The Mentawai forearc sliver off Sumatra: A model for a strike-slip duplex at a regional scale

Berglar, Kai; Gaedicke, Christoph; Ladage, S.; Thöle, Hauke

doi:10.1016/j.tecto.2016.09.014

Cited by 15 publications

(15 citation statements)

References 29 publications

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“…Experiments performed with oblique convergence indeed exhibit landward-vergence thrusting in the rear margin of accretionary wedge (McClay et al, 2004). Based on the undeformed strata in the area between DF and ANF-WAF, it is clear that this area does not belong to the accretionary complex as had been suggested by several authors (Berglar et al, 2017;Izart et al, 1994;Martin et al, 2014;Seeber et al, 2007). The accretionary complex in the oblique Andaman-northern Sumatra subduction zone is bounded by fold-thrust belts in the landward and seaward margins.…”

Section: Discussionsupporting

confidence: 54%

Structural complexity in the boundary of forearc basin – accretionary wedge in the northwesternmost Sunda active margin

Mukti¹

2018

BoMG

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The area from Andaman to northern Sumatran margin is a region where major faults collided that complicates the structural configuration. The origin of structures in the boundary between the accretionary wedge and forearc basin in the northwesternmost segment of the Sunda margin has been a subject of debates. This article reviews several published works on the Andaman – north Sumatran margin to characterize the boundary between forearc basin and accretionary wedge. Complex strain partitioning in this margin is characterized by sliver faults that crossing boundaries between the backarc basin, volcanic arc, forearc basin, and accretionary wedge. The fault zone can be divided into two segments: The West Andaman Fault (WAF) in the north and Simeulue Fault (SiF) in the southern part. A restraining step-over formed in between WAF and SiF. The SiF may extent onshore Simeulue to a strike-slip fault onshore. Strain-partitioning in such an oblique convergent margin appears to have formed a new deformation zone rather than reactivated the major rheological boundary in between the accretionary wedge and forearc basin. The eastern margin of the Andaman-north Sumatra accretionary wedge appears to have form as landward-vergent backthrusts of Diligent Fault (DF) and Nicobar Aceh Fault (NAF) rather than strike-slip faults. This characteristic appears to have formed in the similar way with the compressional structures dominated the eastern margin accretionary wedge of the central and south Sumatra forearc. Keywords: Andaman, North Sumatra, forearc, structure, accretionary wedge, strain partitioningDaerah Andaman - Sumatera bagian utara adalah wilayah di mana patahan-patahan besar saling bertemu dan membuat konfigurasi struktur menjadi rumit. Asal-usul struktur di batas antara prisma akresi dan cekungan busur muka di bagian paling baratlaut dari tepian Sunda telah menjadi topik perdebatan. Artikel ini mengulas beberapa studi yang telah diterbitkan sebelumnya mengenai tepian Andaman - Sumatra bagian utara untuk mengkarakterisasikan batas antara cekungan muka dan prisma akresi. Pemisahan regangan yang kompleks di tepian ini dicirikan oleh sliver fault yang melintasi batas antara cekungan busur belakang, busur vulkanik, cekungan busur muka, dan prisma akresi. Zona sesar tersebut dapat dibagi menjadi dua segmen, yaitu Sesar Andaman Barat (WAF) di utara dan Simeulue Fault (SiF) di bagian selatan. Sebuah restraining step-over terbentuk di antara WAF dan SiF. SiF kemungkinan menerus sampai ke Pulau Simeulue dan menyatu dengan sesar geser. Pemisahan regangan di tepian konvergen yang miring seperti itu tampaknya telah membentuk zona deformasi baru daripada mengaktifkan kembali batas reologi utama di antara prisma akresi dan cekungan busur muka. Batas bagian timur dari prisma akresi di Andaman – Sumatera bagian utara memiliki bentuk sebagai backthrusts berarah darat yaitu Sesar Diligent (DF) dan Sesar Nicobar Aceh (NAF) dan bukan merupakan sesar geser. Karakteristik ini tampaknya terbentuk dengan proses yang mirip dengan struktur-struktur kompresional yang mendominasi bagian timur prisma akresi di daerah Sumatra bagian tengah dan selatan.Kata kunci: Andaman, Sumatera bagian, busur muka, struktur, prisma akresi, pemisahan regangan

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Section: Discussionsupporting

confidence: 54%

Structural complexity in the boundary of forearc basin – accretionary wedge in the northwesternmost Sunda active margin

Mukti¹

2018

BoMG

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“…These faults may confirm the concept of strain partitioning of plate boundary, which was first applied regionally to the Sunda Trench by Moore and Karig (1980). Thus, a series of splay faults connect to the Mentawai Fault and between the Mentawai and the Sumatra Fault zones subdivide the forearc sliver into several tectonic blocks, that being identified by seismic reflection and bathymetry studies by Berglar et al (2017), which located at the northeastern offshore of Siberut island (between Si-berut and Batu Islands). The similar feature of splay fault has been reported by Waldhauser et al (2012) beneath Aceh basin (northwestern offshore of Simeulue) through imaging aftershocks of the 2004 Mw 9.2 Sumatra-Andaman earthquake.…”

