Seismic Anisotropy in the Java‐Banda and Philippine Subduction Zones and its Implications for the Mantle Flow System Beneath the Sunda Plate

Wang, Lingling; He, Xiaobo

doi:10.1029/2019gc008658

Cited by 16 publications

(36 citation statements)

References 105 publications

(179 reference statements)

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“…Several seismic anisotropy investigations have been conducted in the central Sunda Plate and surrounding areas to explore the upper mantle seismic anisotropy and associated mantle deformation (Figure S1; Collings et al., 2013; Di Leo et al., 2012; Hammond et al., 2010; Kong, Gao, Liu, Zhang, et al., 2020; Wang & He, 2020; Xue et al., 2013; Y. Yu et al., 2018). While some SWS studies using local S and XKS (including SKS, SKKS, and PKS) waves suggested that the mantle wedge of the Sumatra subduction zone is generally isotropic (Hammond et al., 2010), trench‐orthogonal azimuthal anisotropy has been observed and attributed to a corner flow system in the mantle wedge using data recorded by two temporary seismic networks (Collings et al., 2013).…”

Section: Introductionmentioning

confidence: 99%

“…Mantle flow dominantly driven by the rollback of the subducted Indian slab was proposed to interpret the pervasively E‐W fast orientations beneath the Indochina Peninsula (Y. Yu et al., 2018). A source‐side sS splitting analysis recently revealed the existence of simple 2‐D corner flow in the Java and Philippine subduction zones (Wang & He, 2020). Thus, the spatial variation of mantle anisotropy and inferred mantle deformation beneath the central Sunda plate are still poorly constrained.…”

Section: Introductionmentioning

confidence: 99%

“…• Table S1 • Table S2 • Table S3 Several seismic anisotropy investigations have been conducted in the central Sunda Plate and surrounding areas to explore the upper mantle seismic anisotropy and associated mantle deformation (Figure S1; Collings et al, 2013;Di Leo et al, 2012;Hammond et al, 2010;Kong, Gao, Liu, Zhang, et al, 2020;Wang & He, 2020;Xue et al, 2013;Y. Yu et al, 2018).…”

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confidence: 99%

“…Yu et al, 2018). A source-side sS splitting analysis recently revealed the existence of simple 2-D corner flow in the Java and Philippine subduction zones (Wang & He, 2020). Thus, the spatial variation of mantle anisotropy and inferred mantle deformation beneath the central Sunda plate are still poorly constrained.…”

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confidence: 99%

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Seismic Anisotropy and Mantle Deformation Beneath the Central Sunda Plate

Song

Gao

et al. 2021

JGR Solid Earth

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The central Sunda plate, which forms the core of Southeast Asia, has been extensively studied based on analyses of data mainly from surface geological observations. In contrast, largely due to the limited coverage by seismic stations in the area, a number of key issues associated with mantle structure and dynamics remain enigmatic. These can possibly be constrained by investigating seismic azimuthal anisotropy in the upper mantle. Here we employ the shear wave splitting technique on three P‐to‐S converted phases from the core‐mantle boundary (PKS, SKKS, and SKS) recorded by 11 stations to systematically explore the spatial variation of azimuthal anisotropy beneath the central Sunda plate. Most of the Malay Peninsula is revealed to possess mostly trench‐perpendicular fast orientations that can be attributed to mantle flow induced by the Indo‐Australian subduction. In addition, the central part of the Malay Peninsula is characterized by a 2‐layered model of anisotropy, which is possibly associated with the joint effects of lithospheric fabrics and a slab tear‐induced toroidal flow. Absolute plate motion (APM)‐parallel anisotropy is observed in northern Borneo and the Nansha Block, where APM‐driven simple shear in the transitional layer between the partially coupled lithosphere and asthenosphere is mostly responsible for the observed anisotropy. The APM‐induced flow may be locally modified by a fossil slab segment beneath Sabah.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seismic Anisotropy and Mantle Deformation Beneath the Central Sunda Plate

Song

Gao

et al. 2021

JGR Solid Earth

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“…In this study, to better understand the deformation characteristics in the complex tectonic region, we show upper mantle anisotropic fabrics constrained by measuring teleseismic SKS-wave splitting from new seismic data collected from seven broadband stations, six of which have been deployed for long-term observation (>12 years). Also, previous shear-wave splitting measurements (Di Leo et al, 2012aLeo et al, , 2012bRoy et al, 2017;L. Wang & He, 2020) and a Vp velocity model UU-P07 by Amaru (2007) are combined to shed light on the regional upper mantle flow patterns at the corner between the Pacific and Tethys domains.…”

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Mantle Flow Patterns Beneath the Junction of Multiple Subduction Systems Between the Pacific and Tethys Domains, SE Asia: Constraints From SKS‐Wave Splitting Measurements

