Stratigraphic division of the marine Triassic in the Coqên area, western Gangdise, Tibet, China

The carbonate rocks below the Dibu Co Formation at the northern margin of the Dibu Co, Gyangrang Township, Coqen County, Tibet, are not the Middle Permian Xiala Formation as deduced previously. The Triassic is identified in carbonate deposits by the conodont biostratigraphic study. The newly found Triassic is divided in ascending order into the Early Triassic Induan to Middle Triassic latest Ladinian Garing Co Formation (newly established), Middle Triassic latest Ladinian to Late Triassic early Carnian Zhuglung Formation (newly established) and Late Triassic Norian Gyangrang Formation. The discovery of the marine Triassic in the Coqen area suggests that the Early Triassic Induan-Late Triassic Norian marine carbonate deposits are developed in the western Gangdise, rather than missing as thought previously.