Elazığ (Türkiye) Batısındaki Neojen Göl Sedimanların Jeokimyası: Kaynak Kayaç ve Tektonik Ortam Tayini

Abstract

Sediment geochemistry of the Neogene lacustrine environment from Karabakir Formation in the western of Elazig, were used to constrain provenance and tectonic setting. The basement of the studied sediments is Permo-Triassic Keban Metamorphics, upper Cretaceous Elazig Magmatics, middle Eocene-upper Oligocene marine Kirkgecit Formation. The Neogene basaltic volcanics are at the top of the lacustrine sediments in the area. The lacustrine deposit of Karabakir Formation consists of clayey limestone and limestones. Clayey-limestone samples were collected from Kurttepe section of the formation, and were analyzed for major, trace and rare earth elements (REEs). Samples were compared with Aksaray Neogene lacustrine occurrences which are very close to the investigated lacustrine sediments. Geochemistry of Kurttepe and Aksaray samples shows similarity. In two group samples, Th, Zr, Nb, Y and Ba are lower, Cu, Zn, Sc, Ni, V, and Y are higher contents of with respect to PAAS which can be explained as the result of lacustrine sediments derivation from more basic source than the PAAS. La/Sc, La/Co, Th/Co, Th/Sc, La/Cr ratios of Kurttepe samples are concordant with andesites and Th/Cr are concordant with basalts. Chondrite normalized of two datagroups show that REE patterns have low LREE/HREE ratios and no Eu anomalies, and different from Post Archean Australian Shale (PAAS), showing the source of two sample groups have basic - neutral in character. The samples fall within the volcanic arc basalt (VIB) and normal MORB (N-MORB) field in the discriminant plot of 2Nb-Zr/4 - Y. Samples fall in the oceanic island arc field in the plot of La/Sc vs. Ti/Zr. All geochemical data show that Elazig Magmatics are the main magmatic unit which could give material to the lacustrine sediments.