Geochemistry of fluids associated with the 1995-1996 eruption of Mt. Ruapehu, New Zealand: signatures and processes in the magmatic-hydrothermal system

Authors
Citation
Bw. Christenson, Geochemistry of fluids associated with the 1995-1996 eruption of Mt. Ruapehu, New Zealand: signatures and processes in the magmatic-hydrothermal system, J VOLCANOL, 97(1-4), 2000, pp. 1-30
Citations number
36
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
ISSN journal
0377-0273 → ACNP
Volume
97
Issue
1-4
Year of publication
2000
Pages
1 - 30
Database
ISI
SICI code
0377-0273(200004)97:1-4<1:GOFAWT>2.0.ZU;2-W
Abstract
The 1995-1996 eruption of Mt. Ruapehu has provided a number of insights int o the geochemical processes operating within the magmatic-hydrothermal syst em of this volcano. Both pre-eruption degassing of the rising magma and its eventual intrusion into the convective zone of the hydrothermal system ben eath the lake were clearly reflected in lake water compositions. The erupti ons of September-October 1995 expelled the lake, and provided the first-eve r opportunity to characterise gas discharges from this volcano. The fumarol ic discharges revealed compositions typical of andesite volcanoes and stron g interaction with the enclosing meteoric and hydrothermal system fluids. S ome 1.1 MT of SO2 gas was released from the volcano between September 1995 and December 1996, whereas ca, twice this amount (2.2 MT equivalent SO2) wa s erupted as soluble (i.e. leachable) oxyanions of sulphur. Significantly m ore sulphur was released from the volcano over this period than can be acco unted for from the magma volume actually erupted. The evidence suggests tha t a sizable component of the evolved sulphur was remobilised from the long- lived hydrothermal system within the volcano during the 1995-1996 activity. (C) 2000 Elsevier Science B.V. All rights reserved.