IGEBA   23946
INSTITUTO DE GEOCIENCIAS BASICAS, APLICADAS Y AMBIENTALES DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Paleomagnetismo y fábrica magnética de ignimbritas del Jurásico superior del sur de Patagonia
Autor/es:
PUIGDOMENECH, CARLA; RENDA EMILIANO; SOMOZA, RUBEN; VIZÁN, HAROLDO; TAYLOR, GRAEME; FERNÁNDEZ, RAÚL; RODRIGUEZ AMENABAR, CECILIA
Lugar:
San Pablo
Reunión:
Congreso; Bienal LatinMag Meeting; 2015
Resumen:
We report paleomagnetic and AMS results from seventeen sites of ca 153 Ma ignimbrites in the Deseado massif, southern Patagonia. AMS results are variable, with the magnetic fabric controlled by ferromagnetic minerals in some of the units and paramagnetic minerals in other units. Directional AMS data reveal the dominance of oblate to triaxial ellipsoids, that in most cases, can be used to explore the local direction of transport from the imbrication of the magnetic foliation and subordinately from the direction of the magnetic lineation. Although the paleomagnetic results may not fully averaged out the secular variation of the paleofield, the computed time-averaged paleomagnetic vector yields a paleopole (Lat. 86° S, Long. 55° E, dp= 12°, dm= 16°) indistinguishable from Jurassic and Cretaceous poles of South America, strongly suggesting that Patagonia has been in its present-day position with respect to the main continent since at least the Late Jurassic. The paleomagnetic data point to a long period (ca 65 Ma.) of ultra-slow polar wander for South America. The results further indicate that ~155 Ma poles from South America (Patagonia) and North America are compatible with a GAD geometry of the paleofield if appropriate plate reconstructions are applied. The South American poles suggest nonoccurrence of a true polar wander episode in the Late Jurassic.