大别山榴辉岩的氦、氩同位素组成及其岩石成因  

ISOTOPE COMPOSTITIONS OF HE, AR AND ORIGIN OF ECLOGITE IN DABEI MOUNTAINS

作　　者：杜建国[1] 张友联 张建珍[3] 常永莲[4] 

机构地区：[1]国家地震局分析预报中心,北京100036 [2]地震出版社,北京100081 [3]石家庄经济学院,石家庄050031 [4]河北师范大学职业师范学院,石家庄050031

出　　处：《地震地质》1999年第4期431-435,共5页Seismology and Geology

基　　金：国家自然科学基金!(49273185)

摘　　要：论述了石榴石和绿辉石的氦、氩同位素地球化学特征,并讨论了大别山榴辉岩的成因。测得3 He/4He 值为(1-19 ～4-63) ×10 - 7 ,40Ar/36Ar 值为1209 ～4416 ,4 He/40Ar 值分布在0-07 ～1-39 范围内,3 He/36 Ar 值的变化范围为(0-59 ～2-85) ×10 - 4 。大别山榴辉岩中保留了原始的稀有气体同位素, 但是退变质作用使氦同位素优先丢失。氦、氩同位素地球化学资料表明,榴辉岩可能形成于亏损的地幔或者是一种亏损型“地幔岩”中。This paper discusses the origin of eclogite in Dabei Mountains, eastern China based on the isotopic geochemical characteristics of helium and argon in garnet and omphacite. 3He/ 4He values are (1 19～4 63)×10 -7 ,and 40 Ar/ 36 Ar values have a wide range of 1209～4416. Ratios of 4He/ 40 Ar and 3He/ 36 Ar are 0 07～1 39 and (0 59～2 85)×10 -4 , respectively. Primordial isotopes of helium and argon have been trapped in garnet and omphacite of eclogite. Helium isotopes are preferentially lost during retrograde metamorphic process. The isotope compositions of helium and argon of the eclogites are concordant with those of some mantle rocks, especially those of olivine and enstatite in the northern part of the continental rifted area of east China. The geochemical data of helium and argon show that the eclogites formed in depleted mantle, and may be a kind of “ depleted mantle rock”.

关 键 词：同位素年龄测定 榴辉岩 大别山 氩 氦 同位素 

分 类 号：P588.3[天文地球—岩石学] P597[天文地球—地质学]