Petrology, geochemistry and tectonic setting of the Panan intrusion in Mamen, Sangri,Tibet
-
摘要: 帕南岩体位于西藏桑日县马门地区，主要由二长花岗岩、二长岩组成。本文通过锆石U-Pb年代学、岩石地球化学和Sr-Nd同位素等研究，探讨其构造背景和岩石成因。LA-ICP-MS锆石U-Pb定年表明，帕南岩体的成岩年龄为80.91±0.48Ma，形成时代为晚白垩世。帕南岩体地球化学特征表现为富钠、高钾、高铝、低钛，属准铝质高钾钙碱性-钾玄岩岩石系列。稀土分馏较明显且富集轻稀土（（La/Yb）N=8.88~11.86），具负Eu异常，相对富集大离子亲石元素，亏损Nb、Ta、P、Ti等高场强元素。Sr-Nd同位素显示，样品具较高的Pb、Sr、Sm、Nd含量，偏低的ISr值（0.70442~0.70486），正εNd（t）值（+1.99~+2.73）。综合帕南岩体的地质、地球化学和年代学特征，认为帕南岩体形成于晚白垩世新特提斯洋向北俯冲背景下的岛弧环境，可能是新特提斯洋俯冲角度变缓进入了平板俯冲阶段之后，由陆壳发生部分熔融产生的正常岛弧岩浆形成，同时也预示着109～80Ma的大规模岩浆活动在该区的落幕。Abstract: The Panan intrusion is mainly composed of monzogranite and monzonite. It is calc-alkaline potassic basanite rock. The zircon LA-ICP-MS U-Pb dating of the Panan intrusive rocks yields a crystallization age of 80.91±0.48Ma, indicating the Panan intrusion was formed in Late Cretaceous. Geochemically, Panan intrusive rocks are rich in large ion lithophile elements and poor in high field-strength elements. The REEs of the rocks are obviously fractionated, with a (La/Yb)N=8.88~11.86 value and a negative Eu anomaly. The Sr-Nd isotopic compositions indicate that the Panan intrusion is characterized by high Pb, Sr, Sm and Nd contents, a low ISr value (0.70442~0.70486), and a positive εNd(t) value (+1.99~+2.73).Based on petrological, geochemical and chronological characteristics, the Panan intrusion may be formed from the normal island arc magma by the partial melting of continental crusts in an island background during the northward subduction of Neo-Tethys oceanic plate. With the development of the subduction angle of the Neo-Tethys ocean slowed down into almost zero degree in the Late Cretaceous, the large-scale magmatic activities in 109-80 Ma ended in the studied areas soon.
-
Key words:
- Panan intrusion /
- adamellite /
- rock geochemistry /
- zircon U-Pb age /
- horizontal subduction
-
-
[1] Ying,A.,Harrison,T.M. Geologic Evolution of the Hi-Malayan-Tibetan Orogen[J].Annual Review of Earth hand Planetary Sciences,2000,28(1):211-280.
[2] 潘桂棠,莫宣学,侯增谦,等.冈底斯造山带的时空结构及演化[J].岩石学报,2006,22(3):521-533.
[3] 莫宣学.岩浆作用与青藏高原演化[J].高校地质学报,2001,17(3):351-367.
[4] 纪伟强,吴福元,钟孙霖,等.西藏南部冈底斯岩基花岗岩时代与岩石成因[J].中国科学(D辑),2009,39(7):849-871.
[5] 李光明,刘波,佘宏全,等.西藏冈底斯成矿带南缘喜马拉雅早期成矿作用——来自冲木达铜金矿床的Re-Os同位素年龄证据[J].地质通报,2006,25(12):1481-1486.
[6] 李光明,段志明,黄勇,等.西藏冈底斯-喜马拉雅地质与成矿[M].武汉:中国地质大学出版社,2017.
[7] 康志强,许继峰,陈建林,等.藏南白垩纪桑日群麻木下组埃达克岩的地球化学特征及其成因[J].地球化学,2009,38(4):334-344.
[8] 康志强,许继峰,陈建林,等.西藏南部桑日群火山岩的时代:来自晚期马门侵入体的约束[J].地球化学,2010,39(6):520-530.
[9] 代作文,李光明,丁俊,等.西藏努日晚白垩世埃达克岩:洋脊俯冲的产物[J].地球科学,2018,43(8):2727-2741.
[10] 赵珍,吴珍汉,胡道功,等.青藏高原冈底斯带南缘泽当多金属矿田多期岩浆活动及年代意义[J].地球学报,2014,35(6):703-712.
[11] 董随亮,黄勇,李光明,等.藏南努日铜-钨-钼矿床晚白垩世石英闪长岩U-Pb定年及其地球化学特征[J].岩矿测试,2015,34(6):712-718.
[12] 姚兴华,张志平,汪宏涛,等.西藏桑日县马门晚白垩世O型埃达克岩年代学、地球化学及构造意义[J].矿产勘查,2019,(6):1327-1338.
[13] Song SG, Su L, Li XH, et al. Tracing the 850Ma continental flood basalts from a piece of subducted continental crust in the North Qaidam UHPM belt, NW China[J].Precambrian Research,2010,183(4):805-816.
[14] Chen F, Siebel W, Satir M, et al. Geochronology of the Karaderebasement(NW Turkey) and implications for the geological evolution of the Istanbul zone[J].International Journal of Earth Sciences, 2002,91(3):469-481.
[15] Ludwig K R.ISOPLOT 3.0:A Geochronological Tool kit for Microsoft Excel[M].Berkeley Geochronology Center,California Berkeley,2003:39.
