Pleistocene ice-proximal glaciomarine sediments in boreholes from the Hebrides Shelf and Wyville-Thomson Ridge, NW UK Continental Shelf

Scottish Journal of Geology - Tập 24 Số 3 - Trang 249-262 - 1988
Martyn S. Stoker1
1British Geological Survey, Murchison House, West Mains Road, Edinburgh EH9 3LA,

Tóm tắt

Synopsis Pleistocene sediments recovered in boreholes from the Hebrides Shelf and Wyville–Thomson Ridge indicate ice-proximal glaciomarine deposition in an outer shelf setting. The sediments are predominantly diamicts and in vertical profile display a general upward-fining trend. The lower part of the succession is characterised by a coarse, crudely stratified-to-massive, clast and matrix-supported diamict assemblage which is interpreted as an amalgamated sequence of debris flows. The upper part consists of finer, massive, matrix-supported diamicts deposited mainly from suspension but with a subsidiary input of ice-rafted material. Thin interbedded lag gravels and sandy sediment gravity flows form a minor component of the succession. This kind of succession is usually associated with a stationary or slowly retreating tidewater ice margin. The morphology of the outer shelf is characterised by a relict glaciated terrain; the sedimentary succession suggests that this is of submarine origin. These data indicate that at some time during the Pleistocene an ice-sheet extended out to the edge of the northern Hebrides Shelf and partly onto the Wyville-Thomson Ridge. The age of this glaciation is unknown but probably pre-dates the last Scottish ice-sheet (Late Devensian/Late Weichselian)

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Scottish Journal of Geology

Tập 24 Số 3

249-262

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