The Silurian Kepingtage Formation in the Tarim Basin is mainly deposited in the tidal flat environment during a relatively stable period of tectonic activity.It is one of the typical marine clastic sequences in the basin.And it is composed of frequently alternating and superimposing medium-fine sandstone and mudstone

and can be obviously divided into three intervals.According to previous research results

the Kepingtage Formation can be approximately correlated with the Telychian

Aeronian and Rhuddanian Stage of the International Stratigraphic Chart

and its deposition period should be within 8.1-12.7 Ma.However

its Milankovitch high-frequency stratigraphic cycle framework is rarely discussed.Ta-king the Gamma-Ray logs of Well Shun-9 as proxies and using spectral analysis method for computation

we found that the Kepingtage Formation in Well Shun-9 recorded the complete Milankovitch cycle.The astronomical cycle significantly controls the cycle thickness

with the cycle thickness of 16.73 m corresponding to the long eccentricity of 405 ka

the cycle thickness of 5.24 m and 3.92 m corresponding to the short eccentricity of 125 ka and 95 ka respectively

and the cycle thickness of 1.59 m and 1.26 m corresponding to the obliquity of 38.1 ka and 31.1 ka respectively.The average sedimentary rate was estimated as 4.15 cm/ka and the depositing time as 10.4 Ma.And a "floating" astronomical time scale was established for the Kepingtage Formation in Well Shun-9 based on Empirical Mode Decomposition(EMD).The Kepingtage Formation was found to have 83 cycles with short eccentricity of 125 ka and 334 cycles with obliquity of 38.1 ka.Finally

we analyzed the superposition differences and their causes of each high-frequency cycle by using the Fischer plots and a standard model for fifth-order cycle division under the control of the short eccentricity of 125 ka.This result provides a new method that is unified and unbiased for high-frequency cycle division of marine clastic strata in this basin and similar basins.