Controlling factor of incoming plate hydration at the north-western Pacific margin

Fujie, Gou; Kodaira, Shuichi; Kaiho, Yuka; Yamamoto, Yojiro; Takahashi, Tsutomu; Miura, Seiichi; Yamada, Tomoaki

doi:10.1038/s41467-018-06320-z

Cited by 79 publications

(112 citation statements)

References 33 publications

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“…However, in Japan, more plate hydration is observed at the Japan Trench with oblique plate fabric, compared with the Kuril Trench with subparallel fabric. The difference is attributed to larger fault offsets at the Japan Trench compared with the reactivated faults at the Kuril Trench (Fujie et al, 2018). Given the ambiguous relationship between incoming plate parameters and degree of hydration, it is unclear if the alignment in fabric would promote more hydration in the south where the seismicity rate is greater.…”

Section: Discussionmentioning

confidence: 99%

“…Normal faulting within the incoming plate seaward of oceanic trenches is observed globally (Craig et al, 2014; Emry & Wiens, 2015), and the bending can produce subhydrostatic or even negative pressure gradients along the faults to promote fluid flow to depth (Faccenda et al, 2009). Serpentinization of the incoming plate mantle has been interpreted in many subduction zones globally, with the amount of hydration dependent on several factors including plate age (Horning et al, 2016), incoming plate fabric (Fujie et al, 2018; Shillington et al, 2015), sedimentation (Contreras‐Reyes et al, 2007), and convergence rate (Contreras‐Reyes et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Seismicity of the Incoming Plate and Forearc Near the Mariana Trench Recorded by Ocean Bottom Seismographs

Eimer

Wiens

Cai

et al. 2020

Geochem Geophys Geosyst

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Earthquakes near oceanic trenches are important for studying incoming plate bending and updip thrust zone seismogenesis, yet are poorly constrained using seismographs on land. We use an ocean bottom seismograph (OBS) deployment spanning both the incoming Pacific Plate and the forearc to study seismicity near the Mariana Trench. The yearlong deployment in 2012-2013 consisted of 20 broadband OBSs and 5 suspended hydrophones, with an additional 59 short period OBSs and hydrophones recording for 1 month. We locate 1,692 earthquakes using a nonlinear method with a 3D velocity model constructed from active source profiles and surface wave tomography results. Events occurring seaward of the trench occur to depths of~35 km below the seafloor, and focal mechanisms of the larger events indicate normal faulting corresponding to plate bending. Significant seismicity emerges about 70 km seaward from the trench, and the seismicity rate increases continuously towards the trench, indicating that the largest bending deformation occurs near the trench axis. These plate-bending earthquakes occur along faults that facilitate the hydration of the subducting plate, and the lateral and depth distribution of earthquakes is consistent with low-velocity regions imaged in previous studies. The forearc is marked by a heterogeneous distribution of low magnitude (<5 M w ) thrust zone seismicity, possibly due to the rough incoming plate topography and/or serpentinization of the forearc. A sequence of thrust earthquakes occurs at depths~10 km below seafloor and within 20 km of the trench axis, demonstrating that the megathrust is seismically active nearly to the trench. Plain Language Summary Studying earthquakes near oceanic trenches is important forunderstanding subduction zones but can be difficult using only distant land-based instruments. This study uses seismographs designed to work on the seafloor to study earthquakes near the central Mariana Trench. As the subducting plate bends, faults form due to the increased extensional stress. These faults can become pathways for water to penetrate into this subducting plate. Understanding the amount of water stored in the plate is essential for constraining the global water cycle, and the earthquake distribution allows us to determine the distribution of active faults. We found that the earthquakes occur shallower than 35-km depth and within 70 km seaward of the trench. We also study earthquakes occurring along the megathrust, which is the interface between the subducting plate and the overriding plate that is prone to seismic activity. We found that the earthquakes show a patchy distribution, indicating that the megathrust interface is not uniform. This could be related to topographic features on the subducting plate interacting with the plate above. We also observed earthquakes at depths shallower than 10 km below the seafloor, indicating that the megathrust can rupture close to the trench.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Seismicity of the Incoming Plate and Forearc Near the Mariana Trench Recorded by Ocean Bottom Seismographs

Eimer

Wiens

Cai

et al. 2020

Geochem Geophys Geosyst

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“…(b) Thinned continental crust: typical continental crust (Christensen & Mooney, 1995), the Jan Mayen ridge and basin (Kodaira et al, 1998), the Moroccan margin (Contrucci et al, 2004), and the Tagus abyssal plain (Afilhado et al, 2008). (c) Oceanic crust: The Tasman Basin (this study), the NW Pacific Ocean >100 km from the Japan trench (Fujie et al, 2013(Fujie et al, , 2016(Fujie et al, , 2018Kodaira et al, 2014), the Liguro-Provencal Basin (Gailler et al, 2009), and the Brazilian margin in the Santos Basin (Klingelhoefer et al, 2014). velocity gradient (Figure 6a).…”

