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• Document evolving chemical weathering indices in Cryogenian and Ediacaran successions of the Nanhua Basin, South China. • Covariant change of chemical weathering trends in South China and Oman reflects several contemporaneous climate cooling events. • Mean Annual Temperature (MAT) differences reach ~20 ℃ between the Marinoan cryochron and nonglacial interlude at around 30° latitude, and ~12 ℃ between Gaskiers cryochron and nonglacial interlude close to the equator. Three major late Neoproterozoic global cryochrons mark the coldest climate state in Earth history, with glaciers covering most, if not all, continents. However, the terrestrial paleosurface temperature differential between cryochron and nonglacial interlude is unknown. Time-equivalent Cryogenian and Ediacaran sedimentary successions from South China and Oman show multiple negative excursions of the corrected values of their chemical index of alteration (CIA corr). These excursions reflect climate cooling and correlate with the Sturtian, Marinoan and Gaskiers cryochrons. Based on the τ Na -MAT transfer function (sodium chemical depletion index-mean annual temperature), we estimate the temperature differential between Cryogenian cryochron and nonglacial interlude reached 20 ± 5.4 ℃ at around 30° paleolatitude, and 12 ± 5.4 ℃ temperature difference between the Ediacaran cryochron and nonglacial interlude near the equator. The fluctuation of CIA corr and MAT trends within individual cryochrons likely indicate cold-warm climate cycling during the Cryogenian cryochron. [ABSTRACT FROM AUTHOR]