Dehydration of serpentinized slab mantle: Seismic evidence from southwest Japan

Seno, Tetsuzo; Zhao, Dapeng; Kobayashi, Yoji; Nakamura, Masao

doi:10.1186/bf03351683

Cited by 120 publications

(100 citation statements)

References 44 publications

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“…These values are consistent with $15-25% serpentinization of the mantle wedge [Carlson and Miller, 2003] and place Costa Rica in the middle range of serpentinization values currently cited [i.e., Graeber and Asch, 1999;Kamiya and Kobayashi, 2000;Rondenay et al, 2001;Seno et al, 2001]. All V P models presented here are consistent with the compositional structure proposed by Sallarès et al [2001] of a basaltic-gabbro mid-crust and mafic granulite lower crust, and the depth of the modeled Moho at JTS is consistent with the Moho depth reported using refraction data [Sallarès et al, 2001].…”

Section: Discussionsupporting

confidence: 73%

“…Dehydration of oceanic slab components may hydrate continental mantle olivine and lead to the formation of serpentine minerals that exhibit both stable sliding and strain rate dependent conditional stability under laboratory conditions [e.g., Hyndman and Peacock, 2003]. Serpentinized mantle wedges have been identified in Chile, Alaska, Cascadia, and Japan [Graeber and Asch, 1999;Kamiya and Kobayashi, 2000;Zhao et al, 1992;Rondenay et al, 2001;Seno et al, 2001] through recognition of decreased P-and S-wave seismic velocities, increased V P /V S , and reduced density [i.e., Hyndman and Peacock, 2003].…”

Section: Introductionmentioning

confidence: 99%

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Evidence for serpentinization of the forearc mantle wedge along the Nicoya Peninsula, Costa Rica

DeShon

Schwartz

2004

Geophysical Research Letters

100

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[1] Characterizing the hydration state of the forearc mantle wedge yields valuable information on frictional stability at the downdip edge of subduction megathrusts. Simultaneous inversion of P-and S-wave arrival times collected as part of the Costa Rica Seismogenic Zone Experiment yields 1D and 3D P-and S-wave velocity models (V P and V S ) for the Nicoya Peninsula segment of the Middle America Trench. Nicoya Peninsula 1D velocity models show similar velocity gradients to country-wide 1D velocity models from 5 -30 km depth but diverge at expected Moho depths due to proximity to the subducting Cocos plate. 3D V P values range from 7.2-7.6 km/sec in the forearc mantle wedge. Receiver functions computed at Global Seismic Network station JTS in northwestern Costa Rica confirm these V P values, yield V P /V S of $1.85, and place the continental Moho at 36 ± 4 km depth. V P and V P /V S are consistent with 15 -25% serpentinization of the forearc mantle wedge.

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Section: Discussionsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Evidence for serpentinization of the forearc mantle wedge along the Nicoya Peninsula, Costa Rica

DeShon

Schwartz

2004

Geophysical Research Letters

100

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“…Beneath the Kii Peninsula, Seno et al (2001) and Yamasaki and Seno (2003) noted possible existence of a double seismic zone within the PHS slab and discussed it from a viewpoint of dehydration of the serpentinized slab mantle. Recently, Aoki (2003) and Miyoshi and Ishibashi (2004) also recognized a double seismic zone beneath the Kii Peninsula from detailed investigation of seismicity.…”

Section: A Possible Source For the Stress Disturbancementioning

confidence: 99%

The September 5, 2004 off the Kii Peninsula earthquakes as a composition of bending and collision

