三江地区澜沧江带南段南林山基性岩体锆石U-Pb年龄及岩石地球化学特征  

Precise ID-TIMS zircon U-Pb age and whole-rock geochemistry of the Nanlinshan mafic intrusion in the southern Lancangjiang arc terrane,Sanjiang area,SW China

作　　者：李钢柱[1,2,3] 苏尚国[1,2] 雷玮琰[1,2] 段向东 

机构地区：[1]地质过程与矿产资源国家重点实验室 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]武警黄金第二支队,内蒙古呼和浩特010010 [4]云南省地质调查局,云南昆明650051

出　　处：《地学前缘》2011年第5期206-212,共7页Earth Science Frontiers

基　　金：国家重点基础研究发展计划"973"项目(2009CB421008);中国地质大学(北京)特聘教授科研启动基金项目(51900902006)

摘　　要：南林山基性岩体位于西南三江地区,岩体主要由辉长岩和闪长岩组成。通过ID-TIMS锆石U-Pb年代学方法对南林山岩体中闪长岩进行精确定年,获得其结晶年龄为(298.44±0.33)Ma,表明南林山基性岩体的形成时代为早二叠世。全岩主量、微量元素与稀土元素等研究表明,辉长岩和闪长岩总体上均呈现轻稀土元素(LREEs)相对于重稀土元素(HREEs)适度富集,高场强元素Nb、Ta、Zr、Hf等亏损的特征。这些特征与大洋岛弧的特征相吻合。因此,我们提出南澜沧江构造带在早二叠世早期为大洋岛弧俯冲带的新认识。The Nanlinshan gabbroic intrusion occurred in the southern Lancangjiang arc terrane,Sanjiang area,SW China,which consists of gabbro and diorite.The U-Pb age of zircons from the diorite determined by ID-TIMS is 298.44±0.33 Ma.The diorite and gabbro samples are all characterized by moderate enrichment of light rare-earth elements relative to heavy rare-earth elements and depletion in some high field strength elements such as Nb,Ta,Zr,and Hf.These characteristics are similar to that of the island arc,and the Nanlinshan intrusion can be considered as an evidence for intra-oceanic subduction in the Early Permian in the region.

关 键 词：U-PB年龄 锆石 ID-TIMS 岛弧 南林山 澜沧江 

分 类 号：P588.124[天文地球—岩石学] P597.3[天文地球—地质学]