宁芜盆地火山基底侵入岩的锆石U-Pb定年和铪同位素研究  

Zircon U-Pb Dating and Hf Isotopic Study on Granitic Intrusions in the Basement of the Ningwu Basin

作　　者：陈志洪[1] 郭坤一[1] 赵玲[1] 

机构地区：[1]中国地质调查局南京地质调查中心,南京210016

出　　处：《矿物岩石地球化学通报》2013年第6期704-712,共9页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金资助项目(41202141);中国地质调查局地质工作项目(1212010781014;1212011085420)

摘　　要：宁芜盆地是长江中下游地区最重要的火山岩盆地之一。本文选取该盆地内研究程度相对较低的火山基底侵入岩类(钾长花岗岩-二长花岗岩),开展了LA-ICP-MS锆石U-Pb定年和Hf同位素的研究,获得钾长花岗岩和二长花岗岩的锆石U-Pb年龄分别为131.0±2.3Ma和128.5±1.7Ma,相对应的锆石εHf(t)分别为-8.26^-0.95和-8.31^-0.53。研究确定的火山基底花岗质侵入岩类的形成时代为131~128Ma,与宁芜盆地内其它火山-侵入岩浆活动的时间(135~127Ma)大致相当,均为早白垩世。同时,也暗示它们可能形成于相同的地球动力学条件下,即区域岩石圈伸展背景下岩浆活动的产物。The Ningwu basin is one of the most important volcanic basins in the Middle-Lower Yangtze Region. In this study, we present precise LA-ICP-MS zircon U-Pb dating and Hf isotope analyses for two granitic intrusions （moyite and monzogranite） in the basement of the Ningwu basin. Zircon LA-ICP-MS U-Pb ages and Hf isotopes re- suits indicate that the moyite and monzongranite were formed at 131.0＋2.3 Ma and 128. 5＋1.7 Ma, respectively, and the corresponding zircon eH （t） values are between -8.26 ^- 0.95 and -8.31 and -0.53, respectively Thus, the time of intrusive activities in the basement is 131-128 Ma, which is contemporary with other intrusive bodies of the Ningwu basin at Early Cretaceous （135-127 Ma）, implying that they all formed in the lithospheric extensional setting.

关 键 词：侵入岩 锆石U-PB定年 Hf同位素 火山基底 宁芜盆地 

分 类 号：P597.3[天文地球—地球化学]