Estratigrafia Magnética do Furo DSDP-511 (Platô das Falklands) durante o Barremiano-Aptiano.

The Barremian-Aptian boundary is one of the most important moments of the Cretaceous period due to its close relationship with drastic geological events in global scale. One example is the beginning of the Cretaceous Normal Superchron (CNS, or “Cretaceous quiet zone”) which lasted from ~120 to 83 Ma. In addition, paleogeographic, biological and geochemical variations of the oceans also occurred in this period. In this work, we present a magnetostratigraphic study of a segment from site DSDP-511 (Falklands Plateau) with the purpose of generating more precise temporal links to establish the rates and the time of paleoenvironmental and paleogeodynamic changes during the Barremian and the Aptian age (Lower Cretaceous). In the 1980s, preliminary magnetic studies were performed throughout the length of the borehole, but the data quality was affected due to a lack of better age control. Recently, detailed chemostratigraphic and biostratigraphic analyzes were carried out with the objective of establishing a reference section for this period, giving rise to the necessity of a paleomagnetic study with higher resolution. In this study, we determined three main polarity zones, which were two zones of normal polarity and a zone of reverse polarity, and a discrete zone of reverse polarity defined at 509.20 meter below sea floor (mbsf). The results obtained present significant differences when compared with previous studies in the same core.