Earth Planets Space, Vol. 58 (No. 10), pp. 1247-1253, 2006
Augusto E. Rapalini1, Sabrina Fazzito1, and Delio Orué2
1INGEODAV, Depto. Cs. Geológicas, FCEyN, Univ. Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
2Universidad Nacional de Asunción, Paraguay
(Received December 20, 2005; Revised April 8, 2006; Accepted April 25, 2006; Online published November 8, 2006)
The Late Permian segment of the South American apparent polar wander path (APWP) is poorly defined and further paleomagnetic efforts on suitable rocks of such age from stable areas of South America are needed. A study was carried out on the Late Permian Independencia Group, which is discontinuously exposed along Eastern Paraguay and consists of several hundred meters of flat lying continental white, pink and reddish sandstones and siltstones, deposited on the western margin of the Paraná basin. Thirteen sites (83 samples) were collected on the top unit of the Group (the latest Permian Tacuary Fm) from outcrops distributed over 1000 square kms. Detailed AF and thermal demagnetization permitted the isolation of within-site consistent characteristic remanence in eleven sites, being generally hematite the main carrier of the remanence. Excluding one outlier, a paleomagnetic pole was computed by averaging 10 virtual geomagnetic poles of mixed polarities (6 reversed, 4 normal), yielding a position at: 80.7°S, 7.0°E, A95: 6.6°. The new pole may be considered key for a better definition of the South American APWP by filling a gap between a relatively reliable Early Permian and a poorly defined Early-Middle Triassic groups of poles.
Key words: Paleomagnetism, South America, Gondwana, apparent polar wander path, paleogeography.