Beitrag
Late-Glacial Diatoms of Kirchner Marsh, Southeastern Minnesota
Florin, Maj-Britt
Nova Hedwigia, Beihefte Beih. 31 (1970), p. 667 - 756
94 Literaturangaben
veröffentlicht: Apr 1, 1970
DOI: 10.1127/nova.beihefte/31/1970/667
ArtNo. ESP051003100025, Preis: 29.00 €
Abstract
Diatom remains assigned to about 230 taxa from the basal 80 cm of lake deposits at Kirchner Marsh indicate four stages in the late-glacial development of the basin. The bottom layer, represented by diatom zone 1, contains eu-terrestrial forms found today in dry habitats, especially Hantzschia amphioxys, Pinnularia borealis and Melosira roeseana. Diatom zone 2 is dominated by benthic aquatic forms that now live in the littoral of inland lakes but also occur in moist or dry habitats. They are here called facultative terrestrial diatoms. Among them should be mentioned species of Cymbella, Epithemia, Eunotia, Fragilaria, and Gomphonema, as well as Actinocyclus normanii, Mastogloia smithii v. lacustris and M. grevillei. Diatome zone 3 contains benthic aquatic forms dominated by species of Navicula and Achnanthes, These represent the first truly limnic stage in Kirchner basin. Upwards in the gyttja this flora is partly replaced by pelagic species, such as Cyclotella caspia, C. comta, C. kiitzingiana v. schumanni, and Fragilaria crotonensis, as water depth increased in the basin, representing diatom zone 4. Remnants of Cretaceous diatoms in the silt at the base of the core are reworked from Cretaceous shales in the glacial sediments. The sequence of diatom zones records the development of a small superglacial lake on the slightly reworked plant debris of a superglacial forest soil.
Schlagworte
Kirchner Marsh • Minnesota • USA • diatom