High-resolution correlation between contrasting early Tonian carbonate successions in NW Canada highlights pronounced global carbon isotope variations

•A robust carbon isotope curve for the early Neoproterozoic prior to 800 Ma.•Integrate sequence and chemostratigraphy for tight correlation between two basins.•Tight correlation between contrasting deep- and shallow-water carbonate deposits.•A more complete carbon isotope profile is clearly recorded in deep-water carbonates.