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This paper outlines the organic petrology and geochemistry of potential hydrocarbon source rocks from southern Caspian Basin. Coals and associated beds from Kalaris member of the Shemshak Formation in the southern Caspian Basin were analyzed megascopically, petrologically and geochemically. Maceral analyses reveal a dominance of duroclarite to clarodurite subgroups. The synthesis of source rock characteristics emphatically surmises that in the Kalaris member, organic matter is ubiquitously of terrestrial origin.
This member displays poor to good and occasionally very good generative potential. The kerogens are predominantly of type III but sometimes type II-III kerogen has also been identified. Such occurrences envisage predominance of gas prone and occasional oil prone source rocks. Vitrinite reflectance values (mostly 0.6 to 1.2% VRo) indicate that the coals are thermally mature.
The depositional environment is interpreted as a peat swamp with a variable density of herbaceous vegetation situated in an upper delta plain.