A new Late Permian paleomagnetic pole for stable South America: the Independencia Group, eastern Paraguay

RAPALINI, AUGUSTO E.; FAZZITO, SABRINA; ORUÉ, DELIO

EARTH PLANETS AND SPACE

Terra Scientific Publishing Company

Lugar: Tokyo; Año: 2006 vol. 58 p. 1247 - 1254

1343-8832

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 poles and a poorly defined Early-Middle Triassic group of poles.