Abstract
Cataclastic bands from the eastern border of Tambillo Pluton are studied. Two band systems are observed: one northeast and the other northwest in strike. The northeast system is the most conspicuous and its kinematic analysis shows dextral displacement. The two directions of bands form right angle and this suggest that they formed from joints in the Tambillo Puton. A number of granodioritic dykes intruded along the bands and thus they constitute weak zones for dyke emplacement. The age of the cataclasis is undoubtely Ordovician and occurred during the Arenigian in a maximum span of time of only 11 m.y. It is assigned to the Ocloyic orogenesis.
Highlights
Ordovician Cataclasite Bands in the Tambillo Monzogranite: Expression of an Early subphase of the Ocloyic movements in the Cordón Lila, northern Chile
Two ‘conjugate’ systems of subvertical ordovician cataclastic bands of metric wide and whose strike are northeast and northwest are studied in the eastern border of Tambillo Monzogranite, of Ordovician age
Cataclasis occurred during the Late Tremadocian and could attain the Darriwillian and it is assigned to an early subphase of the Ocloyic movements
Summary
Las deformaciones ocurridas durante el Ordovícico en los Andes chileno-argentinos se han atribuido a la fase tectónica oclóyica según la definición inicial de Turner y Méndez (1975). Posteriormente, el concepto se aplicó en extensas comarcas, y para distintos tipos de deformación, tanto en la Puna (Ramos, 1986; Mon y Hongn, 1987), el sistema de Famatina (Pérez et al, 1991) y la Precordillera (Astini, 1998) en Argentina como en el Cordón de Lila, en Chile (Mpodozis et al, 1983). Por su parte, Astini (1998) sugirió llamar más bien movimientos oclóyicos a estos rasgos, dejando abierta la posibilidad de que ellos abarquen, en realidad, varias subfases. Se atribuye la cataclasis a una subfase temprana de los movimientos oclóyicos, no reportada anteriormente en la literatura geológica
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