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Proceedings Paper

Biomineral microstructures in ferromanganese nodules: evidence of the biological and abiogenous origin
Author(s): G. N. Lysyuk
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Paper Abstract

Manganese oxides, which are widespread and of great practical importance, are formed and transformed by the active role of microorganisms. Manganese aggregates occur as both crystallized varieties and disordered fine-grained phases with significant ore grade and up to 50-60 vol % of X-ray amorphous components. X-ray amorphous nanosizedMn oxides in Fe-Mn nodules from the Pacific Ocean floor were examined from the standpoint of their biogenic origin. SEM examination showed abundant mineralized biofilms on the studied samples. The chemical composition of bacterial mass is as follows (wt %): 28.34 MnO, 17.14 Fe2O3, 7.11 SiO2, 2.41 CaO, 17.90 TiO2, 1.74Na2O,1.73 A12O3,1.30 MgO, 1.25P2O5,1.25 SO3,0.68 CoO, 0.54 CuO, 0.53 NiO, and 0.50 K2O. The chemical composition of fossilized cyanobacterial mats within the interlayer space of nodules is as follows (wt %): 48.35 MnO, 6.23 Fe2O3, 8.76 MgO, 5.05 A12O3, 4.45 SiO2, 3.63 NiO, 2.30 Na2O, 2.19 CuO, 1.31 CaO, and 0.68 K2O is direct evidence for participation of bacteria in Mn oxide formation. This phase consists of mineralized glycocalix consisting of nanosized flakes of todorokite. Native metals (Cu, Fe, and Zn) as inclusions 10-20 μm in size were identified in ferromanganese nodules as well. The formation of native metals can be explained by their crystallization at highly reducing conditions maintained by organic matter.

Paper Details

Date Published: 23 September 2011
PDF: 6 pages
Proc. SPIE 8152, Instruments, Methods, and Missions for Astrobiology XIV, 815207 (23 September 2011); doi: 10.1117/12.893322
Show Author Affiliations
G. N. Lysyuk, Institute of Geology (Russian Federation)

Published in SPIE Proceedings Vol. 8152:
Instruments, Methods, and Missions for Astrobiology XIV
Richard B. Hoover; Paul C. W. Davies; Gilbert V. Levin; Alexei Yu. Rozanov, Editor(s)

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