Deformation and mantle flow beneath the Sangihe subduction zone from seismic anisotropy

Leo, J. F. Di; Wookey, James; Hammond, James; Kendall, J.‐M.; Kaneshima, Satoshi; Inoue, Hiroshi; Yamashina, Tadashi; Harjadi, P.

doi:10.1016/j.pepi.2012.01.008

Cited by 53 publications

(103 citation statements)

References 128 publications

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“…Previous results of 3‐D numerical modeling and measurement of shear wave splitting in the Molucca Sea region reveal escape of narrow slab‐trapped mantle [ Di Leo et al , , ; Li et al , ]. Our results reproduce this pattern of lateral escape of the subslab mantle (Figures , and and Movies S1–S5).…”

Section: Discussionmentioning

confidence: 99%

“…It is estimated that the total length of the seismically active Molucca Sea plate is 1400–1600 km, 900 km of which was subducted under the Sangihe arc and ~450 km under the Halmahera arc [ Hall and Spakman , ] (Figures c and ). By means of shear wave splitting measurement, mantle flow pattern in response to subduction of the Sangihe and Halmahera slabs was inferred in this region, indicating lateral escape of mantle beneath the Molucca Sea plate [ Di Leo et al , , ].…”

Section: Cenozoic Molucca Sea Subduction Zonementioning

confidence: 99%

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Geodynamics of divergent double subduction: 3‐D numerical modeling of a Cenozoic example in the Molucca Sea region, Indonesia

et al. 2017

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Geological observations reveal existence of a unique form of plate subduction featuring subduction on both sides of one single oceanic plate, which is termed divergent double subduction (DDS). DDS may play an important role in facilitating tectonic processes like closure of oceanic basins, accretion and amalgamation of magmatic arcs, and growth of continents. However, this type of subduction has been largely a conceptual model and the geodynamics behind DDS are still poorly constrained. The Molucca Sea subduction zone in SE Asia has been considered as a Cenozoic example of DDS based on geophysical and geological data and provides an opportunity for detailed assessment of how DDS occurs. Here we present 3‐D numerical modeling with aims to reproduce the geodynamic processes of DDS. Several factors that may have important influences on the evolution of DDS are evaluated, including the geometry of the subducting plate, the order of subduction initiation on both sides, the far‐field boundary conditions and thickness of the overriding plates, and the negative buoyancy of the subducting plate. Our results reproduce the observed asymmetrical shape of the subducting Molucca Sea plate and the bending of Halmahera and Sangihe arcs and suggest that DDS is possible if effective escape of the slab‐trapped upper mantle overcomes the space problem, otherwise the slab‐trapped mantle may hinder the sustainability of subduction. We therefore conclude that DDS is associated with closure of narrow and short oceanic plate, and large‐scale double subduction is rare in nature probably owing to space problem.

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Section: Discussionmentioning

confidence: 99%

Section: Cenozoic Molucca Sea Subduction Zonementioning

confidence: 99%

Geodynamics of divergent double subduction: 3‐D numerical modeling of a Cenozoic example in the Molucca Sea region, Indonesia

et al. 2017

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“…These layers are located from shallow mantle regions down to the transition zone and have been related to mantle peridotitic lithologies containing hydrous phases. The presence of these hydrous phases which could contain a large amount of phase D in deep subduction zones between 410 km and 700 km depth might be the origin of the observed seismic anomalies and also contributes to positive buoyancy forces acting on a slab [ Iwamori , ; Litasov et al ., , ; Mainprice et al ., ; Di Leo et al ., ; Rosa et al ., , ].…”

Section: Introductionmentioning

confidence: 98%

“…Even though general agreement exists on the transport of water via subduction to shallow mantle depths of < 250 km, the abundance of hydrous phases in deep subducted slabs still remains a disputed issue [ Abers , ; Hacker et al ., ; Hirschmann , ]. Indirect evidences for the transport of water via subduction into deeper mantle regions are provided by seismic anomalies in the vicinity of deep slabs, including seismic velocity attenuations [ Lawrence and Wysession , ; Zhu et al ., ], reduced seismic bulk velocities [ Chen and Brudzinski , ], seismic shear wave anisotropies [ Chen and Brudzinski , ; Di Leo et al ., ], deviations from the globally observed depth and thicknesses of the major mantle seismic discontinuities [ Deuss et al ., ], and from observed elevated electrical conductivities [ Guo and Yoshino , ; Ichiki et al ., ]. Additional evidence for the continuous transport of hydrous phases into deep mantle regions are provided by the presence of low‐velocity layers recently detected above subducted slabs in Tonga and Japan [ Savage , ; Tonegawa et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Single‐crystal equation of state of phase D to lower mantle pressures and the effect of hydration on the buoyancy of deep subducted slabs

