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    Organic geochemical characterization and mineralogic properties of Mengen oil shale (Lutetian), Bolu-Turkey
    (Estonian Acad Publishers, 2008) Senguler, I.; Ayyildiz, T.; Onal, Y.; Onal, M.
    Mengen (Bolu) basin extending northeast-southwest contains Neogene limestone, claystone, marl, lignite, and oil shale sequences. Oil shale deposit has been accumulated in shallow restricted back-platform basins during the Middle Eocene. The Middle Eocene (Lutetian) deposit divides into seven levels L1-7. Level L-6 consists of oil shale (thickness ranging from few mm to 4 meters), marl, claystone and siltstone intercalations. Investigated oil shale strata of an average 50-cm thickness are green or dark brown in color. Oil shale samples contain mainly quartz, calcite, ankerite, chabazite and smectite minerals. FTIR spectra and exothermic maximum and minimum peaks of DTA and TGA weight-loss curves of oil shale samples are compatible with TOC values and mineral composition, respectively. Total organic carbon (TOC) and genetic potential (GP) values of the oil shale samples are between 1.13 and 28.32 wt.% and 176.11 and 281.22 mg HC/g rock, respectively. Hydrogen index (HI) and T-max values range from 497 to 968 mg HC/g rock and 430 to 442 degrees C, respectively. TOC and GP values indicate a good source rock potential of this oil shale, and T-max values show its general immaturity. The samples stand mainly between types I and II of the evaluation path but closer to type I. This type of organic matter can generate oil upon pyrolysis.
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    Stratigraphic, mineralogic and geochemical characterization of Gurun oil shales, Central Anatolia, Turkey
    (Estonian Acad Publishers, 2006) Onal, M.; Ayyildiz, T.; Onal, Y.; Akmil-Basar, C.
    A Middle Miocene playa-lake sedimentary sequence containing oil shales and trona is divided into the Gokpinar (the lower oil shale unit) and the Terzioglu (the upper oil shale unit) Members in the Gurun Basin in eastern Turkey. Thermal decomposition of Gurun oil shales was studied by thermo-gravimetry (TGA), differential thermal analysis (DTA), and Rock Eval pyrolysis. Na2O content of oil shales reaches 0.2%, SiO2 content reaches 31.5%, and CaO content ranges from 29.8 to 52.7%. Content of Sr, Cu, Zn, Ba and Zr (ppm) exceeds that of other trace elements. In the lower oil shale unit, TOC reaches 9.03 wt%, whereas in the upper oil shale unit, the maximum TOC value is 1.54 wt%, generally being even lower. Oil shale contains mainly calcite, aragonite and montmorillonite minerals. DTA curves of oil shale samples show that exothermic peaks are compatible with TOC values. Weight loss is compatible with chemical properties, DTA results and TGA curves of oil shale. Organic geochemical analyses indicate that Gurun oil shale contains sufficient amounts of kerogen of good quality to generate both oil and gas upon pyrolysis.