The Sedimentary Characteristics And Significance In The Late Cretaceous Zhou Tian Formation In Xinjiang Basin

Certain characteristics elements in the sediments have a relatively stable c-hemical properties,mainly affected by the content source relatively independentinthe deposition environment and diagenesis,and the content fundmentally remain unchanged with parent rock weathering process,the formation of sediment and function after deposition phase,with the research of stable isotopes,trace elements and rare earth element content and distribution characteristics in sedimentary rocks,especially the study of the characteristics of some element ratios,the sedimentary environment,inversion of the geological conditions can be concluded.The author through the study of the sedimentary characteristics and carbonand oxygen isotopes,trace elements and rare earth elements and sulfur isotopegeochemical analysis from Zhoutian Formation in xinjiang basin,preliminary concluded the following points:(1)Special sedimentary-gypsum,can be a good indicator of the ancient climate in the study area,reflecting the ancient climate types in xinjiang basin Zhoutian Formation cloud be dry,high salinity,water evaporation of climate.(2)The carbon and oxygen isotopic geochemical characteristics of the Calcareous tuberculosis samples in the study area reflect the Zhoutian Formation in xinjiang basin is an opening freshwater lakes in the late cretaceous sedimentary environment and vegetation is given priority to C4 plants type during this period.(3)The trace element geochemical characteristics of the surrounding rock sampless in the study area show that water medium environment of Zhoutian Formation in Xinjiang basin is salt water;lake sediment is warmer temperatures;and the Sedimentary rock in the study area mainly formed in the water column which is an unstrong anaerobic anoxic environment.(4)By the trace element features ratio of Rb/Sr,Th/U,Zr/Th,Sc/Cr and the use of the La-Th-Sc,Th-Co-Zr/10 discriminant figure can draw that the Tectonicenvironment of the source area of surrounding rocks in xinjiang basin Zhoutian Formation has the active continental margin,continental island arc and oceanicisland arc tectonic setting;and the Salt substances in xinjiang basin Zhoutian Formation mainly come from basin edge parent rock weathering denudation zone.(5)The primary sedimentary gypsum in Xinjiang basin main develop in folwing two kinds of environment.