scholarly journals Combined tracers in hot spring waters across the Kii Peninsula, Japan: Implications for the origins of metamorphic fluids of the SW Japan forearc

2021 ◽  
Vol 55 (5) ◽  
pp. 289-300
Author(s):  
Koki Momose ◽  
Makoto Shiogama ◽  
Masako Hori ◽  
Kazuhiko Kandori ◽  
Yoshiro Nishio
Keyword(s):  
Hot Spring ◽  
Kii Peninsula ◽  
Metamorphic Fluids ◽  
Sw Japan

Slab-derived fluid evolution induced from oxygen and hydrogen isotopes compositions of blueschist-facies phengites

2020 ◽  
Author(s):  
Tatsuki Tsujimori ◽  
Daniel Pastor-Galán ◽  
Antonio Álvarez-Valero
Keyword(s):  
Subduction Zone ◽  
Hydrogen Isotope ◽  
Hot Spring ◽  
Far East ◽  
Isotopic Fractionation ◽  
Metasedimentary Rocks ◽  
East Russia ◽  
Japan Subduction Zone ◽  
D Values ◽  
Sw Japan

<p>Phengite is the most common metamorphic mineral in H<em>P</em>-UH<em>P</em> metasedimentary rocks, which can convey H<sub>2</sub>O, LILEs (especially K, Ba, Cs and Rb), Li, B and N in their structure formed at depths up to 300 km. The breakdown of phengite in a downgoing oceanic slab would cause fluid-induced element transport into the overlying mantle wedge. We have investigated the <sup>2</sup>H/<sup>1</sup>H (D/H) and <sup>18</sup>O/<sup>16</sup>O ratios of twenty-four phengite separates from pelitic schists of the Devonian–Carboniferous Renge Belt (SW Japan), Permian Shaiginsky Complex (Far East Russia) and Cretaceous Sambagawa Belt (SW Japan).</p><p>We found the presence of the very light hydrogen isotope (δD < –95‰) in blueschist-facies phengites in the three different metamorphic belts. For example, phengite from the lawsonite- and epidote-grade metasedimentary schists of the Osayama Serpentinite Mélange (OSM) of the Renge Belt are characterized by negative hydrogen isotope compositions (δD values relative to VSMOW) ranging from –113 to –93.9‰ and oxygen isotope compositions (δ18O values relative to VSMOW) ranging from +12.9 to +14.6‰.</p><p>High-Si features and K–Ar ages of the investigated phengites deny the possibility of meteoric-hydrothermal alteration to have caused the low δD values. The light values might be attributed to isotopic fractionation during progressive metamorphic dehydration.Assuming a meamorphic temperatures range of 250–350°C for the OSM schists, the inferred metamorphic fluid compositions in blueschist-facies depth for that fossil slab had a range of δD = ~–40 to –75‰ and δ18O = ~+13 to +15‰. These values are significantly lighter than the slab-fluid induced from the Arima hot spring water in a forearc region of modern SW Japan subduction zone. Our study suggests that slab-derived fluids in ancient Pacific-type subduction zone are characterized by light hydrogen isotope and that the phengite breakdown can affect hydrogen isotope of nominally anhydrous minerals (NAMs) in the deep mantle.</p>

scholarly journals Anisotropic structures of oceanic slab and mantle wedge in a deep low-frequency tremor zone beneath the Kii Peninsula, SW Japan

2013 ◽  
Vol 118 (3) ◽  
pp. 1091-1097 ◽  
Author(s):  
Atsushi Saiga ◽  
Aitaro Kato ◽  
Eiji Kurashimo ◽  
Takashi Iidaka ◽  
Makoto Okubo ◽  
...  
Keyword(s):  
Mantle Wedge ◽  
Low Frequency ◽  
Kii Peninsula ◽  
Anisotropic Structures ◽  
Oceanic Slab ◽  
Sw Japan

scholarly journals Finding Paleogene beds in the uppermost Izumi Group in western Kii Peninsula, SW Japan

2020 ◽  
Vol 126 (11) ◽  
pp. 639-644
Author(s):  
Yukio Isozaki ◽  
Ryo Hasegawa ◽  
Harue Masuda ◽  
Yukiyasu Tsutsumi
Keyword(s):  
Kii Peninsula ◽  
Sw Japan

Chert–clastic sequence in the Cretaceous Shimanto Accretionary Complex on the central Kii Peninsula, SW Japan

Island Arc ◽  
2020 ◽  
Vol 29 (1) ◽  
Author(s):  
Yusuke Shimura ◽  
Makoto Takeuchi ◽  
Tetsuya Tokiwa
Keyword(s):  
Accretionary Complex ◽  
Kii Peninsula ◽  
Sw Japan

Very broadband analysis of a swarm of very low frequency earthquakes and tremors beneath Kii Peninsula, SW Japan

2010 ◽  
Vol 37 (6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Akiko Takeo ◽  
Koki Idehara ◽  
Ryohei Iritani ◽  
Takashi Tonegawa ◽  
Yutaka Nagaoka ◽  
...  
Keyword(s):  
Low Frequency ◽  
Kii Peninsula ◽  
Very Low Frequency ◽  
Sw Japan

scholarly journals Geological traverse across the Shimanto and Sanbagawa belts on the central Kii Peninsula, SW Japan

2020 ◽  
Vol 126 (7) ◽  
pp. 383-399
Author(s):  
Yusuke Shimura ◽  
Makoto Takeuchi ◽  
Tetsuya Tokiwa
Keyword(s):  
Kii Peninsula ◽  
Sw Japan
Sign in / Sign up

Export Citation Format

Share Document