塔里木克拉通北缘库鲁克塔格地块太古宙基底组成与地壳演化  

Archean basement composition and crustal evolution of the Kuluketage block in the northern margin of the Tarim Craton

作　　者：朱文斌[1] 林和丰 葛荣峰[1] 董春艳[2] 颉颃强[2] 刘守竭 万渝生[2] ZHU Wenbin;LIN Hefeng;GE Rongfeng;DONG Chunyan;XIE Hangqiang;LIU Shoujie;WAN Yusheng(State Key Laboratory for Mineral Deposits Research,Institute of Continental Geodynamics,School of Earth Sciences and Engineering,Nanjing University,Nanjing,Jiangsu 210093,China;Beijing SHRIMP Center,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]内生金属矿床成矿机制研究国家重点实验室,南京大学大陆动力学研究院、地球科学与工程学院,江苏南京210093 [2]中国地质科学院地质研究所,北京离子探针中心,北京100037

出　　处：《地质学报》2022年第9期3084-3101,共18页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号92162211,41922017,41872191);中国地质调查局项目(编号DD20190009,DD20190358,DD20190370,DD20190003)联合资助的研究成果。

摘　　要：塔里木克拉通太古宙岩石主要出露在库鲁克塔格、北阿尔金、铁克里克和敦煌等四个边缘基底隆起带。库鲁克塔格地块位于塔里木克拉通东北缘,其中有可靠年代学报道的太古宙岩石主要出露在库尔勒、辛格尔、兴地和帕尔岗塔格四个地区。库鲁克塔格地块的太古宙岩石主要由长英质正片麻岩(含TTG片麻岩)和少量以包体产出的斜长角闪岩组成,真正的太古宙表壳岩较少见。本次研究在库尔勒地区对长英质正片麻岩和石英岩开展锆石SHRIMP U-Pb测年分析,2个长英质正片麻岩样品的年龄分别为2695±9 Ma和2705±8 Ma;石英岩样品中的碎屑锆石核最小年龄峰为2513 Ma,石英岩有可能是太古宙沉积岩;上述岩石样品都经历了古元古代早期(1.9~1.8 Ga)高级变质作用。地球化学分析发现,库鲁克塔格地块新太古代长英质片麻岩的原岩有多种岩石类型,这些长英质岩石都形成于与俯冲作用有关的岛弧构造背景。基性的斜长角闪岩和变质辉长岩可能产出于不同的背景,一部分来源于岛弧地幔楔的部分熔融,另一部分则可能来自于大洋板内,以洋脊玄武岩为主。库鲁克塔格地块太古宙岩石具有2.7 Ga和2.5 Ga两个年龄峰值,2.7 Ga岩浆事件主要发生在库鲁克塔格西部地区,锆石的ε(t)值既有正值也有负值,表明这一时期地壳生长和改造同时并存;~2.5 Ga的岩浆活动分布范围较为广泛,全岩ε(t)和锆石ε(t)值以正值为主,暗示这一时期可能存在显著的大陆地壳生长。The Archean rocks of the Tarim Craton are mainly exposed in the four marginal basement uplift belts, namely Kuruktagh, North Altyn Tagh, Tiekelike and Dunhuang. The Kuluketage block is located in the northeastern margin of the Tarim Craton, in which Archean rocks with reliable chronology reports are mainly exposed in Korla, Xinger, Xingdi and Pargangtage regions. Archean rocks in the Kuluketage block are mainly composed of felsic orthogneiss(including TTG gneiss) and a small amount of amphibolite enclaves, and the true Archean supracrustal rocks are rare. In this study, SHRIMP U-Pb zircon dating of felsic orthogneiss and quartzite in the Korla area shows that the ages of felsic orthogneiss are 2695±9 Ma and 2705±8 Ma, respectively. The minimum age peak of detrital zircon cores in a quartzite sample is 2513 Ma, suggesting that the quartzite may be Archaean sedimentary rocks. The above rock samples all experienced high-grade metamorphism of 1.9~1.8 Ga in the early Paleoproterozoic. Geochemical analysis shows that the protoliths of Neoarchean felsic gneiss in the Kuluketage block are of various rock types, all of which formed in island arc tectonic setting related to subduction. The parent mafic magmas of amphibolites and meta-gabbros may be derived from different geological backgrounds, one part from partial melting of subcontinental mantle wedge under arc, the other from oceanic plate, mainly mid-oceanic ridge basalt. The Archaean rocks of the Kuluketage block have two age peaks of 2.7 Ga and 2.5 Ga, and the 2.7 Ga magmatic event mainly occurred in the western part of the Kuluketage block. The ε(t) values of zircons are both positive and negative, indicating that crustal growth and reworking coexisted during this period. The whole-rock ε(t) and zircon ε(t) values are mainly positive, suggesting significant continental crustal growth in this period.

关 键 词：塔里木克拉通 库鲁克塔格地块 太古宙 地壳演化 

分 类 号：P534.2[天文地球—古生物学与地层学] P548[天文地球—地质学]