期刊
CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
卷 151, 期 1, 页码 112-120出版社
SPRINGER
DOI: 10.1007/s00410-005-0049-0
关键词
-
The fractionation of lithium isotopes between synthetic spodumene as representative of Li-bearing clinopyroxene and Cl- and OH-bearing aqueous fluids was experimentally determined between 500 and 900 degrees C at 2.0 GPa. In all the experiments, Li-7 was preferentially partitioned into the fluid. The fractionation is temperature dependent and approximated by the equation Delta Li-7((clinopyroxene-fluid))=-4.61x(1,000/T [K]) + 2.48; R-2=0.86. Significant Li isotopic fractionation of about 1.0 parts per thousand exists even at high temperatures of 900 degrees C. Using neutral and weakly basic fluids revealed that the amount of fractionation is not different. The Li isotopic fractionation between altered basalt and hot spring water (350 degrees C) in natural samples is in good agreement with our experimentally determined fractionation curve. The data confirm earlier speculations drawn from the Li isotopic record of dehydrated metamorphic rocks that fluids expelled from a dehydrating slab carry heavier Li into the mantle wedge, and that a light Li component is introduced into the deeper mantle. Li and Li isotopes are redistributed among wedge minerals as fluids travel across the wedge into hotter regions of arc magma production. This modifies the Li isotopic characteristics of slab-derived fluids erasing their source memory, and explains the absence of cross-arc variations of Li isotopes in arc basalts.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据