Kinematic and Deformative Analysis for the Santa Rosa and La Telarana Faults

摘要

This study was aimed at analyzing the kinematics and deformation associated with the NE - SW striking Santa Rosa and La Telarana faults located west of the Nevado del Ruiz volcano (VNR) in Colombia. Paleo-stresses for both structures show a compressive regime mainly in the NW - SE direction, and an almost vertical intermediate stress causing predominantly dextral slip; this is evident from striated surfaces, showing kinematic components with a dip in a slightly normal-type. The microstructures along the Santa Rosa Fault establish the presence of ductile deformation in some areas, evidence mainly in the Paleozoic units such as schist belonging to the Cajamarca Complex, where fish-like structures with developing shear dextral bands, dynamic recrystallization of quartz and carbonates, and superimposed brittle deformation (cataclasis) can be observed. In younger lithologies, including Ruiz lavas, Paramillo of Santa Rosa lavas, and Rio Claro ignimbrite, a cataclastic deformation was observed in all units related to both faults, as well as a system of larger NE - SW joints, and a subordinate series ofNW- SE to E-W joints, with centimetric to metric scale cataclasis.