THREE TAPHONOMIC WINDOWS FROM THE KAILI FORMATION (CAMBRIAN SERIES 2-3), SOUTH CHINA

The Kaili Formation in southeastern Guizhou, China contains three types of fossil faunas. The Kaili Lagerstätte, occurred in the Orytocephalus indicus Zone, is one of the most important Burgess Shale-type (BST) deposits in South China and these Burgess Shale–type taxa, including nonbiomineralizing arthropods, discoidal animals, worms, and algae, are commonly preserved as organic carbon films. Phosphatization is restricted to organo-phosphatic brachiopod shells and internal volatile tissues, such as gut glands. Pyrite pseudomorphs are mainly associated with preservation of articulated sponges. Based on more recent work and this study, the unit also contains one of the few Cambrian micro-BST deposits known in the world with rich organic-walled fossils (OWFs). Bulk samples are collected from the Kaili Formation at Miaobanpo, Wuliu, Denzhou, Danzhai and Zhuping sections, and prepared with conventional palynological methods along with modified acid treatment techniques. The results show that the most common types of OWFs are filamentous algae and acritarchs with small amount of brachiopod fragments, Wiwaxia sclerites and other problematic organic pieces. In addition, a new taphonomic window from the limestone interbeds in the lower part of the unit is reported here. Well-preserved siliceous sponge spicules and organo-phosphatic brachiopod shell fragments are recovered from acid residues. This has broadened our understanding on the true fossil diversity of Kaili Formation and increased its potential for global correlation.