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.

BIOCAL

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.

BIOCAL