Quaternary acid magma in New Zealand
@article{Ewart1975QuaternaryAM, title={Quaternary acid magma in New Zealand}, author={Anthony Ewart and Wes Hildreth and Ian Carmichael}, journal={Contributions to Mineralogy and Petrology}, year={1975}, volume={51}, pages={1-27} }
AbstractThe voluminous Pleistocene—Recent Taupo rhyolites typically contain phenocrysts of plagioclase (oligoclase-labradorite), quartz, titanomagnetite, ilmenite, and ferromagnesian silicates. Ferromagnesian assemblages correlate with well defined Fe-Ti oxide equilibration temperature ranges and allow the rhyolites to be subdivided as follows: (1) Cummingtonite (c)—calcic hornblende (hb)—orthopyroxene (opx); 725–755°C, (2) Hb-opx, 750–825°C, (3) Biotite-hb-(c-opx), 720–765°C, (4) Opx…
146 Citations
The 26·5 ka Oruanui Eruption, Taupo Volcano, New Zealand: Development, Characteristics and Evacuation of a Large Rhyolitic Magma Body
- Geology
- 2006
The caldera-forming 26•5 ka Oruanui eruption (Taupo, New Zealand) erupted ~530 km3 of magma, >99% rhyolitic, <1% mafic. The rhyolite varies from 71•8 to 76•7 wt % SiO2 and 76 to 112 ppm Rb but is…
The volatile component of quaternary ignimbrite magmas from the North Island, New Zealand
- Geology
- 1978
AbstractIgnimbrites from the central North Island consist mainly of glass or its devitrified product (70–95%); their phenocryst mineralogy is varied and includes plag., hyp., ti-mag., ilm., aug.,…
Correlation of rhyolitic pyroclastic eruptive units from the Taupo volcanic zone by Fe–Ti oxide compositional data
- Geology
- 1998
Abstract Grain-specific analyses of Fe–Ti oxides and estimates of eruption temperature (T) and oxygen fugacity (fO2) have been used to fingerprint rhyolitic fall and flow deposits that are important…
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- GeologyJournal of the Geological Society
- 2004
The 15.8 ka Rotorua rhyolite eruptive episode from the Okataina Volcanic Centre comprises a plinian pumice fall deposit followed by the extrusion of two rhyolitic lava domes or flows and their…
The petrogenesis of an I-type volcanic-plutonic suite: The St. Marys Porphyrite, Tasmania
- Geology
- 1986
The Devonian I-type St. Marys Porphyrite (388±1Ma) comprises two petrographically similar units, an 800 m thick pyroclastic sheet (compositionally dacite and rhyolite) and a subvolcanic feeder dyke.…
Reactivation of a rhyolitic magma body by new rhyolitic intrusion before the 15 . 8 ka Rotorua eruptive episode : implications for magma storage in the Okataina Volcanic Centre , New Zealand
- Geology
- 2010
The 15.8 ka Rotorua rhyolite eruptive episode from the Okataina Volcanic Centre comprises a plinian pumice fall deposit followed by the extrusion of two rhyolitic lava domes or flows and their…
Status of thermobarometry in granitic batholiths
- GeologyEarth and Environmental Science Transactions of the Royal Society of Edinburgh
- 1996
ABSTRACT: Most granitic batholiths contain plutons which are composed of low-variance mineral assemblages amenable to quantification of the P– conditions that characterise emplacement. Some mineral…
Mineralogy and geothermometry of high-temperature rhyolites from the central and western Snake River Plain
- Geology
- 1992
Voluminous mid-Miocene rhyolitic ash-flow tuffs and lava flows are exposed along the northern and southern margins of the central and western Snake River Plain. These rhyolites are essentially…
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