Hi all! Welcome to our blog, Tektonesiana.
The name of Tektonesiana is derived from the word tectonics and Indonesia. Tektonesiana represents our ‘passion’ on tectonics of Indonesia.
We, Indonesian geologists who share the same interest, use this blog to post articles that represent our works. These articles have been presented in scientific meetings. Some of them also have been published in journals. We have many questions about tectonics of Indonesia, and we want to share them with you. Enjoy our blog!
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The interesting point of this article, which has been presented at INDONESIAN PETROLEUM ASSOCIATION 35th Annual Convention and Exhibition May 2011 is that the deep seismic reflection data acquired by Western Geco and CGGVeritas have provide new information for understanding the evolution Sumatran forearc basins.
This is an abstract of a talk presented at American Geophysical Union, Fall Meeting 2011. Active deformation along the western margin of the present day Mentawai forearc basin appeared as anticlinal ridges. Beneath the anticlinal ridges, the deformation zone exhibits (1) main backthrust, as the upward continuation of the Mentawai Backthrust in forearc basin, (2) seaward verging imbricated thrusts developed in the accretionary wedge and (3) the landward verging thrust developed in the forearc basin. The landward verging Mentawai Backthrust zone and together with the Frontal Thrusts, formed the doubly vergent active tectonics in the Sumatra subduction system.
This article has been published in Nature Geoscience, 2011 . The authors have identified a seamount 3–4 km high and 40 km wide that has been subducted to a depth of 30–40 km below the Sumatra forearc mantle. The seamount has remained intact despite more than 160 km of subduction, and that there is no seismic activity either above or below the seamount. The authors suggest that the subduction of a topographic feature such as a seamount could lead to the segmentation of the subduction zone.
This article notes the structural features in the Mentawai forearc that can be interpreted as products of compression of the accretionary wedge and forearc basin sediments. Compressional phases since the Late Miocene initiated (a) the landward vergent foldthrust belt in the Mentawai Fault Zone (MFZ), (b) reactivation of seaward vergent imbricated thrusts in the retro-accretionary wedge, and (c) uplift of the accretionary wedge and some parts of the forearc basin. The authors interpret that the northwest part of the accretionary wedge underwent higher compression and tilting. The compression of the forearc is suggested to be controlled by the combination of the geometry and position of the continental backstop, and the subducting bathymetric high in the oceanic plate.