[16] Maniar P D, Piccoli P M. Tectonic discrimination of grnitoids[J].Geological Society of America Bulletin, 1989,101:635-643.
[17] Middlemost E A K.Magas and magmatic Rocks[M].London:Longman,1985:1-266.
[18] Peccerillo J,Taylor S R. Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonuarea, Northern Turkey[J].Contributions to Mineralogy and Petrology,1976,58:63-81.
[19] Sun S S, McDonough W F. Chemical and isotopic systematics of oceanic basalt:implications for mantle composition and processes[C].Geological Society,London,Specical Publications,1989,42:528-548.
[20] Pearce J A, Harris N B W, Tindle A G. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[J].Journal of Petrology,1984,25:956-983.
[21] Taylor S R,Mclennan S M.The continental crust;Its composition and evolution[M].Oxford;Blackwell Scientific Publication,1985:1-312.
[22] 韩吟文,马振东.地球化学[M].北京:地质出版社,2003.
[23] 王中刚.稀土元素地球化学[M].北京:地质出版社,1992.
[24] Zi-Qi Jiang,Qiang Wang,Derek A. Wyman,et al. Transition from oceanic to continental lithosphere subduction in southern Tibet:Evidence from the Late Cretaceous-Early Oligocene(~91-30Ma) intrusive rocks in the Chanang-Zedong area,southern Gangdese[J].Lithos,196-197(2014):213-231.
[25] Williarns I S. Some observations On the use of zircon U-Pb geochronology in the study of granitc rocks[J]. Trans. R. Soc.Edinburgh-Earth Sci.,1992,83:447-458.
[26] Belousova E A, 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.
[27] 张丽莹,黄丰,许继峰,等.西藏山南地区花岗质岩石成因及其对地壳结构变化的记录[J].地球科学,2019,44(6):1822-1833.
[28] Setsuya Nakada and Masaki Takahashi. Regional variationin chemistry of the Miocene intermediate to felsic magmas in the Outer Zone and the Setouchi Province of Southwest Japan[J].The Geological Society of Japan,1979,85(9):571-582.
[29] Collins W,Beams S,White A,et al. Nature and Origin of A-type Granites with Particular Reference to Southeastern Australia[J].Contributions to Mineralogy and Petrology,1982,80(2):189-200.
[30] 吴福元,李献华,杨进辉,等.花岗岩成因研究的若干问题[J].岩石学报,2007,23(6):1217~1238.
[31] Li Xianhua,Li Wuxian,Li Zhengxiang.On the genetic classification and tectonic implications of the Early Yanshanian granitoids in the Nanling Range,South China[J].Chinese Science Bulletin,2007, 52(14):1873-1895.
[32] Bea F,Fershtater G,Corretgé L G.The geochemistry of phosphorus in granite rocks and the effect of aluminium[J].Lithos,1992,29(1-2):43-56.
[33] Chappell B W.Aluminium saturation in I-and S-type granites and the characterization of fractionated haplogranites[J].Lithos,1999,46(3):535-551.
[34] 李昌年.火成岩微量元素岩石学[M].武汉:中国地质大学出版社,1992.
[35] Taylor S R, McLennan S M. The geochemical evolution of the continental crust[J].Reviews of Geophysics,1995,33(2):241-265.
[36] Pfander J A, Muinker C, Stracke A and Mezger K. Nb/Ta and Zr/Hf in ocean island basalts-Implications for crust-mantle differentiation and the fate of Niobium[J].Earth and Planetary Science Letters, 2007, 254(1):158-172.
[37] 陈德潜,陈刚.实用稀土元素地球化学[M].北京:冶金工业出版社,1990.
[38] McKenzie, D., Bickle, M.,.The volume and composition of melt generated by extension of the lithosphere[J]. Journal of Petrology,1988,29:625-679.
[39] Foley S, Tiepolo M,Vannucci R. Growth of early continental crust controlled by melting of amphibolite in subduction zones[J].Nature,2002,417(6891):837-840.
[40] Wen D R, Chung S L, Song B, et al. Late Cretaceous Gangdese intrusions of adakitic geochemical characteristics,SE Tibet:Petrogenesis and tectonic implications[J].Lithos,2008,105(1/2):1-11.
[41] Wen D R,Liu Dunyi,Chung Sun-lin,Chu Mei-fei,Ji Jianqing,Zhang Qi,Song Biao,Lee Tung-yi,Yeh Meng-wang,Lo Ching-hua.Zircon SHRIMP U-Pb ages of the Gandese Batho-lith and implications for Neotethyan subduction in southern Tibet[J].Chem Geol,2008,252(3/4):191-201.
[42] 韦栋梁,夏斌,周国庆,等.西藏泽当英云闪长岩的地球化学和Sr-Nd同位素特征:特提斯洋内俯冲的新证据[J].中国科学,2007,42(5):1515-1534.
[43] Chen,L.,Qin,K.Z.,Li,G.M., et al. Zircon U-Pb Ages Geochemistry and Sr-Nd-Pb-Hf Isotopes of the Nuri Intrusive Rocks in the Gangdese Aera, Southern Tibet:Constraints on Timing, Petrogenesis,and Tectionic Transformation[J].Lithos,2015,212-215:379-396.
[44] 梁华英,魏启荣,许继峰,等.西藏冈底斯矿带南缘矽卡岩型铜矿床含矿岩体锆石U-Pb年龄及意义[J].岩石学报,2010,26(6):1692-1698.
[45] 侯增谦,杨竹森,徐文艺,等.青藏高原碰撞造山带:Ⅰ.主碰撞造山成矿作用[J].矿床地质,2006,25(4:):337-358.
-
计量
- 文章访问数: 1376
- PDF下载数: 100
- 施引文献: 0
下载: