Coral Biostrome of Frasnian,Late Devonian,Houshan of Guilin

Key words: 
• Reef /
• Frasnian /
• Houshan /
• Guilin

Abstract: Middle and late Devonian developed best in Guilin area. FromGivetian to Frasnian,reef and shoal Groped out in the different subfacies,moreover,in the different periods,the features of the reefal organisms are changable. Beginning in the late Devonian,stromatoporoids and corals were replaced by thriving algae which played an important role in reef communities. In Houshan,located in 5 km west of Guilin,however, the coral biostrome developed well besides algal-tromatoporoid reefs in out back一reef along inner platform margin. We seldom see such coral biostrome in the late Devonia strata. The coral biostrome are made of fasciculate Smithiphyllum guilinense packed by micrite. lts growth height can be up to 1 m,and it often exhibits low diversity. Other reefal organisms are algae and a few stromatoporoids,the attach-ing一reefal organisms are main brachiopods. Vertically,reefal sequences are composed of(1)cryptalgal micrite microfacies, (2)sand一sice algal intraclastic limestone,( 3 ) cryptalgal mi-crite with zebra structure microfacies and (4) coral biostrome microfacies. Laterally,the reef complex can be recognized with(1)back一reef subfacies,(2) reef flat and margin subfacies,(3) marginal fore一slope subfacies. According to inference from reefal organism,microfacies character and diagenesis of reef and relations with periphery environments,it is not barrier reef but a coral biostromc located the out back一reef nearer platform margin.