Geochronology, Geochemistry and Hf Isotope Characteristics of Yanchangbeishan Granodiorite of Lenghu Area in Qinghai
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摘要: 盐场北山花岗闪长岩位于柴北缘西端青海冷湖地区.岩体高Si(71.19%~71.81%),富Na(4.52%~4.85%).铝饱和指数平均为1.02,属弱过铝质花岗岩.岩体富集大离子亲石元素(K、Rb、Sr、Th),亏损高场强元素(Nb、Ta),具弧型花岗岩特征.LA-ICP-MS锆石U-Pb测年结果表明岩体形成于(265±2) Ma.锆石Hf同位素初始比值176Hf/177Hf分布于0.282 962 0~0.283 048 7,并具有的正εHf(t)值(12.54~15.19),其平均两阶段模式年龄TDM2(Hf)为367 Ma,反映岩体源区可能为新生的镁铁质下地壳,另外,εHf(t)基本位于亏损地幔演化线附近,指示该玄武质下地壳来源于亏损地幔.结合区域地质背景和岩石地球化学特征,认为盐场北山花岗闪长岩与泥盆纪镁铁-超镁铁岩有关,由于宗务隆裂谷小洋盆的向南俯冲,引发其上覆玄武质新生地壳发生熔融形成,进而揭示晚二叠世末柴北缘处于火山弧或活动陆缘的构造环境.Abstract: Granodiorite develops in Yanchangbeishan of Lenghu area in Qinghai, which is located in the west segment of the north margin of Qaidam. The samples have higher SiO2 (71.19%-71.81%) and Na2O contents (4.52%-4.85%). The alumina saturation average index is 1.02, indicating that the granodiorite belong to weak peraluminous granites. Moreover, these samples are depleted in HFSEs (Nb, Ta) intensively, rich in LILEs (K, Rb, Sr, Th), reflecting the characteristics of island-arc magma. LA-ICP-MS zircon U-Pb dating shows that the formation age of the rock is 265±2Ma. The zircon Hf isotope analysis reveal 176Hf/177Hf ratios varying in 0.282 962 0 to 0.283 048 7, with high positive εHf(t) (12.54-15.19) and two-stage Hf model ages (averaged at 367 Ma). In the 176Hf/177Hf-εHf(t) discrimination diagrams, these zircons were plotted nearly on the depleted mantle evolution line, it can be concluded that the rock chiefly derived from the new basaltic lower crust which is originated from depleted mantle. Based on the regional geological background and the geochemical characteristics of the masses, we consider that Yanchangbeishan granodiorite bears similar characteristics of its primary magma with mafic-ultramafic rocks of Devonian, which were supposed to be originated from partial melting of the overlying basaltic juvenile crust as a result of southward subduction of Zongwulong small oceanic basin. Thereby, it is revealed that the north margin of Qaidam was in volcanic arc or active continental margin tectonic environment during Permian epoch.
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郭安林,张国伟,强娟,等.青藏高原东北缘印支期宗务隆造山带[J].岩石学报,2009,25(1):1-12. Guo Anlin, Zhang Guowei, Qiang Juan, et al., 2009. Indosinian orogenic Belt on the Northeastern Margin of the Qinghai-Tibet Plateau[J]. Acta Peeralagica Sinica, 25(1): 1-12.
寇晓虎,张克信,林启祥,等.秦祁昆接合部二叠纪沉积建造时空分布[J].地球科学,2007, 32(5):681-690. Kou Xiaohu, Zhang Kexin, Lin Qinxiang, er al. The Distribution of Permian Sedimentary Sequences in the Adjacent Area of Qingling-Qilian-Kunlun [J]. Earth Science-Journal of China University of Geosiences, 2007, 32(5):681-690.
李广伟,方爱民,吴福元,等.塔里木西部奥依塔克斜长花岗岩锆石 U-Pb年龄和Hf 同位素研究[J].岩石学报,2009,25(1):166-172. Li Guangwei, Fang Aimin, Wu Fuyuan, et al. Studies on the U-Pb Ages and Hf Isotopes of Zircons in the Aoyrake Plagioclase Granite West Tarin[J]. Acta Petrolgica Sinica, 2009, 25(1): 166-172.
郝国杰,陆松年,王惠初,等.柴达木盆地北缘前泥盆纪构造格架及欧龙布鲁克古陆块地质演化[J].地学前缘,2004,11(3):115-122. Hao Guojie, Lu Songnian, Wang Hhuichu, et al. The Pre-Devonian Tectonic Framework in The Northern Margin of Aidam Basin and Geological Evolution of Olongbuluck Palaeoblock[J]. Earth Science Frontiers (China University of Geosciences,Beijing), 2004, 11(3): 115-122.
