Postglacial diatom stratigraphy of Kirchner Marsh, Minnesota

Auteur :
BRUGAM, R. B.

Description :
Fossil diatom assemblages from a 12-m core from Kirchner Marsh were compared with modern surface assemblages from 159Minnesota and Labrador lakes using cluster analysis. The deepest levels of the core (spruce pollen zone 13,000 to 10,200yr BP) resemble modern diatom assemblages from deep oligotrophic lakes of northeastern Minnesota. Diatom assemblages of the pine pollen zone (about 10,200 to 9,500yr BP) have few modern analogs. In the oak zone (9,500yr BP to present) after a brief pulse of diatom species indicative of eutrophication, the assemblages are dominated by species characteristic of shallow lakes, suggesting a drop in the lake water level during the prairie period (5,500 to 7,500yr BP) Macrofossil data of W.A. Watts and T.C. Winter (1966, Geological Society of America Bulletin 77, 1339-1360) show that this shift to shallow-water diatoms occurred when aquatic macrophytes appeared at the site in abundance.


Type de document :
Article de périodique

Source :
Quaternary research New York, 1980, vol. 13, n°. 1, p. 133-146, Références bibliographiques : 29réf.

Date :
1980