A Preliminary Study Of Fossil Assemblage From The Cambrian Jialao Formation At Balang Village,Jianhe County,Guizhou Province

IIThe Jialao Formation of Balang village,Jianhe County is mainly composed of silty,calcareous dolostone and silty shale with diversity fossils.Its lower part is the richest fossil layer dominated by silty shale.By far,22 genera and 1 gen.et.sp.uncertain of early metazoans that were assigned arthropods,brachiopods,mollusk,cnidarias,wiwaxia,macroalgae and trace fossils have been found in the Jialao Formation at Balang,and arthropods are the most diversified oroganisms here.The trilobites of arthropod,from Jialao Formation at Balang included 8 genera,and they were Fuchouia(Parafuchouia),Kootenia,Oryctocephalus,Probowmania,Chittidilla(Diandongaspidella),Solenopleurina,Ehmaniella and Jialaopsis.Fuchouia(Parafuchouia)was comprised the dominant members of trilobites,while the large bivalved arthropod only has Alicaris(?).Brachiopods included Nisusia,Diandongia and Paterina,Nisusia was the dominant member.Mollusk just had Oelandiella,and cnidaria only found 1 genera Byronia.So far,any other soft-body fossil has not been found except Eldoniids.In addition,macroalgae and trace fossils were also the common fossils in the Jialao Formation at Balang.More diversity fossils have been found in the Jialao Formation at Balang than Nangao village.Compared to the Burgess Shale Biota from North America,the character of Jialao Formation is possesses more trilobites,less non-trilobite arthropods and soft-body fossils.These differences may be caused by a lower degree of studying and collection and the different sedimentary environment background.This study confirms the Fuchouia(Parafuchouia)trilobite Zone of the Jialao Formation is the highest trilobite zone in the Cambrian of the southeast of Guizhou and provides information for biostratigraphic division and correlation of the Cambrian both within China and abroad;also the Jialao Formation is the highest layer forOryctocephalus were found in the Cambrian of the southeast of Guizhou.The study of fossil assemblage from the Jialao Formation not only provides new material for understanding its composition,taphonomy and sedimentary environment.Furthermore,its age is close to the Burgess Shale Biota,and it also offers fossil evindence and information for the relation between the diversity of metazoans and their evolution,Meanwhile it provides information for biostratigraphic division and correlation of the Cambrian Series 3.