摘要
流体是变质作用的重要因素之一。流体包裹体是变质作用某一时期流体相的最客观和最真实的记录。本区麻粒岩相变质流体以富CO_2为特点,具有高密度、较低的氧化还原电位和氧逸度。变质流体的演化具有与温压条件演化相同的PTt轨迹。随着变质作用演化,流体具有密度减小、体积增大的趋势,反映了变质过程流体的演化特点及其动力学机制。
The area under study is mainly composed of metamorphic supracrustal rockseries of granulite facies. The study of fluid inclusions shows that CO_2 is dominantin metamorphic fluids of granulite facies. CO_2-rich fluid inclusions often containdetectable amounis of H_2O, CH_4, N_2 CO and H_2S components that are misciblewith CO_2 at low temperatures. They have a high density (ρ=0.786--0.906 g/cm^3)and a low oxygen fugacity (fo_2=7.08 × 10^(-18) Pa) as well as a low oxidation--reduc-tion potential (Eh=-0.75 to-1.90). The formation temperatures of the fluidinclusions average 740℃ and the pressures range from 0.39 to 0.65 GPa. Thesefigures are in agreement with the results calculated with the geothermometerand geobarometer of the mineral pairs. Evolution of metamorphic fluids occurredwith evolving metamorphism. It has the evolutionary features corresponding withthe P--T conditions during granulite--facies metamorphism and a trend of reducingthe density and increasing the molar volume with the evolution of metamorphism.Evolutions of metamorphic fluids and granulite--facies:metamorphism have similarP-T-t paths, indicating typical characteristics of orogenic metamorphism in thearea.
出处
《地质论评》
CAS
CSCD
北大核心
1992年第5期398-406,共9页
Geological Review
基金
国家自然科学基金
关键词
麻粒岩
岩相
变质
流体性状
演化
fluid inclusions
granulite facies
Wulaer
Inner Mongolia
