The Late Cryogenian Warm Interval, NE Svalbard: Chemostratigraphy and genesis

• Published in: Precambrian research 2016-08, Vol.281, p.128-154
• Main Authors: Fairchild, Ian J., Bonnand, Pierre, Davies, Tesni, Fleming, Edward J., Grassineau, Nathalie, Halverson, Galen P., Hambrey, Michael J., McMillan, Emily M., McKay, Elizabeth, Parkinson, Ian J., Stevenson, Carl T.E.
• Format: Article
• Language: English
• Subjects: Chemostratigraphy; Cryogenian; Dolomite; Orbital forcing; Rhythmic sedimentation; Shale
• ISSN: 0301-9268; 1872-7433
• DOI: 10.1016/j.precamres.2016.05.013

•Basal cap carbonate with rising δ13C trend confirms distinct Sturtian and Marinoan glacials.•Chemostratigraphy implies pre-Marinoan interval truncated.•Count of precessional cycles imply minimum 6–8Myr between panglaciations.•Sheath-like structures characterize fluid escape from beneath shallow dolomite-cemented layer.•Model of early diagenetic diachronous dolomitization in organic-poor reducing basin. The Late Cryogenian Warm Interval (LCWI) refers to a non-glacial interval that separates presumed representatives of the Sturtian and Marinoan panglaciations. Its duration is poorly constrained radiometrically and its deposits are relatively poorly known in most geographic regions. This paper aims to constrain the duration, palaeoenvironments and petrogenesis of such deposits in the classic region of NE Spitsbergen, Svalbard. The succession comprises a 200–205m dolomitic shale (Macdonaldryggen Member, known as E3, of the Elbobreen Formation) overlain by oolitic dolomite Slangen Member (E4), 15–25m thick, with limestone developed at top and base of E3 in the south of the area. The assumed age context of the succession has been confirmed by the presence of a typical Sturtian cap carbonate profile of negative to positive δ13C, and primary Sr isotope compositions of basal E3 limestones