Akademik Veri Yönetim Sistemi
LITHOS, cilt.518, 2025 (SCI-Expanded, Scopus)
Leucocratic dykes, including plagiogranites occur in small volumes within ophiolitic sequences and they provide highly valuable insights into the formation processes and timing of ancient oceanic domains. The Tauride Belt Ophiolites, located along southern T & uuml;rkiye in the eastern Mediterranean region, include the Tuzla Ophiolite in the Eastern Taurides, which is unique for preserving plagiogranites formed by distinct petrogenetic processes. The Tuzla Ophiolite consists of mantle rocks and basaltic volcanic rocks representing the upper crustal section, intruded by plagiogranites and dolerites. Geochemical data obtained for the basaltic volcanics, and isolated dikes indicate a supra-subduction zone (SSZ) affinity, consistent with the geodynamic setting of other Tauride Belt ophiolites. Within this framework, we distinguish two types of plagiogranites based on field observations, geochemical data, and crystallization age. Type-I dykes are sheeted, parallel dykes that intrude massive basalts occurring in the crustal section. They exhibit similar ratios of incompatible elements and continuous chemical trends, in conjunction with coexisting basalts and dolerites, and petrogenetic modelling, suggest that high degree (75 %-80 %) fractional crystallization of MORB-type magmas. Type-II dykes intruded through the mantle section of the Tuzla Ophiolite have distinctive REE patterns and they likely reflect partial melting of subducted oceanic crust. The existence of alkali and Fe-Mg rich amphiboles in Type-II dykes, suggests that they were influenced by sea floor hydrothermal metasomatism. LA-ICP-MS U-Pb zircon dating reveals two distinct magmatic phases: Type-I plagiogranites yield an age of 92.2 +/- 0.4 Ma (epsilon Hf(t) = +1.3 to +19.7), marking the SSZ spreading stage of the Inner Tauride Oceanic crust, while Type-II plagiogranites yield an age of 82.8 +/- 0.3 Ma (epsilon Hf(t) = +2 to +12.3), reflecting later-stage magmatic activity derived from sediments and mafic rocks of the subducted slab during ongoing intra-oceanic subduction.