HR: 0830h
AN: GP41A-08    [Abstracts]
TI: New Early Triassic Paleomagnetic Pole for South America from the Alto Paraguay Alkaline Province
AU: * Ernesto, M
EM: marcia@iag.usp.br
AF: University of Sao Paulo, Rua do Matao 1226, Sao Paulo, SP 05508-090 Brazil
AB: The Alto Paraguay Province consists of a series of ring complexes that parallel the Paraguay river (the border between Brazil and Paraguay) for more than 40 km.Intrusive to subintrusive rocks are prodominant, and are usually topped by lava flows and ignimbrites, although one large lava field is also present. The province is well dated by different radiometric methods with ages ranging mainly from 240 to 250 Ma. Samples were collected from different levels of seven complexes which were submitted to both alternating field and thermal demagnetizations. Normal and reversed characteristic magnetic components were isolated, and magnetites were identified as the main magnetic carriers. The resulting paleomagnetic pole is located at 319E 78S ( =6; k=23) based on 26 samples. This pole plots within the large field defined by other available poles supposed to be same age, as they lack precise dating. It matches also the corresponding mean pole for Africa, and represents a good candidate to better define the Early Triassic pole position for South America.
DE: 1525 Paleomagnetism applied to tectonics (regional, global)
DE: 1527 Paleomagnetism applied to geologic processes
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2005 Joint Assembly