The characterization of ferromanganese crust and its redox change, Western Pacific Magellan seamounts

Title
The characterization of ferromanganese crust and its redox change, Western Pacific Magellan seamounts
Author(s)
양기호; 김진욱; 박한범; 백현석; 박경량; 김종욱
KIOST Author(s)
Kim, Jonguk(김종욱)
Publication Year
2015-12-15
Abstract
Biotic/abiotic redox reaction is a ubiquitous process in mineral formation and growth, and changes in elemental redox states, particularly Fe/Mn may reflect the redox conditions in the sediment/ocean when the mineral forms. Samples were dredged from the seamounts in the western Pacific, OSM11 in order to investigate the formation, growth and its implications to geological history. The crust consist of five well-defined layers (here after called “layer 1” (rim) through “layer 5” (core)). Quartz, feldspar, and hematite are detected only in the layer 1 in addition to the poorly crystallined Fe-rich vernadite, which is likely to be associated with slower growth rate compared to the layers 2-5. CFA were identified in layers 4 and 5 under XRD measurement. Visible size of white colored well crystallined CFA were only observed in layer 4 whereas nano-sized CFA in layer 5 were identified by TEM. Clay minerals such as smectite were observed by TEM with SAED pattern and EDX in layers 1 and 3. The oxidation states of Fe and Mn in Fe-rich vernadite in entire layers were determined by EELS analysis. All the layers of Mn oxide minerals was consisted with dominantly Mn4+, which is consistent with appearance of vernadite in Fe-Mn crust. Fe-rich vernadite in layers 1 and 4 were consisted with 26-52 % of Fe3+/Fetot, dominant reduced form of Fe compared to layers 2, 3, and 5. The observed alternative patterns of Fe oxidation state dged from the seamounts in the western Pacific, OSM11 in order to investigate the formation, growth and its implications to geological history. The crust consist of five well-defined layers (here after called “layer 1” (rim) through “layer 5” (core)). Quartz, feldspar, and hematite are detected only in the layer 1 in addition to the poorly crystallined Fe-rich vernadite, which is likely to be associated with slower growth rate compared to the layers 2-5. CFA were identified in layers 4 and 5 under XRD measurement. Visible size of white colored well crystallined CFA were only observed in layer 4 whereas nano-sized CFA in layer 5 were identified by TEM. Clay minerals such as smectite were observed by TEM with SAED pattern and EDX in layers 1 and 3. The oxidation states of Fe and Mn in Fe-rich vernadite in entire layers were determined by EELS analysis. All the layers of Mn oxide minerals was consisted with dominantly Mn4+, which is consistent with appearance of vernadite in Fe-Mn crust. Fe-rich vernadite in layers 1 and 4 were consisted with 26-52 % of Fe3+/Fetot, dominant reduced form of Fe compared to layers 2, 3, and 5. The observed alternative patterns of Fe oxidation state
URI
https://sciwatch.kiost.ac.kr/handle/2020.kiost/24982
Bibliographic Citation
AGU Fall Meeting, pp.1, 2015
Publisher
American Geophysical Union
Type
Conference
Language
English
Publisher
American Geophysical Union
Related Researcher
Research Interests

Geochemistry,Submarine hydrothermal system,Deep-sea mineral,지구화학,해저열수시스템,해양광물자원

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