Caledonia Region Research Articles

Additional records of bathyal ascidians (Tunicata) from the New Caledonia region

Two expeditions EXBODI (2011) and SPANBIOS (2021) sampled the invertebrate fauna of deep bottoms on each side of New Caledonia. Many ascidians were collected and the most part are already known species. Among the 13 species described and figured, two are new to science. All have typical characters of a deep habitat. Variability of the internal anatomy is described for abundant specimens of the same species from the same location. There is no concordance with the littoral ascidian fauna.

Distribution and abundance of leptocephali in the western South Pacific region during two large-scale sampling surveys

Although juvenile anguillid eels live in freshwater/estuarine habitats, and marine eels live in diverse ocean environments ranging from shallow-to-deep continental shelf areas and around islands to deep-benthic habitats and deeper meso- and bathy- pelagic zones, the larvae (leptocephali) of all species mix together in the ocean surface layer. All types of eel habitats are present in the western South Pacific (WSP), so it is a unique region for studying long-lived leptocephali, especially because the westward flowing South Equatorial Current (SEC) and several countercurrents pass through many different WSP island groups and deep waters where both anguillid and marine eels live and spawn. Large mouth-opening IKMT sampling surveys for leptocephali were conducted in the southwest Pacific extending to French Polynesia in Jan-Mar 2013 (99 tows, 78 stations, 1052 larvae) and Jul-Sept 2016 (187 tows, 111 stations, 3976 larvae) that collected about 152 species of 18 anguilliform and elopomorph families. The larvae of mesopelagic serrivomerid eels were the most abundant taxa in all oceanic areas, and they were particularly abundant at northern SEC or equatorial latitudes. Australian and New Zealand anguillid eels had spawned in the western SEC areas, as previously detected, and the larvae of tropical anguillids were also only caught in western areas. The larvae of the mesopelagic nemichthyid and derichthyid eels were also widely distributed at lower abundances and with more patchy distributions, but larvae of Eurypharyngidae, Cyematidae, and Monognathidae were rare. Shallow-water eel larvae were most abundant west of New Caledonia near the banks of the Chesterfield Islands, or near other island-groups, but they were rare in the 2 easternmost 2016 transects passing by both sides of Tahiti. Some conger eels were suggested to have spawned in offshore areas in the western region. Congrid Ariosoma and various shallow-water or slope eels had spawned in the region near the Chesterfield Islands or near New Caledonia where current jets can transport larvae westward, and eastward countercurrents exist. Some taxa of larvae of coastal species (muraenesocids, and elopomorphs) were extremely rare, all non-mesopelagic eel larvae were rare in the far-eastern transects, but the New Caledonia region with large shelf areas appears to be a high biodiversity region for marine eels, as it is for reef/shore fish in general.

An integrative study of some species of Gonaxia Vervoort, 1993 from off New Caledonia, with the establishment of Gonaxiidae as a new family of thecate hydroids (Cnidaria: Hydrozoa).

Ten species belonging to the genus Gonaxia Vervoort, 1993 occur in recent collections gathered by KANACONO (2016), KANADEEP (2017) and KANADEEP 2 (2019) expeditions of the French Tropical Deep-Sea Benthos Program in deep waters of the New Caledonian region. They were studied using the classical, morphological approach, supplemented by the first genetic characterization of the genus undertaken so far. Two species are previously undescribed, namely G. incisa Galea, sp. nov. and G. solenoscyphoides Galea, sp. nov. Additional notes on the remaining species are provided, notably the discovery of the female gonothecae of G. crassicaulis Vervoort, 1993 and G. perplexa Vervoort, 1993. Lofty colonies, with distinctive cladia-bearing branches spirally-arranged around the stem, assignable to the recently-described G. plumularioides Galea, 2016 actually represent fully-developed colonies of G. errans Vervoort, 1993, as demonstrated using molecular markers, the latter nominal species having priority. Its unusual, club-shaped, longitudinally-ridged gonothecae, fully free from the stem, are described for the first time. Supplementary notes on the hydrotheca of G. crassicaulis Vervoort, 1993 are provided, together with the description of a distinctive gutter of perisarc channeling the coenosarc of the colony along the lumen of both the stem and cladia. A multi-locus phylogenetic hypothesis of the Macrocolonia supports the establishment of the family Gonaxiidae Maggioni, fam. nov., to accommodate the species dealt with herein.

