Paleoecology of the Kaili Biota from Middle Cambrian in Taijiang County, Guizhou Province, China

Key words: 
• paleoecology /
• Kaili Biota /
• Middle Cambrian /
• Guizhou province

Abstract: The Kaili Biota is the third most diverse Burgess Shale-type biota after the Burgess Shale and Chengjiang biota. In the paper, on the basis of the study on the burial characteristics of fossils, the ecological be-havior of animal and algae, and the analysis of depositional characteristics and the geochemical parameter, we consider that most animals and algae in the Kaili Biota lived at the shallow water, and these organisms are carried into continental shelf by tempesite or turbidity flow and is buried in contnental shelf. At the same time, the burying mechanism of the Kaili biota is put forward in this paper. On the basis of the analyses of sedimentary sequences and taphonomic sequences of fossil in Kaili Fm. bearing-Kaili Biota, and combining research of geochemistry and paleo-ecology and taphonology, the Kaili Biota is considered that most organisms are characterized by ecological behavior of shallow water, these animals and algae living in shallow water were destroyed by event of tempesite or turbidity flow, and carried into deeper shelf, and buried at shelf. Some researches suggested that the Kaili Biota live at 150～200 meters water in depth; they reached this conclusion from lithology and lithofacies, and trace fossil assemblage in Kaili Formation. We disagree with above-mentioned view about the Kaili Biota lived below 150～200 meter deep, but agree that the Kaili Biota uas buried at shelf below 150～200 meter water in depth. Therefore, we consider that most animals and algae in the Kaili biota lived at shallow water, and they were carried into shelf by tempesite or turbidity flow and were buried in shelf. The conclusion is suggested by the following sedimentary characteristics and fossil assemblage in Kaili Fm. 1, A lot of algal fossils (about 20 genus), containing red algae, blue algae, and brown algae, occur in the Kaili Biota. According to ecological distribution of modern algae, so high diverse algae only live at shallow sea (less than 90 meter in depth). 2, Until now, the Kaili Biota contains more than 100 genus animal fossils, so high diverse animals only live at shallow sea (less than 90 meter in depth). 3, Most fossils were persevered at D layer of tempesite or turbidity sequence, this is the fossil buried sequence C, but shelf shale (analogous to E layer of tempesite or turbidite sequence) only contains few fossils. On the basis of fossil distribution in the tempesite or turbidity sequence, we believe that most organisms were carried into shelf from shallow water region by tempesite or turbidity flow.