希少な深海熱水系を西太平洋で発見、大量の水素を放出(Scientists Discover Rare Deep-Sea Hydrothermal System in Western Pacific Producing Massive Hydrogen Emissions)

2025-08-12 中国科学院(CAS)

西太平洋の海底で、中国科学院海洋研究所(IOCAS)の研究チームが大量の水素を放出する希少な熱水系「崑崙(Kunlun)熱水フィールド」を発見した。場所はカロリンプレート・ムサウ海溝西方約80kmで、直径1km超の大規模な海底陥没が20個集まり、地殻内部の流体やガスを通すパイプ状構造を形成。有人潜水艇「奮闘者」による調査で、高濃度水素(5.9〜6.8mmol/kg)を含む熱水や炭酸塩堆積物を確認した。水温は40℃未満だが、深部は高温で苦灰石生成が進行。年間水素放出量は4.8×10¹¹molで、世界の海底由来無機水素の5%以上を占めると推定。地質的特徴から、ガス噴出→長期熱水循環・鉱物沈殿の段階的進化が示唆される。周辺には水素を利用する化学合成生態系が存在し、初期地球環境や生命起源研究の貴重な場ともなる。

希少な深海熱水系を西太平洋で発見、大量の水素を放出(Scientists Discover Rare Deep-Sea Hydrothermal System in Western Pacific Producing Massive Hydrogen Emissions)
Hydrothermal activities and distribution of pipe swarms on the subducting plate near the Mussau Trench. (Image by IOCAS)

<関連情報>

西太平洋西部における蛇紋岩化に駆動される大規模なプレート内水素豊富熱水系:クンルン A large intraplate hydrogen-rich hydrothermal system driven by serpentinization in the western Pacific: Kunlun

Lianfu Li, Hongyun Zhang, Shichuan Xi, Chenglong Liu, […] , and Weidong Sun
Science Advances  Published:8 Aug 2025
DOI:https://doi.org/10.1126/sciadv.adx3202

Abstract

The Kunlun hydrothermal system near the Mussau Trench in the western Pacific consists of 20 large round/oval craters of hundreds of meters in diameter. The total area is 11.1 square kilometers, i.e., over a hundred times larger than the Lost City. Four of the larger craters were prospected using the human occupied vehicle Fendouzhe and have steep walls similar to those of kimberlite pipes, with depths of up to 130 meters. Ecosystems have been observed in smaller pits on the bottom of these pipes. Hydrogen concentrations of ~5.9 to 6.8 millimoles per kilogram in hydrothermal fluids have been obtained using in situ Raman spectra. The estimated total hydrogen flux of Kunlun is 4.8 × 1011 moles per year, which is >5% of the estimated global submarine abiotic hydrogen flux. Hydrogen-rich, alkaline fluids generated by serpentinization have formed large-scale carbonate rocks within the pipes below the carbonate compensation depth, and both dolomite and calcite have been identified.

1702地球物理及び地球化学
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