Ore-bearing strata of the Dimunalike iron deposit constitute an important stratigraphic part of the south Altun continental-type subduction-collision complex. The emphasis of the study is to ascertain features of the iron ore and rock composition of the ore-bearing strata and to confirm the formation age of the ore-bearing strata. LA-ICP-MS U-Pb dating of zircons from the bottom volcanic breccia yielded an age of (622.6±1.4) Ma and closure epoch 500 Ma for South Altun ocean basin, thus suggesting that the ore-bearing strata and the iron deposit were formed during 500~623 Ma. The results show that the ocean basin in South Altun existed during Ediacaran-Cambrian period.