Seno

2005

Earth Planet Sp

Self Cite

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The 2004 off the Kii Peninsula earthquakes ruptured the subducting Philippine Sea plate near the axis of the Nankai Trough. A series of major events (the fore-and mainshocks with M w >7) showed very peculiar rupture characteristics. The depth extent of the foreshock is around 12-23 km below the sea surface; in contrast, that of the mainshock is around 7-17 km, shallower and closer to the upper surface of the plate than the foreshock. The focal mechanism of the foreshock is almost pure reverse faulting, with a P-axis directing roughly N-S, that is rotated clockwise by 20-25• from the trough normal. In contrast, the mainshock involved a significant component of strike-slip faulting, with a similar P-axis. The OBS survey revealed a double layer of the aftershock activity and the upper NW trending layer contains aftershocks with strike-slip focal mechanisms. These features indicate that the compressional and tensional stress domains due to bending are significantly modified by tectonic stress disturbance and produced the fore-and mainshock ruptures deviated from simple reverse and normal faulting. I show that a supposed N-S compressional stress, which might be produced by the collision south of the Izu Peninsula, can rotate the principal stress axes and change the stress type, which are consistent with the P-axes of these events and the strike-slip component for the mainshock. The complex rupture mode of the mainshock might have been produced by superposition of the depth-dependent tensional bending stress in the upper half of the lithosphere and the collisional stress. This collisional stress should be comparable to the bending stresses in magnitude, which is much larger than the stress perturbation caused by nearby interplate locking.

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“…[43] It is generally accepted that serpentine is important for dynamic processes in subduction zone because of wide stability in mantle lithosphere [e.g., Ulmer and Trommsdorff, 1999;Seno et al, 2001;Bostock et al, 2002] and relatively weak mechanical properties [e.g., Raleigh and Paterson, 1965;Gerya et al, 2002]. Particularly its contribution to exhumation processes has been discussed on the basis of numerous geological and structural studies [e.g., Takasu, 1989;Hermann et al, 2000;Guillot et al, 2000].…”

Section: Serpentine Formation: a Trigger To Exhumationmentioning

confidence: 99%

Structural and petrological constraints on the tectonic evolution of the garnet‐lherzolite facies Higashi‐akaishi peridotite body, Sanbagawa belt, SW Japan

Mizukami

Wallis

2005

Tectonics

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[1] The Higashi-akaishi peridotite body in the Sanbagawa metamorphic belt is a unique example of a kilometer-scale body including garnet-lherzolite facies rocks from an oceanic subduction-type orogen. In this body, four distinct deformational phases D 1 , D 2 , D 3 , and D 4 can be defined. The tectonic significance of D 1 is unclear. Microstructural observations and application of garnet-orthopyroxene geothermobarometry suggest that D 2 took place during high-temperature subduction up to depths of $100 km (from 2.3 GPa to above 2.8 GPa at temperature of 700-800°C) or more. D 3 represents a major phase of exhumation. After exhumation the Higashi-akaishi body became juxtaposed with the adjacent Besshi and Eclogite units at a depth of around 35 km (1 GPa). The common history of the two units after D 3 is shown by the intertectonic growth of tremolite between D 3 and D 4 that corresponds to a stage of intertectonic growth of plagioclase in the Besshi and Eclogite units. Both the spatial distribution and the estimated pressuretemperature (P-T) conditions of this intertectonic phase of mineral growth in the different units are in excellent agreement. The development of an antigorite schistosity during the late stage of D 2 indicates an anticlockwise P-T path with cooling at depths of around 100 km. The association of the antigorite-bearing fabric and the onset of exhumation after the D 2 stage suggest that the density decrease due to antigorite formation may have been sufficient to trigger the exhumation of dense ultramafic body from UHP conditions in subduction zones. Syn-D 2 water introduction and the anticlockwise P-T path are expected when convection in the mantle wedge brings peridotite toward a subduction boundary through mantle wedge or when peridotite is dragged down along a subduction boundary that is progressively cooling immediately after initiation of subduction. Citation: Mizukami, T., and S. R. Wallis (2005), Structural and petrological constraints on the tectonic evolution of the garnet-lherzolite facies Higashi-akaishi peridotite body, Sanbagawa belt, SW Japan, Tectonics, 24, TC6012,

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Dehydration of serpentinized slab mantle: Seismic evidence from southwest Japan

Cited by 120 publications

References 44 publications

Evidence for serpentinization of the forearc mantle wedge along the Nicoya Peninsula, Costa Rica

Evidence for serpentinization of the forearc mantle wedge along the Nicoya Peninsula, Costa Rica

The September 5, 2004 off the Kii Peninsula earthquakes as a composition of bending and collision

Structural and petrological constraints on the tectonic evolution of the garnet‐lherzolite facies Higashi‐akaishi peridotite body, Sanbagawa belt, SW Japan

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