气候变化领域集成服务门户(CCPortal): Experimental constraint on grain-scale fluid connectivity in subduction zones

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DOI	10.1016/j.epsl.2020.116610
	Experimental constraint on grain-scale fluid connectivity in subduction zones
	Huang Y.; Nakatani T.; Nakamura M.; McCammon C.
发表日期	2020
ISSN	0012821X
卷号	552
英文摘要	The dihedral angle (θ) between olivine and aqueous fluid is a critical parameter in identifying the grain-scale fluid connectivity which controls the distribution and migration of aqueous fluids in subduction zones besides physical properties of mantle wedges. Recent magnetotelluric observations have suggested the occurrence of significant fluid circulation in deep fore-arc regions, which can be explained by infiltration of saline fluid with a low θ in the mantle wedge (Huang et al., 2019). Along with the salt component, non-polarized gas such as CO2, is a crucial constituent of subduction zone fluids. CO2 is known to increase the olivine–fluid θ under conditions in which the olivine does not react with CO2, which is in contrast to the effect of NaCl on θ. For a better understanding of the connectivity of multicomponent fluid in the mantle wedge, we experimentally constrained θ in olivine + H2O–CO2 fluid and olivine + H2O–CO2–NaCl (multicomponent) fluid systems at 1–4 GPa and 800–1100 °C. For the H2O–CO2 system, we found that CO2 tends to increase θ at 1 GPa and 800–1100 °C and at 2 GPa and 1100 °C. In contrast, CO2 reduced θ even below 60° at relatively high-pressure (P) and low-temperature (T) conditions, in which the olivine partly reacts with CO2 to form magnesite and orthopyroxene (opx). The consumption of non-wettable CO2 components in aqueous fluid alone cannot explain θ lower than those in a pure H2O system. Additional experiments on olivine–magnesite + H2O and olivine–opx + H2O systems showed that the presence of magnesite or opx decreased the olivine–fluid θ, which implies that coexisting minerals affect the olivine–fluid interfacial energy by changing the fluid chemistry. The results of the multicomponent system showed that the effect of NaCl on θ is much more significant than that of CO2. Strikingly, θ was smaller than 60° in all the magnesite- and opx-bearing multicomponent systems. Our results suggest that slab-derived fluid can infiltrate into the deep fore-arc mantle wedge through an interconnected network even in a CO2-bearing multicomponent system at pressures above 2 GPa, which facilitates significant fore-arc fluid circulation. The contrasting effects of aqueous fluid and silicate melt on the seismic wave velocity in a wide condition may allow for the possibility of mapping partial melt in the mantle wedge. © 2020 Elsevier B.V.
关键词	dihedral angle fluid connectivity mantle wedge multicomponent fluid subduction zone
英文关键词	Dihedral angle; Magnesite; Olivine; Silicates; Sodium chloride; Temperature; Wave propagation; Additional experiments; Coexisting minerals; Fluid circulation; Interconnected network; Multi-component systems; Multicomponent fluid; Seismic wave velocity; Subduction zone fluids; Carbon dioxide; carbon dioxide; experimental study; fluid flow; infiltration; mantle chemistry; olivine; subduction zone; tectonic wedge; wetting
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202662
作者单位	Department of Earth Science, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-Ku, Sendai, Miyagi 980-8578, Japan; Bayerisches Geoinstitut, University of Bayreuth, Bayreuth, 95440, Germany
推荐引用方式 GB/T 7714	Huang Y.,Nakatani T.,Nakamura M.,et al. Experimental constraint on grain-scale fluid connectivity in subduction zones[J],2020,552.
APA	Huang Y.,Nakatani T.,Nakamura M.,&McCammon C..(2020).Experimental constraint on grain-scale fluid connectivity in subduction zones.Earth and Planetary Science Letters,552.
MLA	Huang Y.,et al."Experimental constraint on grain-scale fluid connectivity in subduction zones".Earth and Planetary Science Letters 552(2020).