Trace element mobility during sub-seafloor alteration of basaltic glass from Ocean Drilling Program site 953 (off Gran Canaria)

Trace element concentrations of altered basaltic glass shards (layer silicates) and zeolites in volcaniclastic sediments drilled in the volcanic apron northeast of Gran Canaria during Ocean Drilling Program (ODP) leg 157 document variable element mobilities during low-temperature alteration processe...

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Bibliographic Details
Published in:International journal of earth sciences : Geologische Rundschau 2002-08, Vol.91 (4), p.661-679
Main Authors: Utzmann, A., Hansteen, T., Schmincke, H.-U.
Format: Article
Language:English
Subjects:
Boundary layers
Cations
Clay minerals
Drilling
Geochemistry
Glass
Low temperature
Marine environment
Mineralogy
Minerals
Montmorillonite
Ocean floor
Oceanography
Rare earth elements
Sediments
Silicates
Trace elements
Trace metals
Water column
Zeolites
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Summary:Trace element concentrations of altered basaltic glass shards (layer silicates) and zeolites in volcaniclastic sediments drilled in the volcanic apron northeast of Gran Canaria during Ocean Drilling Program (ODP) leg 157 document variable element mobilities during low-temperature alteration processes in a marine environment. Clay minerals (saponite, montmorillonite, smectite) replacing volcanic glass particles are enriched in transition metals and rare earth elements (REE). The degree of retention of REE within the alteration products of the basaltic glass is correlated with the field strength of the cations. The high field-strength elements are preferentially retained or enriched in the alteration products by sorption through clay minerals. Most trace elements are enriched in a boundary layer close to the interface mineral-altered glass. This boundary layer has a key function for the physico-chemical conditions of the subsequent alteration process by providing a large reactive surface and by lowering the fluid permeability. The release of most elements is buffered by incorporation into secondary precipitates (sodium-rich zeolites, phillipsite, Fe- and Mn-oxides) as shown by calculated distribution coefficients between altered glasses and authigenic minerals. Chemical fluxes change from an open to a closed system behavior during prograde low-temperature alteration of volcaniclastic sediments with no significant trace metal flux from the sediment to the water column.[PUBLICATION ABSTRACT]
ISSN:1437-3254
1437-3262
DOI:10.1007/s00531-001-0247-6