Lake Onego development in the late glacial assessed with the use of GIS technologies

Abstract

The GIS-based reconstructions of Lake Onego development in the Late Glacial (14500–12300 yrs ago) were performed. Reconstructions have been based on the deglaciation model of the Lake Onego depression, digital elevation model of the lake depression, SRTM model of its drainage basin and on the data obtained from the palaeolimnological studies of numerous lake sediment cores. This allowed us to distinguish six main stages of the lake development for which a series of detailed schemes were produced. 1. Formation of the ice-dammed lake as a result of the ice sheet retreating (14.5 cal ka BP). 2. Emerging of the southern and central parts of the lake basin from the ice cover (14.0 cal ka BP). 3. The maximum development of the proglacial lake (13.3 cal ka BP). The lake area in this period was around 33 000 km2. 4. The first regression (13.2 ka BP). 5. The second regression (12.4 ka BP). 6. The third regression (12.3 ka BP), when the area of the lake dropped to 18 000 km2. We created detailed digital maps of the main stages of Lake Onego development during the Late Glacial and calculated the spatial parameters of the lake. The quantitative data obtained in this study would be used in estimation of the volumes of the lake and outflow discharges in the past. Maps are available in electronic form.

Distribution of Elements in Iron-Manganese Formations in Bottom Sediments of Lake Onego (NW Russia) and Small Lakes (Shotozero and Surgubskoe) of Adjacent Territories

“…The catchment area is ca 62,800 km 2 , and the surface area is ca 9720 km 2 [25]. Numerous publications are devoted to the geological structure and development history of Lake Onego and its basin [26][27][28][29][30][31][32]. The northern part of the catchment area of Lake Onego is composed of Precambrian crystalline rocks (granites, gneisses) that are resistant to abrasion processes, as well as deeply metamorphosed volcanogenic and sedimentary rocks of the Lower Proterozoic.…”

“…The chemical composition of FM crusts from Lake Shotozero is as follows: iron zones (%): Fe (37-58), Mn (0-6), Ba (0), O (28-39), P (0.5-2), and total (72-100); manganese zones (%): Fe (0-3), Mn (33-55), Ba (1)(2)(3)(4)(5)(6)(7)(8), O (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42), P (0), and total (56-99). The chemical composition of FM nodules from Lake Shotozero is as follows: granular zones (%): Fe (33-51), Mn (0-2), Ba (0), O (28-39), P (0.5-1), and total (61-96); manganese zones (%): Fe (0-20), Mn (33-56), Ba (1)(2)(3)(4)(5)(6)(7)(8), O (26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36), P (0), and total (60-99). Quite often, in the chemical composition of the FMC, the presence of Si, Al, Na, and Ca is determined in contents from 0.2% to 6%.…”

“…During chemical composition analysis of FM nodules and crusts from these lakes, the constant presence of Ba and Fe in signifficant amounts in manganese zones was revealed, along with the presence of Mn and P impurities in the granular zones. The chemical composition of FM nodules from Lake Surgubskoe is as follows: granular zones (%): Fe (24-67), Mn (0-21), Ва (0-0.5), O (28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42), Р (0.5-2), and total (44-100); manganese zones (%): Fe (1-35), Mn (38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52), Ва (4-12), O , Р (0-1), and total (55-99).…”