湘南中生代火山岩中尖晶石二辉橄榄岩包体Sm-Nd等时线年龄及地质意义  

Sm-Nd Isochron Age of Spinel-Lherzolite Xenoliths from Mesozoic Volcanic Rocks in the South Hunan and Its Geological Significance

作　　者：陈必河[1] 贾宝华[1] 刘耀荣[1] 彭学军[1] 贺春平[1] 

机构地区：[1]湖南地质调查研究院,湘潭411100

出　　处：《地质论评》2004年第2期180-183,共4页Geological Review

基　　金：国土资源部中国地质调查局1:25万道县幅区域地质调查项目(编号2001130000012)资助的成果

摘　　要：湖南宁远太阳山中生代玄武质火山岩内,产较丰富的尖晶石二辉橄榄岩包体。包体经人工碎样,镜下挑选了含铬尖晶石、镁橄榄石、含铬透辉石、斜方辉石、全岩5个样品,由国土资源部天津地质矿产研究所同位素室测试,得出 Sm-Nd全岩-单矿物等时线同位素年龄2702±19 Ma。进而根据测试结果和以往资料综合分析,认为华南陆块岩石圈是沿垂向演化增生的,由下往上依次为:上地幔岩垫托、结晶基底、褶皱基底、褶皱盖层、沉积盖层5个构造层。其中,上地幔岩起着底板垫托作用,形成于新太古代,为该地区最古老岩石。There are a lot of spinel-lherzolite xenoliths in the Taiyangshan Mesozoic basalt in Ningyuan, Hunan province. Five samples of chrome spinel, forsterite, chrome-diopside, orthorhombic and whole rock were picked out under microscope from the brocken pieces, were analysesed in the Isochronology Center, Tianjin Institute of Geology and Mineral Resouces, Geological Survey of China. A Sm-Nd whole rock-single mineral isochron age of 2702 + 19 Ma was got. According to this result and having synthesized the data others got before, writers consider the lithosphere of southern China was vertically multiplicated. From bottom upward in order: upper mantle mat, crystallized basement, folded basement, folded cover and sedimentary cover. Among five structural layers, upper mantle rock plays a role of motherboard oushion, was formed at Neoarchaeoid is the oldest rock in this district.

关 键 词：中生代 火山岩 尖晶石二辉橄榄岩包体 同位素年龄 等时线同位素年龄 湖南 

分 类 号：P588.125[天文地球—岩石学]