The Moho transition zone in the Oman ophiolite-relation with wehrlites in the crust and dunites in the mantle - Université de Lorraine Accéder directement au contenu
Article Dans Une Revue Marine Geophysical Research Année : 2000

The Moho transition zone in the Oman ophiolite-relation with wehrlites in the crust and dunites in the mantle

Adolphe Nicolas
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Résumé

Field data in the Oman ophiolite show that the Moho transition zone (MTZ), which is on average 300 m thick above mantle diapirs, reduces to 50 m away from diapirs, with a sharp transition at the outskirts of the diapirs. We show here that this reduction is dominantly due to compaction of a dunitic mush present above diapirs in the MTZ, with upward injection of a wehrlitic magma in the crust, and, to a lesser extent, due to tectonic stretching. In order to explain the fraction of wehrlites injected into the crust, which is in the range of 25%, it is necessary that mantle upwelling is active, with a mantle flow velocity away from diapirs several times faster than the spreading velocity. If this velocity exceeds 5 times the ridge spreading-rate, a significant part of the MTZ may be entrained down into the mantle, flowing away from the diapir as tabular dunites.

Dates et versions

hal-02378540 , version 1 (02-03-2020)

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Citer

David Jousselin, Adolphe Nicolas. The Moho transition zone in the Oman ophiolite-relation with wehrlites in the crust and dunites in the mantle. Marine Geophysical Research, 2000, 21 (3/4), pp.229-241. ⟨10.1023/A:1026733019682⟩. ⟨hal-02378540⟩
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