Abstract: Careful observation of the field profiles and detailed study on the lithology of the Upper Sinian Kurkak formation in the southwestern margin of Tarim basin indicated that typical turbidaite system is well developed in this formation, with the Bouma sequences and sole structure of turbidite deposit characteristics. The turbidte sequence was formed in the deep-Water turbidite fan environment, which is classified into outer fan factes, mid fan-leaf facies, mid-fan channel factes and mid-fan inter-channel overbank facies. The paper pointed out that scarce of turbidite deposits in the study area mainly came from shore sand, and that the intence faulting effect in Late Sinian was the key factor that triggered the turbidite flow.

Key words: Tarim basin, southwest, Late Sinian, turbidite fan, turbidite deposit, origin