scholarly journals A model for earthquake generation and volcano formation in the NE Japan subduction zone

2006 ◽  
Vol 71 (5) ◽  
pp. 425-434
Author(s):  
Akira Hasegawa
Keyword(s):  
Subduction Zone ◽  
Japan Subduction Zone ◽  
Earthquake Generation ◽  
Ne Japan

scholarly journals Receiver function imaging of the amphibious NE Japan subduction zone ‐ effects of low‐velocity sediment layer ‐

2021 ◽  
Author(s):  
HyeJeong Kim ◽  
Hitoshi Kawakatsu ◽  
Takeshi Akuhara ◽  
Masanao Shinohara ◽  
Hajime Shiobara ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Receiver Function ◽  
Sediment Layer ◽  
Low Velocity ◽  
Japan Subduction Zone ◽  
Ne Japan

scholarly journals Transportation of H2O in the NE Japan Subduction Zone as Inferred from Seismic Observations

2008 ◽  
Vol 117 (1) ◽  
pp. 59-75 ◽  
Author(s):  
Akira HASEGAWA ◽  
Junichi NAKAJIMA ◽  
Saeko KITA ◽  
Yusuke TSUJI ◽  
Kyohei NII ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Japan Subduction Zone ◽  
Ne 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>

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