Mapping the Moho beneath the Southern Alps continent‐continent collision, New Zealand, using wide‐angle reflections

Henrys, S. A.; Woodward, D. J.; Okaya, D. A.; Yu, Jianhua

doi:10.1029/2004gl020561

Cited by 20 publications

(16 citation statements)

References 18 publications

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“…The lower crust, on the other hand, with no place to escape (at least in the central areas of both regions), thickens to produce a crustal root. In both cases, volumes of the crustal roots appear consistent with estimated total convergence [Godfrey et al, 2002;Henrys et al, 2004].…”

Section: Tectonicssupporting

confidence: 66%

A comparison between the transpressional plate boundaries of South Island, New Zealand, and southern California, USA: The Alpine and San Andreas Fault Systems

Fuis

Kohler

Scherwath

et al. 2007

A Continental Plate Boundary: Tectonics at South Island, New Zealand

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Section: Tectonicssupporting

confidence: 66%

A comparison between the transpressional plate boundaries of South Island, New Zealand, and southern California, USA: The Alpine and San Andreas Fault Systems

Fuis

Kohler

Scherwath

et al. 2007

A Continental Plate Boundary: Tectonics at South Island, New Zealand

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“… Van Avendonk et al [2004] calculate, based on the two‐dimensional (2‐D) crustal structure obtained along transect 2, that total amount of crustal shortening is around 80–100 km. Henrys et al [2004] define a partial 3‐D image of the Moho in the central portions of the South Island using seismic reflections, and find a pronounced crustal root approximately 80 km wide, with maximum Moho depth of 45 km on transect 2. Local three‐dimensional lithospheric velocity models are developed for subduction regions of Fiordland [ Eberhart‐Phillips and Reyners , 2001] and Hikurangi [ Eberhart‐Phillips and Reyners , 1997].…”

Section: Introductionmentioning

confidence: 99%

“…In this paper we present a three‐dimensional model of crustal thickness observed on an extensive set of more than 700 receiver functions calculated for 42 stations in permanent New Zealand National Seismic Network (NZNSN) and temporary SAPSE network. This model is based on a direct observation and mapping of P‐to‐S conversion from Moho interface, and as such represents an extension of previous 2‐D and partial 3‐D models, such as ones presented by Scherwath et al [2003], Van Avendonk et al [2004], Henrys et al [2004], and Godfrey et al [2001]. It provides important additional constraints on the 3‐D crustal structure of the South Island, since previous full 3‐D models were defined using traveltime tomography and utilizing first arrivals only [e.g., Kohler and Eberhart‐Phillips , 2002; Eberhart‐Phillips and Bannister , 2002] and were not necessarily based on direct observations of velocity discontinuities, but rather definition of Moho interface from an isovelocity surface.…”

Section: Introductionmentioning

confidence: 99%

Crustal structure and apparent tectonic underplating from receiver function analysis in South Island, New Zealand

Spasojevic¹,

Clayton²

2008

J. Geophys. Res.

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[1] We utilize seismic converted phases on more than 700 receiver functions calculated for 42 stations in the South Island, New Zealand, to infer crustal and uppermost mantle structure. We determine the crustal thickness from direct observations of conversion from the Moho interface and infer zone of the maximum thickness being located along the axis of the Southern Alps, just east from the Alpine fault. The crustal root widens from north to south in the direction perpendicular to the Alpine fault and appears to have an asymmetric structure. Stations in the alpine portion of island show evidence for prominent midcrustal conversions. Significant crustal thickening is developed in response to both the convergent component of the motion on the Alpine fault and subduction in the Fiordland region. We propose two models for a strong uppermost mantle conversion that occurs at depths between 33 and 83 km on 16 stations and forms a large continuous feature along the east coast and in the central portions of the South Island. Our preferred model attributes upper mantle conversion to tectonically underplated oceanic crust formed by late Oligocene-Miocene spreading between the Australian and Pacific plates, which was detached from the Australian plate and tectonically underplated under the South Island. An alternative model attributes the upper mantle conversions to long-lived seismic fabric created by subduction of the Gondwanaland margin.

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“…These differences may partially be due to the different analysis techniques used; for example the dip of the Moho on the western side of the root is much less in T1 but wide-angle CDP stacked images along both profiles suggest that the dip on T1 is steeper than as modelled on the wide-angle velocity models (Henrys et al, 2004).…”

Section: Structure Of the Orogenmentioning

confidence: 94%

Geophysical structure of the Southern Alps Orogen, South Island, New Zealand

Davey

Eberhart‐Phillips

Kohler

et al. 2007

A Continental Plate Boundary: Tectonics at South Island, New Zealand

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The central part of the South Island of New Zealand is a product of the transpressive continental collision of the Pacific and Australian plates during the past 5 million years, prior to which the plate boundary was largely transcurrent for over 10 My.Subduction occurs at the north (west dipping) and south (east dipping) of South Island. The deformation is largely accommodated by the ramping up of the Pacific plate over the Australian plate and near-symmetric mantle shortening. The initial asymmetric crustal deformation may be the result of an initial difference in lithospheric strength or an inherited suture resulting from earlier plate motions.Delamination of the Pacific plate occurs resulting in the uplift and exposure of midcrustal rocks at the plate boundary fault (Alpine fault) to form a foreland mountain chain. In addition, an asymmetric crustal root (additional 8 -17 km) is formed, with an underlying mantle downwarp. The crustal root, which thickens southwards, comprises the delaminated lower crust and a thickened overlying middle crust. Lower crust is variable in thickness along the orogen, which may arise from convergence in and lower lithosphere extrusion along the orogen. Low velocity zones in the crust We first review the range of geophysical data available for the South Island.These data are then used to define the main features of the three-dimensional structure of the orogen and provide the context for the detailed structure and development of the plate boundary zone as defined by the Alpine Fault. The chapter closely complements the previous chapter on the geological data base for the South Island, and uses those and other data to constrain its inferences. The conclusions of the In the south, the mountains are also lower, reaching maximum elevations of about 2500 m, and broader, covering most of the southern South Island (Figure 3c). The morphology of the region is less two-dimensional and reflects the grain of the geology that swings around from a NNE to a ESE trend. The Alpine Fault is a more subdued morphological feature, but it is still remarkably linear until it runs offshore at MilfordSound.

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Mapping the Moho beneath the Southern Alps continent‐continent collision, New Zealand, using wide‐angle reflections

Cited by 20 publications

References 18 publications

A comparison between the transpressional plate boundaries of South Island, New Zealand, and southern California, USA: The Alpine and San Andreas Fault Systems

A comparison between the transpressional plate boundaries of South Island, New Zealand, and southern California, USA: The Alpine and San Andreas Fault Systems

Crustal structure and apparent tectonic underplating from receiver function analysis in South Island, New Zealand

Geophysical structure of the Southern Alps Orogen, South Island, New Zealand

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