Fig. 2: Integrated geochemical data (this study and published) and major biological events of the Ordovician.
From: Volcanism and basalt weathering drove Ordovician climatic cooling
A Conodont oxygen isotopes (δ18Oconodont). B, C Mercury isotopes (Δ199Hg and δ202Hg). D Whole rock Hg content. E Carbonate-free Hg content (Hgcf). F Ratio of Hg content to total organic carbon content (Hg/TOC). G Strontium isotopes of conodont (87Sr/86Srconodont). H Neodymium isotopic ratio (143Nd/144Nd, as ƐNd(t)) of bulk carbonate. I Bulk-carbonate carbon isotopes (δ13Ccarb). J Marine biodiversity curves. In panels B–I, newly generated data, and published Hg data and C-isotopes at Wangjiawan section52,70, are shown in solid circle, diamond or triangle. In A–C, LOWESS analysis of both newly generated and published data are represented by red curves (dashed and solid fits), while analyses performed specifically on newly generated data are shown as black curves (dashed and solid fits). All LOWESS analysis were performed using a fixed smoothing factor of 0.2. In D, F, the red curves represent the means of the highest five values within each bin (using 2-Myr bins at 485.4-450 Ma and 1-Myr bins at 450–438.5 Ma). In F, the black arrows represent values > 1000 ppb/wt%. In panel A, average δ18Oconodont values of all newly and published data for the latest Cambrian-Early Ordovician ( ~ 16.2‰) and Middle Ordovician (~17.8‰) are used as baseline values (dashed blue lines) for identification of the cooling episodes during the Late Floian cooling event (LFCE) and the Late Darriwilian cooling event (LDCE). In D–F, average Hg content of Phanerozoic carbonate rocks (line a, 34 ppb) and shale (line b, 62 ppb)20, median Hg content of our studied carbonate rocks (line c, 2.4 ppb) and organic-rich clastic rocks (line d, 131 ppb), and average Hg/TOC ratio of Phanerozoic sedimentary rocks (line e, 144 ppb/wt%) and sedimentary rocks of TOC > 0.2% (line f, 72 ppb/wt%)20, and median Hg/TOC ratios of our studied carbonate rocks (line g, 70 ppb/%) and organic-rich clastic rocks (line h, 76 ppb/%) are adopted as baseline values (dashed vertical lines) for jointly evaluation of Hg enrichment episodes. In A–F, published δ18Oconodont and Hg geochemical data are archived in Figshare. In G–J, published 87Sr/86Srconodont profiles are from Saltzman et al.24 (red line) and McArthur et al.25 (black line), ƐNd(t) from Conwell et al.71, δ13Ccarb from Cramer and Jarvis72 and Gorjan et al.37, and biodiversity data from Deng et al.2 and Kröger et al.3. The Ordovician timescale is from Goldman et al.28. Light pink fields represent cooling episodes during the LFCE, LDCE, and Hirnantian Glaciation. Fm = Formation; Ord. avg. = Ordovician average; Dap. = Dapingian; Hir. = Hirnantian; Rhud. = Rhuddanian; Aero. = Aeronian; PBDB = Paleobiology Database; SHRIMP = Sensitive high resolution ion microprobe; GIRMS = Gas isotope ratio mass spectrometry; SIMS = Secondary ion mass spectrometry; GOBE = Great Ordovician Biodiversification Event; LOME = Late Ordovician Mass Extinction; LFCE = Late Floian cooling event; LDCE = Late Darriwilian cooling event.
