Abstract
| Language | English |
|---|---|
| Pages | 19-34 |
| Journal | MARINE GEOLOGY |
| Volume | 117 |
| Issue number | 1-4 |
| DOIs | |
| Publication status | Published - Mar 1994 |
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A shallow marine emergent sequence from the northwestern sector of the last British ice sheet, Portballintrae, Northern Ireland. / MCCABE, AM; CARTER, RWG; HAYNES, JR.
Vol. 117, No. 1-4, 03.1994, p. 19-34.Research output: Contribution to journal › Article
TY - JOUR
T1 - A shallow marine emergent sequence from the northwestern sector of the last British ice sheet, Portballintrae, Northern Ireland
AU - MCCABE, AM
AU - CARTER, RWG
AU - HAYNES, JR
PY - 1994/3
Y1 - 1994/3
N2 - At Portballintrae, Northern Ireland, a well-preserved emergent facies sequence formed around 17 kyr B.P. as the Late Devensian ice sheet withdrew from the continental shelf. Three main lithofacies assemblages are recognised: (1) At the base of the sequence a massive muddy diamict was formed by resedimentation of an unstable sedimentary apron deposited in a tidewater setting. (2) Rhythmically-bedded sand and mud units contain a wide range of wave diagnostic features and are separated from the underlying diamict by both transitional and wave-eroded planar contacts. Palaeowave calculations suggest deposition in a coastal tract open to Atlantic waves. The. preservation and range of boreo-arctic foraminifera present are also typical of a lower shoreface, storm-influenced setting. (3) Interbedded gravel and sand facies are separated from the underlying rhythmically-bedded facies by a planar wave-cut surface. This facies occurs as crudely organised beds within cross-cutting, shallow scours which are associated with off-shore directed, storm-induced sediment pulses. Overall the coarsening-upwards sequence is explained by tidewater sedimentation during ice wastage, rapid isostatic rebound and isostatic deceleration in the late glacial. An isostatic-tectonic model comprising a forebulge on the outer continental shelf and a peripheral trough on the inner shelf is presented to resolve the apparent discrepancies between onshore and offshore sea-level data.
AB - At Portballintrae, Northern Ireland, a well-preserved emergent facies sequence formed around 17 kyr B.P. as the Late Devensian ice sheet withdrew from the continental shelf. Three main lithofacies assemblages are recognised: (1) At the base of the sequence a massive muddy diamict was formed by resedimentation of an unstable sedimentary apron deposited in a tidewater setting. (2) Rhythmically-bedded sand and mud units contain a wide range of wave diagnostic features and are separated from the underlying diamict by both transitional and wave-eroded planar contacts. Palaeowave calculations suggest deposition in a coastal tract open to Atlantic waves. The. preservation and range of boreo-arctic foraminifera present are also typical of a lower shoreface, storm-influenced setting. (3) Interbedded gravel and sand facies are separated from the underlying rhythmically-bedded facies by a planar wave-cut surface. This facies occurs as crudely organised beds within cross-cutting, shallow scours which are associated with off-shore directed, storm-induced sediment pulses. Overall the coarsening-upwards sequence is explained by tidewater sedimentation during ice wastage, rapid isostatic rebound and isostatic deceleration in the late glacial. An isostatic-tectonic model comprising a forebulge on the outer continental shelf and a peripheral trough on the inner shelf is presented to resolve the apparent discrepancies between onshore and offshore sea-level data.
U2 - 10.1016/0025-3227(94)90004-3
DO - 10.1016/0025-3227(94)90004-3
M3 - Article
VL - 117
SP - 19
EP - 34
IS - 1-4
ER -