Pre-Variscan granitoids with adakitic signature at west Getic basement of the South Carpathians (Romania): constraints on genesis and timing based on whole-rock and zircon geochemistry

Research on two strata-like intrusions from Slatina-Timiş (STG) and Buchin (BG) at West Getic Domain of the South Carpathians (Semenic Mountains) identified granitoids with adakitic signature in a continental collision environment. Whole-rock geochemical composition high Na2O, Al2O3 Sr, depleted Y (18ppm) HREE (Yb 1.8ppm) contents, Sr/Y (40), (La/Yb)N (10) ratios no Eu anomalies overlaps High-Silica Adakites (HSA) main characteristics, though there are differences related to lower Mg#, heavy metal contents slightly increased 87Sr/86Sr ratios. Comparison HSA, Tonalite-Trondhjemite-Granodiorite (TTG) rocks melts experiments basaltic sources suggests partial melting pressures exceeding 1.25GPa temperatures 800-900ºC (confirmed by calculated Ti-in zircon temperatures) as genetic process, leaving residues garnet amphibolite, granulite or eclogite type. The along variations observed STG-BG indicate oceanic source affected increasing mantle influence decreasing crustal input that may restrict tectonic setting slab during subduction low angle conditions. An alternative model relates magma genesis garnet-amphibolite due decompression heating depth 60-50km syn-subduction exhumation eclogitized fragments cumulates. were entrained into buoyant mélange placed randomly between units. U-Pb ages obtained LA-ICP-MS interpreted Ordovician igneous crystallization time Variscan recrystallization imprint confirmed trace-element characteristics dated zones, connecting magmatism pre-Variscan subduction-collision event. rich inheritance reveals Neoproterozoic juvenile older components represented Neoarchean Paleoproterozoic zircons.