Stratigraphy and geochemistry of the Turoa area, with implications for andesite petrogenesis at Mt Ruapehu, Taupo Volcanic Zone, New Zealand
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Stratigraphy and geochemistry of the Turoa area, with implications for andesite petrogenesis at Mt Ruapehu, Taupo Volcanic Zone, New Zealand. / Waight, T. E.; Price, R. C.; Stewart, R. B.; Smith, I. E.M.; Gamble, J.
In: New Zealand Journal of Geology and Geophysics, Vol. 42, No. 4, 01.01.1999, p. 513-532.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Stratigraphy and geochemistry of the Turoa area, with implications for andesite petrogenesis at Mt Ruapehu, Taupo Volcanic Zone, New Zealand
AU - Waight, T. E.
AU - Price, R. C.
AU - Stewart, R. B.
AU - Smith, I. E.M.
AU - Gamble, J.
PY - 1999/1/1
Y1 - 1999/1/1
N2 - Detailed mapping and sampling on Turoa ski-field and surrounding areas on Mt Ruapehu has enabled identification of individual flow packets that represent small scale eruptive events during the major cone-building episodes previously identified on Ruapehu by Graham & Hackett. The area is dominated by plagioclase-pyroxene-phyric andesitic lavas of Mangawhero Formation, which are petrographically and geochemically typical of post-120 ka Ruapehu lavas. Although the lavas are from a relatively small area of the volcano, geochemical and isotopic compositions show a range in variation similar to that observed for the entire volcano. Examination of geochemical variations between individual flow packets and also between sequential lava flows indicates complex processes of assimilation and influx of “new”, variably evolved and fractionated magmas into high level magma chambers. These chambers are most likely heterogeneous, and individual eruptions may also sample compositionally distinct regions of the same chamber. It is probable that a complex plumbing system exists beneath Ruapehu with at least two levels of magma storage, evolution, and crustal interaction. Consequently, attempts to numerically quantify such a complex system using models such as assimilation-fractional crystallisation processes are inherently oversimplifications.
AB - Detailed mapping and sampling on Turoa ski-field and surrounding areas on Mt Ruapehu has enabled identification of individual flow packets that represent small scale eruptive events during the major cone-building episodes previously identified on Ruapehu by Graham & Hackett. The area is dominated by plagioclase-pyroxene-phyric andesitic lavas of Mangawhero Formation, which are petrographically and geochemically typical of post-120 ka Ruapehu lavas. Although the lavas are from a relatively small area of the volcano, geochemical and isotopic compositions show a range in variation similar to that observed for the entire volcano. Examination of geochemical variations between individual flow packets and also between sequential lava flows indicates complex processes of assimilation and influx of “new”, variably evolved and fractionated magmas into high level magma chambers. These chambers are most likely heterogeneous, and individual eruptions may also sample compositionally distinct regions of the same chamber. It is probable that a complex plumbing system exists beneath Ruapehu with at least two levels of magma storage, evolution, and crustal interaction. Consequently, attempts to numerically quantify such a complex system using models such as assimilation-fractional crystallisation processes are inherently oversimplifications.
KW - Andesite
KW - Geochemistry
KW - Isotopes
KW - New Zealand
KW - Ruapehu
KW - Stratigraphy
UR - http://www.scopus.com/inward/record.url?scp=0033505075&partnerID=8YFLogxK
U2 - 10.1080/00288306.1999.9514858
DO - 10.1080/00288306.1999.9514858
M3 - Journal article
AN - SCOPUS:0033505075
VL - 42
SP - 513
EP - 532
JO - New Zealand Journal of Geology, and Geophysics
JF - New Zealand Journal of Geology, and Geophysics
SN - 0028-8306
IS - 4
ER -
ID: 208730041