Abstract:

The Sinian mixing sediments of carbonate rocks and terrestrial clastic rocks distributed widely in the Yangtzi plateform, China, are benificial for the study on regional tectonics, paleogeography and life evolution. The Sinian strata in the Xuyi area of Jiangsu Province, China are composed of mixing sediments. Based on the research on the mineralogy, lithology, sedimentary facies of 6 measured sections and 67 investigating sections in this area, the sequence and sedmentary environment of the Upper Sinian mixing sediments are provided here. Eight sedimentary facies are recongnized, and the depositional system and sedimentary framework are reconstructed. The results show that during the Late Sinian the sea level changes is drived by the climate under a stable tectonic background, and the terrestrial clastic deposits are accumulated on the costal plain during the selevel rising. The variety of coastal landform suggests a complex evolutionary process of river and the ocean undergone in the Late Sinian. The increasing contribution of river runoff to the ocean made the sea water became supernutrition and low salinity which might have an important influence on the evolution of marine life.

Key words: Yangzte plateform, Jiangsu Province, Sinian, mixing sediments, depositional system, sediments