Andrzej Górszczyk, Rafael Almeida, Romain Brossier, Ludovic Métivier, Stéphane Operto
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引用次数: 0
Abstract
The Tokai area in the eastern Nankai Trough is characterized by the subduction of a rough plate interface caused by bathymetric highs related to the adjacent Izu-Bonin arc and fault fabrics in the oceanic crust. However, the effect of this process on the structural development of its accretionary wedge and megathrust seismicity is still poorly understood. To get better insight into Tokai area we apply full-waveform inversion to legacy wide-angle seismic data exploiting available signal frequency up to 15 Hz. From this model we extract pseudo-reflectivity attributes, which are complementary to the section obtained with Kirchoff pre-stack depth migration of streamer data. The high-resolution images reveal detailed geological characterization of the subducting oceanic crust, the geometry of the megathrust and splay faults, and the structure of the wedge. The latter is characterized by imbricate fans, out-of-sequence thrusts, and duplexes that significantly contribute to its thickening. We compare these features to published structural models and propose that the increased structural complexity in the Tokai segment is due to fault reactivation triggered by the subduction of the bathymetric highs. We suggest that this fault reactivation also controls the shallow seismogenic behavior of this region. We show that the evolution of the forearc basin is related to the ongoing underplating process and out-of-sequence thrusting within the wedge. We compare our seismic imaging results with bathymetric, magnetic, and gravity data, revealing no evidence of large ridges beneath our profile, which previous studies have proposed as a cause of the persistent Tokai seismic gap.
期刊介绍:
Geochemistry, Geophysics, Geosystems (G3) publishes research papers on Earth and planetary processes with a focus on understanding the Earth as a system. Observational, experimental, and theoretical investigations of the solid Earth, hydrosphere, atmosphere, biosphere, and solar system at all spatial and temporal scales are welcome. Articles should be of broad interest, and interdisciplinary approaches are encouraged.
Areas of interest for this peer-reviewed journal include, but are not limited to:
The physics and chemistry of the Earth, including its structure, composition, physical properties, dynamics, and evolution
Principles and applications of geochemical proxies to studies of Earth history
The physical properties, composition, and temporal evolution of the Earth''s major reservoirs and the coupling between them
The dynamics of geochemical and biogeochemical cycles at all spatial and temporal scales
Physical and cosmochemical constraints on the composition, origin, and evolution of the Earth and other terrestrial planets
The chemistry and physics of solar system materials that are relevant to the formation, evolution, and current state of the Earth and the planets
Advances in modeling, observation, and experimentation that are of widespread interest in the geosciences.