吉中地区早石炭世大塘期珊瑚

THE DATANGIAN CORALS OF THE LOWER CARBONIFEROUS IN CENTRAL JILIN

一、前言 吉林中部地区早石炭世大塘期地层发育良好,出露广泛,化石丰富,是研究天山—兴安海西地槽区石炭纪地层及生物群的重要地区之一。本区石炭、二叠纪地层研究始于本世纪40年代,1932年河田学夫将这一时期的地层统称为“吉林层(Kirin formation)”。1942年凑正雄将磐石县明城鹿圈屯后山的一段吉林层进行了草测。

The Lower Carboniferous Strata is spread widely in the central part of Jilin Province, which is situated in 42°50'-43°50' N and 125°30'-126°45' E. It contains North Pansht County and South-west Yongji County,and belongs to a part of the north geosynclinal area of China.The Lower Carboniferous in this region may be subdivided into two parts. The Yufutun Formation of the Lower Datangian deposits at Yantongshan,Pan-shi County consists of volcano-sedimentary strata,i.e.mid-acidic lava,basic volcano-lava tuff and tuff breccia with siltstone and lenses of limestone.Its thickness is about 4,500 m.The lenticular limestone at the top of this fo mation have yielded corals, such as Arachnolasma sinense lophophylloides, A. sine-nse aichiapingense, Lophophyllum sp.; and brachiopods, such as Straiifera sp. Linoproductus cf. tenuistratus, Placatifera sp. The Lujuantun Formation of the Upper Datangian Strata occurs in Panshi,Shuangyang and Yongji Counties, and may be subdivided into two subformations. The lower part is the Qijian-fang Subformation. It is composed of the slates, intercalated lenticular limestones. Its thickness amounts to 1,745 m. The upper part is the Yuanbaoshan Subformation. It consists of lenticular limestones which contain chert nodules and marbles. Its thickness amounts to 768 m. The Lujuantun Formation is richly fossiliferous and yields abundant well-preserved corals and brachiopods. The genus Hexaphyllia also occurs in the Qijianfang Subformation.As based on the study of the corals we consider that the coral elements of the Lujuantun Formation belong to the memebrs of the Yuanophyllum zone in South China. The Yufutun Formation and the Lujuantun Formation respectively correspond to the Chiussu Formation,the Shangssu Formation and the Baizuo Formation of the Souith Guishon.The corals described in this paper are collected from the Lujuantun Formation of the Datang Stage of the Lower Carboniferous at Panshi, Shuang-yang, Yongji Counties, Central Jilin. 1 new genus, 1 new subgenus, 23 new species, 2 new subspecies of the Rugosa, and Hexaphyllia sp. are described in this paper.Palacosmilia(Parapalaeosmilia)Wu et Lin (subgen.nov.)Type species. P. (Parapalaeosmilia) intermedia Wu et Lin(subgen. et sp. nov.Xpl. i , figs. 4a-b: text fig.2)Diagnosis. The corallum is ceriod and parlialtv aphroid. This new sub-genus resembles the genus Palaeosmilia in their internal characters, but they differ from the genus Palaeosmilia in having thinner and partial missing walls.Geographic and Geologic distribution. China and Russia, Upper Visean. Paradipyhphyllum Wu et Lin(gen nov)Type species. Paradiphypyhllum fasciculare Wu et Lin(gen, et. sp. nov.) (p1.3, figs. 0)Diagnosis. Fasciculate corallites. The septa are two orders with zigzag carinae, which are feebly developed.The major septa are short aad extend inward from the epitheca to the inner wall.The minor septa are rather long.The axial tabulae are most complete and gently domed to forming an aulos. The periaxial tabulae are less regular. The columella is stable.Geographic and Geologic distribution. China, Upper Visean.