Abstract: We conducted high resolution cyclostratigraphic studies on the magnetic susceptibility (MS) series of the Upper Ordovician Pagoda Formation in three locations including the Qiaoting section in Nanjiang, Sichuan, the Sanquan section in Nanchuan, Chongqing, and the Liangcun section in Xishui, Guizhou. We identified the hierarchy of Milankovitch 405 ka long eccentricity, 100 ka short eccentricity, 30 ka obliquity and 20 ka precession cycles with strong eccentricity and precessional signals. We also established floating astronomical time scales by tuning the 405 ka eccentricity cycles and determined the precise durations of the Pagoda Formation to be 4.17, 5.64 and 5.05 Ma for the Qiaoting, Sanquan and Liangcun sections, respectively. The average sedimentary rates of the Pagoda Formation were calculated to be 7.67, 4.68 and 6.37 m·Ma-1 for the three sections, respectively, decreasing from north to south in the Sichuan Basin, indicating that the studied area uplifted to become continent before the sedimentary time of the Pagoda Formation and transgressed from south to north. The conodont Hamarodus brevirameus and Protopanderodus insculptus zones in the Pagoda Formation lasted 3.62 and 1.43 Ma for the Liangcun section, respectively, while the trilobites Niuchangella angustilimbata, Dislobosaspis xixiangensis and unnamed zones lasted 2.83, 0.41 and 0.81 Ma for the Qiaoting section, respectively.

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