Restricted platform facies with dominant Amphipora.

Abstract of ref. 1355:
Devonian reefs in Hunan were developed in the late Givetian and early Frasnian. Most reefs have been discovered in the area of carbonate platform facies and regarded as biostromes or patch reefs. Rare oil shows have been found in these kinds of reefs. Some so-called 'reef mounds' have abundant oil shows, but they have been considered to have developed only on a few elevated blocks in the area of inter-platform depressional facies. Based on research on reef distribution and characters of sedimentography and paleoecology, this paper proposes that many so-called 'biostromes' are not layered but instead are narrow along the edges of platforms as barrier reefs. Some 'reef mounds' are only the upper parts of barrier reefs, which extended towards the depressional facies area and were broken by faults. If this is true, they will be found along the edges of platforms and are not restricted within narrow limits. Because these parts of the reefs are preserved in the black shales and have fine oil shows, great attention should be paid to them in oil exploration.