While the magnetic field is relatively weak - you can override it with a small magnet, for example - it is global in extent and that represents the expenditure of a large amount of energy. No plausible means of controlling magnetic forces on other than a very small, local level exist, nor could be envisaged in a foreseeable future.
The IAGA database available through NOAA is out-dated, so don't use it.
The most up-to-date version of the database for your time of interest can be found here http://geomagia.gfz-potsdam.de/
There are two databases, one based on sedimentary analyses, which yields only inclination and relative intensity variations, but of high resolution.
The other, is the archeomagnetic and volcanic database, which has absolute measures of field intensity, but these are only spot readings and often no directional data are available.
There are also global models, which combine the two databases to estimate global variations. These are limited to the last 10,000 years (due to data availability) and inevitably involve smoothing.
On a practical note. South America is a relatively poorly sampled region for paleomagnetism, for a number of reasons. So the data from this region is sparse and often of low quality. I think the S. America data only go back a few thousand years.