Geochemistry and Genesis of Monzonitic Granite from Aikengdelesite Area in East Kunlun, Qinghai
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摘要: 埃坑德勒斯特铜（钼）矿是近年来在东昆仑地区发现的斑岩型铜（钼）矿，矿区位于东昆南复合拼贴带内，花岗斑岩及外围碎裂的二长花岗岩是主要的赋矿围岩。对二长花岗岩进行了岩石地球化学和Sr-Nd同位素研究，讨论了岩浆来源、岩石成因和构造背景。研究表明，岩石富硅，相对富钠贫钙和镁，属钙碱性过铝质系列岩石。岩石明显富集大离子亲石元素（K、Ba、Rb）和活泼的不相容元素（如Th、U），相对亏损高场强元素（Nb、Ta、P、Ti）。样品的ISr值为0.707 05~0.707 37，εNd（t）为-2.2~-1.6，Rb/Sr为0.17~0.32，反映岩浆来源具壳幔混合特点。根据Y+Nb-Rb、La/Nb-Ba/Nb等判别图解及与俯冲有关的蛇绿岩带发育特征，表明该岩体形成于安第斯型活动大陆边缘环境。俯冲作用导致俯冲板片的流体降低熔点和直接交代地幔，使地幔部分熔融形成基性岩浆。幔源岩浆底侵作用提供热能，使基性下地壳物质部分熔融形成花岗质岩浆，其中混入了少量幔源岩浆。Abstract: The Aikengdelesite Cu-Mo deposit is a newly discovered porphyry deposit in the southern compound margin of East Kunlun.The ore bodies are found in granite porphyry and broken monzonitic granite.Based on the studies of geochemistry and Sr-Nd isotope, this paper mainly discusses the petrogenesis, magma source, tectonic setting of the monzonitic granite.The results show that the monzonitic granite is characterized by high SiO2and Na2O, low MgO and CaO contents, belonging to calc-alkaline and peraluminous series groups.The trace elements show the enrichment in LILE (such as K, Ba and Rb)and mobile incompatible elements (such as Th, U), but they are relatively depleted in HFSE (such as Nb, Ta, P, Ti).The results of ISr ratios range from 0.707 05 to 0.707 37, and εNd(t)values vary from -2.2 to -1.6, as well as Rb/Sr ratios from 0.17 to 0.32, indicating that the monzonitic granite was derived with crust-mantle mixed magma.After analyzing the Y+Nb-Rb and La/Nb-Ba/Nbdiagrams, and the Ophiolite belt occurred with ocean subduction, it is suggested that the monzonitic granite was formed in Andean-type active continental margin.Subduction leaded to the subducting slab fluids lower the melting point and directly replace mantle, and then the mantle occur the partial melting to form the basic magma.The basic magma underplated and provided thermo-power.The Aikengdelesite monzonitic granite was finally formed by the partial melting of basic lower crust, which was mixed a small amount of mantle-derived magma.
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Keywords:
- geochemistry /
- Sr-Nd isotopes /
- monzonitic granite /
- Aikengdelesite /
- East Kunlun
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唐仁鲤,罗怀松.西藏玉龙斑岩型铜(钼)矿带地质[M].北京:地质出版社,1995. TANG Renli, LUO Huaisong.Geology of Yulong porphyry Mo (Cu)deposit,Tibet[M].Beijing:Geological Publishing House,1995.
芮宗瑶,张洪涛.试论中国斑岩型矿床系列[J].中国地质科学院院报,1986,14:89-100. RUI Zongyao, ZHANG Hongtao.Porphyry deposit series of China[J].Bulletin of the Chinese Academy of Geology,1986,14:89-100.
郭正府,邓晋福,许志琴,等.青藏东昆仑晚古生代末-中生代中酸性火成岩与陆内造山过程[J].现代地质,1998,12(3):344-352. GUO Zhengfu,DENG Jinfu,XU Zhiqin,et al.LatePalaeozoic-Mesozoic intracontinentalorogenic process and intermediate-acidic igneous rocks from the Eastern Kunlun mountains of northwestern China[J].Geoscience,1998,12(3):344-352.
