Geochemistry and tectonic environment of diverse magma generations forming the crustal units of the Kizildag (Hatay) ophiolite, southern Turkey

Abstract

The Kizildag (Hatay) ophiolite is one of the best preserved Neotethyan oceanic lithospheric remnants in southern Turkey. It is represented by, from bottom to top, mantle tectonites, ultramafic to mafic cumulates, isotropic gabbros, sheeted dike complex, plagiogranites and extrusives (low-K tholeiites and boninites). The ultramafic to mafic cumulate rocks are composed of dunite, wehrlite, olivine gabbro, olivine gabbronorite and gabbro. The crystallization order of cumulus phases, and the presence of highly magnesian olivines and pyroxenes as well as highly calcic plagioclases in the cumulates, indicate a subduction-related tectonic environment and suggest derivation from an island arc tholeiitic magma. The isotropic gabbros are represented by gabbro, diorite and quartz diorite with granular, ophitic to micrographic textures. The sheeted dikes are characterized by diabase and microdiorite with ophitic to intersertal textures. The boninitic volcanics (so-called sakalavites) are basaltic in composition and exhibit hypocrystalline porphyric to hyalopilitic textures. All these rocks are tholeiitic in composition. New geochemical data presented in this paper from the isotropic gabbros, sheeted dikes and sakalavites suggest that there are two main types of parental basic magmas that form the crustal rocks of the Kizildag (Hatay) ophiolite. These are (i) IAT series comprising the Group I isotropic gabbros and sheeted dikes; (ii) Low-Ti boninitic series characterized by the Group II isotropic gabbros, sheeted dikes and sakalavites. The spatial and temporal relations of the IAT and boninitic magma types in the Kizildag ophiolite indicate that different magma sources were contemporaneously active in a fore-arc tectonic setting of the southern branch of Neotethys during the Late Cretaceous.