Document generated on 10/02/2021 11:56 a.m. Géographie physique et Quaternaire Late Glacial Sedimentation and History of the Lake Nipigon Basin, Ontario Sédimentation tardiglaciaire et évolution du bassin du lac Nipigon, en Ontario Spätglaziale Sedimentablagerung und Geschichte des Nipigon-Seebeckens, Ontario Rick M. Lemoine and James T. Teller Volume 49, Number 2, 1995 Article abstract The Lake Nipigon basin lies north of the Lake Superior basin and was the URI: https://id.erudit.org/iderudit/033039ar hydrological link between glacial Lake Agassiz and the Great Lakes during part DOI: https://doi.org/10.7202/033039ar of the last deglaciation. A sequence of glaciolacustrine sediments, composed mainly of silt-clay rhythmites and sand, was deposited in the offshore waters of See table of contents glacial Lake Nipigon by overflow from Lake Agassiz and meltwater from the retreating glacier margin. Sections from six long sediment cores and four lake bluff exposures reveal a sandy (early deglacial) lower section that is overlain Publisher(s) by 300 to 850 silt-clay rhythmites (varves). Deposition of these varves, as well as coarser sediment along the western shore, began after 9200 BP, as the glacial Les Presses de l'Université de Montréal margin retreated northward along the continental divide that separated the Nipigon basin from the higher Lake Agassiz basin to the west. The absence of ISSN ice rafted clasts in the rhythmites suggests that the ice had retreated from the lake by the time they were deposited. On the basis of their elevation in relation 0705-7199 (print) to the lowest raised beach at West Bay, which formed about 9000 BP, most 1492-143X (digital) rhythmites probably were deposited between 9000 and 8000 BP. Species of arboreal pollen are present in early postglacial sediments of the Explore this journal Nipigon-Superior lowlands, suggesting that the Lake Nipigon region became colonized by coniferous and deciduous forests soon after déglaciation. The presence of non-arboreal pollen species suggest that these forests were Cite this article interspersed with open meadows and grasslands, similar to today's floral assemblages. Fossil molluscs recovered from glaciolacustrine sand exposed Lemoine, R. M. & Teller, J. T. (1995). Late Glacial Sedimentation and History of along the eastern side of the basin suggest that the limnological characteristics the Lake Nipigon Basin, Ontario. Géographie physique et Quaternaire, 49(2), of late glacial Lake Nipigon were similar to those of today. 239–250. https://doi.org/10.7202/033039ar Tous droits réservés © Les Presses de l'Université de Montréal, 1995 This document is protected by copyright law. Use of the services of Érudit (including reproduction) is subject to its terms and conditions, which can be viewed online. https://apropos.erudit.org/en/users/policy-on-use/ This article is disseminated and preserved by Érudit. Érudit is a non-profit inter-university consortium of the Université de Montréal, Université Laval, and the Université du Québec à Montréal. Its mission is to promote and disseminate research. https://www.erudit.org/en/ Géographie physique et Quaternaire, 1995, vol. 49, n° 2, p. 239-250, 6 fig., 2 tabl. LATE GLACIAL SEDIMENTATION AND HISTORY OF THE LAKE NIPIGON BASIN, ONTARIO Rick M. LEMOINE and James T. TELLER, respectively, Manitoba Environment, 139 Tuxedo, Winnipeg, Manitoba R3N 0H6, and Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2. ABSTRACT Late glacial sedimentation RÉSUMÉ Sédimentation tardiglaciaire et ZUSAMMENFASSUNG Spàtglaziale and history of the Lake Nipigon basin, On­ évolution du bassin du lac Nipigon, en Sedimentablagerung und Geschichte des tario. The Lake Nipigon basin lies north of Ontario. Le bassin du lac Nipigon situé au Nipigon-Seebeckens, Ontario. Das Becken the Lake Superior basin and was the hy- nord du bassin du lac Supérieur a assuré des Nipigonsees liegt nôrdlich von dem des drological link between glacial Lake Agassiz le lien hydrologique entre le Lac Agassiz et Oberen Sees, und war das hydrologische and the Great Lakes during part of the last les Grands Lacs pendant une partie de la Bindeglied zwischen dem glazialen déglaciation. A sequence of glaciolacustrine dernière glaciation. Une séquence de sédi­ Agassizsee und den groBen Seen wàhrend sediments, composed mainly of silt-clay ments glaciolacustres, surtout composés de eines Teils der letzten Enteisung. Eine rhythmites and sand, was deposited in the rythmites silto-argileuses et de sable, a été Sequenz glaziallimnischer Sedimente, offshore waters of glacial Lake Nipigon by déposée au large du rivage du Lac gla­ hauptsàchlich aus Schlamm-Lehm, Rhyth- overflow from Lake Agassiz and meltwater ciaire Nipigon par les eaux de crue du Lac miten und Sand bestehend, wurde in dem from the retreating glacier margin. Sections Agassiz et les eaux de fonte du glacier en kùstennahen Wasser des glazialen Nipigan- from six long sediment cores and four lake recul. Les coupes dans six carottes de sé­ sees abgelagert durch ùberlauf vom bluff exposures reveal a sandy (early diments et quatre coupes naturelles dans Agassizsee und Schmelzwasser von dem deglacial) lower section that is overlain by la falaise révèlent la présence de sable dans zurùckweichenden Gletscherrand. Absch- 300 to 850 silt-clay rhythmites (varves). la partie inférieure (début de la déglaciation) nitte von sechs langen Sedimentbohrkernen Deposition of these varves, as well as recouverte par 300 à 850 rythmites silto- und vier See-Steilhang-Aufschlùsse zeigen coarser sediment along the western shore, argileuses (varves). La mise en place de einen sandigen (Beginn der Enteisung) began after 9200 BP, as the glacial margin ces varves, comme celle des sédiments unteren Bereich, der von 300 bis 850 retreated northward along the continental plus grossiers le long de la rive ouest, a Schlamm-Lehm-Rhythmiten (Warwen) divide that separated the Nipigon basin from commencé après 9200 BP, alors que la ùberlagert ist. Die Ablagerung dieser the higher Lake Agassiz basin to the west. marge glaciaire reculait vers le nord le long Warwen sowie grôberer Sedimente entlang The absence of ice rafted clasts in the de la ligne de partage des eaux entre le der westlichen Kùste begann nach 9200 rhythmites suggests that the ice had re­ bassin du Lac Nipigon de celui plus élevé v.u.Z., als der Eisrand nordwârts zurùck- treated from the lake by the time they were du Lac Agassiz. L'absence de fragments wich, entlang der Wasserscheide, die das deposited. On the basis of their elevation glaciels dans les rythmites indique que le Nipiganbecken von dem hôheren Agassiz- in relation to the lowest raised beach at glacier s'était déjà retiré. Selon leur alti­ becken nach Westen hin trennte. Das West Bay, which formed about 9000 BP, tude par rapport à la plage perchée la moins Fehlen von Eisfragmenten in den Rhyth- most rhythmites probably were deposited élevée à West Bay, formée vers 9000 BP, miten IaBt vermuten daB das Eis zum between 9000 and 8000 BP. Species of la plupart des rythmites ont été déposées Zeitpunkt ihrer Ablagerung vom See schon arboreal pollen are present in early entre 9000 et 8000 BP. Le pollen arboréen zurùckgewichen dap das Eis zum Zeitpunkt postglacial sediments of the Nipigon-Supe- présent dans les premiers sédiments war. Entsprechend ihrer Erhebung in Bezug rior lowlands, suggesting that the Lake postglaciaires des basses terres Nipigon- auf den niedrigsten gehobenen Strand in Nipigon region became colonized by conif­ Supérieur montre que les forêts de conifè­ der West Bay, der sich um 9000 v.u.Z. erous and deciduous forests soon after res et de décidus se sont établies peu après herausbildete, wurden die meisten déglaciation. The presence of non-arboreal la déglaciation. La présence de pollen non Rhythmite wohl zwischen 9000 und 8000 pollen species suggest that these forests arboréen montre que ces forêts étaient par­ v.u.Z. abgelagert. Baumpol-lenarten in den were interspersed with open meadows and semées de prés ouverts et de prairies, frùhen postglazialen Sedimenten der Su- grasslands, similar to today's floral assem­ comme c'est le cas aujourd'hui. Les mol­ perior-Nipigan-Ebenen legen nahe, daB im blages. Fossil molluscs recovered from lusques fossiles recueillis dans les sables Nipigansee -Gebiet kurz nach der Enteisung glaciolacustrine sand exposed along the glaciolacustres le long du côté est du bas­ Tannen- und Laubwald sich ausbreiteten. eastern side of the basin suggest that the sin montrent que les propriétés limnolo- Das Vorkommen von baumfremden limnological characteristics of late glacial giques du Lac Nipigon sont semblables à Pollenarten zeigt, daB die Wâlder von Lake Nipigon were similar to those of to­ celles d'aujourd'hui. offenen Weiden und Grasland durchsetzt day. waren, àhnlich der heutigen Bewachsung. Schalentier-Fossile, die aus dem glazial- limnischen Sand gewonnen wurden, entlang der ôstlichen Seite des Beckens, zeigen, daB die limnologischen Charakteristika des spâtglazialen Nipigan-sees den heutigen Manuscrit reçu le 23 février 1994; manuscrit révisé accepté le 13 octobre 1994. àhnlich waren. 240 R.M. LEMOINE and JT. TELLER INTRODUCTION the ice margin had retreated north, and Lake Agassiz water flowed directly into Lake Superior via one or more of the The hydrological connection of glacial Lakes Agassiz, eastern outlets (Fig. 1), marking the onset of the Moorhead Nipigon (Lake Kelvin), and Superior has been studied by Phase of Lake Agassiz. Elson (1967), Zoltai (1965, 1967), Teller and Thorleifson (1983, 1987), Clayton (1983), Drexler etal. (1983), Farrand A readvance of Laurentide ice about 10,000 BP shut off and Drexler (1985), Teller and Mahnic (1988), and the overflow of water into the Nipigon and Superior basins, Thorleifson and Kristjansson (1993). Some of these re­ and Lake Agassiz waters were forced to rise and again searchers have speculated on the impact Lake Agassiz overflow out the southern outlet to the Mississippi River overflow had on the Superior basin. Others have discussed basin (Clayton and Moran, 1982).