扬子地块中太古宙地壳增生:来自黄陵背斜南部地区花岗闪长质片麻岩的证据  

Mesoarchean Crustal Accretion of the Yangtze Block: Evidence from the Granodioritic Gneiss in the Southern Huangling Anticline

作　　者：王庆 蒋幸福 WANG Qing;JIANG Xingfu(Xi’an Research Institute Co.Ltd.,China Coal Technology and Engineering Group,Xi’an,Shaanxi 710077,China;School of Earth Sciences,East China University of Technology,Nanchang,Jiangxi 330013,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang,Jiangxi 330013,China)

机构地区：[1]中煤科工集团西安研究院有限公司,陕西西安710077 [2]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [3]东华理工大学地球科学学院,江西南昌330013

出　　处：《现代地质》2023年第2期433-442,共10页Geoscience

基　　金：东华理工大学核资源与环境国家重点实验室开放基金项目(NRE 1911);东华理工大学博士启动基金项目(DHBK2015321);江西省教育厅科技项目(GJJ190375)。

摘　　要：扬子地块黄陵背斜南部出露的花岗闪长质片麻岩是太古宙TTG片麻岩的重要组成单元,具有高Al2O3、Na2O、Sr以及低Rb、Nb等特征,属于高铝TTG系列,且具埃达克质岩石属性。结合片麻岩微量元素蛛网图显示的Nb、Ta和Hf等高场强元素富集以及Th、Pb和U等大离子亲石元素亏损的特征,本文认为该岩石形成于俯冲环境下玄武质洋壳的部分熔融作用。黄陵背斜北部出露的2.9~3.0 Ga TTG片麻岩和弧性质角闪岩,反映该时期是扬子地块陆壳生长的一次重要阶段,且以洋壳俯冲产生岛弧或安第斯型岩浆作用的陆壳水平增生为主,通过微陆块拼贴或规模较小的板块构造模式而形成。Granodioritic gneiss in the southern Huangling anticline of the Yangtze block is an important component of the Mesoarchean tonalite-trondhjemite-granodiorite(TTG)gneisses of the block.Geochemical results show that the granodioritic gneiss possesses high contents of Al2O3,Na2O,Sr,and low values of Rb and Ta,which is classified as the high-Al TTG rock series.Moreover,geochemical features of the gneiss are consistent with adakite affinity.In combination with the enrichment of the HFSE(Nb,Ta,and Hf)and depletion of LILE(Th,Pb,and U)on the primitive mantle normalized diagrams of the granodioritic gneiss,indicating that the gneiss could be generated from partial melting of the basaltic oceanic crust during subduction process.Based on the documented 2.9-3.0 Ga TTG gneisses and arc-affinity amphibolite in the northern Huangling anticline,it is proposed that the 2.9-3.0 Ga TTG gneisses in the Huangling anticline represent an event of continental crustal growth of the Yangtze block by horizontal crustal accretion of the micro-continent or small-scale plate tectonics during the subduction process.

关 键 词：扬子地块 黄陵背斜南部 花岗闪长质片麻岩 高铝TTG系列 地壳增生 

分 类 号：P588.12[天文地球—岩石学]