Fig. 6: Compilations of rare earth element pattern.
From: Active methanogenesis during the melting of Marinoan snowball Earth
All rare earth element (REE) data are normalized to post-Archean Australian shale (PAAS)44. a REE pattern of igneous rocks. All samples show Eu positive anomalies. All except for oceanic island basalt (OIB) show light REE (LREE)-depleted pattern; b REE pattern of porewater. REE pattern of the bottom water is similar to that of seawater. The middle REE (MREE) bulge type is found in Fe rich cores. The heavy REE (HREE)-enriched type is found in Fe lean cores. All samples slightly enrich in HREE45; c REE pattern of hydrothermal fluids and precipitates. Most samples show a flat REE pattern, except for the pedestal slab near chimney showing a MREE-depleted pattern17,19,50. All samples show a positive Eu anomaly except for sulfide from ultraslow spreading ridge. Pedestal slab and Fe–Mn precipitation show a slight Y enrichment50. d REE pattern for Black Seawater. Strong Ce negative anomaly could be characterized in shallow water. Deep water shows flat REE pattern with slight HREE enrichment46. e REE pattern of Fe-oxide deposition. Modern samples are ferrihydrite precipitation on seafloor, while samples from Paleoproterozoic and Archean era are banded-iron-formation (BIF). Modern samples show flat pattern with slight Ce positive anomaly and negative Y anomaly. BIF samples show positive Eu and Y anomaly48. f REE pattern for modern primordial plants including lichen, algae, and moss.53,54 All samples show a flat REE pattern, except for green algae that is slightly depleted Nd (ref. 54). g Fractional coefficient for microbes. Different lines show fractional coefficient for different biomass concentration. Microbes preferentially absorb HREE57. h REE fractionation during Fe(OH)3 precipitation. All data show LREE-depleted pattern with a slight Y negative anomaly. Smaller fractionation is observed in acidic environment47. i Comparison of REE pattern for fluid end-member and sulfide from Logatchev (mid-ocean ridge in Atlantic Ocean) and east Pacific rise (EPR)19. The REE pattern for sulfide and fluid end-member is generally similar. A smaller positive Eu anomaly and slight HREE enrichment might be caused by contamination of seawater19.