刘成东,莫宣学,罗照华,等.东昆仑壳-幔岩浆混合作用:来自锆石SHRIMP年代学的证据[J].科学通报,2004,49(6):596-602. LIU Chengdong, MO Xuanxue, LUO Zhaohua, et al.The Eastern Kunlun Crust-mantle magma mingling:evidences from zircon ICP-MS[J].Chinese Science Bulletin,2004,49(6):596-602.
谌宏伟,罗照华,莫宣学,等.东昆仑造山带三叠纪岩浆混合成因花岗岩的岩浆底侵作用机制[J].中国地质,2005,3(33):386-395. CHEN Hongwei, LUO Zhaohua, MO Xuanxue, et al.Upderplating mechanism of Triassic granite of magma mixing origin in the East Kunlun orogenic belt[J].Geology in China, 2005, 3 (33):386-395.
李碧乐,孙丰月,于晓飞,等.东昆中隆起带东段闪长岩U-Pb年代学和岩石地球化学研究[J].岩石学报,2012,28(4):1163-1172. LI Bile, SUN Fengyue, YU Xiaofei, et al.U-Pb dating and geochemistry of diorite in the eastern section from eastern Kunlun middle uplifted basement and granitic belt[J].Acta Petrologica Sinica,2012,28(4):1163-1172.
杨延乾,李碧乐,许庆林,等.东昆仑埃坑德勒斯特二长花岗岩锆石U-Pb定年及地质意义[J].西北地质,2013,46(1):56-62. YANG Yanqian, LI Bile, XU Qinglin, et al.Zircon U-Pb ages and its geological significance of the monzonitic granite in the Aikengdelesite, Eastern Kunlun[J].Northwestern Geology, 2013, 46(1):56-62
杨经绥,许志琴,李海兵,等.东昆仑阿尼玛卿地区古特提斯火山作用和板块构造体系[J].岩石矿物学杂志,2005,24(5):369-380. YANG Jingsui, XU Zhiqin, LI Haibing, et al.The paleoTethyan volcanism and plate tectonic regime in the Anyemaqen region of East Kunlun, northern Tibet Plateau[J].Actapetrological et Mineralogical,2005, 24(5):369-380.
莫宣学,罗照华,邓晋福,等.东昆仑造山带花岗岩及地壳生长[J].高校地质学报,2007,13(3):403-414. MO Xuanxue, LUO Zhaohua, DENG Jinfu, et al.Granitoids and crustal growth in the East-Kunlun orogenicbelt[J].Geological Journal of China Universities,1998,13(3):344-352.
罗照华,邓晋福,曹永清,等.青海省东昆仑地区晚古生代-早中生代火山活动与区域构造演化[J].现代地质,1999,13(1):51-56. LUO Zhaohua, DENG Jinfu, CAO Yongqing, et al.On late Palaeozoic-early Mesozoic volcanism and regional tectonic evolution of eastern Kunlun,Qinghai province[J].Geoscience,1999,13(1):51-56.
GREEN D H.Genesis of Archean Peridotitic magmas and constraints on Archean geothermal gradients and teetonies[J].Geology,1975,3:1-15.
TAYLOR,S.R.,MCLENNAN,S.M.The continental crust:its composition and evolutioneds[M].United States:Blackwell,1985.
SAUNDERS A D, NORRY M J and TARNEY J.Orign of MORB and chemically depleted mantle reservoirs:trace element constraints.J Petrol[M].Special LithosphereIssue, 1988:425-445
WEAVER B L.The origin of ocean island basalt end-member compositions:trace element and isotopic constraints[M].Earth Planet.Sci., 1991,104:3810
PEUCAT J J, VIDAL P, GRIFFITHS J B, et al.Sr, Nd and Pb isotopic sytematics in the Archean low to high grade transition zone of Southern India:Syn-Accretion vs.Post-Accretion Granulites[J].The Joural of Geology, 1989, 97:537-549.
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