The sedimentology, stratigraphy and14C dating of a turf-banked solifluction lobe: evidence for Holocene slope instability at Okstindan, northern Norway

Abstract

The stratigraphy of a trench excavated through a solifluction lobe lying at an altitude of 860 m a.s.l. on the eastern flank of the Okstindan mountains is described. Sedimentological evidence suggests that the movement was probably dominated by a flow process, with silty sands episodically bursting‐out through a thinly vegetated lobe front in the spring and early summer thaw phases, when pore‐water pressures were likely to be increased. A continuous buried soil extends for some 14 m. Fourteen new radiocarbon age estimates from thin‐slice samples of this buried soil and organic fractions derived from laboratory pre‐treatment procedures are discussed. These data indicate that the solifluction probably commenced in the mid‐Holocene and continued throughout the Neoglacial. The slope instability may be correlated tentatively with the record of glacial variations, shifts in tree lines and archaeological evidence, supporting a link with regional climatic deterioration. Copyright © 1999 John Wiley & Sons, Ltd.

Frontal advance of turf-banked solifluction lobes, Kluane Range, Yukon Territory, Canada

“…The solifluction process is partly controlled by climatic factors (e.g., Å kerman, 1996; Lewkowicz and Clarke, 1998) so past variations in rates of lobe advance have often been interpreted as resulting from changes in regional climate (e.g., Benedict, 1966Benedict, , 1976Alexander and Price, 1980;Gamper, 1983;Ballantyne, 1986;Elliot and Worsley, 1999). However, conclusions on the response of solifluction landforms to climate change have generally been tentative because of: (1) the limited number of 14 C dates used in each study; (2) the uncertainty associated with radiocarbon dating of soils (e.g., Matthews, 1993;Birkeland, 1999, p.140); (3) the unknown representativeness of a particular landform for a given site; and (4) limited understanding of the mechanism of lobe advance.…”

“…Some researchers have dated the upper end of buried organic horizons to infer the onset of active solifluction (Worsley and Harris, 1974;Ellis, 1979;Nesje et al, 1989), and regional chronologies of solifluction activity during the Holocene have been developed based on compilations of these results (Morin and Payette, 1988; Matthews et al, 1993;Veit, 1993). In other studies, buried humus has been sampled at intervals along a continuous organic horizon to obtain a time series of individual lobe movements (Benedict, 1966;Costin et al, 1967;Alexander and Price, 1980;Gamper, 1983;Reanier and Ugolini, 1983;Matthews et al, 1986;Ballantyne, 1986;Smith, 1987a;Elliot and Worsley, 1999). Long-term rates of lobe advance obtained using this method range from 1 to 10 mm yr À 1 (Matsuoka, 2001).…”

Variation in the moisture regime of northeastern interior Alaska and possible linkages to the Aleutian Low: inferences from a late-Holocene δ18O record

“…A sustained westerly AL may have enhanced the amount of snowfall, thereby increasing soil erosion and the input of detrital carbonate (with elevated d 18 O) to Keche Lake during spring snowmelt. In addition, above-average snowfall and winter temperature typically associated with a western AL could have promoted thermokarst activity and thereby increased the sediment load to the lake (Elliott and Worsley 1999).…”

Responses of an arctic landscape to Lateglacial and early Holocene climatic changes: the importance of moisture

“…Today in arctic regions, solifluction accounts for a significant portion of slope denudation (Rapp and ( Akerman, 1993), and it is an important supplier of sediment to streams. In stratigraphic sections, solifluction deposits appear as silty diamictons with elongate clasts that mostly dip downslope at 10-201 (Nelson, 1985;Elliott and Worsley, 1999). In the Arctic Foothills, solifluction sections are exposed most commonly in stream cutbanks within colluvial basins.…”

“…Solifluction can also be enhanced by increased snow cover, which creates higher soil moisture upon melting (Matthews et al, 1993;Elliott and Worsley, 1999). Deeper thawing and increased winter precipitation at the YD/Holocene transition, and possibly during the earlier warm periods of the Lateglacial, are the likely causes of one or more widespread episodes of solifluction in the Arctic Foothills.…”