U–Pb and Sm–Nd geochronology of the ophiolites from the SE Turkey: implications for the Neotethyan evolution

Abstract

The ophiolites in southeast Turkey crop out along two distinct belts. The ophiolites in the north are attached to Tauride active margin and represented by Göksun, Berit, İspendere, Kömürhan and Guleman ophiolites. Whereas the ophiolites in the south are observed as tectonically overlying the Arabian continental margin and characterized mainly by Kızıldağ (Hatay) and Koçali ophiolites. In this paper, new U–Pb and Sm–Nd isotopic ages are presented. The zircons extracted from the gabbroic cumulates of the Kömürhan ophiolite yielded a concordia age of 87.2 ± 3.1 Ma. The zircons in the gabbroic cumulates of the İspendere ophiolite yielded a Concordia age of 84.5 ± 3.9 Ma. Moreover, the Sm–Nd age of the gabbroic cumulates of the İspendere ophiolite yielded 85.1 ± 7.1 Ma (εNd =  + 7.8). The gabbroic rocks of the Kızıldağ (Hatay) ophiolite yielded 110 ± 11 Ma (εNd =  + 7.3) Sm–Nd isochron age. The new and already published U–Pb and Sm–Nd ages from the Kızıldağ ophiolite suggest that the time span between the melt generation in a subduction zone setting and SSZ-type oceanic crust crystallization was ≥3 my. All the ages from the Southeast Anatolian ophiolites suggest that the ophiolites between the Bitlis–Pütürge continent and the Arabian platform formed around 99–102 Ma whereas the ophiolites between the Bitlis–Pütürge continent and the Tauride platform formed around 84–90 Ma, suggesting that the peri-Arabic belt ophiolites are 10 My older than the ophiolite attached to the Malatya–Keban platform in the north. Detailed comparison suggests that there are number of differences between the ophiolites to the north and south of the Bitlis–Pütürge continental unit based on the geological, geochronological, petrological, internal stratigraphy of the ophiolites as well as their relationships with the continental fragments during the late Cretaceous. Therefore, the ophiolites were rooted from two different oceanic basins, one to the north and other to the south of the Bitlis–Pütürge continent.