1. Department of Earth Sciences; Utrecht University; Budapestlaan 4; Utrecht; 3584 CD; The Netherlands
2. Paleomagnetic Laboratory “Fort Hoofddijk”; Utrecht University; Utrecht; The Netherlands
3. Dipartimento di Scienze della Terra; Università degli Studi di Modena e Reggio Emilia; Piazza S. Eufemia 19; 41100, Modena; Italy
4. Department of Geology; University of Salamanca; 37008; Salamanca; Spain