201401006 [4] Coulon, C., Maluski, H., Bollinger, C., et al., 1986. Mesozoic and Cenozoic Volcanic Rocks from Central and Southern Tibet: 39Ar-40Ar Dating, Petrological Characteristics and Geodynamical Significance. Earth and Planetary Science Letters, 79(3-4): 281-302. https://doi.org/10.1016/0012-821x(86)90186-x [5] Du, D. D., Qu, X. M., Wang, G. H., et al., 2011. Bidirectional Subduction of the Middle Tethys Oceanic Basin in the West Segment of Bangonghu-Nujiang Suture, Tibet: Evidence from Zircon U-Pb LAICPMS Dating and Petrogeochemistry of Arc Granites. Acta Petrologica Sinica, 27(7):1993-2002 (in Chinese with English abstract). http://d.old.wanfangdata.com.cn/Periodical/ysxb98201107008 [6] Fan, J. J., Li, C., Liu, J. H., et al., 2017. The Middle Triassic Evolution of the Bangong–Nujiang Tethyan Ocean: Evidence from Analyses of OIB-Type Basalts and OIB-Derived Phonolites in Northern Tibet. International Journal of Earth Sciences, 107(5): 1755-1775. https://doi.org/10.1007/s00531-017-1570-x [7] Hu, X. M., Sinclair, H. D., Wang, J. G., et al., 2012. Late Cretaceous-Palaeogene Stratigraphic and Basin Evolution in the Zhepure Mountain of Southern Tibet: Implications for the Timing of India-Asia Initial Collision. Basin Research, 24(5): 520-543. https://doi.org/10.1111/j.1365-2117.2012.00543.x [8] Huang, Q. T., Li, J. F., Xia, B., et al., 2015. Petrology, Geochemistry, Chronology and Geological Significance of Jiang Tso Ophiolite in Middle Segment of Bangonghu-Nujiang Suture Zone, Tibet. Earth Science, 40(1):34-48 (in Chinese with English abstract). https://doi.org/10.3799/dqkx.2015.003 [9] Jiang, X., Zhao, Z. D., Zhu, D. C., et al., 2010. Zircon U-Pb Geochronology and Hf Isotopic Geochemistry of Jiangba, Bangba, and Xiongba Granitoids in Western Gangdese, Tibet. Acta Petrologica Sinica, 26(7): 2155-2164 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ysxb98201007017 [10] Li, J. X., Qin, K. Z., Li, G. M., et al., 2014a. Geochronology, Geochemistry, and Zircon Hf Isotopic Compositions of Mesozoic Intermediate-Felsic Intrusions in Central Tibet: Petrogenetic and Tectonic Implications. Lithos, 198-199: 77-91. https://doi.org/10.1016/j.lithos.2014.03.025 [11] Li, S. M., Zhu, D. C., Wang, Q., et al., 2014b. Northward Subduction of Bangong-Nujiang Tethys: Insight from Late Jurassic Intrusive Rocks from Bangong Tso in Western Tibet. Lithos, 205: 284-297. https://doi.org/10.1016/j.lithos.2014.07.010 [12] Li, X. H., Li, Z. X., Li, W. X., et al., 2007. U-Pb Zircon, Geochemical and Sr-Nd-Hf Isotopic Constraints on Age and Origin of Jurassic I- and A-Type Granites from Central Guangdong, SE China: A Major Igneous Event in Response to Foundering of a Subducted Flat-Slab?. Lithos, 96(1-2): 186-204. https://doi.org/10.1016/j.lithos.2006.09.018 [13] Liu, D. L., Huang, Q. S., et al., 2014. Subduction