Cao

Zhao

et al. 2021

Geochem Geophys Geosyst

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The term "poly-island ocean" is widely used to describe the Paleo-Tethys tectonic and geographical pattern (Fang, 2002;B. P. Liu et al., 1991). Among the present vast oceans, the Indonesian Archipelago serves as one of the most typical examples of "poly-island oceans" due to its unique geologic features. Specifically, it connects with the open western Pacific to the east and the hinterland of subduction and collision between the Indian-Australian and Eurasian plates to the west. The latter regime inherits the main characteristics of Tethys tectonics related to the northward subduction of the Indian-Australian plate.The Celebes Sea lies to the east of the Indonesian Archipelago. It is an ideal research area to study dynamic interactions between multiple microcontinents and oceans in a "poly-island ocean" domain, owing to its unique geologic location at the junction point of three major tectonic plates: the Indian-Australian, Philippine Sea, and Eurasian plates. In addition, the northeastern, eastern, and southern edges of the Celebes Sea are bordered with several subduction zones, including the Cotabato and North Sulawesi subduction zones and the double-sided subduction of the Molucca Sea plate (Figure 1). Numerical simulations have suggested that dynamic interactions take place in an active, complex tectonic setting composed of multiple

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SASSY21: A 3-D seismic structural model of the lithosphere and underlying mantle beneath Southeast Asia from multi-scale adjoint waveform tomography

Wehner

Blom

Rawlinson

et al. 2021

Preprint

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We present the first continental-scale seismic model of the lithosphere and underlying mantle beneath Southeast Asia obtained from adjoint waveform tomography (often referred to as full-waveform inversion or FWI), using seismic data filtered at periods from 20 to 150 s. Based on >3,000 hr of analyzed waveform data gathered from ∼13,000 unique source-receiver pairs, we image isotropic P-wave velocity, radially anisotropic S-wave velocity and density via an iterative non-linear inversion that begins from a 1-D reference model. At each iteration, the full 3-D wavefield is determined through an anelastic Earth, accommodating effects of topography, bathymetry and ocean load. Our data selection aims to maximize sensitivity to deep structure by accounting for body wave arrivals separately. SASSY21, our final model after 87 iterations across seven period bands, is able to explain true-amplitude data from events and receivers not included in the inversion. The trade-off between inversion parameters is estimated through an analysis of the Hessian-vector product. SASSY21 reveals detailed anomalies down to the mantle transition zone, including multiple subduction zones. The most prominent feature is the (Indo-)Australian plate descending beneath Indonesia, which is imaged as one continuous slab along the 180° curvature of the Banda Arc. The tomography confirms the existence of a hole in the slab beneath Mount Tambora and locates a high S-wave velocity zone beneath northern Borneo that may be associated with subduction termination in the mid-late Miocene. A previously undiscovered feature beneath the east coast of Borneo is also revealed, which may be a signature of post-subduction processes, delamination or underthrusting from the formation of Sulawesi.Plain Language Summary Southeast Asia is one of the world's most tectonically active regions, as evidenced by frequent large earthquakes and volcanic eruptions. We present a large-scale 3-D seismic structural model of this region down to a depth of 800 km that reveals a variety of primary features, including beneath the poorly understood islands of Borneo and Sulawesi. This is possible thanks to the use of a sizable data set of earthquakes recorded by a large number of permanent and temporary stations located in Southeast Asia, and advanced imaging methodology that is better able to capture the true physics of seismic wave propagation compared to more traditional methods. Our new model is capable of resolving variations in seismic properties associated with ongoing subduction (when one tectonic plate descends into the mantle below another plate), particularly along the northern margin of the Australian plate beneath the Sunda Arc. More subtle anomalies associated with remnant subduction, which correspond to plate fragments that remain once subduction stops, can also be imaged. These results are important for achieving a better understanding of the subduction cycle, which plays a central role in plate tectonics, and has important implications for, among other things, the evolut...

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Seismic Anisotropy in the Java‐Banda and Philippine Subduction Zones and its Implications for the Mantle Flow System Beneath the Sunda Plate

Cited by 16 publications

References 105 publications

Seismic Anisotropy and Mantle Deformation Beneath the Central Sunda Plate

Seismic Anisotropy and Mantle Deformation Beneath the Central Sunda Plate

Mantle Flow Patterns Beneath the Junction of Multiple Subduction Systems Between the Pacific and Tethys Domains, SE Asia: Constraints From SKS‐Wave Splitting Measurements

SASSY21: A 3-D seismic structural model of the lithosphere and underlying mantle beneath Southeast Asia from multi-scale adjoint waveform tomography

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