A newly dated Cretaceous hydrothermal event in the Iberian Ranges (EasternSpain) and its significance within the Mesozoic thermal history in the Iberian Peninsula

The Iberian Peninsula hosts the world-class Hg mining district of Almaden. Besides pre-Hercynian ore bodies, alpine-cycle Hg-bearing veins are also pr esent in the eastern Iberian Ranges (Espadan deposits). We present both the first absolute ages (84 +/- 4 and 85 +/- 3 Ma) for a post-Hercynian Hg dep osit in Spain, obtained from primary muscovites, and a complete compilation of published Mesozoic radiometric absolute ages of the Iberian Peninsula. We deduce that there are three main thermal episodes that affected the Iber ian Peninsula, which have been revealed after the comparison among the magm atic, metamorphic and hydrothermal ages. Moreover, the Espadan hydrothermal system was active when both the Cretaceous alkalic magmatism took place in Southern Portugal and in the Pyrenees, and during the opening of the Bay o f Biscay. (C) 1999 Elsevier Science B.V. All rights reserved.