Slab melting and arc magmatism behind the Japan Trench: Evidence from seismic and thermal structure imaging

Wang，Zhi1,2; Jin，Zhenmin3; Lin，Jian1,2,4,5

2022-06-20

10.1016/j.tecto.2022.229340

TECTONOPHYSICS   影响因子和分区

0040-1951

1879-3266

Zones of fluid-bearing anomalies occur in volcanic regions, on a plate interface, or in the mantle wedge of a subduction zone. The various causes include slab dehydration, serpentinization or metamorphic reactions in different thermal regimes. To reveal the impact factors that might have contributed to slab melting and arc magmatism behind the Japan Trench, we determined high-resolution three-dimensional (3-D) structures of seismic velocities (Vp, Vs), Vp/Vs ratio and temperatures. The temperatures (T) were calculated from the inverted seismic structures, and two petrological models of the upper mantle: a peridotite assemblage and a pyrolite assemblage, which differ from the results of the thermal simulation. The multi-parameter structures obtained for Vp, Vs, Vp/Vs and T show good consistency in the upper mantle behind the Japan Trench. The temperatures derived from the peridotite assemblage were found to match the mean geotherm and simulated temperature of the upper mantle more closely than those from the pyrolite model. A layer approximately 10 km thick with low-Vp and Vs, high-Vp/Vs, and slightly high-T anomalies was observed on the upper boundary of the subducting Pacific slab. This distinctive anomalous layer is interpreted as partial melting of the oceanic crust due to deep-seated metamorphic reactions whose characteristics are dependent on the source of fluids, mineral composition, and the thermal regime. Such a process enriches the peridotite content of the basalt underneath the island arc in the mantle wedge. Localized zones of significantly low-Vp and low-Vs, high-Vp/Vs and high-T perturbations were imaged in the mantle wedge under the active volcanoes, suggesting partial melting of peridotite-rich mantle material to produce tholeiitic magma. The present study demonstrates that fluids released from slab dehydration, mineral composition and the thermal regime play crucial roles in both arc magmatism, and slab melting in the subduction zone.

Arc magmatism Joint seismic tomography NE Japan subduction zone Slab melting Thermal structures

SCI ; EI

英语

其他

Chinese Academy of Sciences[131551KYSB20200021 & ISEE2021PY03];National Natural Science Foundation of China[42074047 & 41890813];National Natural Science Foundation of China[92058210];Chinese Academy of Sciences[Y4SL021001, QYZDY-SSWDQC005, 133244KYSB20180029];

Geochemistry & Geophysics

Geochemistry & Geophysics

WOS:000798946800001

ELSEVIER

20221912075653

Dehydration ; Melting ; Structural geology ; Volcanoes

Geology:481.1 ; Seismology:484 ; Earthquake Measurements and Analysis:484.1 ; Chemical Reactions:802.2 ; Chemical Operations:802.3

GEOSCIENCES

2-s2.0-85129400426

Scopus

1.Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou,510301,China
2.Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou),Guangzhou,511458,China
3.State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences (Wuhan),Wuhan,430074,China
4.Department of Ocean Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China
5.Department of Geology and Geophysics,Woods Hole Oceanographic Institution,Woods Hole,02543,United States

Wang，Zhi,Jin，Zhenmin,Lin，Jian. Slab melting and arc magmatism behind the Japan Trench: Evidence from seismic and thermal structure imaging[J]. TECTONOPHYSICS,2022,833.

Wang，Zhi,Jin，Zhenmin,&Lin，Jian.(2022).Slab melting and arc magmatism behind the Japan Trench: Evidence from seismic and thermal structure imaging.TECTONOPHYSICS,833.

Wang，Zhi,et al."Slab melting and arc magmatism behind the Japan Trench: Evidence from seismic and thermal structure imaging".TECTONOPHYSICS 833(2022).