Ａｐｐｌｉｃａｔｉｏｎ ｏｆ Ｇｒａｉｎｓｉｚｅ Ｇｅｎｅｔｉｃ Ｕｎｉｔ ｔｏ ｔｈｅ Ｄｉｖｉｓｉｏｎ ｏｆ Ｂａｓｅｌｅｖｅｌ Ｃｙｃｌｅｓ ｉｎ Ｈｉｇｈ-ｒｅｓｏｌｕｔｉｏｎ Ｉｓｏｃｈｒｏｎｏｕｓ Ｓｅｑｕｅｎｃ

Key words: 
• Chaiwopu basin /
• Loucaogou Formation of Middle Permian /
• high resolution sequence stratigraphy /
• grain-size genetic unit

Abstract: Abstract On the base of the hypothesis of PAC which was presented by Goodwin and Anderson in 1985, considering the division of base-level cycles was extremely indefinite, this paper attached the autocyclicity and allocyclicity to the concepts of base-level cycle. The concept of the grain-size genetic unit and its research methods were put forward, and applied to establish high-resolution isochronous sequence framework of Loucaogou Formation of Middle Permian in Chaiwopu basin. There totally 2 long base-level cycle sequence, 6 middle-term grain-size genetic　units, 5 members equal to 5 system tracts ,were distinguished from Loucaogou Formation of Middle Permian in Chaiwopu basin.