Fig. 2.

Secular distributions and carbon isotopes of Fe-related rocks and the evolution of marine redox and iron states. a Palaeolatitudinal distribution of banded iron formations (BIFs) and marine red beds (MRBs). The data are compiled from Supplementary Table 2. Note that the palaeolatitude data are at a lower confidence level for Archean and early Proterozoic interval. b Temporal distribution of BIFs and MRBs with thickness information (see data in Supplementary Figs. 1, 2 and Supplementary Table 2). c Carbon isotopes in iron-related sedimentary rocks and adjacent carbonates (purple circle are the data from banded iron formations, magenta circles are the data from red beds, black circles are the data from adjacent grey carbonates; see data in Fig. 3 and Supplementary Figs. 3–7 and Supplementary Tables 1, 3). d Evolution of deep-water (below storm wave base) iron concentrations based on numerical model (Fig. 4) and modern analogues. The lower limit of iron concentrations for BIF and MRB are 50 μM and 4 nM, respectively (see discussion in text). e Evolution of deep ocean (below storm wave base) redox states in the Phanerozoic and Precambrian (after refs ^{9, 57})