湘南骑田岭岩体芙蓉超单元的锆石SHRIMPU-Pb年龄及其地质意义  

SHRIMP U-Pb dating of the Furong unit of Qitangling granite from southeast Hunan province and their geological implications.

作　　者：赵葵东[1] 蒋少涌[1] 姜耀辉[1] 刘敦一[2] 

机构地区：[1]南京大学地球科学系成矿作用国家重点实验室,南京210093 [2]北京离子探针中心

出　　处：《岩石学报》2006年第10期2611-2616,共6页Acta Petrologica Sinica

基　　金：基金委优秀创新群体基金项目(40221301);教育部科学研究重大项目(306007)的资助

摘　　要：湘南骑田岭花岗岩体由于与钨锡矿化关系密切而越来越引起人们的关注。骑田岭花岗岩体是一个多阶段侵入的复式岩体,分莱岭、芙蓉和荒塘岭三个超单元。本文报道了对该岩体主体芙蓉超单元的锆石 SHRIMP U-Pb 定年结果。两个花岗岩样品中岩浆结晶锆石的定年结果分别为155.5±1.3Ma(MSWD=1.7)和157.1±1.2 Ma(MSWD=1.7)。这代表了该超单元的形成年龄,这一年龄与莱岭超单元的形成年龄(159-160Ma)也较接近,表明两个超单元可能是同源分异的产物。这次研究同时揭露了古元古代残留锆石核的存在(2445Ma 和1708Ma),为古元古代华夏地块的存在提供了直接的证据,也证实该地区中生代岩浆作用有古老下地壳物质的参与同时也发现了907Ma 的变质锆石残留,其形成可能与扬子地块和华夏地块的碰撞拼贴有关,同时为杭州-诸广山-花山这-低 T_(DM)值花岗岩带可能是扬子地块和华夏地块在新元古代时的一条板块碰撞带提供了证据。The Qitianling granitic stock is located in the southeast Hunan Province, South China. Recently, a giant tin deposit, the Furong, has been found in the southern part of the granite. This granite stock can be divided into three units ; the Cailing, Furong and Huangtangling granites. Detailed SHRIMP U-Pb geochronology of zircons from the Furong granite is reported in this paper, which yield ^206Pb/^238U ages of 155.5 ± 1.3 Ma （ MSWD = 1.7 ） and 157.1 ± 1.2 Ma （ MSWD = 1.7 ） , respectively. This age is consistent with that of the Cailing granites （159 - 160 Ma） , suggesting both of them were emplaced at the same time. Inherited zircon cores yield Paleo- and Meso-Proterozoic ages of 2445 ± 29 Ma and 1708 ± 23 Ma, indicating the presence of Paleo- to Meso-Proterozoic component in the deep crust of this region. An inherited metamorphic zircon was found which yields an age of 907 ± 4. 8 Ma, which is consistent with the age of collision between Yangtze Block and Cathaysia Block. These data further support that the high εNd （ t ） and low TDM Shi-Hang belt in South China may have originated from a collision zone during Neoproterozoic time between Yangtze and Cathaysia blocks.

关 键 词：湘南 骑田岭 锆石 SHRIMP U—Pb定年 

分 类 号：P597.3[天文地球—地球化学]