Novel age constraints for the onset of the Steptoean Positive Isotopic Carbon Excursion (SPICE) and the late Cambrian time scale using high-precision U-Pb detrital zircon ages

The Steptoean Positive Isotopic Carbon Excursion (SPICE) is a prominent +4–5‰ shift in the Cambrian δ13C record used for global chronostratigraphic correlation. onset of this excursion traditionally placed at base Pterocephaliid trilobite biomere (base Furongian Series). Recent studies have documented local controls on expression SPICE and emphasize need standards these complex biogeochemical signals. We build upon prior work western Laurentia by integrating biostratigraphy with high-precision isotope dilution U-Pb detrital zircon maximum depositional ages that are coincident onset, peak, falling limb SPICE. Our study provides first useful numerical age constraint Laurentian biozones requires revision late geologic time scale boundaries several million years.