Efstadalsvatn – a multi-proxy study of a Holocene lacustrine sequence from NW Iceland
Caseldine, C.J., Geirsdo'ttir, A. and Langdon, P.G. (2003) Efstadalsvatn – a multi-proxy study of a Holocene lacustrine sequence from NW Iceland. Journal of Paleolimnology, 30, (1), 55-73. (doi:10.1023/A:1024781918181).
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Multi-proxy data, both lithostratigraphic and biostratigraphic, are presented from Efstadalsvatn, a lake in NW
14 Iceland. The sequence covers the period 10,000 to 3500 C yr B.P. The biostratgraphic data include the first
Icelandic chironomid-based reconstruction of Holocene mean July air temperatures, using a Norwegian training
set in the absence of modern Icelandic data. The results show that deglaciation and ecosystem development
14 14 probably began before 10,000 C yr B.P. and that July temperatures were around 48C at ca. 9500 C yr B.P.
14 Temperatures then rose to ca. 88C at the time of the deposition of the Saksunarvatn tephra (9100 C yr B.P.),
14 reaching ca. 108C by 8500 C yr B.P., high enough for the growth of tree birch, although successful birch
14 colonisation did not take place until 6750 C yr B.P. There is some evidence for cooling immediately preceding
14 9100 C yr B.P. There is little firm biostratigraphic evidence for the 8200 cal. B.P. event, although this may be due
to a relatively low resolution pollen sampling interval, but there are changes at this time in the total carbon (TC)
and mass susceptibility (MS) data. Optimal temperatures and relative vegetation stability may have occurred
14 14 between 8000–6100 C yr B.P. but the chironomid assemblages indicate higher temperatures after 5000 C yr
B.P. This latter interpretation may, however, reflect delayed colonisation of thermophilous taxa and requires
14 further investigation. There is evidence in the lithostratigraphy for greater local terrestrial instability after 6100 C
yr B.P. but it seems unlikely that this led to the redevelopment of ice in the catchment. The biostratigraphic records
appear to show a degree of resistence to climate forcing throughout the early and middle Holocene. The new
chironomid-based temperature reconstruction needs to be refined by further studies in Iceland, particularly the
development of an Icelandic training set, but has already demonstrated the problems of paleoclimatic interpretations
based on pollen and/ or macrofossil evidence alone.
|Keywords:||chironomids, holocene, Iceland, multi-proxy, paleolimnology, paleotemperature, pollen|
|Subjects:||G Geography. Anthropology. Recreation > G Geography (General)
G Geography. Anthropology. Recreation > GE Environmental Sciences
G Geography. Anthropology. Recreation > GB Physical geography
|Divisions:||University Structure - Pre August 2011 > School of Geography > Environmental Processes and Change
|Date Deposited:||01 Aug 2008|
|Last Modified:||06 Aug 2015 02:44|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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