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Influence of inherited basement structures on the active Sumatran Fault and Volcanic Arc, Indonesia
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  • Lukman sutrisno,
  • Jeroen Smit,
  • Damien Bonté,
  • Yunus Daud,
  • Fred Beekman,
  • Widodo Purwanto,
  • Jan Diederik van Wees
Lukman sutrisno
Department of Earth Sciences, Faculty of Geosciences, Universiteit Utrecht

Corresponding Author:[email protected]

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Jeroen Smit
Utrecht University
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Damien Bonté
Department of Earth Sciences, Faculty of Geosciences, Universiteit Utrecht (Presently at IFP Energies Nouvelles, France)
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Yunus Daud
Faculty of Mathematics and Natural Sciences, Universitas Indonesia
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Fred Beekman
University of Utrecht
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Widodo Purwanto
Faculty of Engineering, Universitas Indonesia
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Jan Diederik van Wees
TNO
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Abstract

We present a novel tectonic and structural framework for the Sumatran Volcanic Arc and Sumatran Fault System (SFS), based on a comprehensive compilation of the controls of heterogeneities in both subducting and overriding plate on the local to lithospheric-scale geology. A new conceptual model is proposed to explain the interaction between pre-existing inherited basement structures, which are well exposed along the arc, with the much younger SFS. The model also illustrates the relationship between brittle deformation and nearby magmatism-volcanism. We present a novel structural restoration of the island prior to the SFS strike-slip faulting contributing to in-depth understanding of the initial condition of the island, especially in view of the basement structures underlying the volcanic arc and the inherited basement structures. More detailed structural analysis along the SFS showcases different interaction styles between SFS and the basement structures. Different intersection angles between those two structural features create different deformation styles along the arc. An elongated rhomboidal pull-apart basin is expected where the segments of SFS are parallel or sub-parallel to the basement structures, while a more complex and irregular pull-apart basin is developed where the intersection angle is larger. The structural controls on volcanism along the arc are located along the basement structures, and demonstrate that they are only partially in tune with the SFS fault structures. Furthermore, the different deformation styles and interaction between volcanism-tectonism along the arc have been grouped into two different main tectono-volcanic domains, with distinctive transitional area around the Toba Caldera Complex.