大气^(40)Ar/^(36)Ar端元值及其地质意义  

Metamorphic PT and Oxygen Isotope Studies of Eclogites from Bixiling in the Dabie Mountains

作　　者：王松山[1] 桑海清[1] 裘冀[1] 

机构地区：[1]中国科学院地质研究所

出　　处：《地球学报（中国地质科学院院报）》1997年第3期313-317,共5页Acta Geoscientia Sinica

基　　金：国家自然科学基金

摘　　要：月岩和陨石形成时捕获了太阳风中的Ａｒ同位素。作者对恩施陨石采用４０Ａｒ／－３６Ａｒ技术，并对Ｃｌ的诱发产物进行了校正后，获得了４６００Ｍａ前太阳风中４０Ａｒ／３６Ａｒ比值是０．８９±０．４４。它表明地球大气圈中４０Ａｒ／３６Ａｒ比值经历了从０．８９到２９５．５的演化过程，影响这一过程的主要因素是地球的去气作用。A detailed petrographical study shows that eclogite from the Bixiling domain experienced at least five metamorphic stages:(1)pre_eclogite_facies metamorphism (EcP),(2)coesite eclogite_facies metamorphism(EcC),(3)recrystallized eclogite_facies metamorphism(EcR),(4)retrograde symplectite stage(Sym),and(5)retrograde amphibolite_facies stage(Am).Temperatures estimated based on oxygen isotope analyses of mineral pairs are in good concordance with temperatures derived from cation partition geothermometry and the petrographical study. This suggests that the oxygen isotopic equilibrium has been approached amongthe minerals within eclogite and that the retrograde metamorphism did not distort the isotopic equilibrium. The δ 18 O values of the eclogite are about 3～5‰,indicating a given water/rock interaction between the basaltic precurser of the eclogite and subsurface water prior to eclogitization.

关 键 词：大气 陨石 太阳风 氩40 氩36 比值 地质意义 

分 类 号：P597[天文地球—地球化学] P353.8[天文地球—地质学]