Cisuralian calc-alkaline magmatism in the Herrera Unit of the Iberian Chain (Cantabrian Zone of the Iberian Massif, Spain): age and geodynamic constraints from U–Pb laser ablation inductively coupled plasma mass spectrometry zircon analysis

Abstract

The Herrera Unit of the Iberian Chain (Cantabrian Zone, Iberian Massif) exhibits hundreds of outcrops of calc-alkaline igneous rocks that have been classically attributed to the Upper Carboniferous and the Lower Permian, although only two absolute radiometric ages have been reported. This work, with six new zircon laser ablation inductively coupled plasma mass spectrometry ages obtained from some of the most representative outcrops, provides the most complete age repository for the calc-alkaline magmatism of the prolongation of the Cantabrian Zone within the Iberian Chain. The obtained ages range between 294 and 288 Ma (Cisuralian Epoch) and show a well-defined peak at 290 Ma, which can be attributed to a main magmatic activity stage. This result allows us to correlate and integrate this magmatism within the widespread SW European calc-alkaline magmatism province developed under strike-slip tectonics. Therefore, the Iberian Chain magmatism and its age can be considered as a good temporal marker for the upper limit of the compressive tectonics associated with the Variscan Orogeny and the onset of the extensional tectonics linked to Permo-Triassic rifting. Supplementary material: Analytical settings (1) and analytical data from: the standard zircons (2) and the zircons from the samples of this work (3) are available at https://doi.org/10.6084/m9.figshare.c.6843778