INTRODUCTION Submarine slopes and basins off New-Caledonia (South-Western Pacifie); morphology, biosedimentary environments, sedimentation During the Biocal deep-sea cruise off New-Caledonia, fauna and sediments were sampled and Seabeam maps were drawn. The first geological results are as follows: block-faulting determines the morphology of the slopes, their erosion and the transport of sediments along them towards the Loyalty basin plain; erosion is predominant in the studied areas of the western Caledonian slopes and along the slopes off Lifou island where the canyons are broad and scattered, whereas in front of the passe de Thio, through the reefal barrier, a relatively high detritic influx transits through several narrow canyons; the Loyalty basin has been explored along the Thio-Lifou transect; it exhibits a flat bottom and is fed mainly from the eastern Caledonian slopes by calcareous and argilaceous turbidites, which spread eastward over nearly 50 km and interfinger with hemipelagites; the sediments are constituted by 5 distinct components: 15 to 50% of detritics from New-Caledonia (mainly clay minerais, iron oxydes and silicate minerais); 15 to 25% bioclastic silts and sands derived from the reefal ring and from the lagoon; mixed bioclasts ( 1 to 20%) furnished by benthonic communities living on the slopes and in the basin; planktonic debris (30 to 75%) with a dominant fraction composed of foraminifers and pteropods; and volcanic debris (0,5 to 10%). A sedimentation rate of about 6cm/1000 years (between 16000 and 5000 years B.P.) has been estimated from the explored sector of the Loyalty basin. Oceanologica Acta, 1989, 11, 2, 131-140. La campagne Biocal s'est deroulee au large de la Nouvelle-Caledonie, a bord du N/0 Jean Charcot. Les aspects biologiques, ecologiques et sedimentologiques d'une etude des fonds bathyaux et abyssaux y ont ete abordes simultanement (Cotillon et al., 1985). Dans cette optique, les bordures de la Nouvelle-Caledonie, celles de la ride des Loyaute ainsi qu'une transversale Sud-Ouest/Nord-Est a travers le bassin des Loyaute ont ete explorees (fig. 1 et 2). Outre les operations classiques de dragage, chalutage et carottage, cinq cartes sous-marines d'une superficie moyenne de 140km2 ont ete dressees a l'aide du sondeur multifaisceaux Seabeam. Nous presentons ici les principaux resultats geologiques issus de cette campagne: grands traits morphostructuraux des talus bathyaux, mode de transit des materiaux le long des pentes, origines et mise en place des divers constituants sedimentaires dans le bassin des Loyaute.
The biological pump describes the trans- port of particulate matter from the sea surface to the ocean's interior including the seabed. The contribution by gelatinous zooplankton bodies as particulate organic matter (POM) vectors (''jelly-falls'') has been neglected owing to technical and spatiotemporal sampling limitations. Here, we assess the existing evidence on jelly-falls from early ocean observations to present times. The seasonality of jelly-falls indi- cates that they mostly occur after periods of strong upwelling and/or spring blooms in temperate/subpolar zones and during late spring/early summer. A con- ceptual model helps to define a jelly-fall based on empirical and field observations of biogeochemical and ecological processes. We then compile and discuss existing strategic and observational oceano- graphic techniques that could be implemented to further jelly-falls research. Seabed video- and pho- tography-based studies deliver the best results, and the correct use of fishing techniques, such as trawling, could provide comprehensive regional datasets. We conclude by considering the possibility of increased gelatinous biomasses in the future ocean induced by
Exceptional fossilization of large tetrapod swimming traces occurs in the Cerin Lagerstätte (Jura Mountains, France). These trackways are imprinted in Jurassic (Late Kimmeridgian) lagoonal fine-grained limestones and are attributed to giant turtles, which swam with a simultaneous movement of their forelimbs like the modern ones. These turtles swam in very shallow waters close to land, perhaps near a nesting area. As a major consequence, these new ichnologic data place the origin of true large marine turtles during the Jurassic period and not during the Cretaceous period as previously considered on the basis of skeletal remains.
Abstract On the North-Provence margin, an omission surface with Rhizocorallium often characterizes the sub-Aptian discontinuity between Eocretaceous carbonates and Aptian-Albian marls. This discontinuity is recorded in various successions described along a palaeoslope joining the Vocontian Basin and the Provence platform, between the Jabron valley in the west and the Var valley in the east. The successions including Aptian marls always exhibit an omission surface with Rhizocorallium. Through this area, the Aptian discontinuity equates to at least part of the Goguel Level. The latter is represented by black shales occurring in the Vocontian Basin at the top of Deshayesi zone and is a regional expression of the global anoxic event OAE1a. Thus, the surface with Rhizocorallium can be regarded, on the North-Provence margin, as a marker coincident with the onset of the anoxic event which, in the Vocontian basin, succeeded to a nannoconid crisis. Representing a short event, the surface is also a marker of various processes: (1) current activity, deduced from a dominant orientation of Rhizocorallium. The Barremian-early Aptian carbonate succession is strongly eroded by the formerly more active currents along the Peipin Channel, south-east of Sisteron; these currents also led to the omission of the Bedoulian (= carbonate Lower Aptian) to upper Valanginian series from the top of the hemipelagic palaeoreliefs in the eastern Castellane arc; (2) tectonic activity in the Lower Aptian, marked by N080 degrees to N100 degrees extension faults and slumping of a semi-lithified carbonate sediment. Slumped material and fault scarps are burrowed with Rhizocorallium; (3) differential lithification of the Barremian limestones which has led to distinctive types of current erosion.
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