第30卷
第5期
2016年10月
现代地质 GEOSCIENCE
云南保山东缘早古生代高Si花岗岩
的成因及构造意义
康欢，李大鹏"2，陈岳龙'，鲁震
Vol.30Na.5 Oet.2016
（0008000（）摘要：对保山地块东缘高Si花岗岩开展矿物化学、岩石地球化学及错石U-Pb-Hf系统研究，结果表明该高Si花岗岩为具钙碱性、强过铝质特征的S型花岗岩。锆石U-Pb同位素分析表明，高Si花岗岩侵位于454Ma，并含有800~1100 Ma的继承结石。锆石Hf同位素分析表明其岩浆错石具有与青藏高原及东南缘同时代长英质侵人体相似的Hf同位素组成，暗示其相似的岩浆起源。矿物化学、同位素组成及Melts模拟计算结果表明，保山东缘高Si花岗岩为一系列复杂作用的结果：高硅花岗岩母岩浆起源于该区沉积岩部分熔融；熔体形成后经高度分异演化，在侵位过程中同化混染围岩；岩浆冷凝至固相线下部分矿物再平衡。保山东缘高S花岗岩体与平河花岗岩体具相似年龄和地球化学特征，暗示它们之间可能存在类似的成因机制。
关键词：高Si花岗岩；保山地块；青藏高原；三江地区；原特提斯洋
中图分类号：P588.12*1；P597*.3
文献标志码：A
文章编号：10008527(2016)05102612
Origin and Tectonic Implications of the Early Paleozoic High-Si
GraniteintheEasternBaoshanBlock,Yunnan
KANG Huan', LI Dapeng', CHEN Yuelong', LU Zhen
(1. School of Earth Sciences and Resourees, China Unitersity of Geosciences, Bejing100083, China;
2. The Bejing SHRIMP Center, Institude of Grology, Chinese Academy gf Geological Sciences, Bejing100037, Chine)
Abstract: Integrated mineral chemistry, geochemistry and zircon U-Pb-Hf isotopic analyses were carried out on the high-Si granite in the eastern Baoshan block. Results show that the high-Si granite is S-type and shows calc alkaline, strongly peraluminous features., Zircon U-Pb isotopic analyses show that the high-Si granite emplaced at 454 Ma with 800 to 1,100 Ma inherited zircon grains. Magmatic zircons from the high-Si granite in the east-ermn Baoshan show similar Hf isotope compositions with those from coveal felsic intrusions in the Tibetan Plateau and its southeasterm margin, implying their similar magmatic origin. Lines of evidence including mineral chem istry, zircon Hf isotopes, and geochemical simulation show a complex history of the high-Si granite in easterm Baoshan : the parental magmas of the high-silica granite originated from partial melting of the regional sedimenta ry rocks; the melts underwent high-degree differentiation, and then assimilated wall-rock during emplacement; some minerals experienced solid-state re-equilibration after cooling. Similarities of the high-Si granite in easterm Baoshan and the coeval Pinghe batholithin geochemical features imply their parallel processes of their petrogene-sis.
Key words: high-Si granite; Baoshan block; Tibetan Plateau; Sanjiang region; Proto-Tethyan Ocean
收稿日期：2016-05-17；改回日期：2016-06-30；责任编辑：楼亚儿。
基金项目：国家自然科学基金项目（41502212）；北京市青年英才项目（YETP0664）；中央高校基本科研业务费优秀教师项目
(2652015013）；图家科技基础条件平台北京离子探针中心开放基金课题（DD12-118）。
作者简介：康欢，男，硕士研究生，1991年出生，地质工程专业，主要从事区域地球化学研究。
Email:Khuan351002@163.eom。
通信作者：李大鹏，男，副教授，博士，1983年出生，地球化学专业，主要从事区域地球化学研究和教学工作。
Email: dpli@ cugb. edu, cn.