Paleomagnetismo de la Formación Cañadón Asfalto en el curso medio del río Chubut: implicancias tectónicas

GEUNA, SILVANA; VIZAN, HAROLDO; SOMOZA, RUBÉN

Mendoza

Congreso; XII Congreso Geológico Argentino; 1993

Regional transcurrent faults could have been active in ExtrandinianPatagonia during the Mesozoic. Several authors have studied the extents anddiscuss the sense of the strike-slip motions of these faults. A paleomagneticstudy was carried out in outcrops of Cañadón Asfalto Formation (Upper Jurassic)in an area (Lat. 43o30´S, Long. 69o W) that is located between faults thatbelong to one of the system of the mentioned faults. 26 sampling sites inbasaltic flows yielded a paleomagnetic pole (PP): Long.= 338o E, Lat.= 58o S, A95=5o, which is not in agreement with PP of Jurassic cratonic areas of SouthAmerica. The position of this PP is interpreted as a counterclockwise block-rotationof about 55o along a vertical axis. The rotation could be due to a sinistralstrike-slip motion of faults that belong to "Gastre System". Accordingto the PP of the overlying sequence this rotation could have ocurred before theAptian.