新疆东准噶尔库拉比也铜镍矿床含矿岩体的成因及构造意义:年代学、岩石地球化学和Sr⁃Nd⁃Hf同位素证据  

Genesis and Tectonic Significance of Ore Bearing Rock Mass in Kulabiye Cu⁃Ni Deposit,East Junggar,Xinjiang:Evidence from Chronology,Geochemistry and Sr⁃Nd⁃Hf Isotopes

作　　者：汤贺军 孟贵祥[1,2] 王召林 邓震[1,2] 李成文 祁光[1,2] 薛融晖 Tang Hejun;Meng Guixiang;Wang Zhaolin;Deng Zhen;Li Chengwen;Qi Guang;Xue Ronghui(Chinese Academy of Geological Sciences,Beijing 100037,China;China Deep Exploration Center-SinoProbe Center,China Geological Survey&Chinese Academy of Geological Sciences,Beijing 100037,China;No.2 Regional Geological Survey Team of the Xinjiang Bureau of Geology and Mineral Exploration and Development,Changji 831100,China)

机构地区：[1]中国地质科学院,北京100037 [2]中国地质调查局中国地质科学院地球深部探测中心,北京100037 [3]新疆地质矿产开发局第二区域地质调查大队,新疆昌吉831100

出　　处：《地球科学》2022年第9期3192-3209,共18页Earth Science

基　　金：国家重点研发计划专项(No.2018YFC0604002);中国地质调查局项目(No.DD20221643‐6);中国地质科学院基本科研业务费项目(Nos.JKY21021,JKY202122).

摘　　要：新疆北部是中亚造山带的重要组成部分,具有众多含铜‒镍硫化物的镁铁质‒超镁铁质侵入体,是中国第二大铜镍成矿区.库拉比也铜镍矿床位于新疆阿勒泰富蕴县,是继新疆北部最大的铜镍矿(喀拉通克)发现以来,在东准噶尔北缘铜镍矿找矿的新突破.尽管前人对该矿床的地质、地球物理特征进行了总结,提出了矿床成因及找矿标志,但含矿岩体的成因及构造意义等一些关键问题尚未解决.本文对库拉比也含矿岩体进行了岩石学、年代学、岩石地球化学和Sr-Nd-Hf同位素研究.结果表明,库拉比也铜镍矿床含矿岩体主要为辉长岩,表现出轻稀土富集、重稀土亏损的右倾模式,富集大离子亲石元素Ba、U、K,亏损高场强元素Nb、Ta、Ti、Lu.辉长岩的(^(87)Sr/^(86)Sr)_(i)为0.703948~0.704109,ε_(Nd)(t)在5.28~5.74之间,其锆石的^(176)Hf/^(177)Hf和ε_(Hf)(t)变化较大,分别为0.282851~0.283034和+8.6~+15.1,ε_(Hf)(t)平均值为12.9.主微量元素及Sr-Nd-Hf同位素特征显示源区有壳源物质的加入.库拉比也含矿岩体的形成年龄(约278 Ma)与区域性铜镍矿床的矿化年龄一致(约300~270 Ma),很可能形成于后碰撞伸展环境,其初始岩浆可能与软流圈岩浆上涌并导致被交代的地幔楔的部分熔融与岩浆混合有关.库拉比也成岩成矿时代揭示了早二叠世与铜镍成矿相关的岩浆活动在东准噶尔地区广泛发生,东准噶尔北缘具有很好的铜镍找矿潜力.Northern Xinjiang is the second largest Cu-Ni metallogenic area in China as an important part of the Central Asian Orogenic Belt with many mafic-ultramafic intrusions containing Cu-Ni sulfide.Kulabiye Cu-Ni deposit located in Fuyun County,Xinjiang is a new breakthrough in Cu-Ni prospecting in the northern margin of East Junggar after the largest Cu-Ni deposit(Kalatongke)in northern Xinjiang.Although the geological and geophysical characteristics of the deposit have been summarized and the genesis and prospecting criteria of deposit have been put forward in the previous studies,some key problems such as the genesis and tectonic significance of the ore bearing rock mass have not been solved.In this paper,the petrology,geochronology,chemistry and Sr-Nd-Hf isotope of Kulabiye ore bearing rock mass are studied.The ore bearing rock mass of Kulabiye Cu-Ni deposit are mainly gabbro.They show the right dipping pattern of LREE enrichment and HREE loss,enriched in LILE Ba,U and K,and depleted in HFSE Nb,Ta,Ti and Lu.The(^(87)Sr/^(86)Sr)_(i) of gabbro is 0.703948-0.704109,ε_(Nd)(t)is between 5.28 and 5.74,^(176)Hf/^(177)Hf andε_(Hf)(t)varies greatly,ranging from 0.282851 to 0.283034 and+8.6-+15.1.The average value ofε_(Hf)(t)is 12.9.Trace elements and Sr-Nd-Hf isotopes also show the addition of shell source materials in the source area.The formation age of the Kulabiye complex(about 278 Ma)is consistent with the mineralization age of the regional Cu-Ni deposit(about 300-270 Ma).The Kulabiye complex has probably been formed in a post collisional extensional environment,which is related to the upwelling of asthenosphere magma and the partial melting and magma mixing of the metasomatic mantle wedge.The diagenetic and metallogenic age of Kulabiye also reveals that magmatic activities related to Cu-Ni mineralization in the Early Permian occurred widely in the eastern Junggar area,and the northern margin of the eastern Junggar has superior Cu-Ni prospecting potential.

关 键 词：铜镍硫化物 Sr‐Nd‐Hf同位素 锆石U‐Pb年代学 后碰撞伸展 东准噶尔 地球化学 

分 类 号：P618[天文地球—矿床学]