This study investigates the metabasic rocks forming the core series of the southern Menderes Massif (MM) within the Anatolide–Tauride Block (ATB). In the Babadağ (Denizli) region, these rocks are exposed as sills and stocks intruding the schist units, and are classified as amphibolite, garnet amphibolite, and hornblende gabbro. The metabasic rocks of the southern MM provide important insights into regional geotectonic evolution through major and trace element geochemistry, rare earth element (REE) systematics, and Sr–Nd isotope analyses. These rocks typically display similar mineral assemblages, with widespread retrograde metamorphism and hydrothermal alteration, while primary magmatic textures are locally preserved, especially in hornblende gabbros. Geochemical classification based on immobile element systematics indicates that the metabasic rocks are derived from magmatic protoliths and display transitional alkaline–tholeiitic characteristics, predominantly plotting in the alkali basalt field and partly overlapping the tholeiitic basalt field. Variation diagrams of major and trace elements reveal systematic fractionation, controlled by the removal of clino­pyroxene, olivine, and spinel, as reflected by decreasing CaO/Al₂O₃ ratios, Ni (60–511 ppm), and Cr (22–1265 ppm) concentrations with declining MgO contents (6.07–14.85 wt. %). The enrichment of incompatible elements such as TiO₂, Y, Zr, and Th further supports the cogenetic relationship of these rocks and indicates fractional crystallization from a common parental magma. Primitive mantle-normalized multi-element patterns display enrichment relative to N-MORB and transitional signatures between E-MORB and OIB, with a dominant OIB-like affinity. Chondrite-normalized REE patterns are characterized by strong LREE enrichment ((La/Yb)_cn = 5–16) and nearly flat HREE profiles, suggesting melt generation within the spinel–garnet transition zone. The Sr–Nd isotopic compositions (measured) (⁸⁷Sr/⁸⁶Sr = 0.706633–0.710964; ¹⁴³Nd/¹⁴⁴Nd = 0.512518–0.51267), together with mantle-like Nb/U (16–63) and low Ce/Pb (1.9–7.6) ratios, point to an enriched and compositionally heterogeneous mantle source. Tectonic discrimination diagrams indicate that the magmatism took place in an intraplate extensional setting related to Paleo-Tethyan lithospheric extension along the northern margin of Gondwana.