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Kinematic analysis of the Pakuashan fault tip fold, west central Taiwan: Shortening rate and age of folding inception

Simoes, Martine and Avouac, Jean Philippe and Chen, Yue-Gau and Singhvi, Ashok K. and Wang, Chien-Ying and Jaiswal, Manoj and Chan, Yu-Chang and Bernard, Sylvain (2007) Kinematic analysis of the Pakuashan fault tip fold, west central Taiwan: Shortening rate and age of folding inception. Journal of Geophysical Research B, 112 (B3). Art. No. B03S14. ISSN 0148-0227. http://resolver.caltech.edu/CaltechAUTHORS:20101116-080307482

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Abstract

The Pakuashan anticline is an active fault tip fold that constitutes the frontal most zone of deformation along the western piedmont of the Taiwan Range. Assessing seismic hazards associated with this fold and its contribution to crustal shortening across central Taiwan requires some understanding of the fold structure and growth rate. To address this, we surveyed the geometry of several deformed strata and geomorphic surfaces, which recorded different cumulative amounts of shortening. These units were dated to ages ranging from ~19 ka to ~340 ka using optically stimulated luminescence (OSL). We collected shallow seismic profiles and used previously published seismic profiles to constrain the deep structure of the fold. These data show that the anticline has formed as a result of pure shear with subsequent limb rotation. The cumulative shortening along the direction of tectonic transport is estimated to be 1010 ± 160 m. An analytical fold model derived from a sandbox experiment is used to model growth strata. This yields a shortening rate of 16.3 ± 4.1 mm/yr and constrains the time of initiation of deformation to 62.2 ± 9.6 ka. In addition, the kinematic model of Pakuashan is used to assess how uplift, sedimentation, and erosion have sculpted the present-day fold topography and morphology. The fold model, applied here for the first time on a natural example, appears promising in determining the kinematics of fault tip folds in similar contexts and therefore in assessing seismic hazards associated with blind thrust faults.


Item Type:Article
Related URLs:
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http://dx.doi.org/10.1029/2005JB004198 DOIUNSPECIFIED
http://www.agu.org/pubs/crossref/2007/2005JB004198.shtmlPublisherUNSPECIFIED
Additional Information:© 2007 American Geophysical Union. Received 30 November 2005; revised 2 October 2006; accepted 15 December 2006; published 13 February 2007. The Trimble 5700 RTK GPS system was provided by the CEA (France), and the laser distance meter was provided by Academia Sinica (Taiwan). We wish to thank O. Beyssac, J.-C. Hu, and R.-F. Chen for their valuable help in the field, as well as E. Thauvin for his help with the RTK GPS system. We are also indebted to A. Tyagi for his help in measuring the AYS series of OSL samples. Our study of southern Pakuashan was also made possible by J.-H. Hung, who kindly provided the data from the TC-1 well. This manuscript benefited from discussions with J. Suppe, S. Dominguez, and J. Malavieille and from the thoughtful and constructive reviews by J. Shaw, D. Burbank, and the Associate Editor, J. Dolan. These investigations were initiated thanks to a grant to J.P.A. from CNRS/INSU (France). This study was also partly funded by the Gordon and Betty Moore Foundation. This is Caltech Tectonics Observatory contribution 66.
Group:Caltech Tectonics Observatory, Seismological Laboratory
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Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:kinematics of shortening; blind thrust; morphology
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Caltech Tectonics Observatory66
Record Number:CaltechAUTHORS:20101116-080307482
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20101116-080307482
Official Citation:Simoes, M., J. P. Avouac, Y.-G. Chen, A. K. Singhvi, C.-Y. Wang, M. Jaiswal, Y.-C. Chan, and S. Bernard (2007), Kinematic analysis of the Pakuashan fault tip fold, west central Taiwan: Shortening rate and age of folding inception, J. Geophys. Res., 112, B03S14, doi:10.1029/2005JB004198
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20819
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:17 Nov 2010 21:52
Last Modified:11 Jun 2015 13:57

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