Abstract:

Bioherm developed in the middle of the Wujiaping Formation is less than 100 m thick and belongs to marginal reef of intra-basin platform on shelf.The main features of the bioherm are: 1.It is a low range upwarp which is made of white massive rocks within visible lamination. 2.It contains abundant reef-building organisms such as calcisponges, blue-green algae, Tubiphytes, green algae and red algae. The content is usually 25-30%, locally above 75%. 3.It is composed almost completely of pure carbonate rocks without chertsand terrigenous debris. 4.It has a complete facies assemblage of slump microbreccia in reef-front,algae-sponge reef limestone in reef core and gymnocodium micrite in back-reef. The primary reef-building organisms are calcisponges,tabulozoans,Anthraco-porella, blue-green algae and Tubiphytes. The first group organisms are supporting and baffling ones, and the last two are binding and encasing ones.