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Mantle wedge olivine modifies slab-derived fluids: Implications for fluid transport from slab to arc magma source.
- Source :
-
Geology . Jul2023, Vol. 51 Issue 7, p663-667. 5p. - Publication Year :
- 2023
-
Abstract
- Boron is an effective tracer of fluid processes in subduction zones. High B and δ11B in arc magmas require efficient B transfer from the slab to magma source regions. The Higashi-akaishi metaperidotite body in the Sanbagawa high-pressure belt, Japan, is composed of locally serpentinized mantle wedge peridotites exhumed in a subduction channel. Cores of coarse-grained primary mantle olivine have 1-4 µg/g B, enriched compared to typical mantle olivine, and δ11B of --10%c to --1%o, consistent with incorporation of fluids from dehydrating slab at --90-120 km depth. Rims of primary mantle olivine as well as olivine neoblasts have even higher B (5-20 µg/g) and higher δ11B (--8%c to +2%o) due to incorporating slab fluids at depths of --70-100 km. Antigorite, formed below 650 °C, shows comparable δ11B and B contents as olivine rims. The data show that olivine is capable of scavenging significant amounts of B from fluids by diffusion and recrystallization at sub-arc pressures and temperatures. Considering the large amount of olivine in the mantle wedge, transport of slab-derived material to magma sources requires processes with minimal interaction with mantle peridotite, such as intensely channelized fluid flow or ascent of mélange diapirs, and limited porous fluid flow. [ABSTRACT FROM AUTHOR]
- Subjects :
- *OLIVINE
*MAGMAS
*SLABS (Structural geology)
*SUBDUCTION zones
*FLUIDS
*FLUID flow
Subjects
Details
- Language :
- English
- ISSN :
- 00917613
- Volume :
- 51
- Issue :
- 7
- Database :
- Academic Search Index
- Journal :
- Geology
- Publication Type :
- Academic Journal
- Accession number :
- 164708952
- Full Text :
- https://doi.org/10.1130/G51169.1