广西六寨中泥盆统台地边缘丘状叠置礁内的层孔虫生物礁

南丹六寨中泥盆统台地边缘层孔虫生物群内的层孔虫头骨有块状、柱状、板状、短粗枝状及皮壳包覆状等五大类型(其中块状又可分为孤立的11种类型和复合的9种类型,它们是丘状礁主要的建造格架块状体),分属8个属,可鉴定15个种。层孔虫大多分布于礁相,少数分布于礁相和非礁相,极少数只在非礁相出现。有三点结论:1.造架层孔虫共骨外形表现出较高的稳固性。这些形态基本上限于礁相。它们都具有较强的生长扩展特征。2.共骨外形在礁相的远较在非礁相的多样化,并具多变性。3.环境中底质性质和沉积速率是造架层孔虫生长发育的制约因素;也是层孔虫格架礁形成和发育规模的制约因索。

MIDDLE DEVONIAN STROMATOPOROIDS FROM MOUNTLIKE SUPERIMPOSED BIOHERMS ALONG CARBONATE PLATFORM MARGIN FROM LIUZHAI,NANDAN, GUANGXI

The coenostea of stromatoporoids under study include five forms, namely, themassive, columnar, tabular, dendritic and encrusting forms. The massive forms can be clas-sified into 11 discrete and 9 compound types, which form the main reef-forming masses,and can be assigned to 11 genera and 15 species. Most of them mainly occur in reef facies,with a few in both reef and non-reef facies, but very rare in non-reef facies. The main points of this paper are 1. The external forms of stromatoporoidcoenosteum which are mainly limited to reef facies, have strong growth expansion andhigher stability. 2. The nature of substrates and the sedimentation rate are the factors lim-iting the growth and development of stromatoporoids and the formation and developmentof stromatoporoid-framing reef.