Caracterización geoquímica e isotópica (Sr-Nd) del plutón granítico peralumínico de La Bazana (Macizo Ibérico meridional)

Abstract

The late-Variscan La Bazana pluton (e.g. Galadí-Enríquez et al., 2003) is constituted mainly by biotite-bearing monzogra- nites of magnesian (FeO t/(FeOt+MgO) = 0.68–0.74) and peraluminous (A/CNK = 1.04–1.27) affinity. They display Fe+M- g+Ti (in millications) values of 41–69, with Mg# (Mg/[Fe+Mg]) in the range of 0.39–0.46, and CaO/Na2O ratios that vary between 0.32 and 0.79. Na2O, K2O and P2O5 contents increase with differentiation, as well as Rb/Ba and Rb/Sr values. On the contrary, K/Rb decreases in that sense, like Zr, Y, Th, Hf, Cr, V, and REE contents. Isotopic compositions of studied mon- zogranites comprise variable 87 Sr/86Sri in the range of 0.7068–0.7126 (recalculated at a representative age of 340 Ma), and relatively homogeneous εNdi values encompassed between -8.4 and -8.8. Geochemical and isotopic (Sr–Nd) composition of studied monzogranites contrasts with that of the inversely zoned and metaluminous plutons from the Olivenza–Mones- terio Antiform (e.g. Cambeses et al., 2019). Preliminary results of this work point to a different origin to that of the cited plutons for the monzogranites from La Bazana, which could constitute an appropriate example to study the late-orogenic Variscan magmatism.