摘要
同位素法测年是大洋铁锰结壳测年的主要方法。根据20多年来铁锰结壳同位素测年的实践,特别是近几年最新的一些实验、研究结果,对10Be、U系以及87Sr同位素等测年方法的应用情况以及存在的问题进行了总结分析。一般说来,10Be和230Th两种方法尽管也存在一定问题,但用于结壳测年还是比较成功;而234U以及87Sr两种方法不能用于结壳测年,原因是铁锰结壳中的这两种元素与海水中的元素存在交换,是一种开放系统。
Main achievements and recent developments in isotopic dating of Fe-Mn crusts are summarized.The methods include radiogenic ^(10)Be,^(234)U,and ^(230)Th dating and stable strontium isotopic dating.It is generally held that beryllium and thorium belong to the alleged “particle-reactive group” which has sufficiently low diffusion coefficients in Fe-Mn crusts,and hence ^(10)Be and ^(230)Th dating methods can be used for age determination of the Fe-Mn crusts.Recent study also shows that uranium,along with strontium,has a relatively large diffusion coefficient in crusts(1×10^(-6) and 2×10^(-5) cm^2/a,respectively).It implies that the crusts do not keep a closed system for uranium,and therefore the ^(234)U method cannot be used for dating this material.
出处
《海洋地质动态》
2004年第10期14-18,共5页
Marine Geology Letters
基金
中国大洋矿产资源研究开发协会资助项目(DY105 01 04 08)
