Geochemistry of a Mafic Microgranular Enclave-Bearing Late Paleozoic Pluton: Insights from Major, Trace and Rare Earth Element Systematics of the Variscan Kastoria Intrusion (Northwest Greece)

The Late Paleozoic Kastoria intrusion in NW Greece is an MME-bearing granitoid pluton emplaced within the Pelagonian Zone of the Internal Hellenides. This study integrates major-, trace-, and rare earth element geochemistry to evaluate relationships among the host granitoids (GR) and the mafic microgranular enclaves (MME), magma evolution, and tectonomagmatic affinity. The GR are high-K calc-alkaline and metaluminous to peraluminous rocks, whereas the MME are less evolved and predominantly metaluminous. Both lithologies show LREE and LILE enrichment with negative Nb–Ta–Ti anomalies, indicating shared subduction-related geochemical inheritance. The MME have higher total REE abundances and flatter HREE patterns than the GR. The geochemical data indicate open-system evolution involving mafic recharge, magma mingling, limited hybridization, felsic differentiation, and increasing amphibole- and accessory-phase control. The GR display a moderate high-Sr/Y affinity, but partly decoupled Sr/Y and REE criteria argue against a classical adakite interpretation. On the contrary they suggest a relatively deep, plagioclase-poor stage of magma source evolution. Th/Yb–Ba/La systematics further indicate a sediment-influenced, subduction-modified mafic source. The Kastoria pluton is interpreted as a composite high-K calc-alkaline I-type system emplaced during late/post-collisional Variscan reorganization, with its inherited arc-like signature and slab-failure affinity consistent with slab-related reorganization along the Palaeotethyan ocean closing.