Fig. 1: Dissolved organic and inorganic carbon (DOC/DIC) and δ13C, Δ14C signatures.
From: Radiolytically reworked Archean organic matter in a habitable deep ancient high-temperature brine
a δ13C (circles) and Δ14C measurements (triangles), relative to Vienna Pee Dee Belemnite (V-PDB), for DOC and DIC pools from (b). Reproducibility of δ13C is ±0.3‰ for Moab Khotsong and Kloof samples, and ±2.5‰ for Kidd Creek. δ13CDOC ranges include: (i) reported values for DOC of Witwatersrand Basin fracture waters (full range -24 to -57‰23,35), (ii) extractable organic carbon from Vaal Reef55, (iii) extractable organic carbon from the Kimberley Shales102. δ13CDIC ranges include: (iv) acetogenesis or methanogenesis (full range of −7 to 12‰22,103), (v) reported values for DIC of Witwatersrand Basin fracture waters (full range of -12 to -43‰23,35) (vi) calcites from Moab Khotsong38. δ13CDIC of 0.6‰ for Transvaal Dolomites104 is out of range. b Quantity of DOC and DIC in mg C/L of the Moab Khotsong fracture fluids compared to Kloof Mine35 and Kidd Creek brine20 (Kidd Creek DIC (0.7 mg C/L) is smaller than other plotted samples). Error bars represented as relative standard deviation (% RSD) and are ±1% for Moab Khotsong and Kloof Mine samples and ±20% Kidd Creek, and in some cases, are smaller than the symbols. Percentages in dashed boxes indicate the percentage of low molecular weight organic acid (acetate + formate + propionate + oxalate) comprising the DOC pool. Apparent ages based on Δ14C from (a) are shown in years above each carbon pool ± relative error. Blue ages for DIC of the 1200-level include correction for carbonate dissolution upon aquifer recharge.
