[FPI2019] Estructura y Dinamica de la Tierra

The hypothesis to be tested is that pre-exisitng faults along the continental margin of southeast Eurasia are being reactivated forming transverse zones in the Taiwan thrust-and-fold belt. The study is a continuation of project (CGL2013-43877-P) whose objective was to determine if the pre-existing structures of the margin affect the evolution of thrust systems when approaching the deformation front. In that project, structural data when combined with geophysical and geodetic data, showed the presence of three major transverse zones in the frontal part of the thrust-and-fold belt and its foreland. A causal link was interpreted between reactivation of pre-exisiting structures on the continental margin and along-strike changes in structure, in seismicity, and in topography. In this new project we propose to obtain more field data, which is needed to confidently constrain the location and structure of these transverse zones in the interior part of the thrust belt. Then, building on these new field observations, we will move to the key objective of the research, which is to advance the global understanding of how the reactivation of pre-exisiting structures on the margin link mechanically (observable through analyses of stress tensors derived from earthquake data), kinematically (observable from balanced and restored cross sections and GPS data), and geometrically (observable from surface structure and tomographically derived subsurface structure) through the transverse zones to the thrust-and-fold belt. The first-order observations obtained in this way will then be tested numerically using 3D thermomechanical modelling.

This project will be a collaborative effort between a well-established international research team from the ICTJA-CSIC, University of Salamanca (Spain), and two Taiwanese universities (National Taiwan University, Taipei and National Central University, Zhongli).

The specific objectives of this project include:

1. Structural analysis of the transverse zones.
2. Define the structure at depth, the location and kinematics of faults.
3. Analysis of the topography.
4. 3D thermomechanical modelling.
5. Establish a model for the geometry, connectivity, and transfer of displacement within transverse structures in thrust-and-fold belts.
6. Determine the influence of the reactivation of inherited heterogeneities on the evolution of thrust systems.
The expected results include:
1. A detailed structural model of the transverse zones and how they interact with structures in the thrust-and-fold belt.
2. A 3D structural model of the upper crust in the area of the transverse zones derived from the surface geological data. This will include; serial cross-sections and longitudinal sections, fault branch line maps, and stratigraphic cut-off maps.
3. A model for fault location, geometry, and kinematics at middle and lower crustal levels derived from well-located earthquake hypocenters from focal mechanism analysis.
4. Composite crustal structure derived from high-resolution 3D tomography and gravity modelling.
5. Thermomechanical models that will help illuminate the linkage, displacement transfer, and geometry of transverse zones related to a suite of inherited structures.
6. An integrated, multidisciplinary model for how and why transverse zones work in a fold-and-thrust belt.
7. Results of this research will be published in high impact journals of our specialty and presented at international conferences such as

EGU and AGU conferences.