The Yili basin lies south of the Borohoro Range and is bordered by sutures and fault zones in the western Chinese Tian Shan belt. During the Late Paleozoic, the northern boundary of the Yili basin was an active continental margin related to the southward subduction of the North Tianshan oceanic basin; this boundary is represented by Late Carboniferous turbidite and ophiolitic melange. The southern and northern boundaries have been both reworked by Permian strike-slip faults.