Bedded granitic rocks occurring in Lamo, Dachang, around a granite intrusion, has a distinct geological occurrence, petrogenetic epoch, structure and texture, mineral and chemical composition and REE and trace element geochemical characteristics. They are different from both general metasomatite and normal magmatogenic granite. Its materials might come from both magmas and host rocks, indicating that it was formed when the ichor (or hydrothermal solution) replaced the Devonian siliceous shale and so on. The bedded granitic rocks together with bedded skarns, bedded Zn-Cu ore bodies and bedded Sn-polymetallic mineralization bodies form a bedded metasomatic system formed by the Yanshanian acid magmatism.