Paleomagnetism of Late Neoproterozoic African Dike Swarms from the South Eastern Desert and the Paleo-Neoproterozoic Dataset from Egypt

Abstract

Paleomagnetic analysis has been carried out on Late Neoproterozoic dike swarms from two areas along the Red Sea coast: 13 dikes (87 samples) close to the Um Rus gold mine and eight dikes (59 samples) at Sadi Salem. Rock magnetic experiments indicate that the main carrier of magnetization of these dikes is titanomagnetite and/or magnetite. Most samples display a component of magnetization (CA) that is in agreement with previously published Paleo-Late Neoproterozoic poles from other dikes and from one ore complex. But they cluster around the Cenozoic (0–60 Ma) portion of Torsvik's Gondwana apparent polar wander path (APWP) when plotted in southern African coordinates. We suggest two causes of this behavior (remagnetization related to the opening of the Red Sea or later emplacement of the dikes along pre-existing Paleo-Late Neoproterozoic fractures) will have to be tested with new reliable paleomagnetic data on carefully dated rocks. A second component (CB) seen in many of our samples but which is difficult to estimate is in agreement with Late Neoproterozoic granite poles and a dike supposed to be Triassic in age. However, all these poles plot on the Jurassic-Cretaceous portion (80–200 Ma) of Torsvik's path. These results, as well as the Cambro-Carboniferous sediments from Sinai and the Late Neoproterozoic Dokhan volcanic formation that cluster around the Late Paleozoic portion (280–300 Ma) of Torsvik's APWP, are tentatively interpreted as global viscous remagnetizations acquired, respectively, during the Cretaceous Normal and the Kiaman Reverse superchrons.