Establishment Of Chemical Stratigraphic Framework And Climate Cycle Analysis On The Upper Section Of Shahezi Formation Of Songke 2 Well In Songliao Basin,China

The implementation of the scientific drilling project in Songliao Basin and the development of related research have expanded China's right to speak and international influence in the field of related sciences,and promoted the further development of related research in China.The Cretaceous Continental Scientific Drilling System in the Songliao Basin has obtained continuous,high-resolution continental sedimentary records from paleogene to late Jurassic affected less by the later period,which lays the foundation for establishing a high-resolution time tunnel of greenhouse climate and environmental change in Cretaceous.The Cretaceous Continental Scientific Drilling Program in the Songliao Basin provides us with a unique fine geological record,which is helpful for detailed scientific research.This paper takes the core from the upper section of Shahezi Formation in Songke2 well as the research object,and obtains the experimental data through a handheld XRF scanner and a desktop X-ray fluorescence analyzer.Using some mathematical analysis methods,such as principal component analysis,ordered clustering and other methods,the chemical stratigraphic framework of the upper section of the Shahezi Formation is established.The spectrum analysis method was used to discuss the sedimentary environment and climate change in the upper section of the Shahezi Formation.The EHA analysis was used to preliminary discuss the climate response mechanism.Through principal component analysis and ordered clustering of the data,the upper part of the Shahezi Formation is divided into four geochemical phases:terrestrial clastic phase,carbonate rock phase,clay mineral phase,and redox phase.The Ceemd(Complete ensemble empirical mode decomposition)and EHA(Evolutive Harmonic Analysis)analysis of the element ratio found that the upper part of the Shahezi Formation was mainly affected by the long eccentricity,and the climatechange at that time was mainly represented by dry and wet cycles,which is consistent with the overall characteristics of the Cretaceous greenhouse climate change.