Asymmetric rifting in a continental back-arc environment, North Island, New Zealand

Davey, F. J.; Henrys, S. A.; Lodolo, Emanuele

doi:10.1016/0377-0273(95)00014-l

Cited by 75 publications

(52 citation statements)

References 31 publications

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“…However, the measured data could equally be modeled by a 5 F2m conductive wedge, with graywacke dipping at about 20 ø. Such a structure would be consistent with listric faulting of the basement as suggested for the offshore regions [Davey et al, 1995]. The latter model is also consistent with the expected thickness of volcanic infill into the zone of collapse associated with caldera eruptions.…”

Section: Deep Structure In the Tvzsupporting

confidence: 85%

Electrical resistivity image of the upper crust within the Taupo Volcanic Zone, New Zealand

Bibby¹,

Caldwell²,

Risk³

1998

J. Geophys. Res.

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Abstract. The Taupo Volcanic Zone (TVZ) forms a region of back-arc extension within the continental crust of New Zealand and is notable for its caldera volcanism, high rate of magmatic production, and high heat flow. On the eastern side of the TVZ, volcanism terminates abruptly along a linear margin. We present the interpretation of three multiple-source bipoledipole resistivity surveys across this margin. The major features of the measured data can be reproduced by using two-dimensional models of the resistivity in the upper 10 km of the crust. Along the margin the high-resistivity graywacke basement (300 f•m increasing to 1300 f•m) is downfaulted to the west across a zone about 6 km wide, with a total vertical offset of approximately 2 km. The easternmost fault is overlain by an unbroken 0.24 Ma ignimbrite sheet, suggesting the fault has been inactive for this period. Further to the west, at depths greater than 2 kin, a conductive zone about 15 km wide and of total conductance 180-280 S has been identified. This conductive zone can be modeled by using a range of resistivities (40-3 f•m) and thicknesses (8-2 kin). Models incorporating resistivities less than 15 f•m require the low-resistivity zone to be wedge shaped, so that conductance increases to the west. The low resistivity is believed to be caused by the presence of clay alteration within volcanoclastic rocks. The large volume of volcanic rocks at depth can be linked to a series of caldera-forming eruptions that have taken place along the eastern side of the TVZ.

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Section: Deep Structure In the Tvzsupporting

confidence: 85%

Electrical resistivity image of the upper crust within the Taupo Volcanic Zone, New Zealand

Bibby¹,

Caldwell²,

Risk³

1998

J. Geophys. Res.

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“…But the rarity of dacitic ash offshore (we record one dacitic tephra) indicates either eruptions were of low intensity, or the northern location of dacitic centres precluded much dispersal to the southerly ODP sites. With respect to the offshore parts of the main volcanic zones, geophysical data of Davey et al (1995) tentatively identify volcanic bodies east of the CVZ, and a possible caldera, at least 16 km wide, within the offshore extension of the TVZ.…”

Section: A More Continuous Recordmentioning

confidence: 99%

Deep‐ocean record of major late Cenozoic rhyolitic eruptions from New Zealand

Carter

Alloway

Shane

et al. 2004

New Zealand Journal of Geology and Geophysics

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A 12 m.y. record of large rhyolitic eruptions from the Coromandel (CVZ) and Taupo (TVZ) Volcanic Zones of New Zealand is contained in cores retrieved by Leg 181 of the Ocean Drilling Program. Site 1124, located 670 km from the TVZ, has a maximum of 134 macroscopic tephra layers with a total thickness of 13.18 m. These units, along with between 7 and 63 tephras from 3 other sites, were dated by a combination of magnetostratigraphy, biostratigraphy, isothermal plateau fission track determinations, and geochemical correlation with onshore tephra deposits. Additional time control for the last 3 m.y. came from an orbitally tuned, benthic, oxygen isotope profile for Site 1123.Results extend the incomplete terrestrial record of volcanism by placing the first major rhyolitic eruption in the CVZ at c. 12 Ma, c. 1.6-1 m.y. earlier than previously known. Tephras became thicker and more frequent from the late Miocene into the Quaternary-a trend that probably reflected (1) more frequent and intense volcanism and (2) reduced distances between sources and depositional sites on the evolving Australian/Pacific plate system. The passage from CVZ to Quaternary TVZ occurred without a major hiatus in activity, suggesting the transition was gradational. The ensuing TVZ volcanism was more continuous than known previously from the onshore geology. Ash dispersal was primarily eastward, highlighting the dominance of westerly winds since the middle Miocene. Nevertheless, variations in dispersal patterns suggest periodic changes in wind direction/speed and/or ejection of ash beyond the Roaring Forties.

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“…Strike-slip on a series of subparallel faults within the North Island Shear Belt (or North Island Dextral Fault Belt) and extension in the Taupo Volcanic Zone (Davey et al 1995) account for most of the contemporary margin-parallel motion and rotation in the Hikurangi Margin (Beanland & Haines 1998). The model presented here infers that strike-slip motion along the Hikurangi Margin and opening of the Taupo Volcanic Zone had begun by at least 2 Ma (see also Lamb 1988).…”

mentioning

confidence: 99%