柳小明,高山,袁洪林,等.193nm LA-ICPMS对国际地质标准参考物质中42种主量和微量元素的分析[J].岩石学报,2002,18(3):408-418. Liu Xiaoming, Gao Shan, Yuan Honglin, et al. Analysis of 42 Major and Trace Elements in Glass Standard Reference Materials by 193nm LA-ICPMS[J]. Acta Petrologica Sinica, 2002, 18(3): 408-418.
卢欣祥, 孙延贵, 张雪亭,等.柴达木盆地北缘塔塔楞环斑花岗岩的 SHRIMP 年龄[J].地质学报,2007,81(5):626-634. Lu Xinxiang, Sun Yangui, Zhang Xueting, et al. The SHRIMP Age of Tatalin Rapakivi Granite at the North Margin of Qaidam Basin[J]. Acta Geologica Sinica, 2007, 81(5): 626-634. 陆松年,于海峰,李怀坤,等.中国前寒武纪重大地质问题研究-中国西部前寒武纪重大地质事件群及其全球构造意义[M].北京:地质出版社,2006,1-206. Lu Songnian, Yu Haifeng, Li Huaikun, et al. Precambrian Key Issues in China: Precambrian Important Geological Events in West China and Their Global Tectonic Significance[M]. Geological Publishing House, Beijing, 2006, 1-206.
孟繁聪,张建新,杨经绥.柴北缘锡铁山早古生代HP/ UHP变质作用后的构造热事件-花岗岩和片麻岩的同位素与岩石地球化学证据[J].岩石学报,2005,2(1):45-56. Meng Fancong, Zhang Jianxin, Yang Jingsui. Tectonic-Thermal Event of Post HP/UHP Metamorphism in the Xitieshan Area of the North Qaidam Mountains Western China: Isotopic and Geochemical Evidence of Granite and Gneiss[J]. Acta Petrological Sinica, 2005, 21(1): 45-56.
潘桂棠,李兴振,王立全,等.青藏高原及邻区大地构造单元初步划分[J].地质通报,2002,21(11):701-706. Pan Guitang, Li Xingzhen, Wang Liquan, et al. Prelinminary Division of Tectonic Units of the Qinghai-Taibet Plateau and Its Adjacent Regions[J]. Geological Bulletin of China, 2002, 21(11):701-706.
青海省地质矿产局.青海省区域地质志[M].北京:地质出版社,1991,1-662. 青海省地质矿产局.青海省岩石地层[M].北京:中国地质大学出版社,1997,1-340. 孙延贵,张国伟,王谨,等.秦-昆结合区两期基性岩墙群40Ar/39Ar定年及其构造意义[J].地质学报,2004,78(1):65-71. Sun Yangui, Zhang Guowei, Wang Jin, et al. 40Ar/39Ar Age of the Basic Sill Swarms of Two Periods in the Junction Area of Qinling End Kunlun and Its Tectonic Significance[J]. Acta Geologica Sinica, 2004, 78(1): 65-71. 王德滋,周新民.中国东南部晚中生代花岗质火山-侵入杂岩成因与地壳演化[M].北京:科学出版社,2002, 160-188. Wang Dezi, Zhou Xinmin. Crustal Evolution and Petrogenesis of Late Mesozoic Granitic Volcanic-Intrusive Complexes in Southeastern China[M]. Science Press, Beijing, 2002,160-188.
王绘清,朱云海,林启祥,等.西秦岭同仁隆务峡蛇绿岩矿物成分特征及构造环境[J].岩石矿物学杂志,2009,28 (4):316-328. Wang Huiqing, Zhu Yunhai, Lin Qixiang. Mineral Characteristics and Tectonic Environment of Longwuxia Gorge Ophiolite in Tongren, West Qinling Area[J]. Acta Petrologica ET Mineralogica, 2009, 28(4): 316-328.
王绘清,朱云海,林启祥,等.青海尖扎-同仁地区隆务峡蛇绿岩的形成时代及意义-来自辉长岩锆石LLA-ICP-MS U-Pb年龄的证据[J].地质通报,2010,29(1):86-92. Wang Huiqing, Zhu Yunhai, Lin Qixiang, et al. LA-ICP-MS Zircon U-Pb Dating of the Gabbro From Longwu Gorgeophiolite, Jianzha-Tongren Area, Qinghai, China and Its Geological Significance[J]. Geological Bulletin of China, 2010, 29(1):86-92.
王培俭,王增寿.青海"中吾农山群"及其有关几个问题的讨论[J].青海地质,1980,(3):. Wang Peijian, Wang Zengshou. Discussion of Several Problems of Zhongwulongshan Group in Qinghai[J]. Geology of Qinghai,1980,(3). 王毅智,拜永山.青海天竣南山蛇绿岩的地质特征及其形成环境[J].青海地质,2001,21(1):29-35. Wang Yizhi, Bai Yongshan. Geological Characteristics of Tianjunnanshan Ophiolite in Qinghai End Its Forming Environment[J]. Qinghai Geology, 2001, 21(1):29-35.
