Research Project
Grant-in-Aid for Challenging Exploratory Research
We precisely obtained dihedral angles between olivine and NaCl- (up to 27.5 wt%) and CO2 (XCO2= 0.33 and 0.5)- bearing aqueous fluids at 1-4 GPa and 800-1100°C to reveal the fluid connectivity in the upper mantle. NaCl is now recognized as an important solute in fluids in subduction zone. We found that NaCl significantly decreases the dihedral angle down to < 60° at the pressure and temperature conditions corresponding to the shallow mantle wedge. We found that only 3-5 wt% of NaCl has similarly large effects on the dihedral angle with olivine to that of 15-27.5 wt %. The CO2 increases the dihedral angle at 1 GPa, but at pressures >2 GPa, where magnesite and pyroxene are stable, dihedral angles were smaller than those for pure H2O fluid. Although these results show that it is difficult to obtain the fluid composition from the pore geometry of xenoliths, it is revealed that aqueous fluids are highly connectable in a wide range of the uppermost mantle conditions.
沈み込み帯などでは、マントルのような地下深部にも地下水（熱水）が存在しており、マグマの生成やマントルの流動などに大きな役割を果たしています。しかしどれくらの量で、どのように分布しているのか、よくわかっていません。それを理解するには、熱水が、岩石を構成する鉱物に弾かれて水滴のように分布するのか、それとも、鉱物をよく濡らして沁み込みやすいのかを知ることが重要です。この研究では、従来よりも幅広いマントルの条件を再現し、熱水が岩石中によく染みることを明らかにしました。この結果は、絶縁体であるはずの岩石からなるマントルが、電気を良く通すという最近の観測結果をうまく説明できます。
All 2019 2018 2017 2016 Other
All Journal Article (5 results) (of which Int'l Joint Research: 2 results, Peer Reviewed: 5 results, Open Access: 2 results) Presentation (16 results) (of which Int'l Joint Research: 5 results) Remarks (1 results)
Journal of Geophysical Research: Solid Earth
Volume: 124 Issue: 4 Pages: 00-00
10.1029/2018jb016853
Geochemistry, Geophysics, Geosystems
Volume: 19 Issue: 3 Pages: 838-864
10.1002/2017gc007301
European Journal of Science
Volume: 29 Issue: 6 Pages: 1-9
10.1127/ejm/2017/0029-2663
Geochim. Cosmochim. Acta
Volume: 187 Pages: 195-217
10.1016/j.gca.2016.05.011
Volume: 17 Issue: 8 Pages: 1-27
10.1002/2016gc006295
