Inorganic Geochemical Characteristics And Sedimentary Environment Of Lower Cretaceous Shuinan Formation In Laiyang Basin,Shandong Province

In recent years,with the deepening of the study of cretaceous strata in eastern China,the salt bearing strata of cretaceous have been continuously discovered,but the origin of these salt bearing strata has been disputed in Marine and terrestrial facies.The Shuinan Formation in the Laiyang Basin is the representative stratum of the Laiyang Group,and it is also the sedimentary product during the heyday of lake development in the Laiyang Basin.However,by researching the geochemical characteristics of elements in the Shuinan Formation,some experts believe that the Shuinan Formation in the Jiaolai Basin has marine features.Therefore,it is necessary to study of the inorganic geochemical characteristics that required determining the sedimentary environment of the Shuinan Formation.On this basis,this paper Inferred to invert sedimentary environment and sedimentary background by analyzing the inorganic geochemical characteristics and combination with the paleontological fossils of the Shuinan Formation in the Jiaolai Basin.The first,Establish sedimentary environment evolution and paleoclimate change model by analysis of major elements,trace elements and rare earth elements;quantitative calculation of paleosalinity to find patterns in the vertical direction of the research area.The second,Combining with the previous research results,the characteristics of paleontological fossils(plants,palynology,insects,ostracodes,etc.)in shuinan formation were analyzed,and the sedimentary environment of shuinan formation was discussed through the comparative analysis of geochemical indicators.Finally,analyze and record the lithology and color changes in the study area,establish a vertical lithofacies model,focus on searching and analyzing the sedimentary structures in the Shuinan Formation.And proceed with the soft sedimentary deformation structures in the Lower Cretaceous Laiyang Group of Lingshan Island Contrast provides reference for analysis of sedimentary environment.This paper restores the sedimentary environment by analyzing the inorganic geochemical characteristics of the Shuinan Formation and combining the evidence of paleontology,concluded as follow:The Shuinan Formation in the Laiyang Basin belongs to a continental shallow-bracky water depositional environment,with pale dry climatic conditions that are relatively dry and hot,and belongs to a weak reduction-oxidation environment.This study can not only provide a reference for re-understanding the sedimentary environment of the Shuinan Formation in the Jiaolai Basin,but also help to resolve the disputes of the marine and terrestrial facies existing in the salt-bearing strata in eastern China.The sedimentary sequence of the Cretaceous strata is of great significance,and it is of great significance for understanding the evolution of the Cretaceous paleoenvironment in the Pacific Rim.