Mineral Signatures and Trace and Rare Earth Elements Constraints on the Sources of the Doğanşehir Bauxite Deposit (Malatya-Turkey)

Abstract

In the Eastern Tauride, one of Turkey’s main tectonic belts, the Permo–Triassic Malatya Metamorphics units crop out. Doğanşehir bauxites occur in lenses and are massive in the carbonates of Malatya Metamorphics. The ore paragenesis consists of diaspore, hematite, gibbsite, anatase and zeolite minerals, indicating that the deposit was formed in vadose environments. The results of the geochemical analysis show that Ni, Be, Zr, Cr, Nb, Th and Ta trace elements normalised to the Upper Continental Crust are enriched, while Co, Cu, Rb, Sr, Ba, Mo, Sn and Pb elements are depleted during bauxitization. In bauxite samples, ΣREE is 664–1047 ppm, ∑LREE is 547–948 ppm, ∑HREE is 88–112 ppm. Compared with the Tauride-Anatolide region bauxites in Turkey and some important bauxite deposits worldwide, the Doğanşehir bauxites have been geochemically characterised by high ∑REE content. The Ce/Ce* index in the studied bauxite ores, with values ranging between 0.88 and 1.35, reflects the occurrence of weak negative and positive anomalies during chemical weathering processes. The weathered material would display these Ce anomalies due to the influence of oxidation on reduction processes. The La/Y ratios in samples of Doğanşehir bauxites indicate that basic conditions were dominated during bauxitization. The bivariate diagrams of log Cr vs log Ni and the triangular diagrams of Zr–Cr–Ga revealed that the bauxite that formed in the region had ultrabasic and basic rocks source. Based on the mineralogical and geochemical data, the sources of Doğanşehir bauxites are from basic to ultrabasic rocks.