Titre :

Wet mantle plume account for the genesis of the alkaline basalts in French Massif Central

Auteur(s) :

Chen, Huan [Auteur]
Hohai University
Ingrin, Jannick [Auteur]
Unité Matériaux et Transformations (UMET) - UMR 8207
Deloule, Etienne [Auteur]
Université de Lorraine [UL]
Bi, Yao [Auteur]
University of Science and Technology of China [Hefei] [USTC]
Xia, Qun-Ke [Auteur]
Zhejiang University of Technology

Titre de la manifestation scientifique :

Goldschmidt 2023

Ville :

Lyon

Pays :

France

Date de début de la manifestation scientifique :

2023-07-13

Discipline(s) HAL :

Chimie/Matériaux
Physique [physics]/Matière Condensée [cond-mat]/Science des matériaux [cond-mat.mtrl-sci]
Physique [physics]/Physique [physics]/Géophysique [physics.geo-ph]
Physique [physics]/Astrophysique [astro-ph]
Planète et Univers [physics]/Astrophysique [astro-ph]
Planète et Univers [physics]/Sciences de la Terre

Résumé en anglais : [en]

The genesis of the alkaline basalts in French Massif Central (FMC) has drawn extensive attention as a representative of the Circum-Mediterranean anorogenic Cenozoic igneous province. However, the origin of these basalts ...
Lire la suite >The genesis of the alkaline basalts in French Massif Central (FMC) has drawn extensive attention as a representative of the Circum-Mediterranean anorogenic Cenozoic igneous province. However, the origin of these basalts is still under debated. To shed new light on this issue, we studied the origin of the Ray-Pic alkaline basalts in southeast FMC, which carried abundant fresh peridotite xenoliths. In addition to the major- and trace-element, Sr-Nd-Pb isotope composition of bulk rock, we focused on the oxygen isotope composition, H2O content and crystallization temperature of the Ray-Pic basalts. Compared with normal MORB, the Ray-Pic basalts have the relatively high δ18O values of the clinopyroxene (cpx) phenocrysts (6.41 - 8.44 ‰), high water contents (0.96 - 2.49 wt.%), but similar crystallization temperature of olivine phenocrysts (~ 1200 ℃). The differences of the Sr-Nd-Pb-O isotope composition and the H2O content between the Ray-Pic basalts and peridotite xenoliths conflicted with an amp-rich metasomatized lithospheric mantle source. Instead, the relatively high δ18O values of cpx phenocrysts, high Ni content and Fe/Mn ratios of early crystalized olivine phenocrysts indicated that the recycled oceanic crust was involved in the mantle source of Ray-Pic basalts. Seismic tomography identified the presence of a plume-like low-velocity domain in the upper mantle beneath the FMC and a remnant oceanic slab in the mantle transition zone (MTZ) beneath the western-central Europe [1, 2]. Therefore, the high-water content in the mantle source (> 1000 ppm, wt) and the normal crystallization temperature of Ray-Pic basalts suggest that a wet mantle plume with the component of a recycled oceanic crust originating from the MTZ is involved. Therefore, we proposed that the wet mantle plume in upper mantle probably account for genesis of the alkaline basalts with HIMU feature in the FMC and even the western-central Europe. References: [1] Chevrot, S. et al. (2014). Journal of Geophysical Research: Solid Earth, 119(8), 6399–6420. [2] Fichtner, A. & Villaseñor, A. (2015). Earth and Planetary Science Letters, 428, 52–62.Lire moins >

Langue :

Anglais

Comité de lecture :

Oui

Audience :

Internationale

Vulgarisation :

Non

Établissement(s) :

Université de Lille
CNRS
INRAE
ENSCL

Collections :

• Unité Matériaux et Transformations (UMET) - UMR 8207

Équipe(s) de recherche :

Matériaux Terrestres et Planétaires

Date de dépôt :

2023-06-27T07:55:34Z
2023-06-30T08:16:22Z