A microearthquake survey at the Ngawha geothermal field, New Zealand

Geophysics ◽  
1981 ◽  
Vol 46 (10) ◽  
pp. 1467-1468 ◽  
Author(s):  
Russell Robinson
Keyword(s):  
New Zealand ◽  
Hot Springs ◽  
Geothermal Field ◽  
Hot Water ◽  
Taupo Volcanic Zone ◽  
Thermal Activity ◽  
Volcanic Zone ◽  
Depth Level ◽  
Geothermal Exploration ◽  
The North

A twenty day microearthquake survey of the Ngawha geothermal field, New Zealand, was undertaken in order to establish the level of preproduction seismicity and to test the usefulness of such surveys in geothermal exploration. The Ngawha geothermal field, in the far northwest of the North Island (Northland) is associated with a region of Quaternary basaltic volcanism. It is not a part of the much more extensive Taupo volcanic zone in the central North Island, site of the well‐known Wairakei geothermal field, among others. Although surface thermal activity at Ngawha is limited to a few relatively small hot springs, resistivity surveys have outlined a [Formula: see text] area of hot water at the 1-km depth level (Macdonald et al. , 1977). Test bores to that depth have encountered temperatures of up to 250 °C within Mesozoic graywacke. Overlying the graywacke is about 500 m of Cenozoic claystone and siltstone which forms an impermeable cap.

Taxonomic fidelity of silicified filamentous microbes from hot-spring systems in the Taupo Volcanic Zone, North Island, New Zealand

2003 ◽  
Vol 94 (4) ◽  
pp. 475-483 ◽  
Author(s):  
Brian Jones ◽  
Robin W. Renaut ◽  
Michael R. Rosen
Keyword(s):  
New Zealand ◽  
Hot Springs ◽  
Hot Spring ◽  
Morphological Characteristics ◽  
Colony Morphology ◽  
Taupo Volcanic Zone ◽  
Volcanic Zone ◽  
The North ◽  
Preservation Potential ◽  
Physical Changes

ABSTRACTModern, silica-precipitating hot springs, like those found in the Taupo Volcanic Zone (TVZ) on the North Island of New Zealand, are natural laboratories for assessing microbial silicification. Many of the silicified microbes found in the siliceous sinters of these spring systems seem to be life-like replicas of the original microbes. Such preservation reflects the fact that many of the microbes are replaced and encrusted by opal-A before they are destroyed by desiccation and decay. The taxonomic fidelity of these silicified microbes depends on the preservation potential of those features which are needed to identify them. For example, identification of extant cyanobacteria, relies on as many as 37 different features, most of which are not preserved by silicification.In the hot-spring systems of the TVZ, characterisation of cyanobacteria which have been replaced and encrusted by opal-A is typically restricted to colony morphology, the length, diameter and morphology of the filament, and the presence/absence of septa, branching or a sheath. In many cases, description is limited to a subset of these parameters. Such a limited set of morphological characteristics severely impedes identifications in terms of extant taxa. The physical changes which accompany the stepwise diagenetic progression from opal-A to opal-CT ± opal-C to microcrystalline quartz may lead to further degradation of the silicified microbes and the loss of more taxonomically important features. Clearly, considerable care must be taken when trying to name silicified microorganisms and make palaeoenvironmental inferences.

scholarly journals Mapping Stress and Structure From Subducting Slab to Magmatic Rift: Crustal Seismic Anisotropy of the North Island, New Zealand

2020 ◽  
Author(s):  
Finnigan Illsley-Kemp ◽  
Martha Savage ◽  
Colin Wilson ◽  
S Bannister
Keyword(s):  
New Zealand ◽  
Stress Field ◽  
Large Scale ◽  
Seismic Anisotropy ◽  
Taupo Volcanic Zone ◽  
Volcanic Zone ◽  
The North ◽  
Magma Reservoirs ◽  
Tectonic Forces ◽  
Subducting Slab