New records of deep-sea ascidians (Tunicata, Ascidiacea) from the New Caledonia region.

The deep marine bottoms around New Caledonia have been explored for forty years. The Kanacono (2016) and Kanadeep (2019) campaigns organized jointly by the Musum national dHistoire naturelle (MNHN) and the Institut de Recherche pour le Dveloppement (IRD) are the complement of this investigation. They are a part of the program La Plante Revisite in New Caledonia. Among the deep sea benthos twenty two ascidian species were collected and three represent new species showing the characteristic adaptations to an abyssal life. The high diversity of the tropical deep sea benthos is enhanced by these new results. No relations are found between littoral ascidians and forms living in the bathyal or abyssal areas.

Influence of Subseasonal Variability on the Diurnal Cycle of Precipitation on a Mountainous Island: The Case of New Caledonia

Abstract The relationship between the large-scale intraseasonal variability, synoptic wind regimes, and the local daily variability of precipitation over the main island of New Caledonia (southwest tropical Pacific) is investigated with a focus on the austral summer wet season (November–April). The average diurnal cycle of precipitation over the island is characterized by a sharp afternoon maximum around 1600 local time, with significant differences between the windward east coast, the leeward west coast, and the mountain range. The afternoon peak is related to the afternoon sea-breeze circulation and to the diurnal cycle of convection over land. In general, its magnitude follows the same evolution as the daily mean. In agreement with past studies, a clear modulation of the Madden–Julian oscillation (MJO) on both the diurnal cycle of precipitation and the probability of occurrence of four robust wind regimes can be identified in the New Caledonia region during the wet season. From the evidence that there is a qualitative correspondence between the effects of both the MJO phases and the wind regimes on features in the diurnal cycle of precipitation, a simple model is proposed to inspect the MJO forcing mediated by wind regimes on the diurnal variability of rain. The complete decomposition of the MJO impact shows that the modulation of diurnal cycle by the MJO relies on complex interactions between the MJO and synoptic winds that involve both large-scale MJO convective anomalies and MJO-induced modification of wind patterns.

Three new species of Tridentella Richardson, 1905 (Isopoda: Cymothoida: Tridentellidae) from New Caledonia.

Three new species of Tridentella Richardson, 1905 are described from the New Caledonia region. All three species are smooth bodied or largely smooth bodied, and all were collected from the shelf around New Caledonia at depths from 150-760 metres. Tridentella palmata sp. nov. is characterised by pereopod 4 having numerous large robust setae on the carpus and an exceptionally long dactylus (7.0 times as long as proximal width); Tridentella katlae sp. nov. is the only species in the genus with medially united eyes that fill the head in dorsal view; Tridentella magna sp. nov. is the largest species in the genus (36 mm) and can be identified by the head having an anterior submarginal ridge and three submarginal tubercles on the poster margin. Tridentella takedai Nunomura 2006 (off Arasaki, Hokusuka-Shi, Kyushu, Japan) is formally transferred to Alcirona Hansen, 1905, forming Alcirona takedai (Nunomura, 2006) comb. nov.

Checklist of recent brachiopod species collected during the Terrasses and Exbodi cruises in the New Caledonian region, SW Pacific.

Twenty species belonging to 16 genera, i.e. Neoancistrocrania, Novocrania, Basiliola, Basiliolella, Ebiscothyris, Stenosarina, Kanakythyris, Xenobrochus, Terebratulina, Eucalathis, Fallax, Frenulina, Septicollarina, Campages, Annuloplatidia, and Thecidellina have been identified in the material collected during the Terrasses and Exbodi cruises in the New Caledonian region, SW Pacific. The species Basiliolella grayi (Woodward, 1855) and Fallax neocaledonensis Laurin, 1997 are the most common in the studied collection, while Eucalathis murrayi (Davidson, 1878) is reported for the first time from the New Caledonian region.

