浙闽沿海晚中生代伸展构造作用:来自福建沿海中-基性岩墙群的证据  

LATE MESOZOIC EXTENSION IN THE COASTAL AREA OF ZHEJIANG AND FUJIAN PROVINCES:AN INDICATOR FROM THE BASIC-INTERMEDIATE DIKES,COASTLAND OF FUJIAN PROVINCE

作　　者：杨永峰[1,2] 董传万[2] 闫强[3] 李南美[1,2] 竺国强[2] 宋元青[1] 

机构地区：[1]中国化工部地质矿山总局浙江地质勘查院,浙江杭州310002 [2]浙江大学地球科学系,浙江杭州310027 [3]中国地质科学院矿产资源研究所,北京100037

出　　处：《矿物岩石》2010年第2期87-94,共8页Mineralogy and Petrology

基　　金：国家自然科学基金项目(编号40372035)

摘　　要：对出露于福建沿海晚中生代花岗岩及火山岩中的中-基性岩墙群岩石学和地球化学的研究表明,其岩性有辉绿岩、角闪辉绿岩和石英闪长岩等,并以角闪辉绿岩为主;地球化学分析数据显示,它们属亚碱性系列,w（SiO2）为50.22%~61.10%,w（CaO）3.50%~8.44%,w（Al2O3）14.05%~18.03%,w（TiO2）0.97%~2.41%,w（Na2O＋K2O）4.13%~6.14%,Mg#=42.77~65.74;具有轻稀土元素（LREE）和大离子亲石元素（LILE,如Sr,K,Rb,Ba,Th等）富集、高场强元素（HFSE,如Nb,Ta,Hf等）亏损的特点,表现出与消减带有关的岩石地球化学特性。运用构造环境判别方法,确定岩墙群形成于活动大陆边缘碰撞后的伸展构造环境,系拉张环境中底侵、滞留的玄武质岩浆上侵,最终形成中-基性岩墙群。The study of petrology and geochemistry on the basic-intermediate dikes,which intruded into the Late Mesozoic granite or volcanic rocks in the coastland of Fujian Province,showed that the lithologies of these dikes consisted of diabase,hornblende diabase and quartz-diorite with the diabase as the main type.Geochemically,they are sub alkaline rock series with SiO2 ranging from 50.22% to 61.10%,CaO from 3.50% to 8.44%,Al2O3 from 14.05 to 18.03%,TiO2 from 0.97% to 2.41%,（Na2O＋K2O）from 4.13% to 6.14%,Mg#=42.77~65.74.These rocks are rich in LREE,LILE（Sr,K,Rb,Ba,Th）,depleted in HFSE（Nb,Ta,Hf）,indicating geochemical characteristics related to subduction belt.Tectono-magmatic discriminant diagrams showed that the dikes formed in back-arc extension setting and the possible forming mechanism of the dikes is discussed.The study provides a profound comprehension for the regularity of Late Mesozoic magmatic activity in the coastal area of Southeast China.

关 键 词：岩墙群 岩石地球化学 构造环境 形成过程 福建沿海 

分 类 号：P588.14[天文地球—岩石学]