Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/927
AuthorsCarroll, M. R. 
TitleChlorine solubility in evolved alkaline magmas
Issue Date2005
Series/Report no.48 (4-5)
URIhttp://hdl.handle.net/2122/927
Keywordsalkaline magmas
solubility
chlorine
supercritical fluid
Subject Classification04. Solid Earth::04.08. Volcanology::04.08.01. Gases 
04. Solid Earth::04.08. Volcanology::04.08.03. Magmas 
AbstractExperimental studies of Cl solubility in trachytic to phonolitic melts provide insights into the capacity of alkaline magmas to transport Cl from depth to the earth’s surface and atmosphere, and information on Cl solubility variations with pressure, temperature and melt or fluid composition is crucial for understanding the reasons for variations in Cl emissions at active volcanoes. This paper provides a brief review of Cl solubility experiments conducted on a range of trachytic to phonolitic melt compositions. Depending on the experimental conditions the melts studied were in equilibrium with either a Cl-bearing aqueous fluid or a subcritical assemblage of low- Cl aqueous fluid + Cl-rich brine. The nature of the fluid phase(s) was identified by examination of fluid inclusions present in run product glasses and the fluid bulk composition was calculated by mass balance. Chlorine concentrations in the glass increase with increasing Cl molality in the fluid phase until a plateau in Cl concentration is reached when melt coexists with aqueous fluid + brine. With fluids of similar Cl molality, higher Cl concentrations are observed in peralkaline phonolitic melts compared with peraluminous phonolitic melts; overall the Cl concentrations observed in phonolitic and trachytic melts are approximately twice those found in calcalkaline rhyolitic melts under similar conditions. The observed negative pressure dependence of Cl solubility implies that Cl contents of melts may actually increase during magma decompression if the magma coexists with aqueous fluid and Cl-rich brine (assuming melt-vapor equilibrium is maintained). The high Cl contents (approaching 1 wt% Cl) observed in some melts/glasses from the Vesuvius and Campi Flegrei areas suggest saturation with a Cl-rich brine prior to eruption.
Appears in Collections:Annals of Geophysics

Files in This Item:
File Description SizeFormat 
05Carroll.pdf1.01 MBAdobe PDFView/Open
Show full item record

Page view(s)

123
checked on Apr 23, 2017

Download(s)

367
checked on Apr 23, 2017

Google ScholarTM

Check