Independent hydrogen incorporation in wadsleyite from oxygen fugacity and non-dissociation of H2O in the reducing mantle transition zone
Independent hydrogen incorporation in wadsleyite from oxygen fugacity and non-dissociation of H2O in the reducing mantle transition zone
复制标题
DOI：
10.1016/j.epsl.2021.116755
复制
发表时间：
2021-03
影响因子：
5.3
通讯作者：
D. Druzhbin;H. Fei;T. Katsura
中科院分区：
文献类型：
--
作者：
D. Druzhbin;H. Fei;T. Katsura
地幔过渡带被认为是一个潜在的水在地球内部的水库，因为高的水溶解度在wadsleyite和ringwoodite。然而，这种情况是基于在相对氧化的条件下进行的实验。为了限制H2O在还原性（接近铁-方铁矿缓冲区）地幔过渡带矿物中的溶解度，在17 GPa和1673 K条件下，系统测量了Hf-HfO 2、Mo-MoO 2、Re-ReO 2和Pt-PtO 2缓冲区条件下的水含量与氧逸度的关系。结果表明，氧逸度对水在水铝石中的溶解度没有显著影响。地幔过渡带中的硅铝石可储存高达1.0wt.%的硅铝石H2O，尽管还原条件。H2O分解为H2和O2的作用可以忽略不计，即地幔过渡带中的H2分子量可以忽略不计。
The mantle transition zone is considered as a potential water reservoir in the Earth's interior because of the high H2O solubility in wadsleyite and ringwoodite. However, this scenario is based on experiments performed under relatively oxidized conditions. In order to constrain the H2O solubility in minerals in the reducing (close to iron-wüstite buffer) mantle transition zone, here we systematically measured the water content in wadsleyite at 17 GPa and 1673 K, as a function of oxygen fugacity in the range of Hf-HfO2, Mo-MoO2, Re-ReO2, and Pt-PtO2buffer conditions. The results suggest that the oxygen fugacity has no meaningful effect on H2O solubility in wadsleyite. Wadsleyite in the mantle transition zone can store as much as ∼1.0 wt.% H2O in spite of the reducing conditions. The dissociation of H2O into H2and O2is negligible, namely, there should be negligible molecular H2in the mantle transition zone.