摘要
对青海茫崖石棉矿床中的蛇纹岩和纤蛇纹石石棉进行了氢氧同位素分析,蛇纹岩的δ^(18)O为+5.9—+7.5‰,δD为—115——133‰,纤蛇纹石石棉的δ^(18)O为+7.4—+8.9‰,δD为—115——136‰。共生蛇纹石-磁铁矿同位素温度表明各种蛇纹岩的形成温度为210—320℃,纤蛇纹石石棉为120—170℃。超镁铁质岩的蛇纹石化作用是多阶段的,蛇纹石化作用的水可能以具有一定盐度、CO_2分压较高的深循环大气变质水为主。蛇纹石作用发生在大陆环境中,纤蛇纹石石棉是在蛇纹石化最后阶段于近地表环境中形成的。
Oxygen and hydrogen isotope data have been obtained for 9 serpentines and 3 chrysotile asbestos from the Mongya asbestos deposit. The isotopic compositions of serpentines and asbestos fall in different ranges (serpentines: δ18O = + 5.9-+7.5‰,δD=-115-133‰; asbestos: δ18O = + 7.4-+8.9‰, δD = -115-136‰).The temperatures of serpentinition of ultramafic rocks based on oxygen isotopic fractionation between coexisting serpentine and magnetite are higher (210-320℃) for serpentines but lower (120-180℃) for chrysotile asbestos. The calculated isotopic compositions of waters show that the serpentinization of ultramafic rocks resulted from deep-circulating metamorphic waters higher in salinity and CO2 pressure. The ultramafic rocks were serpentinized in the continental environment, and the chrystile asbestos were formed in the closed environment during the last stage of serpentinization.
出处
《地球化学》
CAS
CSCD
北大核心
1992年第4期366-374,共9页
Geochimica
