碧口群火山岩系是从原碧口系(叶连俊等,1944,后称碧口群)中解体出来的一个岩石单元(陶洪祥等,1993)。虽经过近60年的研究,但对某些关键问题,特别是碧口群火山岩系的时代,仍存在不同认识。在早期研究阶段(20世纪40～50年代)和60～70年代的区域地质调查工作中,碧口群和横丹群被视 Bikou volcanic rocks from the original Bikou (Ye Lianjun et al., 1944, later known as Bikou group) out of a rock unit (Tao Hongxiang et al., 1993). After nearly 60 years of research, different understandings still exist for some key issues, especially the era of Bikou Group volcanic rocks. In the early stage of research (from the 40s to the 1950s in the 20th century) and the regional geological survey from the 60s to the 70s, the Bikou Group and the Hengdan Group were regarded as