Palynology and Evaluation of Petroleum Potential Source of Chaman-Bid Formatiom (Upper Bajocian-Tithonian) in the Eastern Kopet-Dagh Basin, NE Iran

The Kopet-Dagh Basin located in NE Iran, southern Turkmenistan and northern Afghanistan. It contains sediments of Mesozoic and Tertiary Eras. The Chaman-Bid Formation (Bajocian-Tithonian) is composed of shale, marl and marly limestone deposited after the Mid-Kimmerian orogeny in a shallow marine and lagoonal environments. In order to study palynostratigraphy, palynofacies and possibility of hydrocarbon generation, 45 samples were collected and processed palynologically. The studied section can be correlated with Tethyan realm and two events have been identified in the middle part of this section. Based on identified events, the age of Middle part of this section is Oxfordian-Kimmeridgian, while the upper part is Tithonian in age. The lower part of studied section, based on dinoflagellate cysts such as Nannoceratopsis gracilis and N. ridingii, is late Bajocian. Palynofacies study has led to recognition of two types of alternation in the sequence indicating a stagnant anaerobic-dysaerobic bottom condition followed by an energetic and oxygenated condition. Twelve samples rich in dinoflagellate cysts were selected for evaluation of Total Organic Carbon (TOC). These indices show that the potential of hydrocarbon bearing is fair to good and the type of production can be a wet and probably sweet gas; however at this stage the Chaman-Bid Formation is overmature in eastern Kopet-Dagh basin.