U-Pb dating of MVT ore-stage calcite: implications for fluid flow in a Mesozoic extensional basin from Iberian Peninsula

Fluid how responsible for the formation of Mississippi Valley-type (MVT) de posits in the Cretaceous Maestrat Basin (Eastern Spain) has been constraine d by means of U-Pb dating of cogenetic calcite and galena. A precise age (6 2.6 +/- 0.7 Ma) has been obtained from an isochron that combines ore-stage calcite and galena from the Avecilla Mine. Unlike most MVT deposits, which are related to orogenic tectonic settings, the reported age indicates that Zn-Pb ores in the Maestrat Basin precipitated during rift or post-rift stag es in Early Tertiary times. This study confirms that calcite-galena isochro ns can be an effective tool to date MVT deposits. (C) 2000 Elsevier Science B.V. All rights reserved.