Exposures of volcanic rocks (El Castillo) in the Central Iberian Zone near Salamanca, Spain, are representative
of Paleozoic volcanic activity along the northern Gondwanan passive margin. Alkaline basalts and mafic
volcaniclastic rocks of this sequence are structurally preserved in the core of the Variscan Tamames Syncline.
On the basis of the occurrence of graptolite fossils in immediately underlying strata, the El Castillo volcanics
traditionally have been regarded as Lower Silurian in age. In contrast, most Paleozoic volcanic units in western
Iberia are rift-related mafic to felsic rocks emplaced during the Late Cambrian-Early Ordovician, and are
attributed to the opening of the Rheic Ocean. We present new zircon U-Pb TIMS data from a mafic volcaniclastic
rock within the El Castillo unit. These data yield a near-concordant, upper intercept age of 394.7 ± 1.4 Ma
that is interpreted to reflect a Middle Devonian (Emsian-Eifelian) age for the magmatism, demonstrating that
the El Castillo volcanic rocks lie unparaconformably above lower Silurian strata