ISSN:
1573-0417
Keywords:
Valkiajärvi
;
varved lake sediment
;
meromictic lake
;
environmental magnetism
;
pollen stratigraphy
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geosciences
Notes:
Abstract Two varve counts made nearly 20 yrs apart and by different authors in the small and well sheltered meromictic lake of Valkiajärvi were compared with a view to establishing how similar, or otherwise, these two independent varve chronologies might be. The results were significant, the difference between the two varve counts being less than 2% for most of the sediment length, even though the average varve thickness was only 0.3 mm. The continuous and essentially uniform varve record - so far the longest in Finland - covers 8400 yrs and could be applied for accurate dating of palaeoenvironmental indicators in the sediment. As an example, we present a varve-dated pollen diagram for Lake Valkiajärvi. In addition, some magnetic parameters (susceptibility, ARM, SIRM) were measured on the sediment sequence to support the stratigraphic division and correlation of the cores, and to outline the development of the basin since the last deglaciation. Magnetic variables reflected mainly the variation in minerogenic material in the sediment, and were therefore related to changes in the catchment. The magnetic parameters also showed a drastic change some 6000 yrs ago, the reason for which, unfortunately, is still not fully understood.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1008064613031
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