Strong seismic reflections and melts in the mantle of a continental back‐arc basin

Stratford, W.; Stern, T. A.

doi:10.1029/2003gl019232

Cited by 70 publications

(100 citation statements)

References 26 publications

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“…An increase in velocity beneath this region might cause a similar reflection; Harrison and White (2004) deduced that a 16 km-thick quartzo-feldspathic crust is underlain to ~30 km depth beneath the Central North Island by a mafic material containing at least 2% partial melt. In contrast, Stratford and Stern (2004) reported an increase in seismic velocity for the same depth interval beneath the region and suggested that the velocity structure from 16 to 30 km depth represents the presence of anomalously low-velocity upper mantle. Another possible factor is that of reflection due to lateral variations in crustal structure (i.e.…”

Section: Results and Discussion A Attenuation Functionmentioning

confidence: 83%

Estimation of S Waves Attenuation in the Central North Island, New Zealand Using the Non-Parametric Generalized Inverse Technique (Git).

Syuhada¹

2010

J.Ris.Geo.Tam

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We used regional earthquakes records (M l = 2-3.8) with the distance range of 5-55 km in order to estimate the quality factor Q of S-waves in the Central North Island, New Zealand. The non-parametric GIT method with bootstrap inversion was applied to separate the attenuation function from site and source effects. We obtained attenuation function for a set of 20 frequencies ranging between 2 and 10 Hz. The values of Q extracted from the attenuation functions provided values of strong frequencydependent relation, Q s (f)= 6.15±1.22f 1.73±0.12 . The low Q with strong frequency dependence obtained is consistent to that obtained for other volcanic regions.

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Section: Results and Discussion A Attenuation Functionmentioning

confidence: 83%

Estimation of S Waves Attenuation in the Central North Island, New Zealand Using the Non-Parametric Generalized Inverse Technique (Git).

Syuhada¹

2010

J.Ris.Geo.Tam

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“…Reyners et al 2006;Sherburn et al 2003Sherburn et al , 2006, explosion seismology (e.g. Harrison & White 2004;Stratford & Stern 2004 and magnetotelluric studies (Ogawa et al 1999).…”

Section: Subsurface Structure Of Tvzmentioning

confidence: 98%

“…2) within the mantle wedge (Stratford & Stern 2004), but Harrison & White (2004) believe this simply represents the base of the under-plated basaltic crust. This may reflect a pool of magma within the mantle wedge.…”

Section: Subsurface Structure Of Tvzmentioning

confidence: 99%

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Caldera volcanism and rift structure in the Taupo Volcanic Zone, New Zealand

Cole

Spinks²

2009

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The Taupo Volcanic Zone (TVZ) is an active continental volcanic arc/back-arc basin in central North Island, New Zealand. It is the youngest area of volcanic activity that extends southwards from the Coromandel Volcanic Zone (CVZ), where andesitic volcanism began c. 18 Ma and rhyolitic volcanism c. 10 Ma. It is an extensional basin (average c. 8 mm a 21 ) with numerous, predominantly normal (dip .608) faults within the Taupo Rift, but with some strike-slip component. TVZ can be divided into three parts. In the north (Whakatane Graben -Bay of Plenty) and south (Tongariro volcanic centre) volcanism is predominantly andesitic, while in the central part it is predominantly rhyolitic. This central area comprises eight caldera centres; the oldest of which (Mangakino caldera; 1.62-0.91 Ma) may be transitional between CVZ and TVZ. Kapenga caldera (c. 700 ka) is completely buried by younger volcanics, but is probably a composite structure with most recent subsidence related to volcano-tectonic processes. Of the remaining five caldera centres, Rotorua, Ohakuri and Reporoa are all simple, sub-circular structures which collapsed c. 240 ka, and are each associated with one ignimbrirte outflow sheet (Mamaku, Ohakuri and Kaingaroa, respectively). Okataina and Taupo are caldera complexes with multiple ignimbrite eruptions and phases of collapse. The three simple calderas are extra-rift, occurring outside the main fault zone in the centre of the Taupo Rift system, while the two caldera complexes are both intra-rift. There is a close relationship between volcanism and structure in TVZ, and many of the structural caldera boundaries have rectangular geometry reflecting the fault pattern. Intrusion of high-alumina basalts as dykes, parallel to the fault trend, may have had a strong influence in causing rhyolitic eruptions in central TVZ.

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“…associated with the volcanism are crustal thinning (Harrison & white 2004;Stratford & Stern 2004) and active extension (wallace et al 2004) with a measured extension rate in the vicinity of lake Taupo of 9 ± 3 mm/yr, the motion being normal to the trend of the TVZ (darby et al 2000). South of the Mangakino caldera the zone of rifting and crustal thinning lies between bounding fault zones (kaingaroa Fault and Hauhungaroa Fault, Fig.…”

Section: Introductionmentioning

confidence: 99%

Resistivity structure of western Taupo Volcanic Zone, New Zealand

Bibby

Risk

Caldwell

et al. 2008

New Zealand Journal of Geology and Geophysics

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data from two deep-penetration electrical resistivity surveys crossing the western margin of the Taupo Volcanic Zone (TVZ) near Tihoi, northwest of lake Taupo, North island, New Zealand, have been used to identify the elements of the margin. in this vicinity the volcanologically defined boundary of the TVZ includes the andesitic cones of Pureora and Titiraupenga. The faulted margin of the TVZ lies east of these cones and is marked in the resistivity data by a dipping interface (faulted margin) between the resistive greywacke rocks to the west and the relatively conductive volcanic rocks that fill the upper few kilometres of the TVZ. The resistivity and gravity signatures of the margin are coincident in this vicinity. To the immediate east of the margin is a low-resistivity zone c. 10 km wide and 2.5 km deep. The low-resistivity material within this region is identified as old (>1 Ma) volcaniclastics that contain clays produced by low-temperature alteration and devitrification. This material is reversely magnetised. we suggest that this zone was formed following the onset of active extension of the TVZ and has since remained relatively undisturbed while the focus of volcanism and deformation has moved to the east. The eastern boundary of this low-resistivity zone coincides with the western edge of the whakamaru caldera (the boundary of the "young TVZ"). although the resistivity data can be matched using an interface with a dip to either the east or west, an eastward dip would be consistent with the boundary having been formed during the collapse associated with the formation of the whakamaru caldera. The resistivity signature within the whakamaru caldera is consistent with >2 km thickness of younger, more resistive volcanic sequences, suggesting the low-resistivity layers found to the west have been disrupted and downfaulted to be replaced with young, resistive caldera infill.

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Strong seismic reflections and melts in the mantle of a continental back‐arc basin

Cited by 70 publications

References 26 publications

Estimation of S Waves Attenuation in the Central North Island, New Zealand Using the Non-Parametric Generalized Inverse Technique (Git).

Estimation of S Waves Attenuation in the Central North Island, New Zealand Using the Non-Parametric Generalized Inverse Technique (Git).

Caldera volcanism and rift structure in the Taupo Volcanic Zone, New Zealand

Resistivity structure of western Taupo Volcanic Zone, New Zealand

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