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Distribution of REEs and yttrium among major geochemical phases of marine Fe-Mn-oxides: Comparative study between hydrogenous and hydrothermal deposits

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Title Distribution of REEs and yttrium among major geochemical phases of marine Fe-Mn-oxides: Comparative study between hydrogenous and hydrothermal deposits
 
Creator PRAKASH, LS
RAY, D
PAROPKARI, AL
MUDHOLKAR, AV
SATYANARAYANAN, M
SREENIVAS, B
CHANDRASEKHARAM, D
KOTA, D
RAJU, KAK
KAISARY, S
BALARAM, V
GURAV, T
 
Subject Ferromanganese oxide
Hydrothermal
Hydrogenous
Yttrium
Rare earth elements
Elemental speciation
RARE-EARTH-ELEMENTS
MID-ATLANTIC RIDGE
PITCAIRN ISLAND HOTSPOT
FERROMANGANESE CRUSTS
CENTRAL PACIFIC
INDIAN-OCEAN
COMPLEXATION CONSTANTS
ISOTOPE FRACTIONATION
MANGANESE DEPOSITS
TRIPLE JUNCTION
 
Description Mineralogy and geochemistry of the ferromanganese oxides collected from two seamounts in the Andaman Sea have been investigated with special reference to the solid phase partitioning behavior of rare earth elements (REEs). Bulk elemental compositions indicate that the oxides from a volcanic cratered seamount, CSM, are hydrothermal while those from another seamount, SM2, are hydrogenous in origin. The distributions of REEs and yttrium in four geochemical phases (viz. easily exchangeable, Mn-oxide, Fe-oxyhydroxide and residual) of CSM-oxides were distinctly different from that of SM2-oxides. In CSM-oxides, the REEs and yttrium are mainly associated with Fe-oxyhydroxide phase while in SM2-oxides, both Mn-oxide and Fe-oxyhydroxide phases contain the major fraction of these elements. The exchangeable and residual phases of both hydrothermal and hydrogenous oxides have extremely low REE-content. The shale normalized negative Ce-anomalies and relative enrichment of heavy REE, characteristic of hydrothermal oxides, are retained in Fe-oxyhydroxide phase. In hydrogenous oxides, the positive Ce-anomalies occurred in both Fe and Mn-oxide phases while negative Y-anomalies were found only in Fe-oxyhydroxide phase. The phase distribution of REEs and yttrium in hydrothermal oxides is described in terms of co-precipitation and adsorption of their halide complexes and available free ions in hydrothermal solutions. Instead, adsorption of major carbonate species from seawater primarily regulates the partitioning of REEs among the coexisting phases of hydrogenous oxides. (C) 2012 Elsevier B.V. All rights reserved.
 
Publisher ELSEVIER SCIENCE BV
 
Date 2014-10-15T12:52:44Z
2014-10-15T12:52:44Z
2012
 
Type Article
 
Identifier CHEMICAL GEOLOGY, 312127-137
http://dx.doi.org/10.1016/j.chemgeo.2012.03.024
http://dspace.library.iitb.ac.in/jspui/handle/100/14935
 
Language en