湖南邵东中泥盆统棋梓桥组层孔虫生物群及其生态环境

MIDDLE DEVONIAN STROMATOPOROIDS FROM THE CHITZECHIAO FORMATION OF SHAODONG,HUNAN AND THEIR ECOLOGICAL ENVIRONMENT

湖南中部泥盆纪地层和生物礁相当发育。湖南邵东中泥盆世棋梓桥期的泥质石灰岩中层孔虫广泛分布,本文共描述邵东廉桥马鞍山棋梓桥期层孔虫12属18种,其中Stromatopora wenshanensis为一新名,代替1982年根据一个云南标本定名为Stromatopora irregularis的种名。 马鞍山礁是—发育在海底平台上的厚度稍有变化的层状礁,马鞍山礁的沉积相变化过程,是由近岸浅海到展状礁普遍发育的开阔台地,再到封闭或半封闭的泻湖或潮坪环境。生物组合和沉积物也随沉积环境的变化而发生相应的变化。

The Devonian rocks and reefs are well developed in central Hunan. Stromatoporoids are widelydistributed in the carbonate rocks of the Middle Devonian Chitzechiao Formation in Shaodong County,but they have not been systematically studied in detail. Eighteen species of 12 genera ofstromatoporoids are described here from the upper part of the Chitzechiao Formation of the Ma'anshansection, Lianqiao of Shaodong, namely, Clathrostroma interruptum Yang et Dong, Trupetromaassamptum Yang et Dong, Actinostroma cf. baishanense Dong et Wang, A. expansum Dong et Wang,Stromatopora sinopachytexta Yang et Dong, S. wenshanensis nom. nov., Parallelopora ostiolataYavorsky, P. goldfussii Bargatzky, P. sp. indet., Clathrocoilona cf. variabilis Yang et Dong,Argostroma sp., Idiostroma reticulatum Yang et Dong, Paramphipora mankamensis Dong, Columdictyonwenshanense Dong et Wang, Stachyodes fasciculata Dong et Wang, S. costulata Lecompte and S.insignis Yavorsky. The Ma'anshan reefs of the Middle Devonian Chitzechiao Formation of Shaodong, Hunan, mayactually be biostromes with slight variation in thickness devoloped on a platform on the sea--bottom. Atplaces, there may be moundlike superimposed bioherms. The process of deposition and facies change of the Ma'anshan reefs may be as follows: nearshorenormal shallow sea environment--normal open platform environment with biostromes welldeveloped--closed or semiclosed environment of tidal flat or lagoon facies with abnormal salinity. Following the changes in environment, there are also corresponding changes in the biotic assemblages.