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Article Dans Une Revue Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences (1934–1990) Année : 2002

On the origin of noble gases in mantle plumes

N. Coltice
Y. Ricard

Résumé

The chemical differences between deep- and shallow-mantle sources of oceanic basalts provide evidence that several distinct components coexist within the Earth's mantle. Most of these components have been identified as recycled in origin. However, the noble-gas signature is still a matter of debate and questions the preservation of primitive regions in the convective mantle. We show that a model where the noble-gas signature observed in Hawaii and Iceland comes from a pristine homogeneous deep layer would imply a primitive 3He content and 3He/22Ne ratio that are very unlikely. On the contrary, mass balances show that the partly degassed peridotite of a marble-cake mantle can be the noble-gas end-member with an apparent 'primitive'-like composition. This component is mixed with recycled oceanic crust in different proportions in the plume sources and in the shallow mantle. A recycling model of the mantle, involving gravitational segregation of the oceanic crust at the bottom of the mantle, potentially satisfies trace-element as well as noble-gas constraints.
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Dates et versions

hal-02046733 , version 1 (22-02-2019)

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  • HAL Id : hal-02046733 , version 1

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N. Coltice, Y. Ricard. On the origin of noble gases in mantle plumes. Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences (1934–1990), 2002, 360 (1800), pp.2633-2648. ⟨hal-02046733⟩
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