Investigation of the paleodepositional environment of the Middle Miocene aged organic matter rich rocks (Tavas/Denizli/SW Turkey) by using biomarker parameters and stable isotope compositions (13C and 15N)

Abstract

The study area is located 45 km south of Denizli. The purpose of this study is to identify the organic geochemical properties and paleo depositional environment of organic matter rich rocks from Tavas (Denizli/SW Turkey). For this purpose, total organic carbon (TOC, wt.%) and pyrolysis, n-alkane, isoprenoid, sterane, terpane and aromatic hydrocarbon parameters have been investigated of the studied samples. In addition, scanning electron microscopy (SEM) and stable isotope (?13C and ?15N) investigations were also carried out. Organic matter rich rocks which have type III kerogen have got 25.80 and 44.00 wt.% TOC content. Hydrogen index (HI, 73 and 120 mg HC/g TOC) and Oxygen index (OI, 34 and 59 mg CO2/g TOC) values of samples are very low. The values of ?13C and ?15N show the terrestrial C3 ecosystem. The predominance of high molecular weight n-alkanes, degree of waxiness and less dibenzothiophene (DBT) concentrations indicate terrestrial organic matter. At the same time, biomarker and pyrolysis parameters indicate that the organic matter rich rocks (Tavas/Denizli) are in the immature stage. Pr/Ph, C35/C34homohopane biomarker ratios and C35homohopane index values point out oxic-suboxic paleo depositional environment. © 2021 General Directorate of Mineral Research and Exploration (MTA). All rights reserved.