The record of early Silurian climate changes from South China and Baltica based on integrated conodont biostratigraphy and isotope chemostratigraphy

New conodont and stable isotope data are presented from the classical Baizitian section in the Yanbian County of the Sichuan Province, South China. The Telychian to Sheinwoodian strata were sampled and studied for carbon isotope stratigraphy and conodont biostratigraphy. The paired δ13Ccarb and δ13Corg data reveal a pronounced positive excursion, the Manitowoc carbon isotope excursion (Manitowoc CIE, ‘Manitowoc Excursion’) spanning the upper Pterospathodus eopennatus Zone and the lower Pterospathodus amorphognathoides amorphognathoides Superzone, with an increase of ca. 2‰ in δ13Ccarb and ca. 5‰ in δ13Corg. Well-bracketed by conodont biostratigraphy, the Manitowoc CIE is an essential tie-point for correlation between the Baizitian succession and the Telychian strata of Baltica and Laurentia. Our new δ13Ccarb and δ13Corg data imply that the carbon isotope excursion previously recognized as the ‘Ireviken Excursion’ (Early Sheinwoodian Carbon Isotope Excursion) at Baizitian should be revised as being the Manitowoc CIE. The Δ13C data presented in this study further suggest a slight concurrent drop of atmospheric CO2, and thus add evidence for a perturbation of the global carbon cycle during the middle Telychian. Based on the combined information from the conodont apatite oxygen isotope records from Estonia and the significant stratigraphic gaps recognized at the Baizitian section, we propose that the latter stratigraphic gaps should correlate with the Telychian Valgu and the early Sheinwoodian glaciation.