Basic geochemical characteristics of lacustrine rocks in the Neogene Kağızman–Tuzluca Basin, Northeastern Turkey

The Neogene Kağızman–Tuzluca Basin is located in the NE Anatolia and extends eastward into Armenia Oktemberian Basin. The Halıkışlak (Late Oligocene), Turabi and Tuzluca formations (Lower–Middle Miocene) are time equivalents of the organic-rich Oligo-Miocene Maikop Series in the Caspian region. However, depositional conditions within the KBT are appreciably different and source rocks are not as richer as it. The Halıkışlak Formation has little source rock potentials, with very low values of TOC (0.04–0.25%), HI (14–90 mg HC/TOC) and genetic potential-GP (i.e. Rock–Eval S 1 + S 2 = 0.05 to 0.22 mg HC/g rock). Although a peat facies sample has a relatively high TOC (6.78%), T max of 428 °C, HI values are very low (45 mg HC/TOC). TOC and GP values for the Tuzluca Formation are between 0.06 and 0.39 wt%, and 0.16–1.51 mg HC/g rock, respectively. Some levels of the Turabi Formation have TOC contents up to 6.14 wt%; however, mainly T max values are low 435 °C, and HI range from 25 to 54 mg HC/TOC. The extract of one low-maturity Turabi sample possesses biomarker distributions of an immature rock. Low relative abundance of tricyclic terpane and dominant C29 ααα (20R) are in accordance with the immature source rock. Some samples collected from the outcrops nearby Pliocene/Pleistocene lava series show localized maturation stage. We suggest that the Oligocene to Middle Miocene units could be more studied beneath the volcanic plateau.