Microbial Imprints on Sulfide Minerals in Submarine Hydrothermal Deposits of the East Pacific Rise

Abstract

Diverse numbers of iron‐ and sulfur‐oxidizing microbes have been found in submarine hydrothermal deposits. They have played a prominent role in weathering of seafloor sulfide deposits. However, evidence for microbe‐mineral interactions in sediments is rare. Mineralogic analysis and scanning electron microscopy and energy‐dispersive X‐ray spectroscopy (SEM‐EDX) examination of sulfide deposits from the East Pacific Rise demonstrated that (1) sulfide minerals were extensively leached, with characteristic microbial dissolution pits on mineral surfaces; (2) the possible Acidithiobacillus‐like bacteria and metabolites were found closely associated with the dissolution pits in situ. The results provide direct evidence for microbial leaching on the solid mineral crystals, most likely by the contact mechanisms, in the seafloor sulfide deposits.

Microbial biosignatures in ancient deep‐sea hydrothermal sulfides

“…For instance, oxidative dissolution of Fe sulfides by Fe(II)-oxidizing bacteria can result in distinct cell-sized (i.e., μm-scale) etch-marks or pits on mineral surfaces (Andrews, 1988;Rojas-Chapana & Tributsch, 2004;Thorseth et al, 2001). Such features and associated Fe (oxyhydr)oxides resulting from oxidative dissolution were reported on surfaces of sulfide minerals in modern seafloor hydrothermal deposits (Liu et al, 2020). To the best of our knowledge, there are no reports of microbial trace fossils in Precambrian hydrothermal sulfides.…”