Using palynology for high resolution dating of sub-recent Small Water Body sediment cores from North East England

Summers, Philippa Grace (2016) Using palynology for high resolution dating of sub-recent Small Water Body sediment cores from North East England. Masters thesis, Northumbria University.

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Abstract

Little is known about the burial rates of carbon in Small Water Bodies (SWBs <10 km2), since most research has been on larger lakes. Obtaining carbon burial rates of sub-recent (<20 years) sediments requires a high resolution dating technique which permits sub-decadal error ranges. Typically, isotope dating is used to date young sediment cores but is limited to error ranges of 10-20 years.
This thesis examines whether the pollen and testate amoebae record of different types of SWBs from North East England can be matched to records from vegetation monitoring, crop harvests, and rainfall measurements in order to allow precise dating. High resolution pollen and testate amoebae assemblages from short sediment cores of three different types of SWBs are compared with an eighteen-year vegetation dataset. Utilising research on pollen grain morphology and representation, coupled with records from modern pollen surface sediment samples and vegetation mapping, aid the interpretation of pollen assemblages in the SWB sediment cores with the vegetation monitoring record.
The results suggest that the ability of a pollen-vegetation record dating approach is controlled by the type and size of the individual SWB. High resolution pollen analysis and vegetation matching can be used on an open semi-natural SWB to obtain coherent dates throughout the sediment core. SWBs that are constructed to 1m2, or have vegetation growing in the pond, cannot be used for dating. There is a minimum size required for the calculation of sedimentation rates on SWBs, as the 1m2 constructed SWBs were not suitable. Reworking of pollen grains, particularly in the small constructed ponds is identified by the occurrence of a carboniferous spore (Lycospora), reducing the accuracy of matching the pollen and vegetation assemblages in these pond types.
This technique can be applied to other SWBs to further our understanding of sub-decadal carbon burial rates. The approach also allows a documentation of the palynological interactions occurring within a variety of types and sizes of SWBs.

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