Estudios paleomagnéticos preliminares y de fábrica magnética en afloramientos de López Lecube (Latitud 38° S, Longitud 62° O) y González Chaves (Latitud 38° S, Longitud 60° O), Sierras Australes de la provincia de Buenos Aires, Argentina

TOMEZZOLI R.N.; VILAS, J.F.

Revista de la Asociación Geológica Argentina

Asociación Geológica Argentina

Año: 1997 vol. 52 p. 419 - 432

1853-7138

Preliminary paleomagnetic study and magnetic fabric in outcrops of López Lecube and González Chaves (Sierras Australes, Argentine). Paleomagnetic preliminary results from two different localities geologically related to Sierras Australes of the Buenos Aires Province (Ventana Ranges) are presented. The first one is a sianite located at the town of López Lecube, Lat: 38.13° S, Long: 62.7° W, 80 km to the West, the second one, is a succession of sedimentary rocks exposed near of González Chaves city, Lat:38.05° S, Long: 60.07° W, placed 130 km east of the ranges. From three sites at López Lecube, a very consistent reverse magnetic component was found, and a preliminar mean geomagnetic pole (70° S, 343° E, with N=3, 95=13° and k=89) was calculated. This pole position is consistent with late Early to late Permian South American Poles. Normal magnetic components were found at González Chaves. They were interpreted as possible primary directions and a preliminar mean geomagnetic pole (84° S, 216° E, with N=3, 95=17° and k=53) was computed, wich is consistent with triassic directions from South America. Anisotropy of magnetic susceptibility was measure in the López Lecube sienite, a prolate magnetic fabric was found and is equated with the magmatic lineation defined by the preferred orientation of the anisometric crystals.