Abstract:

Carbonate rocks were distributed widely during Middle to Late Devonian in South Hunan Province. Carbonate platform margins can be divided into four types:1. Carbonate ramp; 2. Distally steepened ramp; 3. Accretionary rimmed platform margin; 4. Gully or colluvial margin. Except the influences of sedimentution, eustatism and the migration of basin, the evolution of platform margins or slopes were mainly controlled by synsedimentary fault activities. Since the synsedimentary fault activities in the east and the west sides of the basin unsynchronized, there was distinct differences in the evolution of platform margins or slopes in both sides. The evolution process of the platform margin or slope in west side is considered as:carbonate ramp (D₂¹q)→accretionary rimmed platform margin (D₂¹)→gully or colluvial margin (D₃¹s)→carbonate ramp (D₃²s-D₃¹x); the eastern side is: carbonate ramp (D₂¹q)→accretionary reefs rimmed margin (D₂²q)→distally steepened ramp (D₃¹s)→accretionary shoals rimmed margin (D₃²s)→carbonate ramp (D₃²s).