Skip Navigation

This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (4)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by HARFORD, C. L.
Right arrow Articles by FALLICK, A. E.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Journal of Petrology | Volume 44 | Number 8 | Pages 1503-1523 | 2003
© Oxford University Press 2003

Degassing at the Soufrière Hills Volcano, Montserrat, Recorded in Matrix Glass Compositions

C. L. HARFORD1, R. S. J. SPARKS1,* and A. E. FALLICK2

1 DEPARTMENT OF EARTH SCIENCES, UNIVERSITY OF BRISTOL, BRISTOL BS8 1RJ, UK
2 SUERC, SCOTTISH ENTERPRISE TECHNOLOGY PARK, RANKINE AVENUE, EAST KILBRIDE G75 0QF, UK

* Corresponding author. E-mail: Steve.Sparks{at}bristol.ac.uk

Compositions of matrix glasses from the current eruption of Soufrière Hills Volcano indicate that decompression-driven crystallization results in 20–70 wt % groundmass crystallization during eruption and variable degassing. Variations in crystallinity and volatile contents (water and chlorine) of matrix glasses are attributed to variations in extrusion rates and residence times in the lava dome. Residual water contents in pumice clasts (0·2–0·6 wt %) indicate minimum pressures of 1·1–3·7 MPa in 1997 Vulcanian explosions. Residual water contents of 1·6 wt % in a ballistic block ejected in sub-Plinian explosive activity on 17 September 1996 imply larger pressure drops (~20 MPa). Variable residual water contents in dome samples are consistent with pressure variations of up to 9 MPa in the lava dome interior. Large variation in chlorine contents between lava blocks compared with explosion pumice clasts indicates that shallow-level processes dominate degassing. Low melt chlorine contents of dome samples cannot be explained by open- or closed-system degassing, especially when crystallization is taken into account. Instead, heterogeneous chlorine leaching by circulation of groundwater vapour in the dome is proposed. Variable and elevated matrix glass {delta}D values can also be attributed to interaction with isotopically heavy surface waters. HCl emission during the current eruption can be accounted for by Cl loss from the melt, consistent with the melt being undersaturated in chlorine.

KEY WORDS: andesite; degassing; chlorine; lava dome


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 J PetrologyHome page
M. Pichavant, F. Costa, A. Burgisser, B. Scaillet, C. Martel, and S. Poussineau
Equilibration Scales in Silicic to Intermediate Magmas Implications for Experimental Studies
J. Petrology, October 1, 2007; 48(10): 1955 - 1972.
[Abstract] [Full Text] [PDF]

Home page
 ScienceHome page
E. B. Watson and T. M. Harrison
Zircon Thermometer Reveals Minimum Melting Conditions on Earliest Earth
Science, May 6, 2005; 308(5723): 841 - 844.
[Abstract] [Full Text] [PDF]


Disclaimer:
Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.