Kinematic analysis of the Pakuashan fault tip fold, Western central Taïwan : Shortening rate and age of folding inception - Université de Rennes Accéder directement au contenu
Article Dans Une Revue Journal of Geophysical Research : Solid Earth Année : 2007

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

Résumé

The Pakuashan anticline is an active fault-tip fold that constitutes the frontalmost 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 2 ranging from ~ 19 ka to ~ 340 ka using Optical 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 (N118E) is estimated to be 1010 +/- 160 m. An analytical fold model derived from a sandbox experiment [Bernard, et al., in press] 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 tectonics, 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 on blind thrust faults.

Domaines

Tectonique
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Dates et versions

hal-00138056 , version 1 (31-03-2016)

Identifiants

Citer

Martine Simoes, Jean-Philippe Avouac, Yue-Gau Chen, Ashok K. Singhvi, Chien-Ying Wang, et al.. Kinematic analysis of the Pakuashan fault tip fold, Western central Taïwan : Shortening rate and age of folding inception. Journal of Geophysical Research : Solid Earth, 2007, 112 (B3), pp.B03S14. ⟨10.1029/2005JB004198⟩. ⟨hal-00138056⟩
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