Aw. Tudhope et Tp. Scoffin, PROCESSES OF SEDIMENTATION IN GOLLUM CHANNEL, PORCUPINE SEABIGHT - SUBMERSIBLE OBSERVATIONS AND SEDIMENT ANALYSES, Transactions of the Royal Society of Edinburgh. Earth sciences, 86, 1995, pp. 49-55
Manned submersible dives were conducted in the submarine canyon/channe
l system of Porcupine Seabight, NE Atlantic Ocean. Visual observations
were made, and sediment samples collected and analysed to elucidate t
he nature of the sedimentary regime. In the upper part of the canyon (
480-940 m water depth) sediments consisted of a mixture of terrigenous
quartz rich silts and sands, skeletal carbonate of benthonic and plan
ktonic origin and minor clay minerals and authigenic dolomite. There w
ere localised Lophelia pertusa coral thickets on both the flanks and f
loor of the canyon. Sedimentary structures and physical measurements r
evealed there to be active transport of sediments in the canyon down t
o a depth of at least 940 m, effected by (?tidal) reversing currents a
nd bioturbation. In these parts of the canyon, deposits around glacial
dropstones and coral thickets indicate that there has been a maximum
of 0.1 m of net sediment accumulation since the last glacial period. A
t 3000 m water depth, in the channel system, the sediments were fine c
alcareous ooze with a drape (up to 0.3 m thick) of flocculant phytopla
nkton detritus. At these depths, there was no evidence for present-day
sediment resuspension by currents.