Section: The Padang Earthquake Sequencesupporting

confidence: 61%

“…S2 of Supplementary Data). This finding is reinforced by the finding of the splay fault system by Berglar et al (2017) at the northeastern offshore of Siberut and their extended conclusion that the Mentawai forearc sliver developed as a regional strike-slip duplex that divided by splay faults for each tectonic block.…”

Section: The Padang Earthquake Sequencementioning

confidence: 89%

“…9b may be possible cause of the activity of the USF (Lin et al 2009). A series of such splay faults located beneath Aceh basin (northwestern offshore of Simeulue island) (Waldhauser et al 2012) and at the western edge of the Mentawai basin were identified (Konca et al 2008;Berglar et al 2017). Those faults could be as source of tsunamigenic fault.…”

Section: The Banyak Islands Earthquake Sequencementioning

confidence: 99%

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A study of large earthquake sequences in the Sumatra subduction zone and its possible implications

Haridhi¹,

Huang²,

Wen³

et al. 2018

Terr. Atmos. Ocean. Sci.

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Large subduction earthquakes have repeatedly occurred along the Sumatra subduction zone, where the Australian oceanic plate is subducting beneath the Sunda continental plate. We have analyzed two years (2009 to 2011) earthquake data from a regional seismic network along the Sumatra region that provided by the Badan Meteorologi, Klimatologi, dan Geofisika (BMKG) of Indonesia. Based on those data, a regional one-dimensional velocity model was refined first. Then, all events have been relocated based on the hypocenter double difference technique. Based on the relocated earthquake catalogue, three large earthquake sequences with magnitude greater than Mw 7.5 were well identified with one of them induced significant tsunami, thus, the 30 September 2009 Mw 7.6 Padang earthquake, the 7 April 2010 Mw 7.8 Banyak Islands earthquake, and the 25 October 2010 Mw 7.8 Mentawai tsunami earthquake. The characteristics of these earthquake sequences were analyzed and its possible implications were discussed in this study. A statistical analysis of polynomial linear fitting has been proposed to identify lineation of earthquake pattern in this study. Results indicated that a northwest-southeast dipping of earthquake lineation was identified within the Banyak Islands earthquake sequence and considered as the activity of the upper splay fault. Limited earthquake activity was identified at the Mentawai gap region and considered as a locked asperity. Those faults could be as a major threat of a great source of tsunamigenic fault. This region is considered as a high potential candidate to generate destructive earthquake and tsunami on the Sumatra subduction zone in future.

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“…Deposition and deformation of the Mentawai basin have been strongly influenced by imbricated seaward-vergent fore-thrusts in the accretionary wedge and landward-vergent backthrusts in the Mentawai fault zone [18,22,23] (Figure 3C). This fault zone has both characters of strike-slip fault (e.g., [23]) and back-thrust [18]. The fault zone may have initiated during Early-Middle Miocene and indicates the arc-parallel transpressional features along the boundary between the accretionary wedge and the continental backstop [18].…”

Section: Mentawai Basinmentioning

confidence: 99%

Deposition and Deformation of Modern Accretionary-Type Forearc Basins: Linking Basin Formation and Accretionary Wedge Growth

Noda¹,

Miyakawa²

2017

Evolutionary Models of Convergent Margins - Origin of Their Diversity

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Since a comprehensive review of forearc basins was published by Dickinson more than 20 years ago, a significant amount of new data about them have been published. These recent studies revealed details of depositional and deformation styles in the forearc basins, suggesting the formation processes were not unique. In this chapter, we reviewed modern forearc basins to understand how is the basin stratigraphy related with growth of accretionary wedges. The results indicate forearc basin can be classified into two (singleand two-wedge models) plus one (strike-slip model): (1) the single-wedge model which is characterized by landward tilting of the basin strata ascribed to asymmetrical doubly vergent (single-vergent) uplift of the outer arc high with forethrusts (seaward-vergent thrusts in the pro-wedge); (2) the two-wedge model which is marked by contractional deformation caused by symmetrical doubly vergent uplift of the wedge with forethrusts in the prowedge and back-thrusts (landward-vergent thrusts) in the retro-wedge; and (3) the strike-slip model which is an additional one being represented by transpressional and/or transtensional deformations due to oblique subduction. We speculate that these models spatially and temporally depend on material fluxes at the plate interfaces that affect geometry and mechanical strength of backstops.

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The Mentawai forearc sliver off Sumatra: A model for a strike-slip duplex at a regional scale

Cited by 15 publications

References 29 publications

Structural complexity in the boundary of forearc basin – accretionary wedge in the northwesternmost Sunda active margin

Structural complexity in the boundary of forearc basin – accretionary wedge in the northwesternmost Sunda active margin

A study of large earthquake sequences in the Sumatra subduction zone and its possible implications

Deposition and Deformation of Modern Accretionary-Type Forearc Basins: Linking Basin Formation and Accretionary Wedge Growth

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