Figure 1: Compilation of Mo data together with biodiversity and degree of bioturbation during the Ediacaran–Cambrian transition.
From: Rise to modern levels of ocean oxygenation coincided with the Cambrian radiation of animals
(a) Bioturbation indices and diversities of animals, skeletal taxa and eukaryotic phytoplankton1,20,59. MP: mesozooplankton appeared17; CJ: the Chengjiang Lagerstätte. (b) Mo data from the mid-Cryogenian to the early Cambrian. In the timescale, three major glaciations are marked as snowflakes, S1 to S4 denote the first four Cambrian stages. The colour of the data points denotes local redox: sulphidic (FePy/FeHR>0.7, red), ferruginous (FePy/FeHR<0.7, orange), anoxic (blue, when Fe speciation data are not available, Fe/Al>0.5, trace metal enrichments and other sedimentary characteristics are used to discriminate anoxic conditions) and unknown (grey, no above mentioned data are available, also included are typical carbonates and phosphates, to which Fe-S-C systematics redox proxies cannot easily be applied). The dashed lines mark the average δ98/95Mo value of modern seawater (+2.34‰) and the riverine input (+0.7‰). Data sources, filled circles: this study; open triangles: published data. Mo concentrations of samples from the early Cambrian Ni–Mo ore layer are not shown because of their exceptional enrichment in Mo (in the percent range). The green arrow marks the rising maximal δ98/95Mo values. The graded green shading in a,b denotes postulated oxygenation of the ocean from the late Ediacaran to the early Cambrian. (c) Mo data from the Palaeoarchaean to present (Supplementary Data 1). Symbols as in b, and green colour stands for oxic condition (FeHR/FeT<0.38 and/or Fe/Al<0.5).
