Sédimentation sur la Ride de Terre-Neuve

Abstract

The stratification, in part more or less rhythmic, of a fifteen metre long core of predominantly hemi-pelagic sediment from the northern slope of the Southeast Newfoundland Ridge reflects changing distribution patterns of different water masses during the late Quaternary. In particular, the lithological and microfaunal characteristics of the sediments indicate that, in the area of the core, the cold Labrador Current from the north and the continental slope water have had a permanent influence on the sedimentation pattern, whereas the paths of the Gulf Stream water have shifted intermittently. The influence of the Gulf Stream is clearly identifiable during the Holocene and during the last interglacial (faunal zone X). Ice-rafted debris and relatively coarse turbidite-type beds are more prominent in sequences deposited under a glacial régime, notably in those that accumulated near the end of the late Pleistocene and the beginning of the Holocene. The upper limit of faunal zone X (Sangamon-Würm) is placed close to 1000 cm depth in the core on the basis of the disappearance at this level of Globorotalia tumida flexuosa (Koch). The resulting estimate of the subsequent mean sediment accumulation rate is of the order of 10 cm/1000 y.