福建龙岩大洋花岗岩LA-ICP-MS锆石U-Pb测年、Hf同位素组成及其地质意义  

LA-ICP-MS Zircon U-Pb Ages and Hf Isotopic Compositions of Dayang Granite from Longyan,Fujian Province

作　　者：张承帅[1] 李莉[2] 张长青[3] 王九如 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质图书馆,北京100083 [3]中国地质科学院矿产资源研究所,北京100037 [4]内蒙古第七地质矿产勘查开发院,内蒙古呼和浩特010020

出　　处：《现代地质》2012年第3期433-444,共12页Geoscience

基　　金：国家自然科学基金项目"华南地区中生代板内成矿作用及其动力学背景"(40930419);中央高校基本科研业务费专项资金项目(2011PY0158);国土资源部成矿作用与资源评价重点实验室开放研究项目

摘　　要：对福建龙岩大洋花岗岩的两期岩相进行了LA-ICP-MS锆石U-Pb定年和锆石Hf同位素研究。结果表明:大洋花岗岩的早期黑云母正长花岗岩年龄为(144.8±0.9)Ma,εHf(t)值为-5.58～-2.00,二阶段Hf模式年龄为1 313～1 530 Ma,晚期微斜长石花岗岩的年龄为(127.5±0.4)Ma,εHf(t)值为-7.57～-0.90,二阶段Hf模式年龄为1 246～1 668 Ma。同位素特征表明,大洋花岗岩两期岩体都形成于早白垩世,是在岩石圈伸展的底侵作用下形成的,物源主要是中元古代地壳物质,但晚期有少量幔源组分的加入。A comprehensive research including LA-ICP-MS zircon U-Pb dating and Hf isotopic composition analysis on Dayang granitic pluton was carried out. We obtained the LA-ICP-MS zircon U-Pb ages of （144. 8 ±0. 9） Ma and （ 127.5± 0.4） Ma for the early medium coarse grained biotite granite and the late medium fine grained plagioclase granite in Dayang granitic pluton, respectively. According to zircon Hf isotope analyses, the both εnf（t） values are from -5.58 to -2.00 and from -7.57 to -0.90, and their corresponding Hf two- stage model ages （TDM2） are from 1,313 to 1,530 Ma and from 1,246 to 1,668 Ma, respectively. These data suggest that the magma sources of the two stages in Dayang granite mainly derived from Mesoproterozoic crustal materials, but the second stage involved some portions of mantle component. Dayang granite formed in the Early Cretaceous, which implies that it generated in basaltic underplating under lithosphere extension environment.

关 键 词：LA-ICP-MS锆石U-PB测年 HF同位素 大洋花岗岩 福建龙岩 

分 类 号：P588.13[天文地球—岩石学] P597.1[天文地球—地质学]