© 2019. American Geophysical Union. All Rights Reserved. We use crustal seismic anisotropy measurements in the North Island, New Zealand, to examine structures and stress within the Taupō Volcanic Zone, the Taranaki Volcanic Lineament, the subducting Hikurangi slab, and the Hikurangi forearc. Results in the Taranaki region are consistent with NW-SE oriented extension yet suggest that the Taranaki volcanic lineament may be controlled by a deep-rooted, inherited crustal structure. In the central Taupō Volcanic Zone anisotropy fast orientations are predominantly controlled by continental rifting. However at Taupō and Okataina volcanoes, fast orientations are highly variable and radial to the calderas suggesting the influence of magma reservoirs in the seismogenic crust (≤15 km depth). The subducting Hikurangi slab has a predominant trench-parallel fast orientation, reflecting the pervasive presence of plate-bending faults, yet changing orientations at depths ≥120 km beneath the central North Island may be relics from previous subduction configurations. Finally, results from the southern Hikurangi forearc show that the orientation of stresses there is consistent with those in the underlying subducting slab. In contrast, the northern Hikurangi forearc is pervasively fractured and is undergoing E-W compression, oblique to the stress field in the subducting slab. The north-south variation in fore-arc stress is likely related to differing subduction-interface coupling. Across the varying tectonic regimes of the North Island our study highlights that large-scale tectonic forces tend to dictate the orientation of stress and structures within the crust, although more localized features (plate coupling, magma reservoirs, and inherited crustal structures) can strongly influence surface magmatism and the crustal stress field.

scholarly journals Matrix permeability of reservoir rocks, Ngatamariki geothermal field, Taupo Volcanic Zone, New Zealand

2018 ◽  
Vol 6 (1) ◽  
Author(s):  
J. L. Cant ◽  
P. A. Siratovich ◽  
J. W. Cole ◽  
M. C. Villeneuve ◽  
B. M. Kennedy
Keyword(s):  
New Zealand ◽  
Geothermal Field ◽  
Taupo Volcanic Zone ◽  
Volcanic Zone ◽  
Reservoir Rocks ◽  
Matrix Permeability

scholarly journals Temperature and pH control on lipid composition of silica sinters from diverse hot springs in the Taupo Volcanic Zone, New Zealand

Extremophiles ◽  
2014 ◽  
Vol 19 (2) ◽  
pp. 327-344 ◽  
Author(s):  
Gurpreet Kaur ◽  
Bruce W. Mountain ◽  
Matthew B. Stott ◽  
Ellen C. Hopmans ◽  
Richard D. Pancost
Keyword(s):  
New Zealand ◽  
Lipid Composition ◽  
Hot Springs ◽  
Ph Control ◽  
Taupo Volcanic Zone ◽  
Volcanic Zone

scholarly journals Field-Based Tests of Geochemical Modeling Codes: New Zealand Hydrothermal Systems

1993 ◽  
Vol 333 ◽  
Author(s):  
Carol J. Bruton ◽  
William E. Glassley ◽  
William L. Bourcier
Keyword(s):  
New Zealand ◽  
Nuclear Waste ◽  
Kinetic Data ◽  
Geochemical Modeling ◽  
Geothermal Field ◽  
Hydrothermal Systems ◽  
Taupo Volcanic Zone ◽  
Volcanic Zone ◽  
Mineral Assemblages ◽  
Modeling Code

ABSTRACTHydrothermal systems in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of the hydrothermal systems with predictions of fluid-solid equilibria made using geochemical modeling codes will determine how the codes can be used to predict the chemical and mineralogical response of the environment to nuclear waste emplacement. Field-based exercises allow us to test the models on time scales unattainable in the laboratory.Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei and Kawerau geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions.

U–Pb dating of zircon in hydrothermally altered rocks of the Kawerau Geothermal Field, Taupo Volcanic Zone, New Zealand

2013 ◽  
Vol 253 ◽  
pp. 97-113 ◽  
Author(s):  
S.D. Milicich ◽  
C.J.N. Wilson ◽  
G. Bignall ◽  
B. Pezaro ◽  
B.L.A. Charlier ◽  
...  
Keyword(s):  
New Zealand ◽  
Geothermal Field ◽  
Taupo Volcanic Zone ◽  
Volcanic Zone

3D Anatomy of a 60-year-old siliceous hot spring deposit at Hipaua-Waihi-Tokaanu geothermal field, Taupo Volcanic Zone, New Zealand

2020 ◽  
Vol 402 ◽  
pp. 105652 ◽  
Author(s):  
Kathleen A. Campbell ◽  
Kirsty Nicholson ◽  
Bridget Y. Lynne ◽  
Patrick R.L. Browne
Keyword(s):  
New Zealand ◽  
Hot Spring ◽  
Geothermal Field ◽  
Taupo Volcanic Zone ◽  
Volcanic Zone ◽  
3D Anatomy
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