吴才来,郜源红,吴锁平,等.柴北缘西段花岗岩锆石 SHRIMP U-Pb 定年及其岩石地球化学特征[J].中国科学D辑,2008,38(8):930-949. Wu Cailai, Gao Yuanhong, Wu Suoping, et al. Zircon SHRIMP U-Pb Dating and Geochemical Characteristics of Granites From the Western of the North Margin of Qaidam[J]. Sci China Ser D, 2008, 38(8): 930-949.
吴才来,郜源红,吴锁平,等.柴北缘大柴旦地区古生代花岗岩锆石SHRIMP 定年[J].岩石学报,2007,23(8):1861-1875. Wu Cailai, Gao Yuanhong, Wu Suoping, et al. Zircon SHRIMP U-Pb Dating of Granites From the Da Qaidam are in the North Margin of Qaidam Basin,NW China[J]. Acta Petrologica Sinica, 2007, 23(8):1861-1875.
吴才来,杨经绥, Wooden J L,等.柴达木北缘都兰野马滩花岗岩锆石SHRIMP定年[J].科学通报,2004,49(16):1667-1672. Wu Cailai, Yang Jingsui, Wooden J L., et al. SHRIMP Zircon Dating of Yematan Granite of North Margin of Qaidam[J]. Chinese Science Bulletin, 2004, 49(16): 1667-1672.
吴才来,杨经绥,Wooden J L,等.柴达木山花岗岩锆石 SHRIMP 定年[J].科学通报,2001c,46(20):1743-1747. Wu Cailai, Yang Jingsui, Wooden J L., et al. SHRIMP Zircon Dating of Chaidamushan Granite[J]. Chinese Science Bulletin, 2001c, 46(20): 1743-1747.
吴才来,杨经绥,李海兵,等.祁连南缘嗷唠山花岗岩 SHRIMP 锆石年龄及其地质意义[J].岩石学报,2001a,17(2):215-221. Wu Cailai,Yang Jingsui, Trewor Ireland., et al. Zircon SHRIMP Ages of Aolaoshan Granite from the South Margin of Qilianshan and Its Geological Significance[J]. Acta Petrologica Sinica, 2001a, 17(2): 215-221.
吴才来,杨经绥,王志红,等.柴达木盆地北缘西端冷湖花岗岩[J].中国区域地质,2001b,20(1):67-81. Wu Cailai, Yang Jingsui, Wang Zhi-hong, et al.The Lenghu Granitoids at the Western End of the Northern Marlin of the Qaidam Basin[J]. Qinghai. Regional Geology of China, 2001b, 20(1): 67-81.
吴锁平,王梅英,戚开静.A型花岗岩研究现状及其评述[J].岩石矿物学杂志,2007,26(1):57-66. Wu Suoping, Wang Meiying, Qi Kaijing. Present Situation of Researches on A-Type Granites: A Review[J]. Acta Petrologica Et Mineralogica, 2007, 26 (1):57-66.
吴福元,李献华,郑永飞,等. Lu-Hf同位素体系及其岩石学应用[J].岩石学报,2007,23 (2):185-220. Wu Fuyuan, Li Xianhua, Zheng Yongfei, et al. Lu-Hf Isotopic Systematics and Their Applications in Petrology[J]. Acta Petrologica Sinica, 2007, 23(2):185-220.
辛后田,王惠初,周世军.柴北缘的大地构造演化及其地质事件群[J].地质调查与研究,2006,29(4):311-320. Xin Houtian, Wang Huichu, Zhou Shijun. Geological Events and Tectonic Evolution of the North Margin of the Qaidam Basin[J]. Geological Survey And Research, 2006, 29(4): 311-320.
袁桂邦,王惠初,李惠民,等.柴北缘绿梁山地区辉长岩的锆石U-Pb年龄及意义[J].前寒武纪进展与研究,2002,25(1):37-40. Yuan Guibang, Wang Huichu, Li Huimin, et al. Zircon U-Pb Age of the Gabbros in Luliangshan Area on the Northern Margin of Qaidam Basin and Its Geological Implication[J]. Progress in Precambrian Rsearch, 2002, 25(1): 37-40.
袁洪林,吴福元,高山,等.东北地区新生代侵入体的锆石激光探针U-Pb年龄测定与稀土元素成分分析[J].科学通报,2003,48(14):1511-1520. Yuan Honglin, Wu Fuyuan, Gao Shan, et al.Zircon U-Pb Dating and REE Component Analysis of Intrusion Cainozoic in Dongbei Area[J]. Chinese Science Bulletin, 2003, 48(14): 1511-1520.
