Autocorrelation analysis of ambient noise in northeastern Japan subduction zone

2012 ◽  
Vol 572-573 ◽  
pp. 38-46 ◽  
Author(s):  
Yoshihiro Ito ◽  
Katsuhiko Shiomi ◽  
Junichi Nakajima ◽  
Ryota Hino
Keyword(s):  
Subduction Zone ◽  
Ambient Noise ◽  
Autocorrelation Analysis ◽  
Northeastern Japan ◽  
Japan Subduction Zone

Seismic activity and deformation process of the overriding plate in the northeastern Japan subduction zone

2000 ◽  
Vol 319 (4) ◽  
pp. 225-239 ◽  
Author(s):  
Akira Hasegawa ◽  
Akira Yamamoto ◽  
Norihito Umino ◽  
Satoshi Miura ◽  
Shigeki Horiuchi ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Seismic Activity ◽  
Deformation Process ◽  
Northeastern Japan ◽  
Japan Subduction Zone

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>

Sign in / Sign up

Export Citation Format

Share Document