The Geochemical Cycle Analysis For The 3Rd Member Of Quantou Formation ?K₂q₃?-the 1st Member Of Qingshankou Formation ?K₂qn₁?deposited In The Late Cretaceous From The Songliao Basin

In the 21 st century,with the massive discharge of greenhouse gases such as CO2,the temperature of the earth rises and the world warms,the earth is likely to enter the greenhouse climate.The rise of global temperature and the rise of sea level are all problems that humans should face the serious challenge for a long time.The Songliao Basin preserved the complete continental Cretaceous stratigraphic records,Because of the Songliao Continental Scientific Drilling Engineering Well(referred to SK-1).the continuous adoption of the cores provided valuable high-resolution continental sedimentary records for the study of the Late Cretaceous.The study of the Quantou Formation and the Qingshankou Formation help us understand and restore the paleoenvironment and paleoclimate at that time.In this paper,the geochemical element data of the third member of the Quantou Formation of SK-1(not drilled completely),the fourth member of Quantou Formation and the first member of the Qingshankou Formation are used as study materials,and the lake level curve is restored according to the Quantou Formation and the first member of the Qingshankou Formation rspectively.Principal component analysis divides the geochemical facies and uses complete empirical modal analysis(CEEMD)and spectrum analysis(REDFIT)to analyze the elemental indicators which carried the paleoclimatic information.When the geochemical behaviors and meanings of multiple indicators are stay with the coupled or decoupled state,then find the corresponding orbital factor and explain it.The principal component analysis method was used to classify the geochemical element data of the third member of the Quantou Formation to the fourth Member of the Quantou Formation and the first member of the Qingshankou Formation.The data were divided into four geochemical faciess,such as terrigenous clastic facies,salinity facies,redox facies and nutrient facies.Referring to the variation curve of the lake level of the Quantou Formation,From 1915 m to 1870m: as the depth of water rises,the climate is in a low salinity and arid environment,with less nutrient content;from 1870 m to 1800m: as the water depth decreases,the climate is in a high salinity humid oxidizing environment,nutrient elements Higher content.According to the curve of the lake level of the Qingshankou Formation,from 1785 m to 1766m: during the fluctuation of the lake level,the part of the terrigenous clastic material is also in a fluctuating state,and some of them are reduced first,then increased,and the nutrient content is continuously reduced.For the oxidative drought environment;from 1766 m to 1724m: as the lake level declines,the input of terrigenous debris decreases,the nutrient content increases,and the climate is in a humid reduction environment;from 1724 m to 1705 m,the lake level curve rises,the input of terrigenous debris increases,and the climate In a dry oxidizing environment.The indicators of each geochemical facies are linked together by common wavelengths through complete empirical modal analysis(CEEMD)and spectrum analysis(REDFIT).The indications of Sr/Ca,V/Cr,K/Ti,etc.of the Quantou Formation have different climate meanings.However,with the same wavelength and period,it is found that this cycle is controlled by a long eccentricity of 405 Ka,and the climate change is controlled by the amplitude of the precession.Therefore,the climate change in the third and fourth members of the Quantou Formation is mainly modulated by long eccentricity and precession.The the firsr member of the Qingshankou Formation is mainly controlled by a long eccentricity with a period of 405 Ka,and multiple indicators are coupled to each other,consistent with the climatic environment described above.