Extraterrestrial 3He in marine polymetallic nodules: a potential method for measuring growth rate of nodules  

作　　者：李延河 宋鹤彬 李金城 

机构地区：[1]Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037 China

出　　处：《Science China Chemistry》2002年第z1期38-46,共9页中国科学（化学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant No. 49873002).

摘　　要：The comparative measurements of helium isotope compositions between marine polymetallic nodules and their surrounding sediments, their magnetic fractions and bulk from C-C Zone of the East Pacific Basin are reported. The 4He content and 3He/4He ratio of polymetallic nodules and their surrounding sediments are extremely high; the 3He, 4He concentrations and most 3He/4He ratios of magnetic fractions in nodules and sediments are apparently higher than those in bulk. The helium isotope data points of nodules and sediments are all distributed along or closely to the mixing curve of the interplanetary dust particles (IDPs) and the terrigenous sediments in the chart of 3He-3He/4He. In the same sampling site, the 3He/4He ratios of nodules and their surrounding sediments are very similar, and the changes of both ratios are synchronous. It shows that the high 3He/4He ratios in nodules and sediments may all result from IDPs. So, if the flux of extraterrestrial 3He into the nodules and sediments is constant, the growth rate of polymetallic nodules and the sedimentation rate of sediments can be independently calculated according to the concentration of extraterrestrial 3He in nodules and sediments.The comparative measurements of helium isotope compositions between marine poly- metallic nodules and their surrounding sediments, their magnetic fractions and bulk from C-C Zone of the East Pacific Basin are reported. The ~4He content and ~3He/~4He ratio of polymetallic nodules and their surrounding sediments are extremely high; the ~3He, ~4He concentrations and most ~3He/~4He ratios of magnetic fractions in nodules and sediments are apparently higher than those in bulk. The helium isotope data points of nodules and sediments are all distributed along or closely to the mixing curve of the interplanetary dust particles (IDPs) and the terrigenous sediments in the chart of ~3He-~3He/~4He. In the same sampling site, the ~3He/~4He ratios of nodules and their surround- ing sediments are very similar, and the changes of both ratios are synchronous. It shows that the high ~3He/~4He ratios in nodules and sediments may all result from IDPs. So, if the flux of extrater- restrial ~3He into the nodules and sediments is constant, the growth rate of polymetallic nodules and the sedimentation rate of sediments can be independently calculated according to the concentra- tion of extraterrestrial ~3He in nodules and sediments.

关 键 词：POLYMETALLIC nodules  HELIUM isotope  INTERPLANETARY DUST particles (IDPs). 

分 类 号：P736.1[天文地球—海洋地质]