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对拉萨果嘎布花岗岩类进行了LA-ICP-MS锆石U-Pb年代学和全岩地球化学分析，探讨了成岩时代、岩石成因和源区等。研究结果表明，拉萨果嘎布花岗岩类的LA-ICP-MS锆石U-Pb年龄为(46.5±0.6) Ma～(43.5±0.8) Ma，为始新世岩浆活动的产物，能够代表该区域岩体的成岩时代；拉萨果嘎布花岗岩类属于准铝质-弱过铝质的钙碱性-高钾钙碱性的I型花岗岩，富集Th、U、Hf、Sr、Rb、K等元素，亏损Ba、Ta、Nb、Ti、Y、P等元素，具有弧型岩浆的地球化学属性；经过综合分析后认为，拉萨果嘎布花岗岩类的形成应该与幔源型基性岩浆的底侵作用有关，深部幔源基性岩浆的底侵作用携带了大量的炽热熔融体，导致中下地壳的部分熔融，且在部分熔融过程中深部幔源基性岩浆也参与了花岗质岩浆的演化(即混合作用)，进而形成了始新世花岗岩类。
Abstract：This study conducted LA-ICP-MS zircon U-Pb geochronology and whole-rock geochemical analyses of the Guogabu granitoids in Lhasa. The diagenetic age, petrogenesis, and source area of the granitoids were examined. The results show that the LA-ICP-MS zircon U-Pb ages of the Guogabu granitoids in Lhasa range from(46.5±0.6) Ma to(43.5±0.8) Ma, corresponding to Eocene magmatic activity and representing the diagenetic age of these rocks. The Guogabu granites in Lhasa are classified as quasi-aluminous to weakly peraluminous, calcalkaline to high-potassium calc-alkaline type I granites. These rocks are enriched in Th, U, Hf, Sr, Rb, and K, but depleted in Ba, Ta, Nb, Ti, Y, and P, showing geochemical characteristics of arc-type magmas. Comprehensive analyses suggest that the formation of the Lhasa Guogabu granite involved the intrusion of mantle-derived basic magma at depth, which introduced significant heat and facilitated partial melting of the middle and lower crust. During this process, mantle-derived basic magma also contributed to the evolution of the granitic magma through mixing, ultimately resulting in the formation of Eocene granites.
[1]Zhang Z M, Ding L, Zhao Z D, et al. Tectonic evolution and dynamics of the Tibetan Plateau[J]. Gondwana Research, 2017,41:1-8.
[2]许志琴,李海兵,杨经绥.造山的高原——青藏高原巨型造山拼贴体和造山类型[J].地学前缘,2006,13(4):1-17.
[3]侯增谦,曲晓明,杨竹森,等.青藏高原碰撞造山带:Ⅲ.后碰撞伸展成矿作用[J].矿床地质,2006,25(6):629-651.
[4]徐旺春.西藏冈底斯花岗岩类锆石U-Pb年龄和Hf同位素组成的空间变化及其地质意义[D].北京:中国地质大学,2010.
[5]Wang R, Richards J P, Hou Z Q, et al. Zircon U-Pb age and Sr-Nd-Hf-O isotope geochemistry of the Paleocene-Eocene igneous rocks in western Gangdese:Evidence for the timing of Neo-Tethyan slab breakoff[J]. Lithos,2015(224-225):179-194.
[6]Searle M P, Windley B F, Coward M P, et al. The closing of Tethys and the tectonics of the Himalaya[J]. Geological Society of America Bulletin, 1987,98(6):678-701.
[7]莫宣学,赵志丹,邓晋福,等.印度—亚洲大陆主碰撞过程的火山作用响应[J].地学前缘,2003,10(3):135-148.
[8]莫宣学,董国臣,赵志丹,等.西藏冈底斯带花岗岩的时空分布特征及地壳生长演化信息[J].高校地质学报,2005(3):281-290.
[9]王青.拉萨地体南北两侧碰撞后岩浆作用的岩浆起源和岩石成因[D].北京:中国地质大学,2016.
[10]许志琴,杨经绥,李海兵,等.印度-亚洲碰撞大地构造[J].地质学报,2011,85(1):1-33.
[11]Wang T, Wang X X, Guo L, et al. Granitoid and tectonics[J]. Acta Petrologica Sinica,2017,33(5):1459-1478.
[12]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.
[13]樊炳良,王新然,白涛,等.西藏卡贡地区晚寒武世错多勤石英闪长岩LA-ICP-MS锆石U-Pb年龄及其构造意义[J].地质通报,2020,39(4):471-479.
[14]樊炳良,张鑫利,于涛,等.藏东吉塘复式花岗岩成因——来自锆石U-Pb年龄和地球化学的证据[J].地质通报,2019,38(8):1274-1286.
[15]Liu Y S, Hu Z C, Gao S, et al. In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internalstandard[J]. Chemical Geology, 2008, 257:34-43.
