Conditions of melt generation beneath the Taupo Volcanic Zone: The influence of heterogeneous mantle inputs on large-volume silicic systems

Geology ◽  
2014 ◽  
Vol 42 (1) ◽  
pp. 3-6 ◽  
Author(s):  
Tyrone O. Rooney ◽  
Chad D. Deering
Keyword(s):  
Large Volume ◽  
Taupo Volcanic Zone ◽  
Volcanic Zone ◽  
Heterogeneous Mantle ◽  
Melt Generation

Genesis of Recent Mafic Magmatism in the Taupo Volcanic Zone, New Zealand: Insights into the Birth and Death of Very Large Volume Rhyolitic Systems?

2020 ◽  
Vol 61 (2) ◽  
Author(s):  
Georg F Zellmer ◽  
Jun-Ichi Kimura ◽  
Claudine H Stirling ◽  
Gert Lube ◽  
Phil A Shane ◽  
...  
Keyword(s):  
New Zealand ◽  
Trace Element ◽  
Large Volume ◽  
Mantle Source ◽  
Source Parameters ◽  
Taupo Volcanic Zone ◽  
Volcanic Zone ◽  
Mafic Magmatism ◽  
Mafic Magmas ◽  
Rhyolitic Volcanism

Abstract Mafic magmatism of the rifting Taupo Volcanic Zone (TVZ) of the North Island, New Zealand, is volumetrically minor, but is thought to tap the material that provides the heat source for voluminous rhyolite production through partial melting of the crust, which ultimately results in very large volume explosive eruptions. We have studied the major and trace element chemistry of 14 mafic samples from across the entire TVZ, and the U isotopic composition of whole-rocks, groundmasses and separates of mafic mineral phases from a selection of nine samples (with the remaining five too sparsely phyric for mineral separation). Some minerals yield significant 234U enrichments despite groundmass and whole-rock close to 238U–234U secular equilibrium, pointing to uptake of variably hydrothermally altered antecrystic minerals prior to the eruption of originally sparsely phyric to aphyric mafic magmas. However, incompatible trace element patterns indicate that there are three chemically distinct groups of samples, and that samples may be used to derive primary melt compositions. We employ the latest version of the Arc Basalt Simulator (ABS5) to forward model these compositions, deriving mantle source parameters including mantle fertility, slab liquid flux, mantle volatile content, degree of melting, and P–T conditions of melt segregation. We show that mafic rocks erupted in areas of old, now inactive calderas constitute low-degree, deep melts, whereas those in areas of active caldera-volcanism are high-degree partial melts segregated from a less depleted source at an intermediate depth. Finally, high-Mg basaltic andesites erupted in the SW and NE of the TVZ point to a fertile, shallow mantle source. Our data are consistent with a petrogenetic model in which mantle melting is dominated by decompression, rather than fluid fluxing, and progresses from shallow to deeper levels with time. Melt volumes initially increase to a tipping point, at which large-scale crustal melting and caldera volcanism become prominent, and then decrease owing to progressive depletion of the mantle wedge by melting, resulting in the dearth of heat provided and eventual cessation of very large volume rhyolitic volcanism. ABS5 modelling therefore supports the notion of a direct link between the chemistry of recently erupted mafic magmas and the long-term activity and evolution of rhyolitic volcanism in the TVZ.

FAVORABLE STRUCTURAL SETTINGS FOR POTENTIAL GEOTHERMAL UPWELLINGS IN THE CENTRAL TAUPO VOLCANIC ZONE, NEW ZEALAND

2018 ◽  
Author(s):  
Natalie E. Wigger ◽  
◽  
James E. Faulds ◽  
Samuel J. Hampton ◽  
Josh W. Borella ◽  
...  
Keyword(s):  
New Zealand ◽  
Taupo Volcanic Zone ◽  
Volcanic Zone

scholarly journals Physical property relationships of the Rotokawa Andesite, a significant geothermal reservoir rock in the Taupo Volcanic Zone, New Zealand

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
Paul A Siratovich ◽  
Michael J Heap ◽  
Marlène C Villenueve ◽  
James W Cole ◽  
Thierry Reuschlé
Keyword(s):  
New Zealand ◽  
Physical Property ◽  
Geothermal Reservoir ◽  
Reservoir Rock ◽  
Taupo Volcanic Zone ◽  
Volcanic Zone

Testing Long-Term Predictions from Hydro-Geochemical Models

1993 ◽  
Vol 333 ◽  
Author(s):  
William E. Glassley ◽  
Carol J. Bruton ◽  
William L. Bourcier
Keyword(s):  
Yucca Mountain ◽  
Taupo Volcanic Zone ◽  
Ambient Conditions ◽  
Volcanic Zone ◽  
Site Specific ◽  
Thermally Induced ◽  
Induced Flow ◽  
Geochemical Models ◽  
Kinetics And Thermodynamic

ABSTRACTThermally induced flow of liquid water and water vapor at the potential repository site at Yucca Mountain, Nevada, will extend hundreds of meters away from the repository edge. The resultant transfer of heat and mass will sufficiently perturb the ambient conditions such that a variety of mineralogical and chemical reactions will occur that may modify hydrological properties. The consequences of this “coupling” of geochemical and hydrological processes will vary through time, and will occur to different degrees in four regimes (T < Tboiling; T = Tboiling; T > T boiling; cooling) that will develop within the repository block. The dominant processes in the regimes differ, and reflect the local balance between: 1) kinetics and equilibrium; 2) dissolution and precipitation; 3) evaporation and boiling; and 4) fluid flow in matrix and fractures. Simulations were conducted of the evolution of these regimes, using laboratory derived kinetics and thermodynamic data, and site specific mineralogical and hydrological properties. These simulations identify regions where chemical and mineralogical equilibrium is likely to be achieved, and where net changes in hydrological properties will be concentrated. Tests of the results of these simulations have been initiated using field data from the Taupo Volcanic Zone, New Zealand. A preliminary series of calculations suggest that relative changes in porosity of as much as ± 20% to 30% may be possible for rocks with an initial porosity of 10%.

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