et al. 2013

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[1] An understanding of the physical properties of the hydrous magnesium silicate phase D is important for the interpretation of the seismic anomalies observed in subducted slabs and to evaluate the effect of hydration on slab dynamics. Here we report the equation of state of phase D (Mg 1.1 Si 1.8 H 2.5 O 6 ) up to 65 GPa obtained from high-precision single-crystal X-ray diffraction. A single-crystal of phase D was loaded in a diamond anvil cell using helium as pressure transmitting medium to ensure quasi-hydrostatic conditions during the entire data collection. The volume of phase D decreases smoothly over the entire pressure range, without the anomalies in the compressibility reported at 40 GPa in previous powder diffraction studies. If existing in phase D, a hydrogen bond symmetrization transition as predicted by first-principles calculation is therefore not associated with anomalies in the volume compression behavior. The isothermal bulk modulus K T and its pressure derivative K′ T obtained from the fitting of the unit cell volumes using a third-order Birch

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“…Measurements of shear wave splitting observed in the core‐refracted ( S K ( K ) S ) phases recorded at stations located above subduction zones are often used to infer mantle flow patterns and understand the dynamics of plate motions [ Savage , ; Park and Levin , ; Di Leo et al , , ]. However, since the splitting in S K ( K ) S phases is an integral effect of anisotropy along the raypath from the core mantle boundary to the receiver, this approach does not permit isolation of anisotropy in the subducting slab, subslab mantle, mantle wedge, and the overriding plate.…”

Section: Introductionmentioning

confidence: 99%

Anisotropy in subduction zones: Insights from new source side S wave splitting measurements from India

2017

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This study presents 106 splitting and 40 null measurements of source side anisotropy in subduction zones, utilizing direct S waves registered at two stations sited on the Indian continent, which show null shear wave splitting measurements for SKS phases. Our results suggest that trench‐parallel anisotropy is dominant beneath the Philippines, Mariana, Izu‐Bonin, and edge of the Java slab, while plate motion‐parallel anisotropy is observed beneath the Solomon, Aegean, Japan, and Java slabs. Results from Kuril and Aleutian regions reveal trench‐oblique anisotropy. We chose to interpret these observations primarily in terms of mantle flow beneath a subduction zone. While the two‐dimensional (2‐D) slab entrained flow model offers a simple explanation for trench‐normal fast polarization azimuths (FPA), the trench‐parallel FPA can be reconciled by extension due to slab rollback. The model that invokes age of the subducting lithosphere can explain anisotropy in the subslab, derived from rays recorded at the updip stations. However, when downdip stations are used, contributions from the slab and supraslab need to be considered. In Japan, anisotropy in the subslab mantle shallower than 300 km might be associated with trench‐parallel mantle flow resulting in the alignment of FPA in the same direction. Anisotropy in the deeper part, above the transition zone, is probably associated with 2‐D flow resulting in trench‐normal FPA. Anisotropy in the Mariana Trench might be associated with trench‐parallel mantle flow in the supraslab region, with similar deformation in the upper mantle and the transition zone.

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Deformation and mantle flow beneath the Sangihe subduction zone from seismic anisotropy

Cited by 53 publications

References 128 publications

Geodynamics of divergent double subduction: 3‐D numerical modeling of a Cenozoic example in the Molucca Sea region, Indonesia

Geodynamics of divergent double subduction: 3‐D numerical modeling of a Cenozoic example in the Molucca Sea region, Indonesia

Single‐crystal equation of state of phase D to lower mantle pressures and the effect of hydration on the buoyancy of deep subducted slabs

Anisotropy in subduction zones: Insights from new source side S wave splitting measurements from India

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