4.3 Anticosti Island, Canada
The Point Laframboise section on western Anticosti Island has been studied extensively, including previously published geochemical data for carbon, sulfur, and uranium isotopes in addition to carbonate clumped- and conodont palaeothermometry (Finnegan et al., 2011; Jones et al., 2011; Jones and Fike, 2013; Bartlett et al., 2018). Previous studies have documented the HICE in detail from this section in addition to cooling trends in sea-surface temperatures and increases in global marine anoxia. Our new I/(Ca+Mg) dataset (Fig. 4) from the same section shows low values (< 2 μmol/mol) within the B. gamachiana and S. taugrourdeaui biozones of the mid-inner ramp facies of the Lousy Cove Member, but values increase rapidly to an average of 6 μmol/mol, ranging from ~0.5 to 9 μmol/mol, within the patch reef facies of the Laframboise Member. Subsequently, I/(Ca+Mg) ratios within the early Silurian inner-mid ramp carbonates of the overlying Becscie Formation (Ancyrochitina ellisbayensis andPlectochitina nodifera biozones) show a return to consistently low values (< 1 μmol/mol).