【摘要】 <正> 一前言贵州全境的三叠系,尤其是中三叠统发育良好,分布广泛。早、中三叠世,大致以东面的福泉马场坪开始,向西经青岩、平坝至安顺,折向镇宁经贞丰至册亨,再由册亨向西入云南境一线为界;该线之南、之东,基本上为盆地相沉积,该线之北、之西,基本上为碳酸盐岩台地相沉积;而大致沿该线的南北的一个窄长的条带更多还原

【Abstract】 Marine Triassic sediments containing rich fossils are widespread and fully developed in Guizhou province. The Lower and Middle Triassic deposits in Guizhou can be divided into two parts along a line from Fuquan in the east, through Huishui, Anshun, Pingba, Guanling, Zhenfeng, Ceheng and Anlong, to Xingyi in the west. On the north and west of this line, the deposits are of carbonate platform facies. But on the south and east of this line, the deposits of basin facies are widely distributed. In the Ladinian and Early Carnian, the deposits of basin facies may extend westward to Anshun. Langdai, Xingren and Xingyi. During the Middle Triassic the ammonoidbearing beds are rarely seen in the area of platform facies and, if visible, the genera and species are rather simple, only Progonoceratites fauna is known. Contrastively the large number of ammonoids, characterized by tra- chyceraids, make their appearance in the areas of basin facies and on the margin of carbonate platform facies.The materials dealt with in the present paper were largely collected by the writer in 1963. The specimens recorded by the late T. Y. Hsu are also emended. Altogether, 5 genera and 9 species, including 2 new genera and 5 new species, are here described and illustrated. All of them are collected from 3 levels of the Falang formation in southwestern Guizhou. Based on the faunal characters 3 ammonoid zones may be recognized with 2 belonging to Ladinian and 1 to Early Carnian as tabulated in Table 2. (see Chinese text)1. Xenoprotrachyceras primum zone: This zone, containing Xenoprotrachyceras primum (gen. et sp. nov.), Langdaicems pateriformis (gen. et sp. nov.) and ?Bulogites langdaiensis (sp. nov.), is recognized in the Zhuganpo member of the Falang Formation at Langdai (coll. no. AAN7, AAN9), and succeeded by the beds with Protrachyceras deprati etc., which is very rich in individual but not very well preserved.The present fauna shows a peculiar and interesting character. It includes a typical Early Ladinian form Xenoprotrachyceras (gen. nov.), a new genus Langdaiceras and a doubtful taxon Bulogites. Xenoprotrachyceras primum (gen. et sp. nov.) is very similar to "Protrachyceras" reitzi which is an Early Ladinian index fossil of the "Prot." reitzi zone. Lamgdaiceras is similar to Ticinites Rieber from bed 58 (Polymorphus zone) of M. Grezhitumenzone of Mt. San Giorgio in S. Switzerland. Bulogites is commonly known from the M. and U. Anisian. But ?Bulogites langdaiensis (sp. nov.) is probably a higly advanced form of Bulogites in suture line, It should be pointed out that there is ?Bulogites in bed 61 (Polymorphus zone) of M. Grenzhitumenzone of Mt. San Giorgio in S. Switzerland.Therefore, the present zone may be corresponding with "Prot." reitzi zone and probably with the upper part (bed 57-bed 97) of the Polymorphus zone.2. Protrachycerlas deprati Zone: This zone, widespread in southwestern Guizhou and southeastern Yunnan, is based on the Laishike member of the Falang Formation at Longchang Zhenfeng county. In our collection (AAN1-1), there are 2 genera and 6 species, Protrachyceras pseudo-archelaus (Boeckh), Prot. deprati (Mansuy). Prot. costulatum (Mansuy), Prot. mutabile (sp. nov.), Prot. guizhouense (sp. nov.) and Proarcestes sp. (the last one is not described in this paper), among which, the former is an important member of the Prot. arehelaus zone of the Tethyan region. Other species of Protrachyceras are all endemic forms. Prot. deprati and Prot. costulatum might belong to the group of Prot. ladinum. Prot. mutabile and Prot. guizhouense are similar to Prot. cautileyi Diener in shell shape.The present zone my be correlated with the Protrachyceras archelaus zone of Late Ladinian.It should be noted that the late Hsu first recorded a few ammonoids of the Falang Formation (KF 97, KF 39). They are Trachyceras multituberculatum Hsu, Prot. costulatum, Prot. douvillei (Mansuy) and Prot. archelaus (Laube). After studying Hsu’s original specimens of Protrachyceras and Trachyceras, the present writer thinks that the specimens assigned to Prot. archelaus by Hsu should be referred to Prot. guizhouense (sp. nov.). The specimens of Prot. douvillei are not found in Hsu’s materials. Based on our collection, the Prot. deprati-bearing level (AAN1-1) is continuously succeeded by the Trachyceras multituberculatum-bearing level (AAN1-2).3. Traehyceras multituberculatum Zone: This zone only contains an index species, rich in number, which is first known from the Falang Formation at Falang, Guanling county. It also lies at the top part of the Laishike member and the lower part of the Longchang member of Falang Formation at Longchang Zhenfeng county. According to the strong spines at the umbilical edge and the transversal spiral ribbing composed of small crowded tubercles, this endemic species may be a Carman form of Trachyceras, So the writer is inclined to assign the present fauna to the Early Carnian in age.Langdaiceras (gen. nov.)Typy species: Langdmceras pateriformis (gen. et sp. nov.)Thick discoid shell, large, evolute, with tabulate venter; strong ribs T-shaped, ending in nodes at ventero-lateral edge, not crossing venter. Subeeratitic suture-line; external saddle encroached by serrations upward nearly to the top; 2 umbilical lobes, but the one near umbilical edge very small.The present form is similar to Tieinites Reiber in the shell shape and the ornaments, In the latter form the shell is very evolute, its section is subquadrate; whereas in the former the shell is plate discoid in shape, and the width of whorl is less than the height.Xenoprotrachyceras (gen. nov.)Typy species: Xenoprotrachyceras primum(gen. et sp. nov.)Shell evolute, with a shallow furrow on the venter; section elongate oval in shape; simple and robust ribs covered by ventral nodes and ventrolateral nodes, and occasionally by umbilical nodes and latero-central nodes; ventral nodes large, simple, occasionally spinous; umbilicus large. Ceratitic to faintly subceratitic sutureline, commonly unserrated or serrated by feeble denticulations.The present form is closely related to Eoprotrachyceras Tozer in the suture-line, but the latter is similar to Protrachyceras in the shell shape. It the former form the shell is evolute with shallow ventral furrow, simple ribs and nodes by which it may be differentiated from Eoprotrachyceras.Species included: Xenoprotrachyceras primum (gen. et sp. nov.), "Protrachyceras" reitzi (Boeckh) and "Protrachyceras" recubariense Mojsisovics.更多还原