Gravity interpretation profile across Hikurangi subduction zone using seismic constraints — Hawke's Bay to Hikurangi Trench

Bannister, Stephen

doi:10.1080/03036758.1989.10421842

Cited by 4 publications

(4 citation statements)

References 22 publications

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“…Marine track line data are available from the U.S. National Geophysical Data Center (http://www.ngdc.noaa.gov/mgg/geodas/trackline.html). A map of the combined onshore Bouguer anomaly and offshore free‐air anomaly data (Figure 6a) is dominated by a large NE‐SW minimum, related to the Pacific Plate subducting beneath the North Island [ Bannister , 1989; Stern et al , 1993], and positive anomalies in the north and west that relate to lithospheric structure [ Stern et al , 1987] and the lack of subsidence following deposition of recently deposited sediments offshore in the Taranaki Basin [ Holt and Stern , 1991]. In the vicinity of the Taranaki Fault, these regional long‐wavelength effects (>50 km) tend to mask the shorter wavelength anomalies associated with upper crustal structure, and have been separated by computation of regional and residual gravity fields (Figures 6b and 6c) to reveal the Taranaki Fault.…”

Section: Data Sources and Analysesmentioning

confidence: 99%

“…Earthquake hypocenters, relocated as part of the 3‐D tomographic inversion [ Reyners et al , 2006], which occur within 30 km of the lines, are shown on the models and correlate with the position of the subducting Pacific Plate beneath the North Island. Models are constructed in a similar manner to Bannister [1989] and Holt and Stern [1994], incorporating both the overriding and subducted plate structure beneath the North Island.…”

Section: Data Sources and Analysesmentioning

confidence: 99%

“…Two 2‐D gravity models across the North Island (Figure 7) are also consistent with the interpretation of an eastward dipping fault. The prominent (−100 to −150 mGal) NE‐SW minimum that dominates the gravity anomaly distribution over the North Island [ Robertson and Reilly , 1958; Bannister , 1989] occurs at the eastern end of each gravity profile (Figure 7) and follows the trend of seismicity in the subducting plate. Gravity modeling indicates that no more than about 60 mGal of this negative anomaly can be attributed to the low‐density sediments in the East Coast and Wanganui basins (Figures 6 and 8), with the remaining −50 to −100 mGal regional gravity anomaly inferred to be related to mass deficiencies beneath the sedimentary section.…”

Section: Fault Geometrymentioning

confidence: 99%

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Regional structure and kinematic history of a large subduction back thrust: Taranaki Fault, New Zealand

Stagpoole¹,

Nicol²

2008

J. Geophys. Res.

134

147

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The Taranaki Fault is a back thrust antithetic to the Hikurangi margin subduction thrust. Subduction back thrusts, like the Taranaki Fault, accrue displacement transferred from the subducting plate, and growth analyses of these structures contribute to an improved understanding of subduction processes. The Taranaki Fault forms the eastern margin of the Taranaki Basin and is part of a system that extends for at least 600 km in continental crust of western New Zealand. The fault is preserved beneath young sedimentary cover and provides a rare opportunity to investigate the geometry and kinematic history of a large subduction back thrust. Two‐dimensional seismic reflection lines (2–5 km spacing), tied to recently drilled wells and outcrop, together with magnetotelluric and gravity models are used to examine the fault. These data indicate that the fault is thick skinned with dips of 25–45° to depths of at least 12 km. The fault accommodated at least 12–15 km of dip‐slip displacement since the middle Eocene (circa 40–43 Ma). The northern tip of the active section of the fault stepped southward at least three times between the middle Eocene and early Pliocene, producing a total tip retreat of 400–450 km. The history of displacements on the Taranaki Fault is consistent with initiation of Hikurangi margin subduction during the middle Eocene, up to 20 Ma earlier than some previous estimates. Fault tip retreat may have been generated by clockwise rotation of the subduction margin and associated progressive isolation of the fault from the driving downgoing Pacific Plate.

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Section: Data Sources and Analysesmentioning

confidence: 99%

Section: Data Sources and Analysesmentioning

confidence: 99%

Section: Fault Geometrymentioning

confidence: 99%

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Regional structure and kinematic history of a large subduction back thrust: Taranaki Fault, New Zealand

Stagpoole¹,

Nicol²

2008

J. Geophys. Res.

134

147

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“…Figure 13a shows an interpretation model where the structure is taken directly from the seismic and density constraints discussed above; no load associated with the thrust belt is included. In Figure 13b Bannister 1986;1989].…”

Section: Despite the Scatter Four Important Features In The Gravity mentioning

confidence: 99%

Subduction, platform subsidence, and foreland thrust loading: The late Tertiary development of Taranaki Basin, New Zealand

Holt¹,

Stern²

1994

Tectonics

128

114

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Borehole, seismic, and gravity data are used to investigate deformation of continental lithosphere at a Miocene collisional zone. Deformation is manifested in the three following principal forms: a long wavelength (>500 km) platform subsidence ascribed to mantle convection; flexural deformation on a scale of 100–200 km due to crustal thrusting at the eastern boundary of the Taranaki Basin; and a ductile thickening, evident on the deep seismic section of Taranaki Basin, that occurs on a scale of ∼10 km. Evidence for flexural deformation principally comes from the deep seismic section that shows a 150‐km wavelength bending of the Moho down toward the major zone of thrusting within the Taranaki Fault Zone. Paleowater depths, however, provide evidence for an initial early Miocene regional subsidence that is too long in wavelength to be explained by flexure induced from thrust sheet loading. Instead, we propose that this broad "platform subsidence" was driven by loading from a deep source, probably subduction‐induced flow in the mantle. By ∼22–19 Ma, 1–2 km of water existed over most of the area now occupied by South Taranaki Basin. By ∼19–17 Ma the water depth in the zone east of the Taranaki Basin, the Taranaki Fault Zone, had been replaced by rock due to submarine thrusting and crustal thickening. This build up of submarine topography in the Taranaki Fault Zone constitutes part of the load (25±8 MPa) that created and maintains South Taranaki Basin. Gravity data place further constraints on loading at the thrust front and point to an additional intracrustal loading, equivalent to 15±7 MPa over a 50‐km‐wide zone. This intracrustal load is explained as being due to thick‐skinned thrusting bringing denser, lower‐crustal rocks nearer to the surface in the thrust zone. The complete load on the Taranaki foreland is therefore in three parts; the submarine‐topographic load, the intracrustal load, and the loading of infilling sediments.

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Double-sided onshore–offshore seismic imaging of a plate boundary: “super-gathers” across South Island, New Zealand

2002

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Gravity interpretation profile across Hikurangi subduction zone using seismic constraints — Hawke's Bay to Hikurangi Trench

Cited by 4 publications

References 22 publications

Regional structure and kinematic history of a large subduction back thrust: Taranaki Fault, New Zealand

Regional structure and kinematic history of a large subduction back thrust: Taranaki Fault, New Zealand

Subduction, platform subsidence, and foreland thrust loading: The late Tertiary development of Taranaki Basin, New Zealand

Double-sided onshore–offshore seismic imaging of a plate boundary: “super-gathers” across South Island, New Zealand

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