Late Quaternary Palaeoenvironment of Spring Lake, Alberta, Canada

Abstract

Palaeoenvironmental investigations based upon sediment cores taken from Spring Lake in the Peace River District of Alberta, Canada (latitude 55 ~ N; longitude 119 ~ 35' W) show that the sedimentary record spans the Holocene period. Chemical and diatom changes coincide with regional climatic change since deglaciation (about 11000 yr. B.P.). Calcite laminations in the basal 3 metres of the cores are evident, and were probably formed through elevated water temperature although photosynthetic removal of CO2 undoubtedly contributed. The disappearance of the laminations, and concurrent decrease in calcite X-ray diffraction peaks ca. 5000 yr. B.P. may have been caused by a change from a partially meromictic to a dimictic lake as the climate changed. Benthic and alkaline diatoms dominate before 5000 yr. B.P., while the planktonic Stephanodiscus hantzschii dominated between 5100 and 4200 yr. B.P. probably owing to increased nutrient levels. From ca. 4200 yr. B.P. until the present, benthic Fragilaria spp. and more circumneutral diatoms were dominant. Palaeoproduction, as measured by chlorophyll derivates, was highest in the early developmental stages of the lake, decreased coinciding with a major disturbance of the sediments and lowered water levels, and then gradually increased again until present. Only during the earlier period of peak production does biogenic calcite formation appear more important than calcite deposition caused by high water temperatures.

The Paleoecological Record of 6 ka BP Climate in the Canadian Prairie Provinces

“…Copper Lake (White and Osborn, 1992). (Hickman and White, 1989). Here too, the 6 ka interval appears transitional between low, warm-water conditions of the early Holocene and higher, more stable water levels achieved by 4800 yr BP.…”

“…Boone Lake (White and Mathewes, 1986), 15. Spring Lake (White and Mathewes, 1986;Hickman and White, 1989), 16. West Naniskak Lake (Wilson, 1984), 17.…”

A palaeoenvironmental study of Fairfax Lake, a small lake situated in the rocky mountain foothills of west-central Alberta

“…Where diatoms are found initially, they are present in low numbers. This appears to be a common phenomenon of Alberta lakes where the early Holocene record is obtained (Hickman et al, 1984;Hickman & White, 1989;Hickman, unpublished data). At such early stages in the development of a lake, factors affecting diatom growth, both planktonic and benthic, may include low water temperature, high turbidity, and perhaps an extremely high base status resulting from catchment leaching.…”

“…Many of these studies have been almost entirely confined to the elucidation of terrestrial vegetation and effects of inferred climate change (e.g., Lichti-Federovich, 1970;Ritchie, 1976;MacDonald, 1982;1987a;1987b;; Kearney the responses of the lakes and their biota to changing late Quaternary environments, including climate and edaphic changes. The data have been interpreted in terms of palaeohydrology and fluctuating water levels, palaeoproduction, watershed stability and general effects of climate change upon the lakes, their biota and catchment (eg., Forbes & Hickman, 1981;Hickman & Klarer, 1981;Hickman et aL, 1984;Hickman, 1987;Hickman & White, 1989;Schweger & Hickman, 1989;Hickman et al, 1990). Here we report on a small lake situated in the Rocky Mountain Foothills of west-central Alberta.…”

Paleolimnological records of climatic change in North America

“…A number of studies have used changes in the relative abundance of planktonic vs. littoral and benthic diatoms to reconstruct lake-level change (Hickman and White 1989;Schweger and Hickman 1989). In regions where lake level is under strong climatic control, these data may be useful in documenting major climatic shifts, such as transitions between dry glacial and moist interglacial environments (Bradbury 199 1 a, b); however, in temperate lakes and over time scales where climatic change is less extreme, climatic interpretation from planktonic : benthic ratios (in the absence of corroborative data) is rarely well constrained because of the numerous factors that may affect species abundance in both planktonic and littoral habitats.…”