Milankovitch Cycles Identification and Astronomical Time Scale of Shanxi Formation in Zuoquan Area,Qinshui Basin
The identification of earth orbit parameter period based on stratigraphic cycle signal is one of the effective methods to determine deep time scale.Taking the Shanxi Formation in Zuoquan area of Qinshui Basin as an example,the time series analysis and correlation coefficient methods were uesd to analyze the cyclostratigraphy of the gamma logging curve,and the astronomical time scale of Shanxi Formation was established.Using spectral analysis,the dominant sedimentary cycles of 7.13 m and 1.62～2.23 m were identified in the Shanxi Formation,corresponding to the 405 kyr long eccentricity and the 91.9～126.4 kyr short eccentricity respectively.Through Astronomical testing,it is confirmed that the Shanxi Formation of Qinshui Basin is driven by astronomical periods.Based on the Gaussian band-pass wave filtering,the"floating"astronomical time scale of the Shanxi Formation was established,and nine 405 kyr long eccentricity cycles were identified,the calculated accumulation time of Shanxi Formation is 3.82 Myr.The establishment of astronomical time scale can provide chronology basis for evolution of paleoenvironment,paleoclimate and duration of various geological events of Shanxi Formation in Qinshui Basin.
Shanxi Formationcyclostratigraphyastronomical time scaleorbital parameter periodQinshui basin
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