DISCOVERY OF CARBONATE FLYSCH FORMAT旧N OF THE MIDDLE—UPPER DEVONIAN IN NINGYUAN AREA OF SOUTHERN HUNAN

1.Characteristics of the carbonate flysch form ation a. It is characterized by conspicuous rhythms and every single rhythm is several centimetres or dozens of centimetres thick. It has a series of crinkled beddings of penecontemporaneous deformation formed by submarine slumping.b. Sedimentary structures other than bioherm are well bedded.c. Rudaceous limestones and bioherms are common.d.The formation is dark or dark gray but the light gray is seldom found.e. It is of marine lithofacies and its thickness is more than 1288.6-1600 m。2.Changes of sedimentary environment Two lithofacies are differentiated。One is turbidite fades found in Dabatou area,Ningyuan;It is composed of thin layers of limestone and dark marl,chert beds or siliceous mudstone are also representative;fossils are scares.Floating organ-ism Tentaculites fossil can occasionally be found.Bouma sequence and cronkled beddings of slumping type develop well,the sedimentary environment is from bathy-al to deep sea.The other facies is found in the outer area of Dabatou. It consists of massive reef,colluvial deposit in front of the reef,bioclastic limestone and porous dolo mite etc.The benthonic organisms such as Stromatoporoids,Brachiopods,coral ect.1'he environment is mainly in shallow sea and subtidal belt.