Formation of Natural Silicate Hydrates by the Interaction of Alkaline Seepage and Sediments Derived from Serpentinized Ultramafic Rocks at Narra, Palawan, the Philippines

Shimbashi, Misato; Yokoyama, Shingo; Watanabe, Yasutaka; Sato, Tsutomu; Otake, Tsubasa; Kikuchi, Ryosuke; Yamakawa, Minoru; Fujii, Naoki

Formation of Natural Silicate Hydrates by the Interaction of Alkaline Seepage and Sediments Derived from Serpentinized Ultramafic Rocks at Narra, Palawan, the Philippines

Shimbashi, Misato; Yokoyama, Shingo; Watanabe, Yasutaka et al.

Minerals, 2020, 10(8), 719

Permalink : https://hdl.handle.net/2115/79596

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アクセス権	open access
URI	https://hdl.handle.net/2115/79596
タイトル	Formation of Natural Silicate Hydrates by the Interaction of Alkaline Seepage and Sediments Derived from Serpentinized Ultramafic Rocks at Narra, Palawan, the Philippines
著者	Shimbashi, Misato ; Yokoyama, Shingo ; Watanabe, Yasutaka ; Sato, Tsutomu ; Otake, Tsubasa ; Kikuchi, Ryosuke ; Yamakawa, Minoru ; Fujii, Naoki
著者名 Shimbashi, Misato
著者名 Yokoyama, Shingo
著者名 Watanabe, Yasutaka
e-Rad_Researcher 10313636 著者名 Sato, Tsutomu
e-Rad_Researcher 80544105 著者名 Otake, Tsubasa
著者名 Kikuchi, Ryosuke
著者名 Yamakawa, Minoru
著者名 Fujii, Naoki
言語	英語
キーワード	alkaline seepage
	ophiolite
	silicate hydrate
	smectite
	tobermorite
発行日	2020-08
出版者	MDPI
収録物名	Minerals
巻(号)	10(8)
ページ	719
抄録	In radioactive waste disposal facilities, low-permeability engineered barrier materials are important for inhibiting radionuclide migration. However, dissolution-precipitation reactions under alkaline conditions change the permeability of engineered barriers. To understand long-term dissolution-precipitation reactions under alkaline conditions in chemically complex systems, trenches and drill holes were excavated at Narra in Palawan, where alkaline fluids (pH > 11) have been naturally produced, seeping into clastic sediments derived from serpentinized ultramafic rocks and gabbro of Palawan ophiolite. Interaction between the alkaline seepage and clastic sediments, which have been deposited since 15,000 radiocarbon years before present (C-14 yr BP), led to dissolution of minerals and the precipitation of Si-bearing phases which were divided into two main categories: Fe-Mg-Si infillings and Ca-Si infillings. The former category was composed of iron-magnesium-silicate-hydrate (F-M-S-H) and a nontronite-like mineral and was widely recognized in the clastic sediments. The nontronite-like mineral likely formed by interaction between silicates and alkaline seepage mixed with infiltrated seawater, whereas F-M-S-H formed by the reaction of silicates with alkaline seepage in the absence of seawater infiltration. Ca-Si infillings included 14 angstrom tobermorite and were precipitated from alkaline seepage combined with the Ca and Si supplied by the dissolution of calcite and silicates in the clastic sediments.
資源タイプ	学術雑誌論文
出版タイプ	Version of Record
権利情報	Creative Commons Attribution 4.0 International
権利情報	© 2020 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/).
関連情報 (isIdenticalTo)	出版社版DOI https://doi.org/10.3390/min10080719