Tertiary remagnetization of Paleozoic rocks from the Eastern Cordillera and sub-Andean Belt of Bolivia

Paleomagnetic samples were collected from 98 sedimentary horizons in eight different Devonian to Permian sedimentary units at eight localities in the Eastern Cordillera and the sub-Andean Belt of Bolivia. For 77 sites, therma l demagnetization allowed determination of a characteristic magnetization ( ChRM) with site-mean 95% confidence limit, alpha(95), < 15 degrees. The ChR M is carried predominantly or entirely by hematite. Fold and reversal rests from two of the sampled localities indicate that the characteristic magnet ization is synfolding, likely acquired during the earliest stages of deform ation. Additionally, a modified conglomerate rest at one locality and the n early uniform direction of ChRM across the Devonian to Permian age units cl early reveals the secondary nature of the characteristic magnetization. Fin ally, the ChRM directions are discordant from any expected Paleozoic direct ions. Paleomagnetic poles calculated from the ChRM directions fall near the Cenozoic portion of the apparent polar wander path for South America. We i nterpret these observations to indicate widespread chemical remagnetization of these Paleozoic strata during, but Drier to completion of, Cenozoic And ean folding.