1. a Centro de Geociencias , Universidad Nacional Autónoma de México , 76230 , Querétaro , Mexico
2. b Departamento de Geología Regional , Instituto de Geología, Universidad Nacional Autónoma de México , 04510 , México , D.F. , Mexico
3. c Department of Earth Sciences , St. Francis Xavier University , Antigonish , NS , Canada
4. d Department of Geological Sciences and Geological Engineering , Queen's University , Kingston , ON , K7L 3N6 , Canada