The Norfolk Ridge: A Proximal Record of the Tonga‐Kermadec Subduction Initiation

Collot, Julien; Sutherland, Rupert; Étienne, Samuel; Patriat, M.; Roest, W. R.; Marcaillou, Boris; Clerc, Camille; Stratford, W.; Mortimer, Nick; Juan, Caroline; Bordenave, A.; Schnürle, Philippe; Barker, Dan; Williams, S.; Wolf, Sylvie; Crundwell, Martin P.

doi:10.1029/2022gc010721

Cited by 2 publications

(3 citation statements)

References 128 publications

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“…The acoustic basement of North Zealandia has been imaged in many seismic reflection projects (e.g., Bache et al., 2012; Collot et al., 2023; Gallais et al., 2019; Higgins et al., 2015; Klingelhoefer et al., 2007). In most cases, the isotropic and diffractive nature of acoustic basement indicates the presence of widespread crystalline basement (plutonic, metamorphic and/or complexly deformed sedimentary and/or volcanic rocks).…”

Section: Discussionmentioning

confidence: 99%

“…In most cases, the isotropic and diffractive nature of acoustic basement indicates the presence of widespread crystalline basement (plutonic, metamorphic and/or complexly deformed sedimentary and/or volcanic rocks). However, sporadically observed intra‐basement reflectors suggest the presence of some sub‐horizontally bedded sedimentary terranes (e.g., Bache et al., 2012; Collot et al., 2023; Klingelhoefer et al., 2007). Given the variability in quality of seismic surveys, and variable thickness of sedimentary basins we have not used seismic character to map North Zealandia basement (but see Section 6.1.2 below).…”

Section: Discussionmentioning

confidence: 99%

“…Seismic reflection profiles are generally of more use in outlining sedimentary basins than in subdividing or defining crystalline basement units (Section 6.5). However, intra‐basement seismic reflectors under the Reinga Basin, Norfolk Ridge and southern New Caledonia Trough have previously been correlated with the generally flat‐lying Murihiku Terrane fore‐arc basin strata of the Eastern Province (Bache et al., 2012; Collot et al., 2023; Uruski, 2023). Collectively the sample and seismic data support the case that Eastern Province terranes and their equivalents underlie the entire eastern basement of North Zealandia.…”

Section: Discussionmentioning

confidence: 99%

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Reconnaissance Basement Geology and Tectonics of North Zealandia

Mortimer,

Williams,

Seton

et al. 2023

Tectonics

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New rock dredge samples supply key information to establish the tectonic and geological framework of the northern two‐thirds of the 95% submerged Zealandia continent. The R/V Investigator voyage IN2016T01 to the Fairway Ridge, Coral Sea, obtained poorly sorted poly‐lithologic pebbly to cobbly sandstones, well sorted fine grained sandstones, mudstones, bioclastic limestones, and basaltic lavas. Post‐cruise analytical work comprised petrography, whole rock geochemical and Sr and Nd isotopic analyses, and U‐Pb zircon, Rb‐Sr, and Ar‐Ar geochronology. A Fairway Ridge cobbly sandstone has a ∼95 Ma (early Late Cretaceous) depositional age; two biotite granite cobbles are 111 ± 1 and 128 ± 1 Ma in age, and some volcanic pebbles are also likely Early Cretaceous. Fairway Ridge basalts have intraplate alkaline chemistry and are of Late Eocene age (∼40–36 Ma). By analogy with South Zealandia, we interpret strong positive continental magnetic anomalies of North Zealandia to mainly result from Late Cretaceous to Cenozoic intraplate basalts, many of them rift‐related lavas. A new basement geological map of North Zealandia shows the position of the Mesozoic Gondwana magmatic arc axis (Median Batholith) and other major geological units. This study completes onland and offshore reconnaissance geological mapping of the entire 5 Mkm2 Zealandia continent.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Reconnaissance Basement Geology and Tectonics of North Zealandia

Mortimer,

Williams,

Seton

et al. 2023

Tectonics

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Stress State and Earthquake Triggering on the Outer Rise of the Southern Vanuatu Subduction Zone, Southern New Caledonia

Chin,

Sutherland,

Savage

et al. 2023

Bulletin of the Seismological Society of America

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An analysis of earthquakes recorded in southern New Caledonia (SNC) over 14 months during 2018–2019 reveals focal mechanisms consistent with a normal-faulting stress state. The minimum principal stress is perpendicular to the Vanuatu subduction zone (VSZ), which is 200 km away, and is highly oblique to the local topographic ridge of New Caledonia, which may induce additional tension. An Mw 7.5 earthquake occurred in VSZ on 5 December 2018, and focal mechanisms appear to be different to those before the big earthquake. Significant increase in seismicity rates in both VSZ and SNC are observed following this large earthquake. A strong correlation between local and subduction zone seismicity rates is confirmed by analyses of seismic records before and after large subduction zone earthquakes 200–350 km away during the period of 2000–2018. The local seismicity rate and seismic hazard in SNC is about four times higher immediately after a large subduction earthquake, and Omori decay returns it to background levels after about 30 days. The triggering mechanisms remains unclear, but our study provides the first observations and a framework for future work.

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The Norfolk Ridge: A Proximal Record of the Tonga‐Kermadec Subduction Initiation

Abstract: Subduction zones are the main drivers of plate tectonic motion, but where, when and how subduction initiates remains an open science question and is one of the last great unknowns of plate tectonic theory (Arculus

Cited by 2 publications

References 128 publications

Reconnaissance Basement Geology and Tectonics of North Zealandia

Reconnaissance Basement Geology and Tectonics of North Zealandia

Stress State and Earthquake Triggering on the Outer Rise of the Southern Vanuatu Subduction Zone, Southern New Caledonia

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