RT Journal Article
T1 Deformation mechanics in inclined, brittle-ductile transpression zones: Insights from 3D finite element modelling
A1 Tohid Nabavi, Seyed
A1 Ahmad Alavi, Seyed
A1 Díaz Azpiroz, Manuel
A1 Fernández Caliani, Juan Carlos
AB Most natural examples of transpression zones developed at oblique convergence regime are inherently 3D andhave inclined boundaries. A 3D finite element model with an elasto-plastic rheology is used to investigate thestructural and mechanical evolution of inclined transpression zones in a rock sequence above a frictional basaldetachment. Inelastic constitutive relationships allow permanent strains to develop in response to the appliedloads. FE-modelling results show that oblique convergence is accommodated by discrete deformation at the mainpre-existing inclined faults (¼70 ) and by distributed brittle and ductile deformation at active blocks. Obliquecontraction at the active blocks resulted mainly in layer-parallel shortening, orthogonal to the model outerboundaries, whereas thickening in the horizontal and vertical directions was accommodated via layer-parallel,fault strike-parallel extension and up-dip extrusion (i.e., inclined extrusion). Lateral extrusion should havecompensated the rest and/or volume loss took place. Folding and thickening of the mobile backstop produced anon-cylindrical, asymmetric, bi-vergent anticline where permanent strains developed principally in the steepforelimb. Secondary, conjugate fault zones also accommodate oblique slip and contribute to uplift. Displacementvectors within the transpression zone are rotated counter-clockwise (ca. 20 –30 ) with respect to vectors in thefixed backstop. Areas with higher rotation values seem to correlate with those showing higher ellipticity values.The presence of pre-existing faults favored strain partitioning from the onset of deformation. FE-modelling resultscompared with analytical, natural example, and analogue modelling results show that our mechanicalmodelling can overall match inclined transpression zones geometry that present different modes of strain partitioningand localisation.
PB Elsevier
SN 0191-8141
YR 2020
FD 2020-08
LK http://hdl.handle.net/10272/18906
UL http://hdl.handle.net/10272/18906
LA eng
NO Nabavi, S. T., Alavi, S. A., Díaz Azpiroz, M. ... Fernández Caliani, J. C. (2020). Deformation mechanics in inclined, brittle-ductile transpression zones: Insights from 3D finite element modelling. Journal of Structural Geology, 137, 104082. DOI: https://doi.org/10.1016/j.jsg.2020.104082
NO Seyed Tohid Nabavi thanks Prof. Jordi Carreras and Dr. Elena Dru-guet for their help, and constructive discussions on progressive deformation, shear zones, and transpressive settings during scientific field trips in the Cap de Creus, the Roses and the Axial Zone of Pyrenees during his research visit period in Spain. Moreover, Seyed Tohid Nabavi thanks Dr. Jonas B. Ruh for teaching and discussions on the finite difference method programming during his research visit period in the Institute of Earth Sciences “Jaume Almera” (CSIC-ICTJA), Barcelona, Spain. Manuel Díaz-Azpiroz and Carlos Fernández gratefully acknowledge financial support from the Spanish Ministry of Science, Innovation and University (projects PGC2018-100914-B-I00 and PGC2018-096534- B-I00). This work forms part of the Ph.D. thesis of Seyed Tohid Nabavi at Shahid  Beheshti  University,  Tehran,  Iran.  We  thank  reviewers  Prof. Fernando O. Marques and Prof. Soumyajit Mukherjee for constructive reviews, comments and helpful suggestions which allowed us to improve the original manuscript. Editorial and handling efforts by Prof. Ian Alsop are also gratefully acknowledged.
DS Repositorio Institucional de la Universidad de Huelva
RD 30 may 2026