TAPHONOMY OF BACKSHORE VERSUS DEEP-MARINE COLLECTED NAUTILUS MACROMPHALUS CONCHS (NEW CALEDONIA)

Abstract The extant Nautilus nowadays exclusively lives in the Indo-Pacific Ocean along the slopes of coral reefs, mainly in water depths of 300–400 m. It possesses a complex gas-liquid combined system to regulate its buoyancy in the water column. After death this system is lost and the shells become either positively or negatively buoyant and float for some time or respectively sink to the seafloor where taphonomic processes strongly influence the shell’s condition. A major process in taphonomy is bioerosion. We present herein a detailed study of the influence of taphonomic pathways on bioerosion in backshore collected and deep-water dredged Nautilus shells from the New Caledonia region. Some bioerosion of Nautilus shells may take place during life but most occurs after death and deposition of the shell. The ichnocoenosis found in the shells collected in backshore settings indicates that these shells were positively buoyant after the death of the animals and were initially deposited in a nearshore enviro...

Enigmatic ophiuroids from the New Caledonian region

O’Hara, T.D. and Harding, C. 2015. Enigmatic ophiuroids from the New Caledonian region. Memoirs of Museum

Eocene and Oligocene basins and ridges of the Coral Sea-New Caledonia region: Tectonic link between Melanesia, Fiji, and Zealandia

This paper presents 34 geochemical analyses, 24 Ar-Ar ages, and two U-Pb ages of igneous rocks from the back-arc basins and submarine ridges in the Coral Sea-New Caledonia region. The D'Entrecasteaux Ridge is a composite structural feature. Primitive arc tholeiites of Eocene age (34–56 Ma) are present along a 200 km length of the ridge and arguably were part of the initial line of subduction inception between Fiji and the Marianas; substantial Eocene arc edifices are only evident at the eastern end where Bougainville Guyot andesite breccias are dated at 40 ± 2 Ma. The South Rennell Trough is confidently identified as a 28–29 Ma (early Oligocene) fossil spreading ridge, and hence, the flanking Santa Cruz and D'Entrecasteaux basins belong in the group of SW Pacific Eocene-Early Miocene back-arc basins that include the Solomon Sea, North Loyalty, and South Fiji basins. The rate and duration of spreading in the North Loyalty Basin is revised to 43 mm/yr between 28 and 44 Ma, longer and faster than previously recognized. The direction of its opening was to the southeast, that is, parallel to the continent-ocean boundary and perpendicular to the direction of coeval New Caledonia ophiolite emplacement. Medium- and high-K alkaline lavas of 23–25 Ma (late Oligocene) age on the northern Norfolk Ridge are an additional magmatic response to Pacific trench rollback.

New records and new species of Ophiuroidea (Echinodermata) from Lifou, Loyalty Islands, New Caledonia

New Caledonia is a species-rich region that has been the focus of biodiversity research for over 40 years. The expedition “Atelier Lifou 2000” collected benthic fauna at the island of Lifou, Loyalty Islands, New Caledonia, in November of 2000. This is a taxonomic account of the brittle stars found. 94 species were identified, 51 of them new for the region, and seven new to science, increasing the total number of species known from the New Caledonia region to 204. New species are described in the genera Squamophis, Astroceras, Astrogymnotes, Ophiochondrus, Ophiomoeris, Ophiozonella and Amphipholis. Three species and a subspecies are revised, one of them placed in a new genus. The taxonomic status of Euryale Lamarck, 1816, a junior homonym of Euryale Péron & Lesueur, 1810 (a medusa), is stabilized by formally establishing precedence over the senior name.

