地震地质 ›› 2000, Vol. 22 ›› Issue (s1): 87-.DOI: ISSN:0253-4967.0.2000-S1-011

• 科研简报 • 上一篇    下一篇

长白山天池火山U过剩特征——西太平洋板块深俯冲的又一证据

  

  1. 中国地震局地质研究所|中国科学技术大学地球和空间科学系
  • 出版日期:2000-12-21 发布日期:2009-11-25
  • 基金资助:

    中国地震局地质研究所论著 !2 0 0 0B0 0 6 1

FEATURES OF EXCESS OF U IN VOLCANIC ROCKS OF CHANGBAISHAN TIANCHI——THE EVIDENCE FOR SUBDUCTION OF WESTEM PACIFIC PLATE

  • Online:2000-12-21 Published:2009-11-25

摘要:

应用高精度热电离质谱技术 ,测定了长白山天池锥体 11个火山岩样品的U ,Th同位素组成。结果发现 ,天池火山岩中铀不平衡同位素体系以2 38U放射性过剩为特征 (即2 30 Th/ 2 38U放射性比值小于 1) ,表明了岩浆过程中水的参与作用 ;而样品δ2 34U <10‰ ,说明浅部循环水不是造成上述2 38U过剩的原因。由此推断 ,含水组分在岩浆源区参与了部分熔融过程 ,这可能是太平洋俯冲板块脱水作用的结果

关键词: 火山岩, U, Th同位素, 板块俯冲

Abstract:

samples of lava and pumice from the cone of Changbaishan Tianchi Volcano, Jiling, China were measured for their uranium and thorium isotopic compositions by using the high precision U-series TIMS method. The results indicate that the U-series disequilirium system is characterized by excess of 238U (namely the radioactivity ratio of 230Th/ 238U less than 1), showing the fluids has worked in the magmatic reservoir. This may suggests that the fluids, which participated in the melting of the source r

Key words: Volcanic rock, Uranium and thorium isotopes, Subduction of Pacific plate