Mesoestructuras de las unidades metamórficas del sector Infiernillo y Punta Lobos, Serie Occidental de la Cordillera de la Costa, Chile Central (34,5°LS).

CAMILO PALAPE; FRANCISCO MUÑOZ; GILDA COLLO; SEBASTIÁN OSVALDO VERDECCHIA

San Miguel de Tucumán

Congreso; XX Congreso Geológico Argentino; 2017

Asociación Geológica Argentina

The Western Series that belongs the late Paleozoic metamorphic basement of the Chilean Coast, composed by metabasites, metacherts, greenschists, blue-schists and marbles, represents a basally accretionary complex formed under HP-LT metamorphic conditions, during the subduction of the proto-pacific plate against the southwestern margin of Gondwana. Even though the geologic processes linked to the accretion and exhumation of these rocks were widely studied, the detailed analysis of some structural features could contribute to the better understanding of these processes. We present new structural data of this tectono-metamorphic unit, in a detailed cross section located between Infiernillo and Punta Sirenas peninsulas, recognizing two deformational events D1 and D2. The D1 mesostructures are represented by sheet fold, anastomosed S1 foliation and mineral stretching lineations, associated with S-C structures, boudinage, tension gashes and pressure shadows in albite porphyroblasts consistent with flexural slip of the regional D1 structure limb. The mineral stretch lineation (Le) associated to the S1 foliation and these structural features suggest a hanging wall movement top to the SW. The D2 structures correspond to kink folds with subvertical crenulation cleavage S2 and the B2 axis dips to the W with 20° that fold the S1 foliation.