Significant carbon isotope excursions in the Cambrian and their implications for global correlations

The existing delta C-13 data in the Cambrian from different regions of the world are analyzed here. There are four well-documented carbon isotope excursions with global significance. In ascending order, they are: (1) a large negative excursion, comparable to BACE (BAsal Cambrian Carbon isotope Excursion) event, which occurs near the Precambrian-Cambrian boundary with a magnitude of 4aEuro degrees aEuro10aEuro degrees (PDB); (2) the ZHUCE (ZHUjiaqing Carbon isotope Excursion) event, a distinct positive excursion (over 5aEuro degrees) that can be recognized at the Fortunian Stage to Stage 2 transition; (3) another strong negative one, so-called ROECE (Redlichiid-Olenellid Extinction Carbon isotope Excursion) event, shifting at the interval between Series 2 and Series 3, peaking at -3aEuro degrees aEuroa'5aEuro degrees (PDB); (4) the famous Steptoean positive carbon isotope excursion (SPICE), which has been widely identified at the base of Furongian Series, Paibian Stage, with an amplitude about 4aEuro degrees (PDB). The four sharp delta C-13 shifts correlate well with coeval paleoceanographic changes and bioevents. Besides, there are some delta C-13 excursions from a few sections in previous studies, and more data are required to identify whether they are global or regional ones.