| 论文摘要 |
Based on the new findings of fossil fishes from the Silurian shallow marine red beds at the Gumushan section,Wuhan,Hubei Province,the lower Telychian(Llandovery)red beds are confirmed to be developed in southeastern Hubei. The original Fentou Formation in Wuhan area is emended and subdivided into two parts: the upper part is the emended Fentou Formation,while the lower part is called Qingshui Formation. The redefined Fentou Formation is characterized by yellowish-green,gray-green,and gray-yellow mudstones,argillaceous siltstones,and siltstones bearing abundant brachiopods,bivalves,gastropods,trilobites,and trace fossils. The lower part of the Qingshui Formation consists of purple-red,reddish-brown mudstones and argillaceous siltstones intercalated with quartz sandstones,while its upper part is dominated by purple-red and yellowish-green quartz sandstones intercalated with mudstones,argillaceous siltstones and siltstones containing lots of fossil fishes. Fishes from the upper part of the Qingshui Formation include the galeaspids Hanyangaspis guodingshanensis, Hongshanaspis inexpectatus, Jiangxialepis retrospina,and the chondrichthyans Sinacanthus and Neosinacanthus,all belonging to the Wentang Fish Assemblage of the Zhangjiajie Vertebrate Fauna. The galeaspid J. retrospina can be compared directly to J. jiujiangensis from the Qingshui Formation in Wuning area,Jiangxi Province,as members of the genus Jiangxialepis assignable to the family Shuyuidae,whose members are elements of the Silurian Lower Red Beds in South China. According to comprehensive analysis of the fish assemblage and stratigraphic sequence,the Lower Red Beds in Wuhan,with an age of early Telychian,can be correlated with the Houjiatang Formation in Anhui and Jiangsu,the Tangchiawu Formation in Zhejiang,the Qingshui Formation in Jiangxi,the Rongxi Formation in Hunan,and the Tataertag Formation in Tarim Region. In addition,the distribution pattern of the Silurian Lower Red Beds in the South China Block indicates that the Upper and Lower Yangtze seas were connected by a narrow shallow epeiric water during the early Telychian,which probably provides a precondition for the galeaspids dispersing and communicating between Wuning of Jiangxi and Wuhan of Hubei. |
