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Title: Morphostratigraphy of marginal coastal environments
Author: Barrett-Mold, C. A.
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2013
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This study is concerned with deciphering the evidence for recent variability in external coastal climate and estuary process forcing preserved within the machair/salt marsh deposits of the Loughros More estuary, Donegal, northwest Ireland. Late-Holocene coastal dynamics have contributed to the development of a complex suite of inter-estuary dune, strand, machair, saline and freshwater marsh sedimentary environments. These sedimentary environments occupy a vulnerable position within the tidal frame (MHW ±2m), and exhibit significant morphological change over more recent (10 to 1000 year) timescales as a result of sediment reworking and recycling within the context of the wider estuarine environment. A greater understanding of the functioning of these relatively naturally behaving systems (unmodified by human impacts) is important not only to increase the knowledge of this relatively unstudied region but also to provide supporting evidence for future studies of the currently unclear relative sea-level record of this region. From a coastal conservation perspective, it is important to understand how aeolian, estuarine-marine and fluvial processes drive habitat transitions and shifts in the associated species assemblages, and the sensitivity of these marginal coastal and estuarine sedimentary environments to future climate variability and change. The Loughros More system provides an excellent case study within which to establish the main internal system controls and external driving factors influencing the formation and morphological evolution of low-lying marginal coastal/estuarine habitats in this region. To this end, contemporary morphological and ecological environments are examined with respect to their geomorphology; sedimentary make-up; historical landform changes and ecological characteristics. A stratigraphic approach is taken to examine the temporal (downcore) and spatial (intra-/ inter-site) variations and trends in the sedimentary sequences of estuarine margin deposits. Stratigraphies are presented for 5 cores and downcore sedimentological, geochemical, and ecological variations analysed. Chronological support is provided via 210Pb, 137Cs and optically stimulated luminescence (OSL) dating. Scanning XRF is used to provide exceptionally high-resolution sampling of down-core geochemistry. Results describe depositional transitions from tidal flat to high intertidal vegetated environments, where saltmarsh, maritime grassland and machair characteristics are evident. Complexity is also present throughout the stratigraphies, and here the study demonstrates the potential of high resolution scanning XRF (including time-series and multivariate analyses) in determining correlations and trends in these sedimentary sequences and associated forcing. Variations in regional storminess are determined to be the main external driving factor controlling the deposition of distinctive light and dark sediment layers within the stratigraphy across the study area.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available