scholarly journals A Thermodynamic Model for Hydrous Silicate Melts

1985 ◽  
Vol 93 (2) ◽  
pp. 161-177 ◽  
Author(s):  
Lynn Silver ◽  
Edward Stolper
Keyword(s):  
Thermodynamic Model ◽  
Silicate Melts ◽  
Hydrous Silicate

scholarly journals Iron mobility in slab-derived hydrous silicate melts at sub-arc conditions

2021 ◽  
Author(s):  
Carla Tiraboschi ◽  
Arno Rohrbach ◽  
Stephan Klemme ◽  
Jasper Berndt ◽  
Carmen Sanchez-Valle
Keyword(s):  
Silicate Melts ◽  
Hydrous Silicate ◽  
Iron Mobility

The paragenesis of upper-mantle xenoliths from the Quaternary volcanics south-east of Gees, West Eifel, Germany

1991 ◽  
Vol 55 (378) ◽  
pp. 95-112 ◽  
Author(s):  
F. E. Lloyd ◽  
A. D. Edgar ◽  
D. M. Forsyth ◽  
R. L. Barnett
Keyword(s):  
Upper Mantle ◽  
Free Subgroup ◽  
Mantle Xenoliths ◽  
Silicate Melt ◽  
Silicate Melts ◽  
Hydrous Silicate ◽  
Group I ◽  
Group Ii ◽  
West Eifel ◽  
K Activity

AbstractGroup I xenoliths, orthopyroxene-rich and orthopyroxene-free, contain Cr-spinel and clinopyroxene ± phlogopite, and occur together with Group II clinopyroxenites ± Ti-spinel ± phlogopite in K-mafic pyroclastics southeast of Gees. The petrography and clinopyroxene chemistry of orthopyroxene-rich (opx-rich sub-group) Group I xenoliths is consistent with an ‘original’ harzburgitic mantle that has been transformed to lherzolite by the addition of endiopside. In harzburgites, orthopyroxenes are reacting to diopside + olivine + alkali-silicate melt, and, by inference, the orthopyroxene-free (opx-free subgroup) Group I, dunite-wehrlite series can be linked to the opx-rich sub-group via this reaction. Progressive enrichment of dunitic material in endiopside-diopside has resulted in the formation of wehrlite. Phlogopite is titaniferous and occurs as a trace mineral in opx-rich, Group I xenoliths, whereas substantial phlogopite vein-networks are confined to the opx-free sub-group (dunite-wehrlite series). Interstitial, alkali-felsic glass occurs are veins within, and as extensions of, the phlogopite networks. Clinopyroxenes in phlogopite-veined xenoliths are decreased in Mg/(Mg + FeTotal) (mg) and Cr and increased in Ti, Al and Ca, compared with clinopyroxenes in xenoliths which have trace phlogopite. It is proposed that harzburgitic and dunitic mantle has been infiltrated by a Ca- and alkalirich, hydrous silicate melt rather than an ephemeral carbonatite melt. Dunite has been transformed to phlogopite wehrlite by the invasion of a Ca-, Al-, Ti- and K-rich, hydrous silicate melt. Ca-activity was high initially in the melt and was reduced by clinopyroxene precipitation. This resulted in enhanced K-activity which led to phlogopite veining of clinopyroxene-rich mantle. Group II phlogopite clinopyroxenites contain Ti-spinel and salites that are distinct in their Ti, Al and Cr contents from endiopsides and diopsides in Group I xenoliths. It is unlikely that these Group II xenoliths represent the culmination of the infiltration processes that have transformed dunite to wehrlite, nor can they be related to the host melt. These xenoliths may have crystallised from Ca- and K-bearing, hydrous silicate melts in mantle channelways buffered by previously precipitated clinopyroxene and phlogopite. Gees lherzolites contain pyroxenes and spinel with distinctly lower Al contents than these same minerals in lherzolites described previously from other West Eifel localities, which may reflect a distinctive lithology and/or processes of modification for the Gees mantle.

Growth of diamond in hydrous silicate melts

2010 ◽  
Vol 161 (2) ◽  
pp. 229-236 ◽  
Author(s):  
Andrew J. Fagan ◽  
Robert W. Luth
Keyword(s):  
Silicate Melts ◽  
Hydrous Silicate

Phase Relations Involving Hydrous Silicate Melts, Aqueous Fluids, and Minerals

2007 ◽  
Vol 65 (1) ◽  
pp. 129-185 ◽  
Author(s):  
A. C. Hack ◽  
A. B. Thompson ◽  
M. Aerts
Keyword(s):  
Phase Relations ◽  
Silicate Melts ◽  
Hydrous Silicate
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