Adnan Döyen

The Bauxite deposits of Seydişehir region (Mortaş and Doğankuzu deposits); Their geological, mineralogical and geochemical characteristics

Turkey hosts essential bauxite deposits, typically of the karstic-type. The most economically important bauxite deposits of Turkey form in the Seydisehir-Akseki region of the central Taurides Mountains. The Mortas and Dogankuzu deposits are the most important deposits in that region. The bauxite beds contain boehmite, hematite, rutile, smectite, quartz, diaspore, calcite, pyrite, marcasite and goethite. Brown to red-colored bauxite minerals are massive, oolitic – pisolitic textured. The Seydisehir schists could be possible parent rocks of bauxites, and have unearthed acidic source (mostly granite) with hornblende and plagioclase minerals. The schists were compositionally mature with minimal alkali feldspar sediments. The Mortas deposit is 400 m long and up to 40 m thick; it averages 10 m thick. It has about 5 million tons of ore reserves, with ~50 percent Al2O3. The Dogankuzu bauxite deposit is situated 2 km southwest of the Mortas deposit, with 14.9 million metric tons of ore at 61 percent Al2O3. The Dogankuzu ore was deposited on a fault-controlled karst surface of Cenomanian limestone succession, which was overlain by 5- to 10-cm-thick Santonian limestones. The bauxite has been mined by the Seydisehir aluminum factory, which was founded in 1973, and privatized in 2005. The plant is capable to produce 65.000 ton liquid aluminum per year, around 15% of Turkey’s Aluminum demand.

Stratigraphic Features of the Yesilova Ophiolite, Burdur, South-Western Turkey

The Yesilova ophiolite is located in the Alpine zone as a major part of the Lycian nappes of western Taurus. It was formed at the southern branch of Neo-Tethys, and was abducted over the southern edge of the Menderes Massif during the Cenonian during Laramian orogenesis. The ophiolite in the study area starts with tectonite, consisting mainly of harzburgites (37.02 % MgO, 38.77 % SiO2, and 0.42 % Cr2O3) and smaller amounts of dunite and chromite pods. The sequence continues with cumulates, including (from bottom to top) dunite, wehrlite, clinopyroxenite, layered and nonlayered gabbro (45.53 % SiO2, 11.92 % Al2O3, and 13.11 % MgO), and plagiogranite (77.41 % SiO2, 0.25 % K2O). The tectonite and cumulates have been cut by isolated gabbro and diabase dikes. The altered volcanites are found at the top of ophiolitic sequence, and were abducted by the Upper Cretaceous Kizilcadag Melange, with limestone, chert–radiolarite blocks, and ophiolitic rock fragments. The upper Eocene Varsakyayla Formation rests over the melange; it contains abundant nummulites and is composed of conglomerate sandstone, limestone, and conglomerate towards the top. The stratigraphic sequence continues with the Pliocene–Quaternary Niyazlar Formation, consisting of terrigenous conglomerate intercalated with sandstone, and ends with rock talus and alluvium.