Sedimentary rocks deposited during the Ediacaran period (∼630–542 Ma) contain carbonates whose carbon isotopic ratios show a marked negative excursion consisting of a precipitous drop from +5‰ to −12‰, followed by a sub‐linear recovery to positive δ13C values. Isotopic ages (U/Pb) and thermal subsidence modelling are combined to constrain the excursion in time and indicate an onset at ∼600 Ma, and duration of recovery of approximately 50 Myr. The excursion is widely recognized in Oman and has potential correlatives in Ediacaran strata elsewhere, and may thus represent a characteristic feature of the Ediacaran period. The amplitude of this carbon isotope excursion far exceeds those of other Neoproterozoic anomalies. The isotopic trend of negative excursion and long‐term recovery spanned at least one short‐lived glacial episode (at 580 Ma), but appears unrelated to glaciation, which indicates that negative anomalies in the Neoproterozoic marine carbon isotope record are not directly or uniquely linked to ice ages.

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The Neoproterozoic is widely considered to have experienced some of the most severe climatic perturbations recorded in Earth history, with extensive glaciations often referred to as 'Snowball Earth' events. The Snowball Earth and competing hypotheses seek to explain a wide range of geological data on Neoproterozoic pre-, syn-and post-glacial successions including glacial sedimentology, chemostratigraphy, palaeoceanography, geochronology, palaeomagnetism and palaeogeography, geodynamics, tectonics, palaeontology and palaeobiogeochemistry. However, our understanding of the Phanerozoic and particularly the Cenozoic and contemporary glacial geological record is often relatively neglected when evaluating the evidence for apparent severe and prolonged periods of globally synchronous glaciation. This paper presents a review of the available geological data for Neoproterozoic glacial successions in the light of what we know about the Cenozoic and recent glacial record. Most Neoproterozoic successions are shown to exhibit spatial and temporal variability, with sediment stacking patterns and facies associations indicative of dynamic ice masses. These characteristics are typical of sedimentary sequences deposited along glaciated continental margins throughout Earth history, without the need for global synchroneity or necessarily severe climatic excursions. Although recurrent very widespread glaciation is envisaged in the Neoproterozoic, the presence of analogous glacigenic and interglacial successions in the Neoproterozoic and Cenozoic suggest the operation of a similar set of processes across a similar range of depositional environments. Consequently, an unambiguous sedimentary record of hydrological shutdown during a prolonged global glaciation appears to be lacking. This indicates either a preservational bias in Neoproterozoic successions of the advance and recessional stages of glacial epochs, or the occurrence of dynamic, non-global glaciations during the Neoproterozoic.

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