gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1998.62A.2.248 SHRIMP Age-Constraints for the Calc-Alkaline Volcanism in the Olivenza-Monesterio Antiform (Ossa Morena, SW Spain) Ordóñez-Casado B. Gebauer D. Department of Earth Sciences, ETH Zürich, Sonneggstrasse 5, CH-8092 Zürich, Switzerland Eguíluz L. Departamento de Geodinámica, Universidad del País Vasco, C.P. 644, E-48080 Bilbao, Spain 1998 62A 2 1112 1113 Copyright © 1998, The Mineralogical Society 1998