An Integrated Sedimentological and Multi-proxy Geochemical Investigation of the Neoproterozoic Climatic Paradox

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The unique geological paradox of glaciomarine diamictites intercalated within apparently warm-water carbonates at tropical latitudes on all major cratons during the Neoproterozoic remains an unsolved puzzle. A global preglacial negative carbon excursion begins 10 to 20 of metres below the tillites, and the carbon isotope profile is negative for several tens of metres in the postglacial cap carbonate succession before returning to Neoproterozoic background levels. Several models have been proposed to explain these apparent rapid swings between climatic extremes, termed the Neoproterozoic climatic paradox (NCP), and the associated isotopic changes in seawater chemistry. The "soft" and "hard" Snowball Earth models have generated most scientific interest and propose at least two global glaciations occurred. Several other models exist, not all of which invoke dramatic climatic changes. We propose an integrated sedimentological and multi-proxy geochemical study in outcrop and core to investigate the NCP. The study will use a multidisciplinary approach involving collaboration of a larger group of specialists. Research will focus on the critical intervals in three areas, Namibia, Southern Australia and the Urals and include the succession below (preglacial) and above (postglacial) the diamictites, the diamictite units themselves, and the interglacial rocks between the older Sturtian and younger Marinoan diamictites.