安徽月山闪长岩的成因探讨——锆石U-Pb定年及Hf同位素证据  

Petrogenesis of Yueshan Pluton:Zircon U-Pb Dating and Hf Isotope Evidence

作　　者：刘园园[1] 马昌前[2,3] 张超[1] 佘振兵[2] 张金阳[4] 

机构地区：[1]中国地质大学研究生院,武汉430074 [2]中国地质大学地球科学学院 [3]中国地质大学地质过程与矿产资源国家重点实验室,武汉430074 [4]中国地质大学资源学院,武汉430074

出　　处：《地质科技情报》2009年第5期22-30,共9页Geological Science and Technology Information

基　　金：国家科学技术部国际科技合作项目(2007DFA21230);国家自然科学基金重点项目(40334037);国家自然科学基金委员会创新研究群体基金项目(40821061);教育部和国家外国专家局高等学校学科创新引智计划项目(B07039)

摘　　要：对安徽月山岩体开展了锆石原位U-Pb测年及Lu-Hf同位素研究。锆石的LA-ICP-MS年代学研究表明,月山闪长岩的U-Pb年龄为(139.3±1.5)Ma,与长江中下游成矿带早白垩世成铜岩体的年龄一致。月山闪长岩中的锆石具有均一的Hf同位素初始比值,介于0.282 430~0.282 491间。这些锆石的ε(Hf)(t)介于-9.05^-6.90间,亏损地幔模式年龄介于1.06~1.17 Ga间。结合长江中下游地区岩浆岩其他地球化学特征,认为月山岩体可能是在俯冲体系下由幔源岩浆经结晶分异作用且局部伴有一定程度的同化混染作用所形成。This study carries out in situ U-Pb dating and Lu-Hf isotope analyses of zircon from the Yueshan diorite in Anhui Province. Zircon U-Pb dating by LA-ICP-MS technique indicates the crystallization age of the diorite at （139.34-1.5）Ma is coincident with the age of most of the early Cretaceous intrusive rocks associated with copper mineralization in the Middle-Lower Yangtze River metallogenic belt . Zircon Hf isotope analyses show relatively homogeneous initial Hf isotopic compositions, which is between 0. 282 430 and 0. 282 491. And these zircons have e（Hf）（t） values from --9.05 to --6.90 , yielding depleted mantle mode age from 1.06 to 1.17 Ga. Other common geochemical characteristics of the Middle-Lower Yangtze River area suggest that the Yueshan pluton might be originated from partial melting enriched mantle under the condition of plate subduction, following fractional crystallization accompanied with local assimilation.

关 键 词：锆石 U-PB定年 HF同位素 月山岩体 

分 类 号：P581[天文地球—岩石学] P597.3[天文地球—地质学]