Geochronologic and C and Sr chemostratigraphic information of late Neoproterozoic-early Mesoproterozoic marine carbonate successions are used to propose a reference C and Sr chemostratigraphic framework for the Mesoproterozoic-Neoproterozoic transition. While late Mesoproterozoic marine carbonates display decreasing δ13C values, from ~4 to ~−2‰, carbonates from the Mesoproterozoic-Neoproterozoic transition display a positive C isotope anomaly, from δ13C values ~−2‰ to values ~+2‰, followed by a subsequent decrease to δ13C values ~−1‰. This decrease in δ13C values is followed by a new increase to predominantly positive δ13C values in the early Neoproterozoic. The reference chemostratigraphic framework also suggests that late Mesoproterozoic carbonate successions display predominantly lower 87Sr/86Sr values than early Neoproterozoic carbonates. The late Mesoproterozoic oceans registered an increase in the marine multicellular/sexual eukaryotic photosynthetic life, which parallels an increase in δ53Cr and δ34/32S values of several late Mesoproterozoic carbonates. Although these data suggest an increase in the atmospheric oxygen levels and intensified oxidative weathering, the occurrence of unfractionated δ98/95Mo values found in a single carbonate succession (Vazante Group) suggests in contrast an oxygen-depleted ocean. This incongruence in the isotopic records of redox-sensitive elements may be related to a nonsteady-state late Mesoproterozoic Mo isotope cycle.