Oblique back arc rifting of Taupo Volcanic Zone, New Zealand

Abstract

[1] Taupo Volcanic Zone (TVZ) is a back arc rift in North Island, New Zealand. Its geometry and kinematics are investigated using shaded relief images, field examination of faults and offset stream channels. The results show that TVZ trends NNE, is $250 km long by $20 km wide and consists of five segments. Extension is principally manifest as steeply dipping (60°-90°) normal faults parallel to TVZ; these, in the last 300 kyr, have experienced a component of dextral shear. TVZ is therefore an oblique back arc rift. The dextral shear is $37% of the total displacement, which, for previously estimated spreading rates $7 mm/yr, corresponds to $2.6 mm/yr. This value is similar to previous estimates of the dextral shear from the back arc to the forearc domains in the North Island. Distributed dextral shear across TVZ thus suggests that strain partitioning across the plate boundary at latitudes of TVZ is less significant than previously thought.

Weak Tectono-Magmatic Relationships along an Obliquely Convergent Plate Boundary: Sumatra, Indonesia

“…Therefore, this study highlights a limited structural control on volcanism along obliquely convergent arcs experiencing strikeslip motions, even though this may reflect local, shallower crustal conditions. This feature is somehow intermediate between those observed in extensional arcs, where magmatism couples with the structure of the arc (as along the Taupo Volcanic Zone; Acocella et al, 2003) and shows shallow magma reservoirs (Chaussard and Amelung, 2012) and those in contractional arcs, where the arc configuration is largely independent of the shallow structural features (as in NE Honshu, Japan; Acocella et al, 2008). However, the overall lack of magmatic systems makes the strike-slip Sumatra arc more similar to the contractional ones.…”

“…Magma-assisted processes similar to those observed in rifts may occur also along magmatic arcs experiencing extension, as the Taupo Volcanic Zone of New Zealand (Acocella et al, 2003;Rowland et al, 2010;Allan et al, 2012). Indeed, the tectono-magmatic architecture of "highly" extending arcs (∼1 cm/year or more) is similar to that of moderately extending continental rifts (Acocella, 2014).…”

Intra-arc extension in Central America: Links between plate motions, tectonics, volcanism, and geochemistry

“…Evidence for extension behind the arc is a long-accepted fact in Guatemala (Burkart and Self, 1985;GuzmanSpeziale,2001;Lyon-Caen et al, 2007), where it is usually attributed to be a byproduct of the interaction of the Caribbean-North American plate boundary with the Middle American Arc. Coupled shear and extensional arc deformation have been well-documented in the tectonically analogous Taupo segment of the New Zealand subduction zone (Webb and Anderson, 1998;Acocella et al, 2003). Arc-normal extension is also well known to have been associated with rifting and ultimate splitting of the oceanic Marianas Arc to create the modern Marianas back-arc spreading center at~6Ma (Taylor and Karner, 1983), even earlier splitting of the proto-Marianas arc at~30Ma to create the relict Kyushu-Palau Ridge (Taylor and Karner, 1983), and similar splitting of the Lau-Tonga Arc at~6Ma to create the relict Lau Ridge (Weissel, 1977).…”

Potential impact of ash eruptions on dairy farms from a study of the effects on a farm in eastern Bay of Plenty, New Zealand; implications for hazard mitigation

“…Most eruptions from the OCC in the past 22,000 years have been rhyolitic, although there is some uncertainty whether this trend is expected to continue with increasing basaltic interaction (Nairn et al, 2004;Acocella et al, 2003). Future eruptive episodes are likely to follow past activity with multiple vent localities, potentially across the 10 km of either vent zone, and confined to one vent zone (Haroharo or Tarawera; Nairn, 2002).…”