[16]Liu Y S, Gao S, Hu Z C, et al. Continental and oceanic crust recycling-induced melt-peridotite interactions in the Trans-North China Orogen:U-Pb dating, Hf isotopes and trace elements in zircons of mantle xenoliths[J]. Journal of Petrology,2010,51:537-571.
[17]Sun S S, McDonough W F. Chemical and isotopic systematics in ocean basalt:Implication for mantle composition and processes[J].Earth and Planetary Science Letters, 1989,35:429-448.
[18]吴元保,郑永飞.锆石成因矿物学研究及其对U-Pb年龄解释的制约[J].科学通报,2004(16):1589-1604.
[19]纪伟强,吴福元,锺孙霖,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:地球科学),2009,39(7):849-871.
[20]孟元库,许志琴,高存山,等.藏南冈底斯带中段始新世岩浆作用的厘定及其大地构造意义[J].岩石学报,2018,34(3):513-546.
[21]丛源,肖克炎,翟庆国,等.西藏南木林普洛岗岩体锆石定年和Hf同位素特征及其地质意义[J].吉林大学学报(地球科学版),2012,42(6):1783-1795.
[22]丁小稀.西藏南冈底斯东部新生代侵入岩地球化学与年代学[D].北京:中国地质大学,2016.
[23]喻思斌.冈底斯中段始新世复式花岗岩体的成因及其对构造演化的启示[D].南京:南京大学,2017.
[24]Whalen J B, Chappell B W. Opaque mineralogy and maficmineral chemistry of I-and S-type granites of the Lachlan fold belt,southeast Australia[J]. American Mineralogist,1988,73(3-4):281-296.
[25]Chappell B W, White A J R. I-and S-type granites in the Lachlan Fold Belt. Transactions of the Royal Society of Edinburgh[J].Earth Sciences,1992,83(1-2):1-26.
[26]王德滋,刘昌实,沈渭洲,等.桐庐I型和相山S型两类碎斑熔岩对比[J].岩石学报,1993,9(1):44-54.
[27]Boztu D, Harlavan Y, Arehart G B, et al. K-Ar age,whole-rock and isotope geochemistry of A-type granitoids in the Divri iSivas region, eastern-central Anatolia, Turkey[J]. Lithos,2007,97(1-2):193-218.
[28]DePaolo D J, Daley E E. Neodymium isotopes in basalts of the southwest basin and range and lithospheric thinning during continental extension[J].Chemical Geology, 2000,169(1-2):157-185.
[29]Taylor S R , Mclennan S M.The continental crust:its composition and evolution[J].The Journal of Geology, 1985, 94(4):57-72.
[30]Skjerlie K P, Patio Douce A E. The fluid-absent partial melting of a zoisite-bearing quartz eclogite from 1.0 to 3.2 GPa:Implications for melting in thickened continental crust and for subduction-zone processes[J]. Journal of Petrology,2002,43(2):291-314.
[31]Kemp A I S, Hawkesworth C J, Foster G L, et al. Magmatic and crustal differentiation history of granitic rocks from Hf-O isotopes in zircon[J]. Science, 2007,315(5814):980-983.
[32]Hoskin PWO and Schaltegger U. The composition of zircon and igneous and metamorphic petrogenesis[J]. Reviews in Mineralogy and Geochemistry,2003,53(1):27-62.
[33]Schiano P, Monzier M, Eissen J P, et al. Simple mixing as the major control of the evolution of volcanic suites in the Ecuadorian Andes[J]. Contributions to Mineralogy and Petrology,2010,160(2):297-312.
[34]董铭淳,赵志丹,朱弟成,等.西藏林周盆地中酸性脉岩的年代学、地球化学和岩石成因[J].岩石学报,2015,31(5):1268-1284.
[35]邱检生,王睿强,赵姣龙,等.冈底斯中段早侏罗世辉长岩-花岗岩杂岩体成因及其对新特提斯构造演化的启示:以日喀则东嘎岩体为例[J].岩石学报,2015,31(12):3569-3580.
基本信息:
DOI：10.16249/j.cnki.2096-4617.2025.04.006
中图分类号:P597.3;P588.121;P534.613
引用信息:
[1]于涛,李梦月,陈正鹏,等.西藏拉萨果嘎布地区始新世花岗岩类地球化学特征及LA-ICP-MS锆石U-Pb年代学研究[J].高原科学研究,2025,9(04):49-61.DOI:10.16249/j.cnki.2096-4617.2025.04.006.
基金信息:
西藏卡贡地区1:5万四幅区域地质调查项目（DD20160016-21）; 国家自然科学基金项目（41967059）; 西藏大学青年培育基金青苗计划项目（ZDQMJH22-12）;西藏大学自治区级大学生创新创业训练计划项目（S202610694060）
2025-12-15
2025-12-15