New Caledonian carbon sinks at the onset of Antarctic glaciation

Research Article| September 01, 2011 New Caledonian carbon sinks at the onset of Antarctic glaciation Douglas N. Reusch Douglas N. Reusch Department of Geology, University of Maine at Farmington, 173 High Street, Farmington, Maine 04938, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Douglas N. Reusch Department of Geology, University of Maine at Farmington, 173 High Street, Farmington, Maine 04938, USA Publisher: Geological Society of America Received: 09 Dec 2010 Revision Received: 24 Mar 2011 Accepted: 28 Mar 2011 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2011 Geological Society of America Geology (2011) 39 (9): 807–810. https://doi.org/10.1130/G31981.1 Article history Received: 09 Dec 2010 Revision Received: 24 Mar 2011 Accepted: 28 Mar 2011 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Douglas N. Reusch; New Caledonian carbon sinks at the onset of Antarctic glaciation. Geology 2011;; 39 (9): 807–810. doi: https://doi.org/10.1130/G31981.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract During the latest Eocene, as Earth's climate transitioned from a greenhouse to an icehouse state, likely forced by declining atmospheric carbon dioxide pressure (pCO2), a large tract of basic and ultrabasic seafloor breached sea level in the New Caledonian region of the southwestern Pacific Ocean. A plausible mechanism for CO2 drawdown at this precise time, 35–34 Ma, invokes weathering of the seafloor rocks, composed of highly soluble Ca- and Mg-rich silicates, and related organic carbon burial. Carbon burial fluxes based on estimates of paleo-area, paleo–erosion rate, and paleo–sedimentation rate suggest a peak perturbation of 0.3–0.5 Emol (1018 mol) m.y.−1 This perturbation may have been sufficient to lower atmospheric pCO2 ∼100 ppmv, thus triggering growth of the East Antarctic ice sheet and a host of related environmental changes. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Tectonic stresses seaward of an aseismic ridge—Trench collision zone. A remote sensing approach on the Loyalty Islands, SW Pacific

The Loyalty Islands are a series of limestone karstified islands on the Australian Plate that are presently approaching the Vanuatu subduction zone (SW Pacific). They are deformed due to the combined effects of the bulging of the subducting lithosphere and the beginning collision between the Loyalty Ridge and the Vanuatu subduction zone. Therefore, they constitute a series of markers for early phases of ridge arc collision. Lineaments deduced from remote sensing images (aerial photos, SPOT3, SPOT4 and ENVISAT data), termed here as fractures, are analyzed by comparison with planar structures measured during field studies and termed as geological data. Fracture data indicate a stable main N110 direction with a large variance of nearly 15° in rms and two minor directions 45° apart which may constitute shear directions associated to the major one. A scale dependent analysis shows that fractures longer than 2000 m are close to the N110 direction and that their orientation shifts progressively to reach the N125 direction for L < 400 m. Geological data which are generally measured on 1–10 m long structures, reveal a main N135 direction in Lifou, which may be considered as the continuation of the trend of fracture data for decreasing lengths, and are dispersed in Maré. Since the shortest scale structures are being subjected to local disturbances, the longest ones are considered as indicative of the present stress state of the Loyalty Islands. They are modeled as tension cracks resulting from the elastic bulging of the Australian lithosphere before its subduction at the Vanuatu Trench and from a single force corresponding to the beginning collision. It is suggested that the stress field deduced from this model may help constraining general models of ridge arc collision and that the Vanuatu–New Caledonia region could be a valuable natural example to calibrate such models.

Biodiversity of shallow-water brachiopods from New Caledonia, SW Pacific, with description of a new species

SUMMARY: Twelve species of recent brachiopods belonging to the genera Lingula, Discradisca, Novocrania, Xenobrochus, Eucalathis, Frenulina, Argyrotheca, Campages, Thecidellina and Lacazella were identified in samples collected during shallow-water cruises around New Caledonia, southwest Pacific. Six genera, Lingula, Xenobrochus, Eucalathis, Frenulina, Campages and Thecidellina, have been already reported from the New Caledonian region, while four genera, Discradisca, Novocrania, Argyrotheca and Lacazella are the first records from this region. Additionally, Discradisca stella is the first discinid brachiopod recognized in the New Caledonia area. One new species is described, the megathyridid Argyrotheca neocaledonensis n. sp. The biogeographical affinities of the New Caledonia brachiopod faunas are briefly discussed.