of the Bangong-Nujiang Ocean: Constraints from Granites in the Bangong Co Area, Tibet. Geological Journal, 49(2): 188-206. https://doi.org/10.1002/gj.2510 [14] Liu, F., Lian, D. Y., Niu, X. L., et al., 2018. Dongbo MORB-Type Isotropic Gabbro Emplaced as an Oceanic Core Complex in Western Yarlung Zangbo Suture Zone, Tibet. Earth Science, 43(4):952-974 (in Chinese with English abstract). https://doi.org/10.3799/dqkx.2018.702 [15] 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 [16] Nima, C. R., Wang, G. C., Dun, D., et al., 2017. Zircon U-Pb Ages, Geochemical Characteristics and Tectonics Implications of Late Jurassic Intermediate Intrusive Rocks in Shiquanhe Area, Western Tibet. Journal of Geomechanics, 23(5):673-685 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dzlxxb201705005 [17] 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 [18] Rollinson, H. R., 1993. Using Geochemical Data: Evaluation, Presentation, Interpretation. Longman Scientific Technical, London. [19] 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 [20] Whalen, J. B., Currie, K. L., Chappell, B. W., 1987. A-Type Granites: Geochemical Characteristics, Discrimination and Petrogenesis. Contributions to Mineralogy and Petrology, 95(4): 407-419. https://doi.org/10.1007/bf00402202 [21] Wu, F. Y., Li, X. H., Yang, J. H., et al., 2007. Discussions on the Petrogenesis of Granites. Acta Petrologica Sinica, 23(6):1217-1238 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ysxb98200706001 [22] Wu, Y., Chen, S. Y., Qin, M. K., et al., 2018. Zircon U-Pb Ages of Dongcuo Ophiolite in Western Bangonghu-Nujiang Suture Zone and Their Geological Significance. Earth Science, 43(4):1070-1087 (in Chinese with English abstract). https://doi.org/10.3799/dqkx.2018.710 [23] Wu, H., Xie, C. M., Li, C., et al., 2016. Tectonic Shortening and Crustal Thickening in Subduction Zones: Evidence from Middle-Late Jurassic Magmatism in Southern Qiangtang, China. Gondwana Research, 39: 1-13. https://doi.org/10.1016/j.gr.2016.06.009 [24] Yan, J. J., Zhao, Z. D., Liu, D., et al., 2017. Geochemistry and Petrogenesis of the Late Jurassic Xuru Tso Batholith in Central Lhasa Terrane, Tibet. Acta Petrologica Sinica, 33(8):2437-2453 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ysxb98201708007 [25] Ye, C. L., Huang, B. X., Wang, Y., et al., 2018. Zircon U-Pb Ages of the Late Jurassic Volcanic Rocks from the Zenong Group in the North of Zabuyechaka Area, Tibet and Its Geological Significances. Geological Journal of China Universities, 24(4): 525-535 (in Chinese with English abstract). http://d.old.wanfangdata.com.cn/Periodical/gxdzxb201804006 [26] Ye, P. S., Wu, Z. H., Hu, D. G., et al., 2004. Geochemistry and Tectonic Setting of Ophiolites in West of Namco Lake, Tibet. Geoscience, 18(2):237-243 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=xddz200402014 [27] Ye, P. S., Wu, Z. H., Hu, D. G., et al., 2005. Geochemical Characteristics of Ophiolites in Yongzhu-Guomangcuo, Tibet and Its Tectonic Significance. Geoscience, 19(4):508-514 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=xddz200504005 [28] Zhang, Z., Geng, Q. R., Peng, Z. M., et al., 2011. Geochemistry and Geochronology of the Caima Granites in the Western Part of the Bangong Lake-Nujiang Metallogenic Zone, Xizang. Sedimentary Geology and Tethyan Geology, 31(4):86-96 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=yxgdl201104013 [29] Zhu, D. C., Li, S. M., Cawood, P. A., et al., 2016. Assembly of the Lhasa and Qiangtang Terranes in Central Tibet by Divergent Double Subduction. Lithos, 245: 7-17. https://doi.org/10.1016/j.lithos.2015.06.023 [30] Zhu, D. C., Zhao, Z. D., Niu, Y. L., et al., 2011. The Lhasa Terrane: Record of a Microcontinent and Its Histories of Drift and Growth. Earth and Planetary Science Letters, 301(1-2): 241-255. https://doi.org/10.1016/j.epsl.2010.11.005 [31] 陈士海, 王斌, 张健仁, 等, 2014.班公湖-怒江成矿带西段弗野花岗岩体的岩石地球化学特征及年代学研究.东华理工大学学报(自然科学版), 37(1):37-44. doi: 10.3969/j.issn.1674-3504.2014.01.006 [32] 杜德道, 曲晓明, 王根厚, 等, 2011.西藏班公湖-怒江缝合带西段中特提斯洋盆的双向俯冲:来自岛弧型花岗岩锆石U-Pb年龄和元素地球化学的证据.岩石学报, 27(7):1993-2002. http://d.old.wanfangdata.com.cn/Periodical/ysxb98201107008 [33] 黄强太, 李建峰, 夏斌, 等, 2015.西藏班公湖-怒江缝合带中段江错蛇绿岩岩石学、地球化学、年代学及地质意义.地球科学, 40(1):34-48. http://earth-science.net/WebPage/Article.aspx?id=3014 [34] 姜昕, 赵志丹, 朱弟成, 等, 2010.西藏冈底斯西部江巴、邦巴和雄巴岩体的锆石U-Pb年代学与Hf同位素地球化学.岩石学报, 26(7):2155-2164. http://d.old.wanfangdata.com.cn/Periodical/ysxb98201007017 [35] 刘飞, 连东洋, 牛晓露, 等, 2018.雅鲁藏布江缝合带西段东波MORB型均质辉长岩的大洋核杂岩成因.地球科学, 43(4):952-974. http://earth-science.net/WebPage/Article.aspx?id=3784 [36] 尼玛次仁, 王国灿, 顿都, 等, 2017.西藏狮泉河地区晚侏罗世中性侵入岩锆石U-Pb年龄、地球化学特征及构造意义.地质力学学报, 23(5):673-685. doi: 10.3969/j.issn.1006-6616.2017.05.005 [37] 吴福元, 李献华, 杨进辉, 等, 2007.花岗岩成因研究的若干问题.岩石学报, 23(6):1217-1238. doi: 10.3969/j.issn.1000-0569.2007.06.001 [38] 武勇, 陈松永, 秦明宽, 等, 2018.西藏班公湖-怒江缝合带西段洞错蛇绿岩中的辉长岩锆石U-Pb年代学及地质意义.地球科学, 43(4): 1070-1087. http://earth-science.net/WebPage/Article.aspx?id=3793 [39] 闫晶晶, 赵志丹, 刘栋, 等, 2017.西藏中拉萨地块晚侏罗世许如错花岗岩地球化学与岩石成因.岩石学报, 33(8):2437-2453. http://d.old.wanfangdata.com.cn/Periodical/ysxb98201708007 [40] 叶春林, 黄柏鑫, 王燚, 等, 2018.西藏中冈底斯扎布耶茶卡北部晚侏罗世则弄群火山岩的锆石U-Pb年代学及其成因意义.高校地质学报, 24(4):525-535. http://d.old.wanfangdata.com.cn/Periodical/gxdzxb201804006 [41] 叶培盛, 吴珍汉, 胡道功, 等, 2004.西藏纳木错西岸蛇绿岩的地球化学特征及其形成环境.现代地质, 18(2):237-243. doi: 10.3969/j.issn.1000-8527.2004.02.014 [42] 叶培盛, 吴珍汉, 胡道功, 等, 2005.西藏永珠-果芒错蛇绿岩的地球化学特征及其构造意义.现代地质, 19(4):508-514. doi: 10.3969/j.issn.1000-8527.2005.04.005 [43] 张璋, 耿全如, 彭智敏, 等, 2011.班公湖-怒江成矿带西段材玛花岗岩体岩石地球化学及年代学.沉积与特提斯地质, 31(4):86-96. doi: 10.3969/j.issn.1009-3850.2011.04.013 -
下载:
点击查看大图
图(11)
计量
- 文章访问数: 4002
- HTML全文浏览量: 1581
- PDF下载量: 46
- 被引次数: 0
