A Tectono-magmatic correlation of basaltic rocks from ophiolite mélanges at the North-Eastern tip of the Sava-Vardar suture Zone, Northern Croatia, constrained by geochemistry and petrology

Ophiolite melanges of Mts. Kalnik and Ivanscica form the northern sector of the Kalnik Unit and represent the northeasternmost exposed tip of the Sava- Vardar Suture Zone. Petrological; geochemical and isotopic characteristics of extrusive rock blocks incorporated in the melanges; particularly of pillow basalt altered to spilite; in association with radiolarian cherts; allow the rocks to be separated into five distinct groups. Each group has an age-marker based on the radiolarian assemblage in the associated cherts and/or on isotope dating which; along with previously published data on the Kalnik Unit; provide detailed analysis of the approximately 80 Ma long geodynamic evolution of the Repno Oceanic Domain - a part of the Meliata-Maliak ocean system. The rock groups are: (1) Late Anisian alkali basalts [(La/Lu)cn = 5.9-7.2; eNd(T) = +2.96; Cpx-TiO2 = 3-6wt%] related to a terminal phase of intracontinental rifting; (2) enriched E-MORB-type basalts [(La/Lu)cn = 2.4-2.8; eNd(T) = +4.74; Cpx-TiO2 = 2.1-2.9wt%] and depleted E-MORB-type basalts [(La/Lu)cn ~ 1.5; eNd(T) = +5.26; Cpx- TiO2 = 1.9-2.3wt%] which reflect successive proto-oceanic crust formed at the ridge during the early Ladinian and late Ladinian; respectively; (3) middle Carnian T-MORB-type basalts [(La/Sm)cn = 0.79-0.87; eNd(T) = +6.63; Cpx-TiO2 = 1.2-2.2wt%]; representing crust from an evolved spreading center; (4) NMORB- type basalts [(La/Sm)cn = 0.67-0.87; eNd(T) = +6.58; Cpx-TiO2 = 0.6-1.9wt%] with inherited supra-subduction signature that diminish from the Late Carnian basalts [(Nb/La)n = 0.81] to the Bajocian basalts [(Nb/La)n = 1.1]; and Middle Jurassic (Bathonian?) N-MORB-type basalts with recurrent subduction related influence [Nb/La)n = 0.72; (La/Sm)cn = 0.76; eNd(T) = +6.23]; (5) late Bathonian medium-Ti [(Nb/La)n = 0.24-0.72; eNd(T) = +6.30; Cpx-TiO2 = 0.6- 1.1wt%] to late Oxfordian low-Ti IAT-type basalts [(Nb/La)n = 0.12-0.22; eNd(T) = +6.31; Cpx-TiO2 = 0.2-0.6wt%] which reflect melts derived from a metasomatized and successively depleted mantle wedge in an extensional proto-arc setting.