摘要
通过对中国东南大陆几条变质带和武夷山变质地体近100个氧同位素分析数据研究表明:大别山变质带中榴辉岩氧同位素组成,石英δ^(18)O接近于零,角闪石类δ^(18)O为—1～—5.7‰,矿物对平衡温度490～570℃;萍乡-象山变质带石英的δ^(18)O为+16～+18.35‰,角闪石类δ^(18)O增至+6.5～+11‰,矿物对平衡温度550～623℃;沿海变质带矿物对平衡温度470～900℃,石英的δ^(18)O为+4～+9‰,角闪石类δ^(18)O为+4～—1.8‰;基底变质杂岩的氧同位素组成与世界各地的片麻岩-片岩类δ^(18)O值接近。阐明了δ^(18)O值的变化,与原岩成分和环境密切相关,并已基本达到平衡。
Systematic study on O isotopic composition in three boundary tectonic belts and Fuyishan metamorphic terrane of southeast China continent indicates that O isotopic compositions contain not only information about primitive rock properties and metamorphic condition but also geochemical information about material composition during crust growth process, meanwhile, O isotopic composition and concentration vary in different tectonic background.
O isotopic composition characteristics of boundary metamorphic belt and basement metamorphic complex are as follows: δ^(18)O value is usually lower in the eclogites of high pressure facies in Dabie Mountains, δ^(18)O value in different minerals is all less than 0 except for quartz mineral(near 0), isotopic equilibrium temperature of the associated mineral couple varies in 490～570℃; ^(18)O isotopic composition appears to be rich in middle temperature facies of Pingxiang-Xiangshan metamorphic belt, δ^(18)O values of whole rock and single mineral are all more than 0, isotopic equilibrium temperature of associated minerals varies in 340～620℃; compared with the middle temperature facies, ^(18)O isotopic composition of lower temperature facies in growth continental margin generally appear to be poor, isotopic equilibrium temperature is 636℃. δ^(18)O in basement metamorphic complex is very similar to δ^(18)O values of gneiss-schists in different place in the world.
O isotopic composition reflects differences in primitive rock type: δ^(18)O near +2‰ in eclogites, δ^(18)O=+7～+8‰ in metamorphic spilites, δ^(18)O=+5～+2.7‰ in intermediate acidic volcanic rocks of continental facies, δ^(18)O=+10～+12‰ in sedimentary-volcanic frag-mental rocks.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1993年第2期125-135,共11页
Acta Petrologica Sinica
基金
地质矿产部重大项目成果
关键词
氧同位素
平衡温度
榴辉岩
变质带
Oxygen isotopic composition
Equilibrium temperature
Metamorphic belt
Eclogite
