1:250 000 Yagra, Burang, Horba and Babazhadong Sheets in Xizang

Two successions of strata composed of siliceous rocks and basalts are found to be overlain upon the Denggang Formation and renamed the Guoyala and Yanduo Formations of Eocene in age in the southern subzone of the Yarlung Zangbo zone. The rhythmic succession composed of sandstones and shales beneath the Gaxue Formation is renamed the Sangguo Formation in the northern subzone of it. The Devonian Mayum Group and Carboniferous Kangtog and Lasha Formatigns and Lower Permian Caibanong Formation are re-established in the Zhongba stratigraphic subprovince. The middle and lower parts of the formerly Kangrinboqe Formation and the lower part of the Orma Formation are renamed the Danzengzhukang Formation of Miocene in age, and the upper strata of the formerly Kangrinboqe Formation is defined as the Orma Formation of Pliocene in age, both of the Formations are incorporated into the Kangrinboqe Group. The ophiolites and melanges are grouped into seventeen mappable units. The oceanic-floor bidirectional subduction once took place during the Middle Jurassic in the southern subzone of the Yarlung Zangbo zone.