Cyclical stratigraphic analysis and establishment of astronomical chronograph of Hanjiang Formation in Lufeng Sag

As a typical Cenozoic Marine basin, the Pearl River Mouth Basin is also an important offshore oil and gas production base in China. Many scholars have studied the stratigraphic division and correlation of the Pearl River Mouth Basin, but the research accuracy is not enough. In order to improve the accuracy of stratigraphic division and correlation of Hanjiang Formation in Lufeng Sag, Pearl River Mouth Basin, the natural gamma ray data series of Hanjiang Formation in Well A and Well B in Lufeng Sag were selected as paleoclimate surrogate indexes, and the cyclic stratigraphy was analyzed by spectral analysis and filtering methods. Through depth domain spectral analysis and wavelet analysis, it is identified that Milankovich cycle is preserved in the formation, and it is mainly affected by the 405 ka long eccentricity period. Using the stable 405 ka long eccentricity period for astronomical tuning, combined with the paleontological stratigraphic dating frame, the absolute astronomical dating scale of Lufeng Depression was established. Combined with the carbon and oxygen isotope change curves, the duration of two carbon isotope negative shift events and one positive shift event was estimated. Using the sedimentation rate calculated by astronomical cycle, it is found that the change of sedimentation rate is correlated with the change of sea level.