Water partitioning in the Earth's mantle
Water partitioning in the Earth's mantle
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DOI：
10.1016/j.pepi.2010.08.003
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发表时间：
2010-11-01
影响因子：
2.3
通讯作者：
Yurimoto, Hisayoshi
中科院分区：
文献类型：
--
作者：
Inoue, Toru;Wada, Tomoyuki;Yurimoto, Hisayoshi
我们分别在1673 K和1873 K下进行了wadsleyite和ringwoodite之间以及ringwoodite和钙钛矿之间的水分配实验。这些实验是为了约束上地幔、地幔过渡带和下地幔中H2O的相对分布。我们成功地合成了沃氏辉石-菱木矿和菱木-钙钛矿共存的矿物组合，它们的体积足够大，可以用次级离子质谱法（SIMS）测量水的含量。结合我们之前的水分配数据（Chen et al., 2002）和本研究结果，在富水流体饱和条件下，橄榄石、wadsleyite、ringwoodite和钙钛矿之间的水分配分别为6:30:15:1。由于wadsleyite中最大储水容量约为3.3 wt%（例如Inoue et al., 1995），橄榄石高压多晶岩中可能的最大储水容量如下：橄榄石（上地幔略高于410 km深度）约为0.7 wt%, wadsleyite （410-520 km深度）约为3.3 wt%，环伍德石（520-660 km深度）约为1.7 wt%，钙钛矿（下地幔）约为0.1 wt%。如果我们假设在最近的电导率测量（例如Dai和Karato， 2009）估计的地幔过渡带wadsleyite中H2O含量为0.2 wt%，那么整个地幔的H2O含量估计如下：橄榄石（上地幔略高于410公里深度）的重量为0.04%，瓦德斯莱岩（410-520公里深度）的重量为0.2%，环伍德岩（520-660公里深度）的重量为0.1%，钙钛矿（下地幔）的重量为0.007%。因此，与上地幔和下地幔相比，地幔过渡带应该在地球的地幔中包含一个大的水库。(C) 2010 Elsevier B.V.版权所有
We have conducted H2O partitioning experiments between wadsleyite and ringwoodite and between ringwoodite and perovskite at 1673 K and 1873 K, respectively. These experiments were performed in order to constrain the relative distribution of H2O in the upper mantle, the mantle transition zone, and the lower mantle. We successfully synthesized coexisting mineral assemblages of wadsleyite-ringwoodite and ringwoodite-perovskite that were large enough to measure the H2O contents by secondary ion mass spectrometry (SIMS). Combining our previous H2O partitioning data (Chen et al., 2002) with the present results, the determined water partitioning between olivine, wadsleyite, ringwoodite, and perovskite under H2O-rich fluid saturated conditions are 6:30:15:1, respectively. Because the maximum H2O storage capacity in wadsleyite is similar to 3.3 wt% (e.g. Inoue et al., 1995), the possible maximum H2O storage capacity in the olivine high-pressure polymorphs are as follows: similar to 0.7 wt% in olivine (upper mantle just above 410 km depth), similar to 3.3 wt% in wadsleyite (410-520 km depth), similar to 1.7 wt% in ringwoodite (520-660 km depth), and similar to 0.1 wt% in perovskite (lower mantle). If we assume similar to 0.2 wt% of the H2O content in wadsleyite in the mantle transition zone estimated by recent electrical conductivity measurements (e.g. Dai and Karato, 2009), the estimated H2O contents throughout the mantle are as follows; similar to 0.04 wt% in olivine (upper mantle just above 410 km depth), similar to 0.2 wt% in wadsleyite (410-520 km depth), similar to 0.1 wt% in ringwoodite (520-660 km depth) and similar to 0.007 wt% in perovskite (lower mantle). Thus, the mantle transition zone should contain a large water reservoir in the Earth's mantle compared to the upper mantle and the lower mantle. (C) 2010 Elsevier B.V. All rights reserved.