1. School of Science and Technology – Geology Division, University of Camerino, Via Gentile III da Varano, I-62032 Camerino (MC), Italy
2. Department of Earth Sciences, Carleton University, Ottawa, ON K1S 5B6, Canada
3. Università degli Studi di Milano, Dipartimento di Scienze della ‘Terra A. Desio’, Via Mangiagalli 34, I-20133 Milano, Italy
4. Saudi Geological Survey, 21514 Jeddah, Saudi Arabia