A layer characterized by the ostracod genus Paraparchites species formation outbreak exists in the Lower Permian Kungurian stage section of the Urals, Precaspian basin and northern part of the Caspian Sea. This layer is regarded as a Paraparchites biofacies, which has a certain place in the lateral series of sedimentation environments. Commercial hydrocarbon accumulations are associated with it within the northern flatbed zone of the Precaspian basin.
