This paper deals with the problem whether it still subducted in Early-Middle Triassic or not. The authors not only emphatically studied geochemical features of Early-Middle Triassic volcanic rocks lying in Chaqupu area but also investigated mineralogical characteristics and age of meta-basic volcanic rocks of Chasagang Formation in Gongbujiangda area. The results show that the young shells can be divided into two groups by their ages, one group yielded (237.7±7.1) Ma (MSWD=1.3) which is consistent with the island arc produced (IAP) in Early-Middle Triassic, the other yielded (273.4±5.5) Ma (MSWD=0.15) which is consistent with the IAP of Early-Middle Permian.