Saline systems of the Great Plains of western Canada: an overview of the limnogeology and paleolimnology

Abstract

In much of the northern Great Plains, saline and hypersaline lacustrine brines are the only surface waters present. As a group, the lakes of this region are unique: there is no other area in the world that can match the concentration and diversity of saline lake environments exhibited in the prairie region of Canada and northern United States. The immense number of individual salt lakes and saline wetlands in this region of North America is staggering. Estimates vary from about one million to greater than 10 million, with densities in some areas being as high as 120 lakes/km 2 .Despite over a century of scientific investigation of these salt lakes, we have only in the last twenty years advanced far enough to appreciate the wide spectrum of lake types, water chemistries, and limnological processes that are operating in the modern settings. Hydrochemical data are available for about 800 of the lake brines in the region. Composition, textural, and geochemical information on the modern bottom sediments has been collected for just over 150 of these lakes. Characterization of the biological and ecological features of these lakes is based on even fewer investigations, and the stratigraphic records of only twenty basins have been examined.The lake waters show a considerable range in ionic composition and concentration. Early investigators, concentrating on the most saline brines, emphasized a strong predominance of Na + and SO 4 -2 in the lakes. It is now realized, however, that not only is there a complete spectrum of salinities from less than 1 ppt TDS to nearly 400 ppt, but also virtually every water chemistry type is represented in lakes of the region. With such a vast array of compositions, it is difficult to generalize. Nonetheless, the paucity of Cl-rich lakes makes the northern Great Plains basins somewhat unusual compared with salt lakes in many other areas of the world (e.g., Australia, western United States). Compilations of the lake water chemistries show distinct spatial trends and regional variations controlled by groundwater input, climate, and geomorphology. Short-term temporal variations in the brine composition, which can have significant effects on the composition of the modern sediments, have also been well documented in several individual basins.From a sedimentological and mineralogical perspective, the wide range of water chemistries exhibited by the lakes leads to an unusually large diversity of modern sediment composition. Over 40 species of endogenic precipitates and authigenic minerals have been identified in the lacustrine sediments. The most common non-detrital components of the modern sediments include: calcium and calcium-magnesium carbonates (magnesian calcite, aragonite, dolomite), and sodium, magnesium, and sodium-magnesium sulfates (mirabilite, thenardite, bloedite, epsomite). Many of the basins whose brines have very high Mg/Ca ratios also have hydromagnesite, magnesite, and nesquehonite. Unlike salt lakes in many other areas of the world, halite, gypsum, and calcite are relati...

MINERALOGY AND CRYSTAL CHEMISTRY OF CARBONATES FROM THE HOLOCENE SEDIMENTS OF LAKE KIRAN (western Transbaikalia): CONNECTION WITH PALEOCLIMATE

“…В то же время малые водоемы, формирование которых в Северном по-лушарии зачастую приурочено к началу-середине относительно теплого и влажного атлантического периода, весьма чувствительны к таким изменениям. В мировой практике наиболее перспективными для палеоклиматических реконструкций считаются осадочные разрезы мелководных минеральных озер, нередко плайевых, с карбонатным типом седиментации, возникших на территориях с засушливым кли-матом [Страхов и др., 1954;Страхов, 1962;Hammer, 1986;Last, 1990Last, , 2002Smoot, Lowenstein, 1991;Cohen, 2003;Last, Ginn, 2005]. Подобные отложения представляют собой, как правило, доступные и детальные природные архивы, в которых зафиксирован целый ряд необходимых для проведения палео-реконструкций биологических, минералогических и геохимических откликов озерной системы на изме-нения параметров окружающей среды.…”

Canada's grasslands as habitat for arthropods

“…No other area in the world can match the density and diversity of saline lakes found in this region of Canada and in the adjoining regions of the United States (Last and Ginn 2005). Estimates of the number of saline ponds and lakes vary from about 1 million to more than 10 million.…”

“…Saline lakes are common across southern and central Alberta and Saskatchewan in closed basins (Last and Ginn 2005). These lakes are fed principally by surface inflow from runoff and small streams and are associated with dry climates, where evaporation exceeds precipitation (Hammer 1986).…”

“…31) west of Moose Jaw, the shorelines are shallow and the mud flats are extensive with high concentrations of salts. Other lakes such as Ingebrigt Lake north of Maple Creek, Saskatchewan, have deposits of salts about 43 m thick (Last and Ginn 2005).…”

“…Big Quill and Old Wives lakes are among the six largest inland saline water bodies on the continent. Even Lake Manitoba, North America's 13th largest lake, is a saline lake (Last and Ginn 2005).…”