The Microstratigraphy of Two Peat Sequences from Northeastern Newfounland
Commonly, the ombrotrophic peats of Newfoundland have a well-defined banded appearance. Each band consists of a light-coloured lower section and a dark upper component. The bands are separated by abrupt recurrence surfaces. The regularity of the bands implies cyclicity. The physical, elemental, micr...
| Published in: | Géographie physique et Quaternaire |
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| Main Authors: | , |
| Format: | Text |
| Language: | English |
| Published: |
Les Presses de l'Université de Montréal
1987
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| Subjects: | |
| Online Access: | http://id.erudit.org/iderudit/032691ar https://doi.org/10.7202/032691ar |
| Summary: | Commonly, the ombrotrophic peats of Newfoundland have a well-defined banded appearance. Each band consists of a light-coloured lower section and a dark upper component. The bands are separated by abrupt recurrence surfaces. The regularity of the bands implies cyclicity. The physical, elemental, micro- and macro-stratigraphies of two banded profiles from the Wesleyville area were examined in an attempt to document the differences and to provide insight into cause. Ash content, fibre content, bulk density, water content and water retention were measured. The latter three showed consistent changes through each profile. There were no obvious patterns in the values for the biologically active elements that were measured (Mg, Cl, Ca, Na, Al, Mn and I), but the curves for Br, V, and U, biologically inert elements, showed systematic variations that appear to reflect variations in peat accumulation rate. The pollen, spore and macrofossil stratigraphies were generally complacent, although the representation of Sphagnum macrofossils and spores varied regularly as did pollen and spore concentrations. Each light-dark sequence appears to reflect a cycle of self-sustaining hydrologie changes involving changes in community composition, and in oxidation and accumulation rate, rather than climate. The cycles appear to be ca. 700 years in length, and are system-wide, but with variable lag times. Les tourbes ombrothrophes de Terre-Neuve présentent d'ordinaire des couches nettement définies. Chaque couche comporte une partie inférieure claire et une partie supérieure foncée. Les couches sont séparées par des surfaces de récurrence abruptes. La régularité des couches suppose l'existence d'un phénomène cyclique. Les micro et macrostratigraphies physique et celles des éléments de deux coupes de deux profils rubanés de la région de Wesleyville ont été étudiés en vue d'en observer les différences et de déterminer les causes de ces différences. Les teneurs en cendres et en fibres, le poids volumétrique, la teneur en eau et la rétention ... |
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