A high-resolution, continuous δ13C record spanning the Ordovician–Silurian boundary on Anticosti Island, eastern Canada

A high-resolution, continuous δ13C record from Anticosti Island reveals distinct isotopic excursions at the Ordovician–Silurian boundary, offering a more precise and complete stratigraphic framework than previous studies. The record identifies two positive Hirnantian Isotope Carbon Excursions (HICE), with peak values of +2.5‰ in the lower part of the Ellis Bay Formation and +4.5‰ in its upper section, suggesting the O–S boundary may be stratigraphically higher than previously thought. This study rectifies gaps in earlier δ13C curves by sampling a nearly complete 300-meter interval at high resolution (∼0.5 m), providing a more accurate depiction of global isotopic trends. The findings highlight the significance of active subsidence and moderate water depths in preserving this sedimentary succession, which captures a comprehensive and reliable δ13C record across the critical O–S transition.

Mauviel, A., & Desrochers, A. (2016). A high-resolution, continuous δ¹³C record spanning the Ordovician–Silurian boundary on Anticosti Island, eastern Canada. Canadian Journal of Earth Sciences, 53(8), 795–801. https://doi.org/10.1139/cjes-2016-0003