Magnetic fabrics of the Serra do Mar swarms from Rio de Janeiro State: implications for South Atlantic Ocean opening

Abstract

This research aims to apply the magnetic anisotropy methods in the outcropping dikes in the Rio de Janeiro State that belong to the Serra do Mar dams swarm. The main objective is to determine the anisotropy of remanent magnetization and the magmatic flow of these bodies through magnetic susceptibility anisotropy, as well as to obtain information on the relative positioning between source(s) and fractures, as was done for the dikes of the same swarm that outcrop on the north coast of São Paulo State. It will be verified if the magnetic lineation given by the anisotropy of remanent magnetization obtained for these dikes is similar to that found for the dikes of the north coast of São Paulo, which is concordant with the extension efforts responsible for the opening of the South Atlantic Ocean. For this, it is intended; (I) to determine the magnetic anisotropies of the dikes (of susceptibility and magnetic remanence) (II) to carry out a detailed study of rock magnetism in order to identify the minerals responsible for the magnetic anisotropies and the remanent magnetization.It is intended to associate the results of the magnetic anisotropies with existing geochronological, geochemical and paleomagnetic data, in an attempt to establish the positions, in time and space, of the source (s) dykes during geological time. This study is expected to provide a better understanding of the Meso-Cenozoic tectonic processes during the opening of the South Atlantic. (AU)