Abstract:

 Based on the geological survey of 1∶250 000 scale in Kana and Ritu Areas, we recognized the vertical and horizontal variation of sedimentation, studied the sedimentary environment and reestablished the JurassicCretaceous sedimentary sequence in three strata areas of western Bangong LakeNujiang suture zone. It was specified that the sedimentation in Bangong LakeNujiang middle Tethys oceanic basin was clearly different from both the southern and northern continental margin of the ocean in JurassicCretaceous period. The evolution of the middle Tethys Oceanic basin can therefore be divided into three stages as earlymiddle Jurassic deepwater ocean, later Jurassic to early Cretaceous relict basin with shallowwater sedimentary rocks and later Cretaceous remnant oceanic basin withering away.

Key words: MesoTethys; basin evolution; JurassicCretaceous; Bangong LakeNujiang suture zone; Tibet