NEW RECOGNITION OF THE“GEDICUN FORMATION”

Th name“Gedicun Formation”was first used on the Qamdo sheet at a scale of 1:1,000,000,and according to the fossil plants contained in it,its age is assigned to Rhatian（Late Triassic）.This name has long been used in the literature at home as a formation in the uppermost part of the Xik- ang Group”.However,when the name was frist proposed,there was no measured section to control the strata and the contact relationships had not been ascertained. When we made regional svreys to prepare the 1:200,000-scale Luohuo Sheet,we measured a section at its naming locality,ascertained its contact relationships with its overlying and underlying strata,and collected abundant animal and plant fossils.According to these data,the“Gedicun hormation” is now assigned to the lower member of the Lianghe Formation and its age is determined to be early Norian（Late Triassic）.For the origin of the conglomerate therein,we suggest an origin of debris flow in a tectonic belt. These important new advances are not only of important significance for correction understanding the history of tectonic evolution of the Songpan- Garze fold system but also raise a new subject for the study of the time limit of the Tokio flora and the enrironment of coal formation.