Estructura del cuerpo ultramáfico de La Cocha, Sierra Chica de Córdoba, Argentina.

ANZIL, P.A.; MARTINO, R.D.

La Plata

Congreso; XVI Congreso Geológico Argentino; 2005

Asociación Geológica Argentina

STRUCTURE OF THE LA COCHA ULTRAMAFIC BODY, SIERRA CHICA OF CORDOBA; ARGENTINA Patricia A. Anzil and Roberto D. Martino CONICET and Cátedra de Geología Tectónica. Facultad de Ciencias Exactas, Físicas y Naturales. Universidad Nacional de Córdoba. Av. Vélez Sarsfield 1611. X 5016 GCA - Córdoba. E-mails: panzil@com.uncor.edu, rdmartino@com.uncor.edu Keywords: Ultramafic rocks - structure - La Cocha hill - Sierra Chica - Córdoba - Argentina ABSTRACT The serpentinic body of La Cocha is located 2 Kmts south of Bosque Alegre Astronomic Observatory in the Sierra Chica of Córdoba. The serpentinite is modally classified like a spinelic harzburgite. It is a light to dark green rock, mineralogically composed by serpentinized olivine and agregates or isolated crystals of enstatitic piroxene partially or totally transformed to bastite, with spinel inclusions. The texture is porphyritic. The metamorphic S2 foliation is a compositional banding defined by the enlargement and concentration of piroxenes in irregular layers, alternating with more regular olivine layers. This S2 foliation is crosscuted at high (at fold hinge zone) or low angles (at fold flank zone) by another foliation S3 mineralogically composed by serpentine. The general structure of the ultramafic body is a low cylindricity reclined fold which could be interpreted like a major domic "a" type seath fold now deeply eroded.