对比日本秋吉生物礁论湖南石炭纪生物成礁条件

一个完好的石炭纪生物礁发育在日本秋吉地区的玄武岩熔岩和火山碎屑岩之上.其礁核相可划分为6个亚相.主要的造礁生物是钙藻类、剌毛虫、珊瑚和苔藓虫.这些造礁生物在湖南中部某些地区的石炭纪地层中也十分常见,其生物组成、形态和生态特征可以和秋吉礁礁核各亚相中的生物特征进行对比.湖南中部地区石炭纪浅海的海底地形存在高低差异,在地势较高的中高能地带具备生物礁发育的各种条件,已发现一些生物层,完全有可能发现生物礁.

ON FACTORS OF CARBONIFEROUS REEF DEVELOPING IN HUNAN: A COMPARING STUDY WITH AKIYOSHI REEF IN JAPAN

A perfact Carboniferous reef complex developed on top of a volcanic seamount on the oceanic floor in the Akiyoshi Terrane, Southwest Japan. There are three major facies zones in the reef complex, and the reef core facies zone can be divided into six subfacies zones. The main reef building organisms are calcareous algae, chaetetids, tabulate and rugose corals, and bryozoans. These organisms have different growth forms and functional roles in the different facies and subfacies. During the Carboniferous, especially the period from Staffera zone to Pseudostaffera zone, the sea water in Hunan was warm and the salinity was also normal. In the district along the line from Zhadu of Lengshuijiang to Xiandong of Lianyuan, the relief of the sea bottom was elevated, the water was clear and the hydrodynamic energy of waves acting on the sea floor was intermediate to strong. The factors of this environment were very suitable for flourished growth of benthic organisms, including abundant reef building organisms. The reef building organisms in this district were very similar to that of Akiyoshi reef in many ways, such as organism variety, categories, growth forms and ecological characters. Calcareous algae and chaetetids encrusted massive or dendroid tabulate and rugose corals, and formed framestones and bindstones. The biostromes formed by these organisms have been found in many localities. Comparing with the factors of reef developing in the Akiyoshi Terrane, the possibility of existence of Carboniferous reefs in Hunan is proposed.