Quantifying temperature variation between Neoproterozoic cryochron – nonglacial interlude, Nanhua Basin, South China

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.