Metamorphic and mineralogical characterization of two units of the Sierra de Mojotoro?s basement (Lower Cambrian), Eastern Cordillera, Argentina

PAMELA APARICIO GONZÁLEZ; AGNES IMPICCINI; MARIA CRISTINA MOYA

Congreso; XII Congreso Geológico Chileno; 2009

Metamorphic and mineralogical characterization of twounits of the Sierra de Mojotoro?s basement (Lower Cambrian), EasternCordillera, ArgentinaAparicio gonzález, Pamelaa.1,2; Impiccini agnes2, Moya M. Cristina1 1CIUNSa-CONICET. UniversidadNacional de Salta, Facultad de Ciencias Naturales, Geología. Buenos Aires 177 ?(4400) Salta, Argentina. E-mail:pamelaaparicio@gmail.com 2CIMAr.Universidad Nacional del Comahue,Departamento de Geología y Petróleo. Buenos Aires 1400, 8300 Neuqué, Argentina..Three clastic units were recognized in the basement of the Sierra deMojotoro, this abstract describes two of them. These units present differentlithologies, structures and metamorphic grades, but mineralogically preserve avolcanic contribution evidence: mainly an acid volcanism, probably fromlower-middle Cambrian.One of the units is principally a sandy level,Alto de la Sierra Formation (nomen. novum.).It consists of quartzose, lithic, and feldespathic wakes with a seriate textureand evidences of superimposed metamorphism. These wakes are interlayered withpurple mudstone composed mainly of illite and traces of illite/smectitemixed-layer. The measured illite Kubler index indicates that the rocks wereaffected by a metamorphism of a very