Preliminary in phase and out of phase AMS study and paleomagnetism of ~870 MA mafic dikes in Wst Africa (Ghana).

Mid-Neoproterozoic is a period of transition between the supercontinent Rodinia and the amalgamation of Gondwana. An incomplete paleomagnetic database does not allow to constrain the precise paleogeography of this transition. This study concerns the West African craton, which remains the least studied craton in paleomagnetism. We propose a preliminary AMS study before showing the first paleomagnetic results obtained on the Manso dike swarms (~867 Ma). For the first time, in-phase and out-of-phase susceptibility was used to study the anisotropy fabric of dikes. Few differences were observed between classical AMS and out-of-phase AMS and require further magnetic mineralogy study to understand the implications. It was possible to isolate a characteristic direction during this pilot study on these dykes in order to obtain a new paleomagnetic pole of reference for the West African craton.