Preservación de diatomeas en sedimentos turbosos

Abstract

[Abstract] This paper describes a comprehensive survey of the quality of diatom preservation in the recent sediment record from two close peatbogs but with different geomorphological features, Villaseca and La Mata (NW Spain). Twenty samples have been analysed from each core, focusing especially in the preservation of diatom frustules along the upper part of the core (from Late Glacial), which change during the main trophic events. In Villaseca peatbog, between 50 and 160 cm with high organic sediment, the diatoms are rare and bad preserved (from Boreal to present times). Between 160 and 260 cm, with a high clay content, the diatoms are abundant and well preserved (Late Glacial to Boreal). Between 50 and 200 cm (Preboreal to historical times) the diatom flora is made up of litoral species adapted to oligotrophic conditions. In La Mata the diatoms are absent from all samples except in the two samples from the upper-most part of the core where the valves are abundant but bad preserved. At this stage the diatom assemblages are also characteristic from oligotrophic and shallow waters. The data suggest that diatom preservation is controlled by the relationship between the geomorphology, the source of water and the trophic level.