Sedimentary Environment Evolution And Event Deposition Of The Lower Neoproterozoic In Xuzhou Area

The lower neoproterozoic of Zhaishan profile in Xuzhou is continuously and completely emerged, which includes Jiayuan formation, Zhaowei formation and Niyuan formation. It has representative lithology combination, abundant sedimentary phenomenon, and it is rich in stromatolite and event deposition.The stratigraphic boundary of Jiayuan-Niyuan Formation has been discussed according to the lithologic features. There are 8 genuses of stromatolite in Zhaowei formation, which has same combination and evolution compared to Huainan-JilinLiaoning area. Neoproterozoic of Xuzhou and Huainan uses the same stratigraphic column system, the latest Sr, C and zircon U-Pb isotopic age shows that its deposition time is among 1000-800 Ma. The comparison of stromatolite and isotopic age all support the conclusion that Neoproterozoic of Xuzhou–Huainan-Jilin-Liaoning are sediments in the same basin. The latest isotopic age, stromatolite decline event and glacial events prove that this set of strata should be put in Qingbaikou System.Based on the lithology combination, Jiayuan formation is divided into 4 sections, Zhaowei formation is divided into 2 sections, Niyuan formation is divided into 3 sections. Combined with the petrological characteristics and sedimentary facies marks, the sedimentary facies has been analysed. Jiayuan-Niyuan formation has undergone a a total process from shallow to deep and then from deep to shallow, the evolution of sedimentary environment has gone through shore slope, platform edge bank, shallow slope, reef of platform margin, shallow slope, gentle slope, deep slope, restricted platform, evaporate platform, restricted platform and evaporate platform.Event deposition includes Seismite Sediments and Tempestite Sediments. This paper emphatically discusses the shape, permutation, combination and occurrence characteristics of MT and formation process of plate-spine breccia in Seismite Sediments. There are 4 types of storm sedimentary sequence, their distribution reflect different hydrodynamic conditions and palaeogeographic locations. Through the research on the relations between MT and storm sedimentary sequence, we build the comprehensive sedimentary model of event deposit.Neoproterozoic is a special era that supercontinent collage and breakup, low latitude glaciers develop. Palinspastic map of Rodinia supercontinent and paleomagnetic datas show that the North China plate has been in low to mid latitudes of the Northern Hemisphere during 1000-700 Ma. Low latitudes, hot and humid climate before the Sturtian glacier and specific water condition are the reasons to form the thick carbonate construction of Xuzhou–Huainan-Jilin-Liaoning area. Palaeogeographic position makes this area frequently influenced by storm, and plate movements caused by magmatic activities triggered continuously earthquakes, to form event depositon. Storms caused by earthquakes have made the MT occurrence in the storm sediments.