Comparative radiocarbon dating of terrestrial plant macrofossils and aquatic moss from the ice-free corridor of western Canada

Journal Article · Tue Sep 01 00:00:00 EDT 1987 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1987)15<837:CRDOTP>2.0.CO;2· OSTI ID:5276533

MacDonald, G M; Beukens, R P; Kieser, W E; Vitt, D H

In order to assess the reliability of aquatic moss for radiocarbon dating, /sup 14/C analyses were performed on a stratigraphic series of terrestrial plant macrofossils and samples of Drepanocladus crassicostatus from a small, hard-water lake (pH = 8.2) in the ice-free corridor of Alberta. All /sup 14/C dating was done by using accelerator mass spectrometry. Mazama Ash provided an independent chronological control. The aquatic bryophyte samples consistently produced /sup 14/C ages significantly older than the terrestrial macrofossils. The relation between the radiocarbon dates from the macrofossils and the moss was not linear, and age differences ranged from approximately 1400 to 6400 yr. The /sup 14/C content of D. crassicostatus growing in the lake at present was less than 85% modern. Despite the apparent inability to take up /sup 14/C-deficient carbon by the direct incorporation of bicarbonate, the bryophytes clearly do not provide reliable material /sup 14/C dating. The /sup 14/C deficiency of aquatic mosses may be explained by the generation of /sup 14/C-deficient CO/sub 2/ through isotopic exchange, the formation of CO/sub 2/ from bicarbonate by chemical processes, and metabolic CO/sub 2/ production. These results demonstrate the potential unreliability of /sup 14/C dates from aquatic mosses and raise serious concerns about the deglaciation dates from the ice-free corridor that were obtained from aquatic Drepanocladus.

• Research Organization: McMaster Univ., Hamilton, Ontario, (Canada)
• OSTI ID: 5276533
• Journal Information: Geology; (United States), Vol. 15:9
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ISOTOPE DATING
PERFORMANCE
MOSSES
CANADA
CARBON 14
CARBON DIOXIDE
COMPARATIVE EVALUATIONS
FOSSILS
GLACIERS
ISOTOPIC EXCHANGE
LAKES
QUATERNARY PERIOD
SEDIMENTS
AGE ESTIMATION
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON OXIDES
CENOZOIC ERA
CHALCOGENIDES
EVEN-EVEN NUCLEI
GEOLOGIC AGES
ISOTOPES
LIGHT NUCLEI
NORTH AMERICA
NUCLEI
OXIDES
OXYGEN COMPOUNDS
PLANTS
RADIOISOTOPES
SURFACE WATERS
YEARS LIVING RADIOISOTOPES
580100* - Geology &amp; Hydrology- (-1989)