Controls on the stability and composition of amphibole in the Earth’s mantle

High Pressure Phase Relations of a Depleted Peridotite Fluxed by CO2‐H2O‐Bearing Siliceous Melts and the Origin of Mid‐Lithospheric Discontinuity

“…This would mean that in potassic systems, not all the alkali would get incorporated in amphibole and therefore the correlation of alkali content in amphibole and its pressure stability may no longer hold. Indeed, the empirical barometer proposed by Mandler and Grove () based on the alkali contents of amphibole does not reproduce the experimental pressures of our experiments, within the error of the calibration. This is because of the presence of phlogopite, which is expected to affect the correlation between pressure and amphibole alkali content, as already noted by Mandler and Grove ().…”

“…Indeed, the empirical barometer proposed by Mandler and Grove () based on the alkali contents of amphibole does not reproduce the experimental pressures of our experiments, within the error of the calibration. This is because of the presence of phlogopite, which is expected to affect the correlation between pressure and amphibole alkali content, as already noted by Mandler and Grove (). Otherwise, the amphibole‐out boundary bracketed in our study (Figure ) is broadly consistent with the previous studies that have bracketed amphibole stability of peridotite systems, with the boundary being close to those expected for bulk compositions that are either H 2 O‐fluid undersaturated or with very little excess fluid (bulk H 2 O < 1 wt.%).…”

“…This is vital in reconciling modal abundance of these hydrous phases in light of permissible chemistry of the cratonic mantle. Moreover, the mechanism of volatile addition could also influence mineral stability, as is evidenced by variable stability of amphibole and phlogopite in ultramafic lithologies of various fertility and alkali/H 2 O ratios (Mallik et al, ; Mandler & Grove, ). In the following section, we thus compare the stability of hydrous/carbonate phases from this study with previous experimental studies to understand how phase stability can be linked to the observed geophysical characteristics of cratons.…”

“… Upper stability limits of amphibole (Fumagalli et al, ; Green, ; Grove et al, ; Mandler & Grove, ; Mengel & Green, ; Millhollen et al, ; Mysen & Boettcher, ; Niida & Green, ; Olafsson & Eggler, ; Tumiati et al, ; Wallace & Green, ) and phlogopite (Allen et al, ; Barton & Hamilton, ; Conceicao & Green, ; Condamine & Médard, ; Elkins‐Tanton & Grove, ; Enggist et al, ; Enggist & Luth, ; Esperança & Holloway, ; Konzett & Ulmer, ; Kushiro, ; Kushiro et al, ; Mallik et al, ; Mitchell, ; Modreski & Boettcher, ; Sato et al, ; Yoder & Kushiro, ) from previous studies depicted as the red and purple stippled band, respectively. The width of the stability limit bands results from stability limit variation of the hydrous phases as a function of bulk composition.…”

Plutonic xenoliths from Martinique, Lesser Antilles: evidence for open system processes and reactive melt flow in island arc crust

“…Amphibole compositions have been shown to have a strong pressure dependence (e.g. Niida and Green 1999;Mandler and Grove 2016). The relative pressure changes between xenolith types are explored using the pressure sensitive Al-Tschermack substitution, shown by Al IV versus Al VI (Fig.…”