Physical modeling of nucleation and development of structures related to strike-slip tectonics
Strike-slip faults; Riedel fractures; analogue modelling.
The present work investigates structures associated to the transcurrent tectonics, through the analogical physical modeling. This experimental method simulates the development of geological structures and its main advantage is the possibility of accompanying each stage of its development, while in nature only the final stage is available. The physical experiments aimed at understanding the nucleation and development of first and second order structures in a dextral transcurrent tectonics. The experiments were grouped into two series, based on their rheological configuration: i) models with a single type of material, to simulate these structures in rheologically homogeneous layers; ii) models with stacking of rheologically distinct material, simulating mechanical stratigraphy. Particle Image Velocimetry (PIV) was used for the monitoring of the models, in the acquisition of high-resolution images in addition to conventional photographs and the Laser Scanner for the preparation of three-dimensional models. The physical properties of the granular analog materials were characterized with the Ring Shear Tester (RST). During the deformation evolution of the experiments, the fractures R, R ', P, Y, pull-apart basin, positive and negative flowers (transpression and transtration sites, respectively) were analyzed. The data generated by the PIV showed very early phases of nucleation of these structures (absent in conventional photos). The geometry, linkage processes and evolution during deformation were also examined, as verified by the fractures R and R', the first ones to be nucleated, which presented an en echelon arrangement and spaced between them, showing R with low angle and R' with high angle to the main fault. As well, by the principal transcurrent fault, which was formed by Y-segments linkage, during the deformational progression.