RESEARCHES ON TURBIDITY AND OTHER GRAVITY FLOW SEDIMENTATION IN CHINA

In China, there has been a rapid development of research on turbidity and other gravity flow sediments since middle 1970's. The First National Symposium on Tur-bidite was held in Nanning, Guangxi, China from 14th to 21st October,1983.Twenty seven papers about turbidite and other gravity flow sediments were read out at the meeting. This symposium will undoubtedly bring about a great advance in the study of turbidity and other gravity flow sedimentations. In this paper, the development in researches on turbidity and other gravity flow sedimentations has been summarized. In the last ten years,the researches showed that gravity flow deposits were widespread both in geologic time and space. It was reported that turbidites were spreaded in Late Archean,Proterozoic, Cambrian, Ordovician, Silurian, Devonian, Carboiferous,Permian,Triassic,Jurassic, Cretaceous,Tertiary and Quaternary. The locations at which turbidite occurred were dispersed almost in every province of China. The Paleogeographic environments in which turbidite was formed were of great variety, including modern and ancient fault lake basin, continental rift, aulacogen, foreand back-arc basin, slope of sea mount, ocean basin and passive continental margin, etc. It has been found that some pyroclastic turbidites with great thickness are spread extensively such as those in middle-late Permian and early Triassic in Yunnan-Guizhou-Guangxi basin. Some new types of turbidites have been reported, e. g. the ophiolite-fragment turbidite from Cretaceous in Tibet and tuff-bearing siliceous turbidite within Proterozoic Yanbian ophiolite suite, Sichuan Province. There have been some results in the study on carbonate gravity flow sediments. For example, Mei Zhichao et al. ( 1982 ) reported the carbonate debris flow sediments from Middle Ordovician in Shaanxi Province and Gao Zhenzhong and Liu Huai-po(1983) studied the Triassic carbonate gravity flow deposit in Shiwandashan Mountain Range. Based on these results, several models of gravity flow sedimentations have been established and some inferences have been made about the tectonic sitting in which these sediments deposited. The potential resources in turbidites and other gravity flow deposits have been explored. Turbidite hydrocarbon reservoirs are found in many oil fields. Li Jiliang et al. ( 1978 ) reported the sedimentary characteristics of oil-bearing turbidite. According to the depositional trend, they predicated the existence of deltaic sand body which is confirmed now. It is noticed that there are metallogenetic conditions of multi-metal, gold and uranium in some turbidites. Some new methods have been used to study gravity flow sedimentation by Chinese sedimentologists, such as deep water sampling,seismic stratigraphic technique, x-ray photography and study of trace fossils. In this paper,some proposals for further research on gravity flow sedimentation have been put forward.