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由３期火山岩和两期风化壳构成的鱼鳞山复合堆积物为了解高原夷平面的形成过程及环境提供了难得的条件．通过火山岩及风化壳地球化学、~（４０）Ａｒ／~（３９）Ａｒ和Ｋ／Ａｒ年代学的研究，揭示风化壳形成在干旱、半干旱的亚热带环境，时代为３０～２４ Ｍａ．羌唐地区的夷平面最后定位于２０ Ｍａ左右．
The volcanic scale assemblage composed of three volcanic rocks and two weathering crusts provides a rare condition for understanding the formation process and environment of plateau flat surface. The geochemical study of volcanic rocks and weathering crust, ~ (40) Ar / ~ (39) Ar and K / Ar geochronology reveals that the weathering crust is formed in arid and semi-arid subtropical environments with ages from 30 to 24 Ma. The Qiangtang area was finally located at about 20 Ma.