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Title: Intraplate mantle oxidation by volatile-rich silicic magmas

Abstract

The upper subcontinental lithospheric mantle below the French Massif Central is more oxidized than the average continental lithosphere, although the origin of this anomaly remains unknown. Using iron oxidation analysis in clinopyroxene, oxybarometry, and melt inclusions in mantle xenoliths, we show that widespread infiltration of volatile (HCSO)-rich silicic melts played a major role in this oxidation. We propose the first comprehensive model of magmatism and mantle oxidation at an intraplate setting. Two oxidizing events occurred: (1) a 365–286 Ma old magmatic episode that produced alkaline vaugnerites, potassic lamprophyres, and K-rich calc-alkaline granitoids, related to the N–S Rhenohercynian subduction, and (2) < 30 Ma old magmatism related to W–E extension, producing carbonatites and hydrous potassic trachytes. These melts were capable of locally increasing the subcontinental lithospheric mantle fO2 to FMQ + 2.4. Both events originate from the melting of a metasomatized lithosphere containing carbonate + phlogopite ± amphibole. The persistence of this volatile-rich lithospheric source implies the potential for new episodes of volatile-rich magmatism. Similarities with worldwide magmatism also show that the importance of volatiles and the oxidation of the mantle in intraplate regions is underestimated.

Authors:
; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1410109
Resource Type:
Journal Article
Resource Relation:
Journal Name: Lithos; Journal Volume: 292-293; Journal Issue: C
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Martin, Audrey M., Médard, Etienne, Righter, Kevin, and Lanzirotti, Antonio. Intraplate mantle oxidation by volatile-rich silicic magmas. United States: N. p., 2017. Web. doi:10.1016/j.lithos.2017.09.002.
Martin, Audrey M., Médard, Etienne, Righter, Kevin, & Lanzirotti, Antonio. Intraplate mantle oxidation by volatile-rich silicic magmas. United States. doi:10.1016/j.lithos.2017.09.002.
Martin, Audrey M., Médard, Etienne, Righter, Kevin, and Lanzirotti, Antonio. Wed . "Intraplate mantle oxidation by volatile-rich silicic magmas". United States. doi:10.1016/j.lithos.2017.09.002.
@article{osti_1410109,
title = {Intraplate mantle oxidation by volatile-rich silicic magmas},
author = {Martin, Audrey M. and Médard, Etienne and Righter, Kevin and Lanzirotti, Antonio},
abstractNote = {The upper subcontinental lithospheric mantle below the French Massif Central is more oxidized than the average continental lithosphere, although the origin of this anomaly remains unknown. Using iron oxidation analysis in clinopyroxene, oxybarometry, and melt inclusions in mantle xenoliths, we show that widespread infiltration of volatile (HCSO)-rich silicic melts played a major role in this oxidation. We propose the first comprehensive model of magmatism and mantle oxidation at an intraplate setting. Two oxidizing events occurred: (1) a 365–286 Ma old magmatic episode that produced alkaline vaugnerites, potassic lamprophyres, and K-rich calc-alkaline granitoids, related to the N–S Rhenohercynian subduction, and (2) < 30 Ma old magmatism related to W–E extension, producing carbonatites and hydrous potassic trachytes. These melts were capable of locally increasing the subcontinental lithospheric mantle fO2 to FMQ + 2.4. Both events originate from the melting of a metasomatized lithosphere containing carbonate + phlogopite ± amphibole. The persistence of this volatile-rich lithospheric source implies the potential for new episodes of volatile-rich magmatism. Similarities with worldwide magmatism also show that the importance of volatiles and the oxidation of the mantle in intraplate regions is underestimated.},
doi = {10.1016/j.lithos.2017.09.002},
journal = {Lithos},
number = C,
volume = 292-293,
place = {United States},
year = {Wed Nov 01 00:00:00 EDT 2017},
month = {Wed Nov 01 00:00:00 EDT 2017}
}