摘要
对北大别变质杂岩中的麻粒岩包体进行详细的氧同位素地球化学研究,发现其全岩δ^(18)O值偏低,为3.3‰～4.4‰。在麻粒岩相变质条件下,大别山麻粒岩包体的共存矿物对之间达到并保存了氧同位素平衡,后期退变质作用未明显破坏这种平衡。由矿物氧同位素地质测温得到的顶峰变质温度800～875C,与一般麻粒岩相变质温度相吻合。在变质作用之前或顶峰变质作用过程中,大别山麻粒岩包体的原岩曾与一δ^(18)O值低于3‰的外来流体发生了高温水—岩交换作用,并且这种交换作用在一定范围内是相对均一的。
Oxygen isotope composition of granulite inclusions from metamorphic complex in the Dabie Mountains was determined. The results show that the δ18O values of the granulite inclusions is as low as 3. 3‰ to 4. 4‰ relative to SMOW. Oxygen isotopic equilibrium has been achieved and preserved among various co-existing mineral pairs in the inclusions under granulite facies metamorphic conditions, and has not been reset significantly during retrograde metamorphism. The peak metarnorphic temperatures calculated by the oxygen isotope geothermometry of mineral pairs in the granulite inclusions are 800 to 875C, being consistent with the known metamorphic temperatures of granulite facies. The fluid-rock interaction at high temperatures would take place homogeneously in a given range between the protoliths of the granulite inclusions and external fluids with a δ18O value as low as 3‰ prior to metamorphism or during peak granulite-facies metamorphism.
出处
《地质论评》
CAS
CSCD
北大核心
1998年第2期181-187,共7页
Geological Review
基金
国家自然科学基金(编号49794042和49453003)
中国科学院重大项目基金
关键词
流体作用
地质测温
氧同位素
麻粒岩包体
大别山
fluid-rock interaction
geothermometry
oxygen isotope
granulite inclusion
Dabie Mountains
