The basin occupies a microcontinent in the Hercynian accreted terrane. Thick Triassic and Jurassic through Tertiary clastic sediments overlie a carbonate platform of the microcontinent. Most of the discovered oil reserves of the basin are in a thick clastic rock section of middle Pliocene age. This zone contains good reservoir sandstones that were deposited in the paleo-Volga River delta. Southward, the quality of reservoir rocks deteriorates significantly.
Oil dominates in the discovered reserves, but gas accumulations are more common seaward.
Recent large-field discoveries along the onshore part of the shelf suggest that a high resource potential exists for the adjacent area of the Caspian Sea. The basin is significantly gas-prone due to the abundance of coaly organic matter in the Lower to Middle Jurassic section and to the deep occurrence and overmaturation of Upper Jurassic marine source rocks. The basin is moderately explored to depths of approximately 3 km. The undiscovered resources of the basin are judged to be limited, owing to intensive faulting leading to poor preservation conditions for petroleum. The intermontane Fergana basin is a deep Neogene molasse depression overlying Paleogene and Mesozoic platform rocks of a microcontinent in the Alpine foldbelt.