摘要：Abstract
A paleomagnetic studystudywork was carried
out on the Alto Paraguay Province (APP), a belt of alkaline
complexes that parallel the Paraguay river for more
than 40 km at the border of Brazil and Paraguay. The
province is well dated by 40Ar/39Ar method giving ages in
the range 240–250 Ma with a preferred age of 241 Ma. Intrusive
rocks are predominant but the stocks may be topped
by lava flows and ignimbrites. Paleomagnetic work on
stocks, dikes and flows of the APP identified normal and
reversed magnetic components which are carried mainly
by titanomagnetites. The calculated paleomagnetic pole
located at 319ºE 78ºS (α95 = 6º; k = 23) is in agreement
with other South American poles of Permo-Triassic age.
Most of the sampling sites showed large variations in rock
magnetization, but similar patterns in the variation of the
within-site magnetizations, mainly in dikes, suggest geomagnetic
polarity transition records. The magnetization
data along with the anisotropy of magnetic susceptibility
determinations suggested that the South and North areas
of the province have different evolution characteristics.
关键词：Keywordsalkaline magmatism paleomagnetism magnetic
anisotropy Alto Paraguay Province
