Lateglacial–Holocene shoreface progradation offshore eastern Scotland: a response to climatic and coastal hydrographic change |
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| Authors: | MARTYN S STOKER NICK R GOLLEDGE EMRYS R PHILLIPS IAN P WILKINSON MAXINE C AKHURST |
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| Institution: | British Geological Survey, Murchison House, West Mains Road, Edinburgh, EH9 3LA, Scotland, UK;;British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham, NG12 5GG, England, UK |
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| Abstract: | Seismic facies, provenance and marine faunal associations of a nearshore prograding sediment wedge offshore eastern Scotland are studied to investigate environmental changes in the adjacent North Sea during Lateglacial–Holocene time. The sediments form part of the St. Andrews Bay Member (Forth Formation), which is divided into four lithozones (L1–L4) that represent distinct pulses of sedimentation during the sequential growth of the sediment wedge. Radiocarbon dates, combined with the local curve of relative sea level change, indicate that progradation was initiated as a fluvio-deltaic deposit (L1) during the Younger Dryas Stadial. Further construction of the sediment package took place during the mid- to late Holocene by sublittoral tidal processes that deposited three discrete, highstand shoreface wedges (L2–L4), which display both progradation and longshore migration (to the NE), and may have experienced episodic brackish marine conditions. A depositional cyclicity of about 1000 years is proposed for lithozones L2–L4, separated by hiatuses of 1000–2000 years. We tentatively suggest that the Holocene development of the prograding wedge offshore eastern Scotland was a response to phases of strong westerly winds driving an enhanced influx of Atlantic Water into the North Sea. A concomitant increase in rainfall may account for the freshening of the coastal zone at this time. However, correlation with the recently postulated global periods of Holocene rapid climate change remains unclear. |
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