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标题：Chromite oxidation by manganese oxides in subseafloor basalts and the presence of putative fossilized microorganisms
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作者：Magnus Ivarsson ; Curt Broman ; Nils G Holm 等
期刊名称：Geochemical Transactions
电子版ISSN：1467-4866
出版年度：2011
卷号：12
期号：1
页码：1-10
DOI：10.1186/1467-4866-12-5
出版社：BioMed Central
摘要：Chromite is a mineral with low solubility and is thus resistant to dissolution. The exception is when manganese oxides are available, since they are the only known naturally occurring oxidants for chromite. In the presence of Mn(IV) oxides, Cr(III) will oxidise to Cr(VI), which is more soluble than Cr(III), and thus easier to be removed. Here we report of chromite phenocrysts that are replaced by rhodochrosite (Mn(II) carbonate) in subseafloor basalts from the Koko Seamount, Pacific Ocean, that were drilled and collected during the Ocean Drilling Program (ODP) Leg 197. The mineral succession chromite-rhodochrosite-saponite in the phenocrysts is interpreted as the result of chromite oxidation by manganese oxides. Putative fossilized microorganisms are abundant in the rhodochrosite and we suggest that the oxidation of chromite has been mediated by microbial activity. It has previously been shown in soils and in laboratory experiments that chromium oxidation is indirectly mediated by microbial formation of manganese oxides. Here we suggest a similar process in subseafloor basalts.
关键词：Chromite;Manganese Oxide;Ocean Drill Program;Filamentous Structure;Rhodochrosite