Petrology and zircon U–Pb dating of granitoid rocks in the Highiş massif (SW Apuseni Mts., Romania): Insights into Permian plutonic–volcanic connections

Abstract

Permian granitoids in the Highiş massif (SW Apuseni Mts., Romania) are anorogenic (A-type), having a peraluminous, subalkaline, alkali-calcic or calc-alkalic, and ferroan character with granodioritic to granitic compositions. Trace elements suggest the crustal origin of the studied samples that derive from a common or similar source associated with post-collisional rifting. Based on trace elements and zircon U–Pb ages (~268–263 Ma), a plutonic– volcanic connection was revealed between the Highiş granitoids and the Mid-Permian (~267–260 Ma) felsic volcanic rocks that are widespread in the Tisza Mega-unit. Felsic plutonic and volcanic rocks (along with mafic–intermediate plutons and lavas in the Apuseni Mts.) represent a Mid-Permian, cogenetic magmatic system. Our results suggest that the study area belongs to the Tisza Mega-unit, in contrast to recent studies considering it as part of the Dacia Mega-unit. Despite the Europe-derived nature of the Tisza Mega-unit, its Permian igneous formations are significantly younger than those of the stable Europe (~300–290 Ma). However, the studied rocks show correlations with some analogous formations in the ALCAPA Mega-unit, including Permian A-type granitoids and felsic volcanic rocks in the Western Carpathians (Gemeric, Veporic, and Silicic Units). On the other hand, many other rocks of similar age in the Western Carpathians and Eastern Alps bear completely different geochemical compositions (S-type character). The latter suggest at least two main types of magma source coevally within the Permo-Triassic post-orogenic setting in the Central European Variscides.