Article Figures & Data
Figures
- Fig. 1.
Generalized map of Paleoproterozoic outcrop belts. Circled numbers indicate those successions utilized in this study. See Supplementary material for data and data sources.
- Fig. 2.
Coastal–evaporitic–nearshore-marine facies in Lomagundi–Jatuli Event (LJE)-bearing strata of the Onega (a–c, e, f, h, k–m) and Franceville (d, g, i, j) Basins. (a) Stromatolites. (b) Tepee in red–grey mudstone with evaporite pseudomorphs. (c) Evaporite pseudomorph in red–grey mudstone. (d). Tepee developed on palaeokarst breccia and eroded by overlying dolostone grainstone. (e). Poorly sorted coarse doloarenite and mudstone overlain by disrupted red–brown mudstone with abundant chicken wire fabric. (f)–(h) Micritic dolostone broken and disrupted by variably developed palaeokarst and evaporite pseudomorph fabrics. (i), (j) Cross-bedded doloarenite. (k) Herringbone cross-lamination with mud drapes. (l) Tidal couplets of graded fine doloarenite and red–grey mudstone–dolomarl. (m) Tidal bundle of fine doloarenite and grey dolomarl and mudstone with abundant millimetre-scale gypsum pseudomorph needles overlain by dolorudite. Scale bars c. 2 cm.
- Fig. 3.
Open- and deeper-marine facies of LJE-bearing strata in Franceville (a–d) and Onega (e–g) basins. (a) Low-angle laminated graded fine doloarenite beds overlain by flake–breccia debrite (coin c. 2 cm). (b) Dark grey to black shale (outcrop c. 5 m in height; contact with dolostone of 3a at base of ledge); pale colours represent deeply weathered intervals. (c), (d) Thin graded beds of fine dolostone with sets of low-angle plane- to wavy-parallel laminae. (e)–(g) Grey and cream–pink–green fine dolostone (‘krivozerite’) in millimetre- to centimetre-thick graded beds marked by millimetre-scale ripples and plane- to wavy-parallel laminae; arrows in 3e denote individual graded beds. Scale bars c. 2 cm.
- Fig. 4.
Box-and-whisker plots for δ13Ccarb data classified by palaeoenvironmental setting. (a) Data for the Francevillian and Karelia–Kola regions. (b) LJE data worldwide. (c) Timeline trend of palaeoenvironmental settings from Neoarchaean through to specific Phanerozoic time periods (Rec, Recent; Mess, Messinian; Perm, Permian; Trias, Triassic). See Supplementary material for C-isotope data.
- Fig. 5.
C-isotope profile of Tulomozero and lower part of Zaonega Formations, Onega Basin. OPH, Onega Parametric Hole; R-S, Raiguba and Shunga localities. See Supplementary material for C-isotope data.
- Fig. 6.
δ13Ccarb data for marine carbonate rocks between 3.0 and 1.0 Ga in age in 100 Myr age bins (see Supplementary material for sources of data). (a) LJE-bearing successions are in red and those recording the purported decline of the LJE in light red; running bootstrap average shown as a blue line. (b) 2D density plot that shows the abundance and consistency of δ13Ccarb values between 0 and 4‰ across the entire 2 Gyr time span. (c). The lower panel shows the consensus view of a direct one-to-one match between the LJE and postulated rise in atmospheric pO2 (PAL: present atmospheric level; adapted after Lyons et al. 2014). The upper panel shows the new understanding of the LJE excursion as a consequence of palaeoenvironmental setting (consensus view is shown by dashed outline). The light-grey bar highlights the LJE. Deeply negative δ13Ccarb values that post-date the LJE have been shown in two studies of the Onega Basin rocks to reflect post-depositional overprinting or methane recycling (Črne et al. 2014; Kreistmann et al. 2019, 2020).
Tables
- Table 1.
Summary δ13Ccarb data for Lomagundi–Jatuli Event successions (N = number of measurements; C.I. = confidence interval). See Supplementary material for data and data sources
Table 1. Lomagundi–Jatuli Event (LJE) δ13Ccarb (‰ V-PDB) summary data Palaeoenvironment N Bootstrapped mean Bootstrap mean 95% C.I. lower Bootstrap mean 95% C.I. upper Francevillian–Karelia–Kola regions intertidal–coastal–sabkha (evaporitic) 273 9.3 9.1 9.5 Nearshore-marine–inner shelf 325 6.8 6.6 6.9 open and deeper marine 130 2.0 1.6 2.3 all LJE successions worldwide intertidal–coastal–sabkha (evaporitic) 562 8.1 7.8 8.4 Nearshore-marine–inner shelf 705 6.2 6.1 6.4 open and deeper marine 771 1.5 1.3 1.7
The grandest of them all: the Lomagundi–Jatuli Event and Earth's oxygenation
- Article
- Abstract
- The LJE and the carbon cycle
- Methods
- Facies of LJE-bearing successions and C-isotope values
- Assessing the LJE globally
- The significance of high C-isotope values occurring in deeper-water facies
- The LJE: a new understanding
- The LJE and Earth's oxygenation: summary and conclusions
- Acknowledgments
- Author contributions
- Funding
- Data availability
- Footnotes
- References
- Figures & Data
- Info & Metrics