张克信,朱云海,林启祥,等.青海同仁县隆务峡地区首次发现 镁铁质-超镁铁质岩带[J].地质通报,2007,26(6):661-667. Zhang Kexin, Zhu Yunhai, Lin Qixiang, et al. Discovery of A Mafic-Ultramafic Belt in the Rongwoxia Area, Tongren, Qinghai, China[J]. Geologial Bulletin of China, 2007, 26(6): 661-667.
张旗,王焰,熊小林,等.埃达克岩和花岗岩:挑战与机遇[M].北京:中国地质大学出版社,2008:45-68. Zhang Qi, Wang Yan, Xiong Xiaolin, et al. Adakite and Granite: Challenge and Opportunity[M]. China University of Geoscience Press, Beijing, 2008, 45-68.
张以茀.对青海地质构造若干基本特征的认识[A].青藏高原地质文集,1982,3. Zhang Yifo. Understanding of Some Basic Characteristics of the Geologic Structural in Qinghai[J]. 1982, Issue 3.
Batchelor R. A., Bowderr P. Petrogenetic Interpretation of Granitoid Rock Series Using Multication Parameters [J]. Chem Geol,, 1985, 48: 43-55.
Chappell B. W. And White A. J. R. Two Contrasting Granite Type [J]. Pac Geol, 1974, 8: 173-174.
Chappell B. W. And White A. J. R. I-and S-Type Granites in the Lachlan Fold Belt Transactions of the Royal Society of Edinburgh [J]. Earth Sci, 1992, 83: 1-26.
Collins W. J., Beans S. D., White A. J. R. Nature and Origin of A Type Granites with Particular Reference to Southeastern Australia. Contrb [J]. Mineral. Petrol., 1982:80-200.
Corfu F. And Stott G. M. Age and Petrogenes is of Two Late Archean Magmatic Suites, Northwestern Superior Province,Canada: Zircon U-Pb and Lu-Hf Isotopic Relations [J].Journal Petrol., 1993, 34: 817-838.
Frost C. D. And Frost B. R. Reduced Rapak Iv I-Type Granites the Tholeiite Connection [J]. Geology, 1997, 25: 647-650.
Gao S., Liu X. M., Yuan H. L., Bodo Hattendorf., et al. Determination of Forty-Two Major and Trace Elements in USGS and NIST SRM Glasses By Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry [J].Geostandard Newsletters, 2002, 26(2): 181-196.
Griffn W. L., Wang X., Jackson S. E. et al. Zircon Chemistry and Magma Genesis, SE China: in-Situ Analysis of Hf Isotopes, Tonglu and Pingtan Igneous Complexes [J]. Lithos, 2002, 61:237-269.
Loiselle M. C., Wones D. R. Characteristics and Origin of Anorogenic Granites [J]. Geological Society of America (Abstracts with Programs), 1979, 11: 468.
Maniar P. D., Piccoli P.M. Tectonic Discrimination of Granitoids. Geol [J]. Soc. Am. Bull., 1989, 101, 635-643.
Pearce J. A., Harris N. B. W., Tindle A. G. Trace Element Discrimination Diagrams for the Tectonic Interpretation of Granitic Rocks [J]. Petrol, 1984, 25: 956-983.
Peter D. K.And Roland M. Lu-Hf and Sm-Nd Isotope Systems in Zircon [J]. Reviews in Mineralogy and Geochemistry, 2003, 53(1):327-341.
Scherer E E, Cameron K. L. and Blicheri-Toft JLu-HI Garnet Geochronology: Closure Temperature Relative to the Sm-Nd System and the Effects of Trace Mineral Inclusions. Geochim [J]. Cosmochim. Acta, 2000, 64:3413-3432. Simonen A. Plutonic Rocks of the Svecfennidea in Finland. Geol. Surv [J]. Finland Bull, 1960, 189 (1): 100-102.
Song S. G., Zhang L. F., Niu Y. L., 2004. Ultra-Deep Origin of Garnet Peridotite From the North Qaidam Ultrahigh-Pressure Belt,Northern Tibetan Plateau, NW China [J]. American Mineralogist. 2004, 90: 1 330-1336.
Sylvester P. J. 1998. Post-Collisional Strongly Peraluminous Granites [J].Lithos, 45(14):29-44.
Whalen J. B., Currie K., Chappell B. W. A-Type Granites: Geochemical Characteristics, Discrimination and Petrogenesis [J]. Contrib Mineral Petro1, 1987, 95: 407-419.
Wu Cailai., Wooden J. L., Rohinson P. T. Geochemisty and Zircon SHRIMP U-Pb Dating of Granitoids from the West Segment of North Qaidam [J]. Science in China； Series D, 2009, 52(11): 1771-1790.
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