冀北赤城花岗岩的锆石SHRIMP年龄及其地质意义  

ZIRCON SHRIMP U-Pb DATING OF GRANITE IN CHICHENG COUNTY,NORTHERN HEBEI PROVINCE AND ITS GEOLOGICAL IMPLICATIONS

作　　者：刘胤[1] 倪志耀[1] 翟明国[2] 石玉若[3] 严刚[1] 卢俊生[1] 

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]中国科学院地质与地球物理研究所,北京100029 [3]中国地质科学院北京离子探针中心,北京100037

出　　处：《矿物岩石》2010年第2期38-44,共7页Mineralogy and Petrology

基　　金：国家自然科学基金项目(40472041;40672128;40234050)

摘　　要：冀北赤城侵位于红旗营子群中的花岗岩体主要有马营的红墩梁、清泉堡的冰山梁、云州水库的舍身崖和镇宁堡的东沟楼等岩体,属于陆壳成因的钙碱性系列花岗岩类。其中,红墩梁、舍身崖和东沟楼等岩体为黑云二长花岗岩,以富SiO2,贫Al2O3,Na2O和K2O为特征,εNd(t)为-13.25^-15.80,锆石SHRIMP年龄介于136 Ma与144 Ma之间,形成于燕山期;冰山粱岩体为花岗闪长岩类,以贫SiO2,富Al2O3,Na2O和K2O为特征,εNd(t)为-12.18,锆石SHRIMP年龄为228 Ma之间,形成于印支期。花岗岩的锆石SHRIMP年龄数据表明赤城地区存在有印支期和燕山期两次花岗岩浆活动事件,可能反映出华北克拉通破坏始于印支期,而在燕山期达到高潮。The Mesozoic granitic rocks in Chicheng of Heibei Province distribute widely in Neopaleozoic Hongqiyingzi Group,which is mainly composed of biotite plagioclase gneiss.The granites are calc-alkalic granitic rocks which developed from continental crust,and mainly occurred at Hongdunliang,Bingshanliang,Sheshenya and Donggoulou area.Based on analyses of the 4 granitic bodies,they can be classified into two groups：（1） the Hongdunliang,Sheshenya and Donggoulou rock bodies are the biotite monzogranite and have a zircon SHRIMP U-Pb isotopic age of 136Ma to 144 Ma.The biotite monzonitic granites have higher SiO2 contents,lower Al2O3,Na2O and K2O,and their εNd（t） ranges from-13.25 to-15.80.（2） The Bingshanliang rock body is granodiorite and characterized by lower SiO2 and higher Al2O3,Na2O and K2O,with εNd（t） of-12.18.Zircon SHRIMP U-Pb dating reveals that the Bingshanliang body formed at 228 Ma,that is,in Indo-Chinese epoch.The zircon SHRIMP U-Pb isotopic age data also show that two stages of magmatic activities of Yanshan and Indo-Chinese epochs,exist in the Chicheng area,indicating that the destruction of North China Craton（NCC） began at Indo-Chinese epoch,and came to peak at Yanshan epoch.

关 键 词：SHRIMP年代学 锆石 花岗岩 赤城 冀北 

分 类 号：P597.3[天文地球—地球化学] P588.121[天文地球—地质学]