Open AccessCharacterization and Quantification of Magnetofossils Within Abyssal Manganese Nodules From the Western Pacific Ocean and Implications for Nodule Formation
Author(s) -
Jiang X. D.,
Zhao X.,
Chou Y. M.,
Liu Q. S.,
Roberts A. P.,
Ren J. B.,
Sun X. M.,
Li J. H.,
Tang X.,
Zhao X. Y.,
Wang C. C.
Publication year - 2020
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2019gc008811
Subject(s) - biomineralization , biogeochemical cycle , abyssal zone , abyssal plain , geology , manganese , nodule (geology) , magnetite , seafloor spreading , geochemistry , mineralogy , oceanography , paleontology , environmental chemistry , chemistry , organic chemistry , structural basin
Abyssal manganese nodules have been explored widely for their economic potential and paleoenvironmental significance. Debate about whether biogenic or physical‐chemical processes are responsible for their formation remains because of difficulties in quantifying ancient microbiological contributions. To address this question, we investigated microbial fossils in manganese nodules from the western Pacific Ocean by integrating scanning electron microscope, transmission electron microscope, and synchrotron transmission X‐ray microscope observations. Our results suggest that the nodules host abundant fossil biogenic magnetite and manganese‐oxidizing bacteria. These organisms engage in redox reactions or live in environments with redox gradients. By combining magnetic properties and observations of fossil biogenic magnetite morphology, we estimate magnetofossil abundances and further assess fossil biogenic manganese oxide in nodules. Our results imply that manganese nodule formation appears to be dominated by biomineralization with an additional terrestrial contribution. Extensive biomineralization in ultralow‐productivity oceanic environments suggests that manganese nodule formation is an important aspect of biogeochemical cycling in abyssal seafloor environments.