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Nouméa, New Caledonia

Folcher N.,CNRS Matter and Environment Multidisciplinary Research | Sevin B.,CNRS Matter and Environment Multidisciplinary Research | Quesnel F.,Bureau de Recherches Geologiques et Minieres | Quesnel F.,CNRS Earth Sciences Institute of Orleans | And 4 more authors.
Australian Journal of Earth Sciences | Year: 2015

The poorly studied iron-rich terrestrial sediments, referred to as the Fluvio-lacustrine Formation, that crop out in the southern part of the Grande Terre of New Caledonia document the last 25 Ma of the geological history of the island. The age of this formation, which is mainly derived from the erosion of an ultramafic regolith, is not tightly constrained yet; however, it has recorded several episodes of post-obduction erosion and sedimentary infill preceded and followed by weathering and reactivated erosion. A correlation with early Miocene slab break-off, which may have triggered a first stage of erosion marked by coarse conglomerate, is suggested. Thereafter, sediments filled topographic lows and were in turn weathered during an interval of tectonic quiescence. Finally, Holocene sea-level drop and southward tilt of southern New Caledonia, owing to the involvement of eastern Australian Plate in the New Hebrides (Vanuatu) subduction zone, locally changed the drainage pattern and deeply eroded the sediments. © 2015 Geological Society of Australia.

Chevrel S.,Bureau de Recherches Geologiques et Minieres | De Boissieu F.,IRD | Sevin B.,Geological Survey of New Caledonia | Despinoy M.,IRD | And 3 more authors.
EAGE/GRSG Remote Sensing Workshop | Year: 2012

Recently, regolith mapping based on hyperspectral remote sensing has stirred up a growing interest, in particular for mining exploration purposes. For an island like New Caledonia, which nickel resources are one of the most abundant on Earth, and which economy is mainly based on nickel exploitation, regolith mapping is of first interest. In 2010 airborne hyperspectral remote sensing data were acquired for the first time over several mining sites of New Caledonia. At the same time, field spectrometradiometric measurements were made on the same sites. One site was selected to evaluate the potential of airborne hyperspectral remote sensing for the mapping of the regolith. Combining the analysis of the field measurements and the processing of the airborne data, we managed to map the regolith with great results. In the following we present broadly the geological context of New Caledonia, the dataset acquired, the method developped and the results.

Sevin B.,Geological Survey of New Caledonia | Sevin B.,CNRS Matter and Environment Multidisciplinary Research | Cluzel D.,CNRS Matter and Environment Multidisciplinary Research | Maurizot P.,Bureau de Recherches Geologiques et Minieres | And 6 more authors.
Tectonics | Year: 2014

A lower Miocene coarse conglomerate that crops out in the Népoui Peninsula does not represent the base of the marine transgression that followed obduction in New Caledonia. Instead, the conglomeratic alluvial fan that contains peridotite cobbles and reworked weathering products records a short-lived episode of terrestrial erosion intercalated between two intervals of subsidence marked by marine carbonate deposition. Considering the Miocene sea level evolution reported in the literature, it is concluded that neither lower Miocene transgression nor erosion were driven by sea level variation. In contrast, a southeastward propagating slab tear that initiated at the latitude of the high pressure/low temperature metamorphic complex of northern New Caledonia likely generated east to west tilting of New Caledonia, subsidence along the West Coast and hence fringing reef development together with moderate erosion of older regolith. Coincidence between conglomerate deposition and hence prominent erosion that closely followed emplacement of postobduction granitoids influenced by a slab window suggests a genetic link. Therefore, it is concluded that short-lived lower Miocene erosion was due to slab breakoff and subsequent uplift that occurred at ∼ 22 Ma. Lower Miocene erosion profoundly dissected the Peridotite Nappe and in the northern half of New Caledonia only left isolated klippes along the West Coast. ©2014. American Geophysical Union.

Sevin B.,Geological Survey of New Caledonia | Sevin B.,CNRS Matter and Environment Multidisciplinary Research | Ricordel-Prognon C.,Bureau de Recherches Geologiques et Minieres | Quesnel F.,Bureau de Recherches Geologiques et Minieres | And 3 more authors.
Terra Nova | Year: 2012

Comparing palaeolatitudes estimated from remanent magnetization data of ferricrete developed over laterite at two sites (Goro and Tiébaghi) against the apparent polar wandering path of Australia provides new time constraints for the peridotite weathering in New Caledonia. The Tiébaghi Massif of the West Coast klippes displays a single episode of ferricrete development during latest Oligocene times. By contrast, the Goro site in the southern part of the 'Massif du Sud' reveals a more complex history with several episodes of ferricrete development from latest Oligocene to Pliocene-Quaternary times. These data have made it possible to constrain the post-obduction geodynamics and associated morphogenesis of New Caledonia since related uplift probably prevented regolith development until latest Oligocene times. Moreover, the later uplift and deep erosion of the West Coast klippes during the Early Miocene probably prevented further regolith preservation. © 2011 Blackwell Publishing Ltd.

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