Paleomagnetism of the Medicilandia Sill from the Central Atlantic Magmatic Province, Amazon Basin, Brazil.

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. The main magnetic carriers are magnetite or low-Ti titanomagnetites. The paleomagnetic pole calculated for eight sites is coherent to other South American CAMP paleomagnetic poles for which good age control is available. However, this new pole differs from the existing pole for the Penatecaua dykes located to the northwest of the sill, and for which no reliable age exists so far.