Late Quaternary evolution of a hyperactive rhyolite magmatic system: Taupo volcanic centre, New Zealand

Abstract

Taupo volcanic centre has been active for c. 300 000 years. Since the c. 26.5 ka caldera-forming Oruanui eruption 28 eruptions have occurred from Taupo, varying between 0.1 and >45 km 3 in minimum bulk volume, and with repose periods ranging from c. 20 to 6000 years. All magma erupted post-26.5 ka is compositionally and mineralogically distinct from pre-Oruanui and Oruanui eruptives, and is inferred to have formed at or after 26.5 ka. Four post-Oruanui magma types are identified on the basis of whole rock and mineral compositions: one dacitic, forming three eruptions between 20.5 ka and 17 ka, and three subtly distinct rhyolite compositions erupted in discrete periods from 11.8 to 9.95, 7.05 to 2.75 and 2.15 to 1.74 ka. Stepwise compositional variations between, and limited variation within, rhyolite groups suggest emplacement of three petrogenetically separate batches of magma within only 10 000 years. The 15-35 km 3 of magma erupted at 1.77 ka evidently appeared in <10 3 years; this short residence time may have contributed to the lack of zonation within this magma chamber. Taupo is unusual amongst large rhyolite volcanoes in terms of the high frequency of activity since 26.5 ka, rapid stepwise changes in rhyolite compositions, and insignificant differentiation within individual subgroups. These traits are attributed to the combined effects of the extensional arc setting, thermal energy from mafic magma, and the shallow slope of the plagioclase-saturated rhyolite liquidus.

Tephrostratigraphy and geochemical fingerprinting of the Mangaone Subgroup tephra beds, Okataina Volcanic Centre, New Zealand

“…At the Taupo Volcanic Centre, the eruption of the large-volume 26 ka Oruanui event was followed by a change in the glass and mineral chemistry, and T-fO 2 of the subsequent tephra beds (Shane 1998(Shane , 2000Sutton et al 2000), suggesting a new magma source had recharged the chamber. The eruptions that predate the Mangaone Subgroup, Rotoehu Tephra, and the associated large-volume Rotoiti Ignimbrite, and Earthquake Flat tephra beds, are compositionally (Fig.…”

Tephrochronology and its application: A review

“…Analyses have tended to be undertaken (typically on pumices) mainly to help explain magmatic processes (e.g., Arakawa et al, 1998;Sutton et al, 2000;Schmitz and Smith, 2004;Snyder et al, 2004). Sr isotopes were assayed on glass shards in two of the late Quaternary…”

“…Taupo-derived tephras studied by Sutton et al (2000). In Antarctica, Basile et al (2001) used Sr and Nd isotopes, together with major-and trace-element data, of glass from 15 visible tephras in the Vostok core to identify their sources (Antarctic Peninsula, West Antarctica, southern South America, South Sandwich Islands) and to help model past atmospheric circulation processes.…”

Fine-scale temporal recovery, reconstruction and evolution of a post-supereruption magmatic system

“…The first post-Oruanui eruptions (21-17 ka) were dacitic and erupted from the northern segment of the Oruanui caldera (units Ψ, Ω and A). The remaining eruptions are clustered into three temporally and chemically distinct rhyolitic subgroups (SG1-3), erupted from multiple vents in discrete periods from 11.8 to 9.95 ka (SG1: units B-E), 7.05-2.75 ka (SG2: units F-W) and 2.15-1.8 ka (SG3: units X-Z) (Sutton et al 1995(Sutton et al , 2000 Fig. 1; Table 1).…”