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    Geochemistry and provenance of Maastrichtian clastic rocks in the Dikmendede formation of Orhaniye in Kazan-Ankara-Turkey region
    (Wiley-Blackwell Publishing Asia, 2011) Ozkan A.M.; Ayaz-Bozdag A.
    An integrated petrographic and geochemical study of the sandstones of the Maastrichtian-aged in the Orhaniye (Kazan-Ankara-Turkey) was carried out to obtain more information on their provenance, sedimentological history and tectonic setting. Depending on their matrix and mineralogical content, the Maastrichtian sandstones are identified as lithic arenite/wacke. The Dikmendede sandstones derived from types of provenances, the recycled orogen and recycled transitionaI. The chemical characteristics of the Dikmendede sandstones, i.e., fairly uniform compositions, high Th/U ratios (>3.0), negative Eu anomalies (Eu/Eu* 0.72-0.99) and Th/Sc ratios (mostly less than 1.0), favor the OUC (old upper continental crust) provenance for the Dikmendede sandstones. The SiO2/Al2O3, Th/Sc (mostly <1.0) and La/Sc (<4.0) ratios are; however, slightly lower than typical OUC, and these ratios may suggest a minor contribution of young arc-derived material. The rare earth element (REE) pattern, and La/Sc versus Th/Co plot suggests that these sediments were mainly derived from felsic source rocks. The Dikmendede sandstones have high Cr (123-294 ppm) and Ni (52-212 ppm) concentrations, Cr/Ni ratio of 1.93, and a medium correlation coefficient between Cr and Ni and corresponding medium to high correlation of both (Cr and Ni, respectively) elements with Co. These relationships indicate a significant contribution of detritus froni 0phi0Utic rocks. As rare earth element data are available for the Dikmendede sandstones, the Eu/Eu* is compared with LaN/YbN. Samples plot in the area of overlapping between continental collision, strike-slip and continental arc basins. The predominantly felsic composition of the Dikmendede sandstones is supported by the REE plots, which show enriched light REE, negative Eu anomaly and flat or uniform heavy REE. The Dikmendede sandstones have compositions similar to those of the average upper continental crust and post-Archean Australian shales. This feature indicates that the sediments were derived mainly from the upper continental crust. The Dikmendede sandstones have chemical index of alteration (CIA) values of 28-49, with an average of 40 indicating a low degree of chemical weathering in the source area. The compositional immaturity of the analyzed sandstone samples is typical of subduction-related environments, and their SiO2/Al2O 3 and K20/Na20 ratios and Co, Sc, Th and Zr contents reflect their oceanic and continental-are settings. The Dikmendede sandstones were developed as flysch deposits derived from mixed provenance in a collision belt.
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    Sedimentology of beykoyu formation (miocene) around beykoyu - Kuskuncuk - Gokceyazi (Eregli - Konya - Turkey)
    (2008) Ozkan A.M.
    The basement of the investigated area consists of Upper Permian - Upper cretaceous aged the Bolkardagi Group and several formations situated in the Bolkardagi Unit, tectonostratigraphic units of the Taurus, viz., Paleocene - Lower Eocene aged the Güneyda?i{dotless} formation, and Upper Paleocene - Eocene aged the Halkapi{dotless}nar formation. The limestone of the Guneydagi{dotless} formation is observed as a basement rock in the area, and is overlied with angular unconformity by Miocene aged the Beykoyu formation, which is made up of members of the Kabaktepe gypsum and the Kayalidagtepe stromatolitic limestone. The Beykoyu formation is overlied with an angular unconformity by Upper Pliocene - Holocene aged the Kuskuncuk formation, which consists of alternation of conglomerate, sandstone and mudstone including caliche bands in some levels. While the Beyköyü formation was formed in lacustrine environment, the Kuskuncuk formation was developed in environments of alluvial fan and braided stream. The Kabaktepe gypsum member, basement of the Beykoyu formation, is white - gray in colour and is usually massive, rondomly medium to thick strata and have a laminae. The gypsum of the Kabaktepe gypsum member is usually white in colour and cyrstalized texture, at some levels they are prismatic and transparent, and folded in places. At some places, at the bottom of the gypsum, alternating of conglomerate - sandstone and mudstone can be observed. Through the upper part, the alternating of greenish - gray, brown sandstones and green - red coloured mudstones are present. In the upper levels they are in the form of gypsum with muddy stone interlayer. Over the gypsum, stromatolitic limestones belonging to the Kayalidagtepe member are found. The stromatolites are beige, brown in colour, medium to thick layered, and these are in the types of lateral linked hemispheroidal (LLH type), stacked hemispheroidal (SH type) and onkoides (SS type). The stromatolitic limestones have interlayering gray mudstones, red conglomerate, sandstones and mudstones. In some levels the stromatolites can be seen as sandy - gravel limestones which have ostrocode and gastropoda fossiliferous limestones alternating with marls. The formation of stromatolitic limestones belonging to the Kayali{dotless}da?tepe member is strictly depending on the blue - green algae of Shizothrix sp., Phormidium sp. and Scytonema sp.