9:00 AM - 9:15 AM
[MZZ44-01] Submicron-scale petrography of hydrogenetic ferromanganese crusts for growth processes and environments
Keywords:ferromanganese crust, petrography, SEM, growth environment, microstructure
Hydrogenetic ferromanganese oxide precipitates are long-range sediment archives and future mineral deposits. Our recent studies include the discovery of modern precipitation of Fe and Mn oxide particles (Usui et al., 2021, Scientific Reports), and the well-correlated microstratigraphy within the world ocean scales (Hino & Usui, 2023), the molecular-level metal adsorption properties (Kishiwabara et al., 2000), and water-depth depency of crust composition to the water structure (Usui et al., 2017), etc., although the results suggested some unresolved problems.
Their the physical, chemical, and biological factors are not well understood due to their low-crystalline, metastable, and multi-origin nature of ferromanganese deposits. Here, we aimed to characterize the compositional and mineralogical properties of each submicron-sized constituent. On the other hand, in-situ adsorption experiments have confirmed that coccoid-shape vernadite precipitates (aggregates) of 1 to 2 μm in diameter are the major form in marine waters, and that the precipitate is in fact a common constituent of hydrogenetic ferromanganese crusts. Specifically, 1) the coccoidal masses of ferromanganese oxide is the main constituent of hydrogenetic crusts, 2) the crusts contain a large amount of silicate particles of multiple origins, 3) they are likely to be formed during the initial fixation process of sedimentation, and 3) the structure suggest, re-precipitation or diagenetic alteration.
Their the physical, chemical, and biological factors are not well understood due to their low-crystalline, metastable, and multi-origin nature of ferromanganese deposits. Here, we aimed to characterize the compositional and mineralogical properties of each submicron-sized constituent. On the other hand, in-situ adsorption experiments have confirmed that coccoid-shape vernadite precipitates (aggregates) of 1 to 2 μm in diameter are the major form in marine waters, and that the precipitate is in fact a common constituent of hydrogenetic ferromanganese crusts. Specifically, 1) the coccoidal masses of ferromanganese oxide is the main constituent of hydrogenetic crusts, 2) the crusts contain a large amount of silicate particles of multiple origins, 3) they are likely to be formed during the initial fixation process of sedimentation, and 3) the structure suggest, re-precipitation or diagenetic alteration.