Molecular fossils as a tool for tracking Holocene sea‐level change in the Loch of Stenness, Orkney

ABSTRACT Sediments deposited in the Loch of Stenness (Orkney Islands, Scotland) during the Holocene transgression, previously dated to between ~5939–5612 bp, were analysed for molecular fossils – lipids and chlorophyll pigments from primary producers – that complement conventional microfossil and li...

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Bibliographic Details
Published in:Journal of quaternary science 2020-10, Vol.35 (7), p.881-891
Main Authors: Conti, Martina L. G., Bates, Martin R., Preece, Richard C., Penkman, Kirsty E. H., Keely, Brendan J.
Format: Article
Language:English
Subjects:
Algae
Antarctic ice sheet
Chlorophyll
chlorophylls
Fossils
Freshwater lakes
Holocene
Ice sheets
Lipids
Lithology
molecular fossils
Pigments
sea level
Sediments
Terrestrial environments
Vegetation changes
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Summary:ABSTRACT Sediments deposited in the Loch of Stenness (Orkney Islands, Scotland) during the Holocene transgression, previously dated to between ~5939–5612 bp, were analysed for molecular fossils – lipids and chlorophyll pigments from primary producers – that complement conventional microfossil and lithological approaches for studying past sea‐level change. While microfossil and lithological studies identified a transgression between 102 and 81 cm core depth, key molecular fossils fluctuate in occurrence and concentration between 118 and 85 cm, suggesting an earlier start to the transgression. Terrestrial lipid concentrations decreased and algal‐derived, short‐chain, n‐alkanoic acid concentrations increased at 118 cm, indicating a disruption of the freshwater lake conditions associated with the early stages of the marine transgression. The lipid and pigment analyses provided information that complements and extends that from microfossil analysis, presenting a more complete record of Holocene sea‐level changes and local vegetation changes in the Loch of Stenness. The isostatic stability of Stenness during the Holocene points towards other factors to explain the transgression, such as regional factors and/or melting of the Antarctic ice sheet (which occurred up to 3 ka).
ISSN:0267-8179
1099-1417
DOI:10.1002/jqs.3238