A Gas Hydrate Site with Bi-verging Detachment and Trishear Folds in the Outer Wedge Offshore SW Taiwan: An Example of Mechanical Compaction and Methane Flow
Abstract
Understanding structural evolution and fluid flow source at hydrate sites helps hydrocarbon research along convergent boundaries. Here we propose the history of evolution of a set of doubly-plunging, oppositely-verging structures referred to as Ridge A and the Four-Way Closure Ridge (FWCR) offshore southwestern Taiwan. The structures exhibit 1) Initial deformation along a decollement forming a detachment fold, followed by 2) a landward-verging trishear fold about 8 km seaward of the detachment fold, and 3) a seaward-verging low-angle thrusting modifying the detachment and trishear folds. Furthermore, finite strain analyses based on the kinematic model suggest high pore space reduction between the detachment and trishear folds. The volume of methane possibly expelled during the pore space reduction is not enough to explain the high hydrocarbon concentration. Methane-rich fluid migration along such bi-vergent structures from depth is the likely mechanism to form this hydrate-rich site.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.T51G0247B
- Keywords:
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- 1209 Tectonic deformation;
- GEODESY AND GRAVITYDE: 4430 Complex systems;
- NONLINEAR GEOPHYSICSDE: 8150 Plate boundary: general;
- TECTONOPHYSICSDE: 8158 Plate motions: present and recent;
- TECTONOPHYSICS