Dergi makalesi Açık Erişim

Paleoenvironmental significance of biomarker and stable isotope (H-2, C-13, N-15, O-18, and S-34) investigations on a Pliocene coal-bearing sequence (Denizli Basin, southwestern Turkey)

2020    Koralay, Demet Banu

Pliocene coal, clayey coal, and coaly claystone sediments from the Yatagan Formation (Denizli Basin, southwestern Turkey) have been investigated with respect to maceral association, mineralogical composition, n-alkane, isoprenoid and saturated-aromatic biomarker characteristics, and stable isotopes (H-2, C-13, N-15, O-18, and S-34). The main purpose of the present study was to determine the hydrocarbon potential and paleodepositional conditions of coals in the Denizli Basin. The abundances of huminite, liptinite, and inertinite macerals were 46.14%, 8.06%, and 1.57%, respectively. The huminite/vitrinite reflectances (%Ro) of the coal, clayey coal, and coaly claystone samples ranged between 0.26 and 0.37 %Ro, implying sub-bituminous B and C coal ranks. The total organic C (TOC, wt.%) content and the T-max values of the investigated samples ranged between 0.74 and 43.80 wt% and 390-440 degrees C, respectively. In addition, the coaly horizons were characterized by very low H index (HI), O index (OI), production index (PI), and Tmax values. Moreover, a high waxiness degree, C preference index (CPI), odd-to-even predominance (OEP), terrigenous/aquatic ratio (TAR), and high C-19 tricyclic terpane/C-23 tricyclic terpane (C-19/C-23 TT) and C-24 tetracyclic terpane/C-26 tricyclic terpane (C-24*/C-26 TT) biomarker ratios indicated a terrestrial plant input. These results were supported by stable isotope (H-2, C-13, and N-15) investigations. Although the Pliocene coals have source rock potential according to the TOC content and pyrolysis analyses, they have been determined to be at the diagenesis and immature stages as a result of organic petrographic, and saturated-aromatic biomarker investigations.