Neoproterozoic chemostratigraphy and correlation of the Port Askaig glaciation, Dalradian Supergroup of Scotland

The delta(13)C of preglacial carbonates beneath the glaciogenic Port Askaig Formation falls from +5 parts per thousand to negative values, while least -altered Sr-87/Sr-86 values are close to 0.7067. Postglacial 'cap carbonate s' of the Bonahaven Formation begin with negative delta(13)C(carb) values, jumping sharply to +11.7 parts per thousand near the top, which we correlat e with excursions above the Elbobreen-Wilsonbreen glaciations of Svalbard a nd putative Sturtian (not Varanger) glaciations elsewhere, dated at c. 720 Ma. Much of the succeeding Terminal Neoproterozoic is missing in NE Svalbar d and East Greenland, raising doubts about their use for global Sr and C is otope curves in the Neoproterozoic.