Leaf fossils of Proteaceae tribe Persoonieae from the Late Oligocene - Early Miocene of New Zealand

Fossils from the Newvale lignite mine, Southland, are the first substantiated foliar records of Proteaceae subfamily Persoonioideae. The fossils possess very large stomata, a probable synapomorphy for Persoonioideae, and within Proteaceae the combination of this feature and more or less parallel-aligned, brachyparacytic stomatal complexes and undulate anticlinal epidermal cell walls is uniquely found in this subfamily. The new genus Persoonieaephyllum is described to recognise affinity of the fossil leaves and cuticles with tribe Persoonieae of Persoonioideae and their distinction from its only other extant representative, Placospermum. Two new species are described. P. ornatum is represented by linear leaves less than 20 mm wide and possessing more or less parallel-aligned major veins. These leaves closely match those of extant hypostomatic, broad-leaved species of tribe Persoonieae and are distinct from Placospermum in venation and several cuticular details. P. villosum has so far been recovered only as cuticular material in disaggregated lignite. It is distinct from P. ornatum in having abundant trichome bases, an absence of surface tubercules, and even larger stomata (guard cells often &gt;70 μm long). The fossils extend the known record of Persoonioideae in the New Zealand–New Caledonia region by ~20 million years.

Recent Brachiopoda from the Norfolk Ridge, New Caledonia, with description of four new species

Twenty-two brachiopod species belonging to 19 genera have been recognized in the material collected during two cruises, Norfolk 1 and Norfolk 2, to the Norfolk Ridge south of New Caledonia, at depths of 180 to 1150 m. Thirteen species are reported for the first time from this locality, while four genera, Aulites, Septicollarina, Annuloplatidia and Campages, are noted for the first time from the New Caledonian region. Thecidellina minuta is recorded for the first time from the Pacific. Four new species are described ― Cryptopora norfolkensis sp. nov., Aulites crosnieri sp. nov., Septicollarina zezinae sp. nov. and Annuloplatidia richeri sp. nov. The distribution of the particular species and their abundance vary considerably between the 15 sampled seamounts, with Stenosarina crosnieri and Fallax neocaledonensis being most widely distributed, and the seamount Crypthelia having the highest biodiversity. The seamount brachiopods show considerable affinity to the brachiopods of adjacent regions, and only three species ― C. norfolkensis, A. crosnieri and A. richeri ― can be regarded as potential endemics. The brachiopod fauna is more similar to that in the area around Fiji than to that around Australasia.

A reappraisal of the diversity of geomorphological and genetic processes of New Caledonian coral reefs: a synthesis from optical remote sensing, coring and acoustic multibeam observations

The diversity of oceanic and continental reef structures of New Caledonia is reviewed, taking into account their geological history and in particular, that since the last interglacial period. To guide this review, a new path is provided by following the diversity of units that have been mapped and characterized using high spatial resolution optical remote sensing data for the main New Caledonian coral reef complexes (banks, atolls, uplifted reefs, drowned reefs, fringing reefs, barrier reefs, patch reefs) and their individual reef-forming units. This interpretation, based on geomorphology, depth, and exposure has provided 161 unit types distributed across 4,537 km2 of reef area and 31,336 km2 of non-reef area. In addition to shallow reefs (0–30 m) described by optical remote sensing, the bathymetry of deep slopes between −20 to −1,000 m were recently mapped using multibeam acoustic data providing additional data to explain the morphological diversity. With the detailed three-dimensional topographic information acquired, hitherto unrecognized marine terraces and faulting became visible, indicating different episodes of formation of the barrier reef and of sea level variations. Finally, dating and coring corals provided a more accurate understanding of the genesis of the present reef structures. In contrast with the synoptic remote sensing data, cores provided only point data, but allowed the addition of a precise temporal dimension to the description of New Caledonian reefs. Cores provided a significant body of the information necessary for the establishment of models of reef settlement and development during the last interglacial ages in the New Caledonian region. The combined examination of the different sources of data, and the exhaustive description of remotely sensed reef units, allow a qualitative synoptic parallel to be drawn between the morphology of modern reefs and the contrasting patterns of reef growth, subsidence, and uplift rates occurring around New Caledonia.

