PALEOGEOGRAPHIC DISTRIBUTION AND TAPHONOMY CHARACTERISTICS OF Naraoia FROM CAMBRIAN BALANG FORMATION IN GUIZHOU PROVINCE

Naraoia, an extinct genus of arthropod, is mainly preserved in Cambrian strata. In eastern Guizhou, the Naraoia from Cambrian Balang Biota are distributed in the sedimentary facies of Jiangnan slope, where lots of Naraoia fossils have been found in the Balang Formation in Taijiang and Jianhe areas. Based on the 213 specimens collected from Lazizhai section in Jianhe County, the fossils are identified to be Naraoia taijiangensis, which are accumulated mainly in three fossil enrichment layers. By analyzing the lithologicl characteristics, sedimentary environment and fossil preserved situation of the three fossil layers, it is confirmed that the fossil preservation is related to a rapid sedimentation event. The preservation is characterized by fossil impression, with local mineralization. The intact individuals of N. taijiangensis are found at the bottom of thick rapid sedimentary layer, while the fragmentary fossils are preserved in thinner layer. This discovery provides a basis for the burial characteristics of the Balang Biota in the slope facies area.