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Biolaminated sedimentation in a High Arctic freshwater lake



A laminated sequence of lacustrine sediment from an Arctic coastal lake was examined for potential chronological and successional information. The laminae are microbially induced sedimentary structures, the unlithified precursor of stromatolites and are previously unreported in the Arctic. The inferred annual sequence was interpreted to contain a basal clastic unit, overlain with successive cyanobacterial and extracellular polymeric substance units. The complex succession of laminae and inconclusive dating provide a challenge for identifying the chronological nature of the sedimentary structures. Markov chain and time series analyses suggest that a plausible, quasi-annual sequence can be identified to provide a context for palaeo-environmental reconstruction. Recognition of sedimentary structure in recent biolaminated sediments offers a first step towards the palaeo-environmental evaluation of the geomicrobiological sequence.