Search

Principles of fractal geometry have been applied to the description of quartz grain borders and to the assessment of deformation temperature in milonitic rocks at the Santa Maria de la Alameda Ductile Shear Zone (Central System). This shear zone have evolved during late variscan tectonic period in a large temperature range, which goes from regional metamorphic pick conditions (Amphibolite facies) to temperatures lower than for Greenschists facies. Using fractal dimension analysis techniques and the temperature calibration performed by Kruhl y Nega (1996), have been established a temperature sequence, diminishing from around 490°C to 325°C during the simultaneous processes of milonitization and retrogressive metamorphism. These results are in agreement with temperatures obtained from deformation mechanisms in quartz and potassium feldspar showming the validity of fractal geometry method to deformation temperature assessment

Principles of fractal geometry have been applied to the description of quartz grain borders and to the assessment of deformation temperature in milonitic rocks at the Santa Maria de la Alameda Ductile Shear Zone (Central System). This shear zone have evolved during late variscan tectonic period in a large temperature range, which goes from regional metamorphic pick conditions (Amphibolite facies) to temperatures lower than for Greenschists facies. Using fractal dimension analysis techniques and the temperature calibration performed by Kruhl y Nega (1996), have been established a temperature sequence, diminishing from around 490°C to 325°C during the simultaneous processes of milonitization and retrogressive metamorphism. These results are in agreement with temperatures obtained from deformation mechanisms in quartz and potassium feldspar showming the validity of fractal geometry method to deformation temperature assessment

The Santa Maria de Alameda (Madrid) Ductile Shear Zone is a complex mylonitic belt trending east -West and dipping 30°-60° southward. The hanging wall block sinks towards the South-Southeast. Its kinematics is in relation to an extensional tectonic regime with North-south stretching direction. This large structure belongs to the early stages of the Malagon tectonic period, where important faulting and dike emplacement were produced. The shearing process was developed in retrograde metamorphic conditions in a wide range of temperature, which goes from 400° C to 150° C. The age of this deformation is constrained by the variscan regional metamorphic peak and the intrusion of late variscan granitoids (Las Navas del Marques adamellites), being therefore, between early Namurian and Stephanian

The Santa Maria de Alameda (Madrid) Ductile Shear Zone is a complex mylonitic belt trending east -West and dipping 30°-60° southward. The hanging wall block sinks towards the South-Southeast. Its kinematics is in relation to an extensional tectonic regime with North-south stretching direction. This large structure belongs to the early stages of the Malagon tectonic period, where important faulting and dike emplacement were produced. The shearing process was developed in retrograde metamorphic conditions in a wide range of temperature, which goes from 400° C to 150° C. The age of this deformation is constrained by the variscan regional metamorphic peak and the intrusion of late variscan granitoids (Las Navas del Marques adamellites), being therefore, between early Namurian and Stephanian