eCite Digital Repository

Degassing of the H2O-rich rhyolites of the Okataina Volcanic Center, Taupo Volcanic Zone, NZ


Johnson, ER and Kamenetsky, VS and McPhie, J and Wallace, PJ, Degassing of the H2O-rich rhyolites of the Okataina Volcanic Center, Taupo Volcanic Zone, NZ, Geology, 39, (4) pp. 311-314. ISSN 0091-7613 (2011) [Refereed Article]

Restricted - Request a copy

Copyright Statement

2011 Geological Society of America. Geological Society of America, P.O. Box 9140, Boulder, CO 80301-9140 USA (

DOI: doi:10.1130/G31543.1


The Taupo Volcanic Zone (TVZ), New Zealand, is the most active region of rhyolitic volcanism on Earth, with >50 rhyolitic eruptions and ∼780 km3 of magma erupted in the past 60 k.y. Here we use analyses of quartz-hosted melt inclusions from eight eruptions in the Okataina Volcanic Center (OVC) of the TVZ to constrain magmatic volatile contents, pressures, and temperatures of quartz crystallization, and degassing of H2O, Cl, and minor CO2 from the rhyolitic magmas. The OVC melt inclusions trapped volatile-rich melts with ≤6 wt% H2O and ≤0.27 wt% Cl. Our data indicate that vapor-saturated crystallization of quartz occurred at low temperatures (760805 C) over a wide range of pressures (50200 MPa). For some eruptions, variations in volatiles and major and trace elements provide evidence for simultaneous crystallization and partial loss of H2O, Cl, and CO2 into a vapor phase. Using the combination of melt inclusion and pumice glass volatile contents, we calculate minimum volatile emissions of ∼3 1011 to 8 1012 kg H2O and ∼7 109 to 4 1010 kg Cl during the OVC eruptions. We estimate that emissions from the smaller volume (<13 km3 magma) OVC rhyolitic eruptions would have been equivalent to ∼15%40% of the yearly global arc flux of H2O and ∼10%50% of the global arc flux of Cl, whereas the large-volume (≥100 km3) Rotoiti eruption ca. 60 ka would have been equivalent to >100% of the global arc H2O flux and as much as 90% of the global arc Cl flux. These results underscore the importance of individual magmatic provinces in creating large temporal variations in global arc volatile fluxes to Earth's hydrosphere

Item Details

Item Type:Refereed Article
Keywords:rhyolite degassing Taupo New Zealand
Research Division:Earth Sciences
Research Group:Geology
Research Field:Volcanology
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:Johnson, ER (Dr Emily Johnson)
UTAS Author:Kamenetsky, VS (Professor Vadim Kamenetsky)
UTAS Author:McPhie, J (Professor Jocelyn McPhie)
ID Code:74065
Year Published:2011
Web of Science® Times Cited:35
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2011-11-10
Last Modified:2012-04-17

Repository Staff Only: item control page