Neogene to Quaternary evolution of carbonate and mixed carbonate-siliciclastic systems along New Caledonia's eastern margin (SW Pacific)

Tournadour, Elsa; Jorry, Stéphan; Étienne, Samuel; Collot, Julien; Patriat, M.; BouDagher‐Fadel, Marcelle K.; Fournier, François; Pelletier, Bernard; Roy, Pascal Le; Jouet, Gwénaël; Maurizot, Pierre

doi:10.1016/j.margeo.2021.106524

Cited by 3 publications

(4 citation statements)

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“…The Neogene is characterised by extensional tectonics, causing the opening of the back-arc Norfolk and North Fiji basins [51]. Intense intraplate volcanism also affected the region during this period leading to the formation of the Lord Howe Seamounts Chain [52] (Figure 1B) and of numerous isolated guyots and seamounts [53][54][55][56]. The Middle Miocene is also the time when the North-East dipping Vanuatu subduction zone initiated along the Vitiaz Lineament and rolled back to its present-day position [36,57].…”

Section: Regional Settingsmentioning

confidence: 99%

Origin and Composition of Ferromanganese Deposits of New Caledonia Exclusive Economic Zone

et al. 2022

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Located in the South-West Pacific, at the northern extremity of the mostly submerged Zealandia continent, the New Caledonian Exclusive Economic Zone (EEZ) covers 1,470,000 km² and includes basins, ridges and seamounts where abundant ferromanganese crusts have been observed. Several investigations have been conducted since the 1970s on the nature and composition of ferromanganese crusts from New Caledonia’s seamounts and ridges, but none have covered the entire EEZ. We present data from 104 ferromanganese crusts collected in New Caledonia’s EEZ during twelve oceanographic cruises between 1974 and 2019. Samples were analysed for mineralogy, geochemical compositions, growth rates, and through a statistical approach using correlation coefficients and factor analysis. Crust thicknesses range from 1 mm to 115 mm, with growth rates between 0.45 mm/Ma and 102 mm/Ma. Based on textures, structures, discrimination plots, and growth rates, we distinguish a group of hydrogenetic crusts containing the highest mean contents of Co (0.42 wt%), Ni (0.31 wt%), and high contents of Mo, V, W, Pb, Zn, Nb, from a group of hydrothermal and/or diagenetic deposits showing high mean contents of Mn (38.17 wt%), Ba (0.56 wt%) and low contents of other trace metals. Several samples from this later group have exceptionally high content of Ni (0.7 wt%). The data shows that crusts from the southern part of the EEZ, notably seamounts of the Loyalty Ridge and the Lord Howe Rise, present high mineral potential for prospectivity owing to high contents of valuable metals, and constitute a great target for further investigation.

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Section: Regional Settingsmentioning

confidence: 99%

Origin and Composition of Ferromanganese Deposits of New Caledonia Exclusive Economic Zone

et al. 2022

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“…Earthquakes are much less frequent and their maximum magnitudes are likely smaller in SNC than in the NHV (Figure 8), but tectonic stresses related to flexure of the subducting plate (Cabioch et al., 1996; Dubois et al., 1974; Flamand, 2006; Monzier et al., 1990; Pelletier, 2003) and post‐obduction isostatic processes and topographic stresses (Collot et al., 2017; Lagabrielle et al., 2005; Patriat et al., 2018; Tournadour et al., 2021) result in higher rates of earthquake activity than elsewhere in the northern Australian plate (∼3.8 M km 2 , zone 18 of Johnson et al., 2021). Our magnitude‐frequency relation for SNC suggests that the frequency of SNC earthquakes is 2.7 times of that in Johnson et al.…”

Section: Probabilistic Seismic Hazardmentioning

confidence: 99%

“…These ophiolite nappes cover southern GT and overlie deformed Late Cretaceous to Paleogene sedimentary rocks and late Paleozoic to Mesozoic basement (Maurizot, Bordenave, et al, 2020;Paris, 1981). The nappes and basement rocks are cut by high-angle normal or strike-slip faults, which were likely the result of post-obduction isostatic equilibration and topographic stress (Collot et al, 2017;Lagabrielle et al, 2005;Patriat et al, 2018;Tournadour et al, 2021). To the northeast of GT, LR is probably volcanic in origin, but exposure is limited (Guyomard et al, 1996;Lapouille, 1977).…”

Section: New Caledonia and Loyalty Ridgementioning

confidence: 99%

“…Earthquakes are much less frequent and their maximum magnitudes are likely smaller in SNC than in the NHV (Figure 8), but tectonic stresses related to flexure of the subducting plate (Cabioch et al, 1996;Dubois et al, 1974;Flamand, 2006;Monzier et al, 1990;Pelletier, 2003) and post-obduction isostatic processes and topographic stresses (Collot et al, 2017;Lagabrielle et al, 2005;Patriat et al, 2018;Tournadour et al, 2021) result in higher rates of earthquake activity than elsewhere in the northern Australian plate (∼3.8 M km 2 , zone 18 of Johnson 2021) predict that local seismic sources near Nouméa contribute significantly, but less to seismic shaking hazard for the city than those from the NHV. We re-evaluate hazard for Nouméa from local sources (our catalog) by combining probabilities of earthquake magnitude M, distance R, and exceedance of PGA:…”

Section: Probabilistic Seismic Hazardmentioning

confidence: 99%

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Earthquakes and Seismic Hazard in Southern New Caledonia, Southwest Pacific

et al. 2022

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We use 12 temporary and 9 permanent broadband seismometers that were operating for ∼400 days from October 2018 to November 2019 to generate the first published earthquake catalog and local magnitude function for southern New Caledonia (SNC). Local hypocenters mostly have depths <20 km, but east of the New Hebrides‐Vanuatu subduction zone they deepen to >100 km. Our local magnitude estimates ML for 107 earthquakes in the subduction zone are consistently 1.1 units smaller than Mw and mb over a range of Mw from 4.5 to 7.5, as determined by the United States Geological Survey. Our catalog has 460 earthquakes with Mw≥3.7 in the subduction zone and the largest event in SNC has ML 3.8. Seismicity rates in SNC are low, but ML> 5 earthquakes are 2.7 times more frequent than elsewhere in the northern Australian plate. The probability of an ML> 5 event in 50 years is 0.6 in SNC. The hazard of damaging seismic shaking in SNC is dominated by local moderate‐magnitude earthquakes, rather than large‐magnitude subduction events. The predicted peak ground acceleration for Nouméa at 10% probability of exceedance in 50 years is 0.08 g. Residual analysis of ground accelerations demonstrates that the hazard for Nouméa from subduction zone earthquakes is currently overestimated and that new regionally specific ground motion prediction equations (GMPEs) are needed. Our results highlight the inadequacy of current GMPEs in subduction zone footwall settings and the need for additional studies of this type of setting.

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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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Neogene to Quaternary evolution of carbonate and mixed carbonate-siliciclastic systems along New Caledonia's eastern margin (SW Pacific)

Cited by 3 publications

References 78 publications

Origin and Composition of Ferromanganese Deposits of New Caledonia Exclusive Economic Zone

Origin and Composition of Ferromanganese Deposits of New Caledonia Exclusive Economic Zone

Earthquakes and Seismic Hazard in Southern New Caledonia, Southwest Pacific

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

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