Diatom and stable isotope records of late-Holocene lake ontogeny at Indrepollen, Lofoten, NW Norway: a response to glacio-isostasy and Neoglacial cooling

• Main Authors: Mills, K, Mackay, AW, Bradley, RS, Finney, B
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: SAGE PUBLICATIONS LTD 2009
• Subjects: Diatoms; stable isotopes; sea-level; lake ontogeny; land uplift; glacio-isostasy; palaeoconductivity; Lofoten; Norway; late Holocene; SEA-LEVEL CHANGES; SEDIMENTARY ORGANIC-MATTER; NORTH-ATLANTIC OSCILLATION; BALTIC SEA; RADIOCARBON CALIBRATION; SHORE DISPLACEMENT; COASTAL SEDIMENTS; LITORINA SEA; CLIMATE; HISTORY; Borg; Indrepollen; Level Lake; North Atlantic; North Atlantic oscillation; Northern Norway
• Online Access: http://discovery.ucl.ac.uk/54724/

Borg Indrepollen is a coastal lake on the island of Vestvagoy Lofoten NW Norway. A sedimentary sequence spanning the last 4500 cal. yr BP was analysed for diatom, C/N and stable isotopes (delta C-13 and delta N-15). The record provides clear evidence of glacio- isostatic rebound in the Lofoten region. Five distinct lithostratigraphic-geochemical zones (I-V) and four major diatom zones (A-D) were identified. The early record (I-III, A-Biii; 4500-550 cal. yr BP) contains coarse sedimentary material and diatoms indicative of more marine conditions. The correlation between the isotopic date (high delta C-13 and low C/N) and trends in the biological data (marine/brackish flora) suggest the marine influence on the Indrepollen basin is a controlling factor of the source of organic material. The latter part of the record (IV, C; 550 cal. yr 550-226) indicates a transitional phase from marine-dominated diatom to brackish taxa and is coincident with a section of microlaminations in the core. The youngest zone (V, D; 226 cal. yr BP-present) is indicative of an isolated basin, with the deposition of fine sediments; freshwater diatom taxa dominate the biological record and delta C-13 are indicative of fresh-water conditions. C/N suggests a shift to terrestrial source of organic matter. The proxies show a transition from full marine conditions, when Indrepollen was a submerged fjord, to more freshwater, lacustrine conditions in the last 200 years. The record of land uplift from Borg Indrepollen mirrors changes in sedimentary records from across Northern Norway and relative sea-level curves for the region.