Section: Exhumed Mantlementioning

confidence: 90%

Crustal Structure Across the Lord Howe Rise, Northern Zealandia, and Rifting of the Eastern Gondwana Margin

et al. 2019

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During the Late Cretaceous, the fragmentation of eastern Gondwana led to the formation of the narrow eastern Australian margin and the wide Lord Howe Rise during the opening of the oceanic Tasman Basin. To provide crustal‐scale constraints on this margin, a 680‐km‐long, east‐west oriented refraction transect with 100 ocean bottom seismometers was acquired from the Tasman Basin to the Lord Howe Rise. After traveltime tomographic inversion of the first refracted arrivals and reflected arrivals from the Moho, the final P wave velocity model reveals strong variations in crustal thickness. The Tasman Basin is floored by a two‐layered and 7‐km‐thick oceanic crust. To the east, the Middleton Basin separates the Dampier Ridge, with 16‐km‐thick continental crust, from the Lord Howe Rise, where the extended continental crust is 20–23 km thick. Below the Middleton Basin, Moho reflections are recorded at the base of 7‐km‐thick crust. The velocity gradient of this two‐layer crust suggests an oceanic origin for the Middleton Basin. Our results show no clear evidence for mantle exhumation or a sizable igneous intrusion within three separate and relatively narrow (<70 km) necking zones. The northwestern Zealandia margin thus appears to be magma poor and, despite the considerable width of this margin (>1,000 km), the lack of evidence for mantle exhumation, the evidence for oceanic crust under the Middleton Basin, and the narrow necking zones combine to suggest that northern Zealandia is not a hyperextended margin.

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“…Journal of Geophysical Research: Solid Earth to a combination of increased porosity and mineral alteration Miller & Lizarralde, 2016;Korenaga, 2017). Such velocity reductions are commonly observed in the outerrise region of subduction zones where bend-related normal faults penetrate many kilometers beneath the Moho (Cai et al, 2018;Faccenda et al, 2009;Fujie et al, 2018;Ranero et al, 2003;Shillington et al, 2015;Van Avendonk et al, 2011). In Cascadia, bend-related faulting is observed to extend 6-7 km beneath the Moho in~8.5-Myr lithosphere .…”

Section: Isotropic Structure Of Gorda and Juan De Fucamentioning

confidence: 99%

“…This is in part due to a lack of seafloor instrumentation. Constraints on the physical state of oceanic lithosphere come primarily from 2-D reflection/refraction profiles (e.g., Canales et al, 2017;Fujie et al, 2018;Han et al, 2016Han et al, , 2018Horning et al, 2016;Lizarralde et al, 2004;Ranero et al, 2003;Shillington et al, 2015;Van Avendonk et al, 2011) and a small number of 3-D seismic deployments over geographically limited areas (e.g., Cai et al, 2018;Dunn et al, 2005;Paulatto et al, 2017;Toomey et al, 2007;VanderBeek et al, 2016). Results from these studies suggest that the hydration state of the oceanic plate prior to subduction is highly heterogeneous and is shaped by its tectonic history.…”

Section: Introductionmentioning

confidence: 99%

Pn Tomography of the Juan de Fuca and Gorda Plates: Implications for Mantle Deformation and Hydration in the Oceanic Lithosphere

VanderBeek

Toomey

2019

JGR Solid Earth

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Tomographic analysis of Pn arrivals—the guided P wave propagating within the lithospheric mantle—is ideal for studying uppermost mantle structure. While plate‐scale seismic images of Pn velocities are common beneath the continents, similar scale studies have not been possible within ocean basins due to the sparse distribution of seismic stations. The Cascadia Initiative (CI) data set provides the first opportunity to image spatial variations in lithospheric structure from accretion to subduction across an entire oceanic plate. We invert Pn travel times from local earthquakes for 3‐D variations in isotropic and anisotropic P wave velocity and event hypocentral parameters. Despite surficial evidence of extensive faulting, we find that the velocity structure of the Gorda uppermost mantle is remarkably consistent with predictions from a conductive cooling model. Limited brittle deformation at mantle depths is supported by seismic anisotropy measurements, which show the fast direction of P wave propagation rotates in concert with the magnetic anomaly lineations. This rotation may be explained by local plate kinematics without internal deformation and hydration of the shallow mantle. In contrast to Gorda, the seismic velocity structure of the Juan de Fuca (JdF) plate does not exhibit a clear age dependence. Anomalously slow mantle velocities are found along the southern edge of the JdF plate and are spatially associated with the termini of pseudofaults. We attribute these velocity reductions to mantle alteration by seawater. Our results highlight the heterogeneous nature of the oceanic mantle lithosphere and show that patterns of mantle alteration are not readily discerned from surficial indicators of seafloor deformation.

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Controlling factor of incoming plate hydration at the north-western Pacific margin

Cited by 79 publications

References 33 publications

Seismicity of the Incoming Plate and Forearc Near the Mariana Trench Recorded by Ocean Bottom Seismographs

Seismicity of the Incoming Plate and Forearc Near the Mariana Trench Recorded by Ocean Bottom Seismographs

Crustal Structure Across the Lord Howe Rise, Northern Zealandia, and Rifting of the Eastern Gondwana Margin

Pn Tomography of the Juan de Fuca and Gorda Plates: Implications for Mantle Deformation and Hydration in the Oceanic Lithosphere

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