PSEUDOTAQUILITAS Y CATACLASITAS EN EL CERRO PAN DE AZÚCAR: EVIDENCIAS DE REACTIVACIÓN DE LA MEGAFRACTURA VALLE FÉRTIL, SAN JUAN

FUENTES, MA. GABRIELA; MALISIA, CAROLINA; CASTRO DE MACHUCA, BRÍGIDA; LÓPEZ, MARÍA GIMENA

Cordoba

Congreso; XIII Congreso de Mineralogía y Metalogenesis y VI Congreso de Petrología Ignea, Metamórfica y Metalogénesis Asociada; 2019

Asociacion Geologica Argentina

Associated with cataclasites, breccias and low-grade mylonites there are pseudotachylites formed as a result of frictional melting along seismogenic fault zones. In Cerro Pan de Azúcar, Western Sierras Pampeanas, N-S trending mylonitic shear zones record a long history of deformational and metamorphic events. Brittle fault- related rocks (pseudotachylites and cataclasites) with similar orientation to that of the ductile structures have been found overprinting the mylonites. Pseudotachylite veins (with evidence of melt, e.g. microliths, cooling margins, flow bands); injection veins and cataclastic veins (cataclasis without melt) were recognized. The pseudotachylites were originated by partial melting of host rocks along faults indicating reactivation of basement structures in the upper levels of the crust. The fault zones are linked to the tectonic activity and paleoseismic character of the Valle Fértil megafracture that influenced the geometry and kinematics of the whole region.