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Lithological control on the deformation mechanism and the mode of fault slip on the Longitudinal Valley Fault, Taiwan

Thomas, Marion Y. and Avouac, Jean-Philippe and Gratier, Jean-Pierre and Lee, Jian-Cheng (2014) Lithological control on the deformation mechanism and the mode of fault slip on the Longitudinal Valley Fault, Taiwan. Tectonophysics, 632 . pp. 48-63. ISSN 0040-1951. doi:10.1016/j.tecto.2014.05.038.

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The Longitudinal Valley Fault (LVF) in Taiwan is creeping at shallow depth along its southern half, where it is bounded by the Lichi Mélange. By contrast, the northern segment of the LVF is locked where it is bounded by forearc sedimentary and volcanoclastic formations. Structural and petrographic investigations show that the Lichi Mélange most probably formed as a result of internal deformation of the forearc when the continental shelf of South China collided with the Luzon arc as a result of the subduction of the South China Sea beneath the Philippine Sea Plate. The forearc formations constitute the protolith of the Lichi Mélange. It seems improbable that the mechanical properties of the minerals of the matrix (illite, chorite, kaolinite) in themselves explain the aseismic behavior of the LVF. Microstructural investigations show that deformation within the fault zone must have resulted from a combination of frictional sliding at grain boundaries, cataclasis (responsible for grain size comminution) and pressure solution creep (responsible for the development of the scaly foliation and favored by the mixing of soluble and insoluble minerals). The microstructure of the gouge formed in the Lichi Mélange favors effective pressure solution creep, which inhibits strain-weakening brittle mechanisms and is probably responsible for the dominantly aseismic mode of fault slip. Since the Lichi Mélange is analogous to any unlithified subduction mélanges, this study sheds light on the mechanisms which favor aseismic creep on subduction megathrust.

Item Type:Article
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URLURL TypeDescription
Thomas, Marion Y.0000-0002-4335-8841
Avouac, Jean-Philippe0000-0002-3060-8442
Additional Information:© 2014 Elsevier B.V. Received 7 November 2013. Received in revised form 26 May 2014. Accepted 30 May 2014. Available online 7 June 2014. This study was supported by the Gordon and Betty Moore Foundation through grant GBMF 423.01 to the Caltech Tectonics Observatory, and by the Keck Institute for Spaces Studies at Caltech. This is Tectonics Observatory contribution # 262. We thank the anonymous reviewer and Stéphane Dominguez for their insightful detailed comments that helped us improve the manuscript.
Group:Keck Institute for Space Studies, Caltech Tectonics Observatory. Taiwan Tectonics and Seismicity, Caltech Tectonics Observatory, Seismological Laboratory, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
Gordon and Betty Moore FoundationGBMF 423.01
Keck Institute for Space Studies (KISS)UNSPECIFIED
Subject Keywords:Longitudinal Valley Fault; Aseismic slip; Deformation mechanism; Lichi Mélange; Pressure solution creep; Frictional sliding
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Caltech Tectonics Observatory262
Record Number:CaltechAUTHORS:20141121-083842997
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Official Citation:Marion Y. Thomas, Jean-Philippe Avouac, Jean-Pierre Gratier, Jian-Cheng Lee, Lithological control on the deformation mechanism and the mode of fault slip on the Longitudinal Valley Fault, Taiwan, Tectonophysics, Volume 632, 29 September 2014, Pages 48-63, ISSN 0040-1951, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:52029
Deposited By: Ruth Sustaita
Deposited On:21 Nov 2014 17:06
Last Modified:10 Nov 2021 19:19

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