Geofísica

The West African Craton (WAC) is one of the major cratons in the Rodinia jigsaw puzzle (~1000–750 Ma). In the Rodinian models, the position of West Africa is mainly constrained by the assumption that it had been a partner of Amazonia since the Paleoproterozoic.

The Penatecaua magmatism occurring in northern Brazil (Pará State) belongs to the so-called Central Atlantic Magmatic Province (CAMP), w h i c h preceded the Pangaea breakup. Near the city of Medicilandia, a large diabase sill outcrop along road cuts for nearly 50 km. Recent 40Ar/39Ar dating give an age of ~201 Ma for the CAMP magmatism in the area. The paleomagnetic study on 9 sampling sites of the Medicilandia sill, revealed stable characteristic magnetization components through alternating magnetic field and thermal demagnetizations.

A paleomagnetic and rock magnetic study was carried out in the Ediacaran Avellaneda (∼570 Ma) and Cerro Negro (∼555 Ma) Formations belonging to the La Providencia Group, in the upper part of the Neoproterozoic sedimentary cover of the Tandilia region, in the Río de la Plata craton.

Speleothems are secondary mineral deposits formed in caves and may represent excellent recorders of variations of the Earth’s magnetic field. Magnetic studies of speleothems provide two important forms of data: i) continuous and high-resolution records of short-term variations of the geomagnetic field (GMF), and conversely the use of paleomagnetism as a dating tool of speleothems; and ii) high-resolution records of climate variability by linking rock magnetic properties to climate and environmental forcing parameters acting on soils.