Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.14/128264
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- Title
- Isotopic decoupling during porous melt flow : a case-study in the Lherz peridotite
- Related
- Earth and planetary science letters, Vol. 279, Issue 1-2 (2009), p.76-85
- DOI
- 10.1016/j.epsl.2008.12.033
- Publisher
- Elvsevier BV
- Date
- 2009
- FoR/RFCD Code(s)
-
040600 Physical Geography and Environmental Geoscience
020100 Astronomical and Space Sciences
040300 Geology
- Author/Creator
- Le Roux, V
- Author/Creator
- Bodinier, J.-L
- Author/Creator
- Alard, O
- Author/Creator
- O'Reilly, S. Y
- Author/Creator
- Griffin, W. L
- Description
- Most peridotite massifs and mantle xenoliths show a wide range of isotopic variations, often involving significant decoupling between Hf, Nd and Sr isotopes. These variations are generally ascribed either to mingling of individual components of contrasted isotopic compositions or to time integration of parent-element enrichment by percolating melts/fluids, superimposed onto previous depletion event(s). However, strong isotopic decoupling may also arise during porous flow as a result of daughter-elements fractionation during solid–liquid interaction. Although porous flow is recognized as an important process in mantle rocks, its effects on mantle isotopic variability have been barely investigated so far. The peridotites of the Lherz massif (French Pyrenees) display a frozen melt percolation front separating highly refractory harzburgites from refertilized lherzolites. Isotopic signatures observed at the melt percolation front show a strong decoupling of Hf from Nd and Sr isotopes that cannot be accounted for by simple mixing involving the harzburgite protolith and the percolating melt. Using one dimensional percolation–diffusion and percolation–reaction modeling, we show that these signatures represent transient isotopic compositions generated by porous flow. These signatures are governed by a few critical parameters such as daughter element concentrations in melt and peridotite, element diffusivity, and efficiency of isotopic homogenization rather than by the chromatographic effect of melt transport and the refertilization reaction. Subtle variations in these parameters may generate significant inter-isotopic decoupling and wide isotopic variations in mantle rocks.
- Description
- 10 page(s)
- Subject Keyword
- 040600 Physical Geography and Environmental Geoscience
- Subject Keyword
- 020100 Astronomical and Space Sciences
- Subject Keyword
- 040300 Geology
- Subject Keyword
- isotopic decoupling
- Subject Keyword
- melt transport
- Subject Keyword
- diffusion
- Subject Keyword
- melt-rock reaction
- Subject Keyword
- Lherz peridotites
- Resource Type
- journal article
- Organisation
- Macquarie University. National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC)
- Identifier
- http://hdl.handle.net/1959.14/128264
- Identifier
- ISSN:0012-821X
- Identifier
- mq-rm-2008001537
- Language
- eng
- Reviewed
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