Architecture and detailed kinematic analysis of an active shear zone. The Alhama de Murcia Fault (SE Iberia).
Abstract
This study is composed of both ongoing and definitive results of analyses done with the aim of unravel the architecture of the shear zone and the complexities of its kinematics of different domains that compose the Alhama de Murcia Fault (AMF), a main active fault of southeastern Spain. We have applied the analytic model of general triclinic transpression with oblique extrusion. This study offers the possibility of testing the model with absolute data of active deformation such as GPS velocity gradients and opens a new methodological approach in the study of active fault zones, combining quantitative kinematics, microtectonics and geochemical analyses. The application of this model has been possible by means of an exhaustive exploration of the predictions of the model and their comparison with the orientation data of field kinematic markers (fault-slip data and reorientation of fold hinges during progressive deformation), GPS data and the kinematic study of the fault gouge. We constrained the values of the kinematic vorticity number, the orientation of the vorticity vector, the orientation of the local and regional convergence vectors, the angle of extrusion in the shear zone and the amount of extrusion. The obtained results point to a highly partitioned heterogeneous shear zone with domains showing competency contrasts: a low competency domain composed by the fault gouge, ductilely deformed, with low vorticity values, which probably experienced a steady-state, aseismic slip that reflects regional convergence vectors (convergence Eurasia-Nubia); and a domain out of the fault gouge that accommodates elastic energy, with higher vorticity values, and showing convergence vectors which are parallel to the local convergence vectors calculated from the GPS velocity field.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T43C0445A
- Keywords:
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- 8011 Kinematics of crustal and mantle deformation;
- STRUCTURAL GEOLOGY;
- 8012 High strain deformation zones;
- STRUCTURAL GEOLOGY;
- 8030 Microstructures;
- STRUCTURAL GEOLOGY;
- 8031 Rheology: crust and lithosphere;
- STRUCTURAL GEOLOGY