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).