Elemental and stable isotopes geochemistry of Paleoproterozoic dolomites from Fecho do Funil Formation, Quadrilátero Ferrífero – Brazil

Geochemical and C‐O Isotopic Study of Ophiolite‐Derived Carbonates of the Barzaman Formation, Oman: Evidence of Natural CO2 Sequestration Via Carbonation of Ultramafic Clasts

“…Depletion of Ce, relative to the neighboring REEs (Auer et al., 2017; German & Elderfield, 1990; Morad & Felitsyn, 2001), is an important feature of the groundwater (Semhi et al., 2009) and modern seawater (Zhang & Nozaki, 1996) resulting from oxidation of Ce 3+ to a less soluble Ce 4+ ion, which is easily scavenged by the suspended particles (Nogueira et al., 2017). The values for Ce/Ce* (Bau & Dulski, 1996) are >0.5 for all the samples, and range from 0.53 to 0.96, except for the Kd8 sample (0.36).…”

“…This means that heavy metals ions, especially the highly mobile Ni 2+ (83 picometer) ion, can compete with Mg 2+ (86 picometer) and Ca 2+ (114 picometer) ions to form bicarbonate and hydroxide species in alkaline and hyperalkaline waters (e.g., Mg 2+ -HCO 3 and Ca 2+ -OH -; Chavagnac, Neal & Stanger, 1985;Paukert et al, 2012; ). As a result, higher metal concentrations in these waters may eventually be fingerprinted in precipitating carbonates, as shown by significantly higher nickel concentrations in analyzed samples (i.e., mean = 145 ppm; Table 2) relative to other carbonate rocks (e.g., 11-21 ppm; Nogueira et al, 2017Nogueira et al, , 2019, suggesting that ophiolitic rocks could be a potential source of heavy metals.…”