Study On The Meter-scale Cyclical Sequence And Lithofacies-Microphase Of Mantou Formation In Xuzhou Area

The development of Cambrian system in Xuzhou region was very complete andits sedimentary symbol and geocyclicity are easy to be recognized. Hereinto, MantouFormation represents the geological characters of south east formation in the NorthChina plate. Based on a lot research of Mantou Formation profile in XuzhouDabeiwang area, it is concluded that the integral development of Cambrian system inXuzhou region was developed from the sedimentary environment ofplatform-lagoon-tidal flat in the shoals of shallow water. According to thecombination of different sedimentary facies symbols and rock symbols, twelvemacroscopical lithofacies have been divided and its microcosmic characters also aredescribed. In addition, sedimentary environments of different lithofacies and thediagenetic process of the rock are discussed respectively. On the basis ofcyclostratigraphy theory, at the same time, with the Milankovitch cycling, elevenmeters scale cyclic sequences are divided; in the meanwhile their sedimentaryenvironments and lithofacies constituents are discussed. Most of single meter scalecycles belong to the sixth cycle, however, the meter scale cycles gradually becomeinto a sequence from bottom of flooding surface. Finally, based on the analysis weobtained the following conclusions that the eleven fifth cycles and two and a halffourth cycles are merged from the all the cycles. And each cycle contains thecompleted sequence with marine transgressions and regressions.