Magnetostratigraphy of marine cores from the South-Eastern Brazilian equatorial margin

Abstract

The Brazilian Equatorial Margin (BEM) is characterised as a classic passive and stable continental margin that developed following the opening of the central Atlantic Ocean in the mid-Cretaceous. The margin hosts large marine successions in offshore adjacent sedimentary basins that developed during the Early Cretaceous. Suggestions of the interplay of Cenozoic climatic changes, sea-level fluctuation and regional tectonics make the margin a compelling natural site for understanding long-term continental margin marine successions and paleoenvironmental records.For this purpose, this proposed study seeks to provide rock magnetic and paleomagnetic measurements of marine cores collected along the BEM. An investigation of the magnetic minerals (i.e., magnetofossils) in marine successions from the margin would be used to decipher paleoenvironmental indicators and climatic conditions based on its correlation and integration with geochemical (stable isotope values) of the host marine successions. The rock magnetic data yielded in this study (i.e., magnetic susceptibility, the coercivity of magnetic minerals; Saturation Isothermal Remanent Magnetization (SIRM), HIRM, and hysteresis loops) will be integrated with inferred paleoenvironment of the lithofacies in the BEM marine cores.The development of a magnetostratigraphic framework and rock magnetic data based on the analysis of the magnetic properties of marine successions from the margin will serve as a useful tool for inferring climatic conditions and associated sea-level fluctuations. Interpretation of these aspects of the study will provide insights into the paleoenvironmental conditions and the Earth's magnetic field geodynamics during the deposition of marine successions. These result could improve our understanding of terrigenous detrital influx to the Brazilian margin during the regression and transgression periods of the South Atlantic Ocean through geologic time. Also, inferences and inventory of the results from this project will allow for establishing the link between varying paleoenvironmental conditions, sea-level fluctuations and associated global equatorial currents, and the earliest isolation between the West and East Atlantic regions. (AU)