Plate reconstructions and tomography reveal a fossil lower mantle slab below the Tasman Sea

The Southwest Pacific region is tectonically complex and is home to numerous fossil and active subduction zones. At the Earth's surface, there remains a geological controversy regarding the polarity and continuity of fossil subduction zones in New Zealand and New Caledonia, the origin of obducted ophiolites, the presence of high-pressure metamorphism, the occurrence of widespread Cenozoic magmatism, and the potential disappearance of one or more ocean basins. This controversy can be solved by looking at the lower mantle rather then at the Earth's surface. New P-wave and S-wave mantle tomography models from the Southwest Pacific are presented, which identify a previously unrecognized lower-mantle high-velocity anomaly that cannot be linked to Pacific subduction. The anomaly is located below the Tasman Sea at ~ 1100 km depth, strikes NW–SE and is ~ 2200 km by 600–900 km in lateral extent. By combining relative and absolute plate motions it is demonstrated that when the geological structures at the surface are reinterpreted as a single northeast-dipping 2500-km middle Cenozoic subduction zone (the so-called New Caledonia subduction zone) the lower mantle anomaly can be accounted for, as it is found at the predicted location and depth. Discovery of the lower mantle slab anomaly thereby solves a long-standing geological controversy in the New Zealand–New Caledonia region. Finally, reconstructions and analytical calculations predict a lower mantle slab sinking velocity of ~ 1.5 cm/yr and a lower mantle viscosity of ~ 10 22 Pa·s.

What are the origins of the Antarctic Intermediate Waters transported by the North Caledonian Jet?

The trajectories of several Argo floats are studied to investigate the mid‐depth circulation in the southwest Pacific that coincides with the spreading of the Antarctic Intermediate Waters (AAIW). Before entering the Coral Sea, the floats converge and join the North Caledonian Jet (NCJ) south of 15°S. These observations suggest that the waters transported by this jet do not have a unique source. Hydrologic parameters and oxygen concentration confirm that the characteristics of the AAIW in the NCJ result from a convergence and a mixing of waters from the northern limb of the subtropical gyre and from the south‐eastern New Caledonian region. The northern contribution is associated with the water masses transported by the North Vanuatu jet that re‐circulate in the region between the D'Entrecasteaux reefs and the Vanuatu archipelago. It is shown that such complex dynamical features could be reproduced by numerical models when their horizontal resolution is sufficiently high.

Fitting Northland, New Caledonia and dlEntrecasteaux geology into the Late Cretaceous-Cenozoic Southwest Pacific tectonic framework

Late Cretaceous to Cenozoic reconstructions of the Southwest Pacific region show a large degree of discrepancy. Moreover, some do not incorporate the geology of the New Caledonia region, most do not incorporate the geology from Northland, New Zealand, and none incorporates the lithospheric-scale structure from the d?Entrecasteaux zone. A new tectonic model is proposed that incorporates the regional geology from these three regions into the large-scale and well-defined tectonic framework of relative motion between the Australian plate, Pacific plate and Lord Howe Rise microplate. In the new model, the d?Entrecasteaux zone is interpreted as a dextral transform fault. The New Caledonia and Northland regions are interpreted to bear the hallmarks of a former northeast dipping subduction zone with an east dipping subduction segment in between, located west of the Three Kings Ridge. The subduction zone formed at 50-45 Ma, a period when Australia-Pacific relative motion changed from strike-slip to oblique convergence. Subduction was primarily realized by east to southeast-directed anticlockwise slab rollback of the South Loyalty Basin lithosphere and tearing of the slab at the surface along the d?Entrecasteaux zone. The subduction rollback process resulted in formation of the North Loyalty-South Fiji back-arc Basin and induced arc volcanism along the d?Entrecasteaux-Loyalty-Three Kings Ridge-Northland Plateau seamount chain. The final stage of the subduction process resulted in southwest-directed obduction of ophiolites in New Caledonia at 38-34 Ma and in Northland at 25-22 Ma.