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| Titel |
Serpentinization of sintered olivine during seawater percolation experiments |
| VerfasserIn |
Linda Luquot, Muriel Andreani, Marguerite Godard, Philippe Gouze, Benoit Gibert |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250042636
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| Zusammenfassung |
| Hydration of the mantle lithosphere exposed along detachment faults at slow-spreading
ridges leads to strong modification of rock rheological, geophysical and geochemical
properties, and to the emission of large amounts of H2 and CH4, and of complex carbon
molecules that support primitive ecosystems. The sustainability and efficiency of this
hydration process, serpentinisation, and of associated reactions, requires penetration and
renewal of fluids at the mineral-fluid interface. However, precipitation of material along flow
paths will affect porosity and permeability that, in turn, will have feedbacks effects on the
reactions. It is thus necessary to investigate the sustainability of flow paths, and the evolution
of reaction rates for a dynamic system under representative conditions. We investigate
these processes by percolation experiments carried out under P, T representative
conditions, using the ICARE Microlab experimental bench. We present the preliminary
results of seawater percolation within samples of sintered San Carlos olivine. The
experiments were carried out under a confined pressure of 190 bars and a temperature of
190Ë C and water flow was set at a constant specific discharge of 0.06 ml/h.. The
experiments were performed at very slow flow rate to be more representative of
natural systems. ICARE Microlab allows measuring continuously the permeability
changes during the percolation experiment and sampling the brine at the outlet of the
sample.
After 20 days of experiments, poorly crystallized serpentine and iron oxide formed within
the micro-cracks while permeability strongly decreases. Such rapid precipitation of
serpentine results in clogging of fluid paths. The chemical composition of the outlet fluid is
dominated by Si and is depleted in Mg relative to stoechiometric dissolution of olivine
during the whole experiment suggesting that brucite possibly formed. SEM and
AEM/TEM are used to characterize the reactive interfaces and the neoformed materials. |
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