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Stratigraphic Architecture and Sediment Facies of the Western Document généré le 27 sept. 2021 06:10 Géographie physique et Quaternaire Stratigraphic Architecture and Sediment Facies of the Western Oak Ridges Moraine, Humber River Watershed, Southern Ontario Architecture stratigraphique et faciès sédimentaire de la moraine occidentale de Oak Ridges, bassin de la rivière Humber, sud de l’Ontario Hazen A.J. Russell, Robert W.C. Arnott et David R. Sharpe Glacial History, Paleogeography and Paleoenvironments in Glaciated Résumé de l'article North America La moraine de Oak Ridges, sud de l’Ontario, est une crête de sable et de gravier Volume 58, numéro 2-3, 2004 orientée est-ouest d’une longueur de 160 km au nord du lac Ontario. L’étude de la moraine de Oak Ridges dans le bassin de la rivière Humber permet de URI : https://id.erudit.org/iderudit/013141ar comprendre son rôle dans le système de drainage de la vallée Laurentienne. La DOI : https://doi.org/10.7202/013141ar moraine de Oak Ridges a été édifiée en trois phases. La phase I consiste en une sédimentation rapide par hyperconcentration des écoulements, où les chenaux en tunnel se déversent dans un lac sous-glaciaire du lac Ontario. Le bassin de Aller au sommaire du numéro sédimentation de faible énergie de la phase II est sous-glaciaire et touche à un inlandsis ayant d’importantes crevasses. La phase III se caractérise par un changement de faciès très rapide, par la présence d’eskers, de cônes Éditeur(s) aquatiques et de bassins sédimentaires. Les analyses sédimentaires détaillées ébranlent l’hypothèse que la moraine de Oak Ridges ait été formée par la fonte Les Presses de l'Université de Montréal des glaces saisonnière, les fluctuations climatiques près des marges glaciaires, ou dans une position interlobaire. Notre interprétation indique plutôt qu’elle a ISSN été mise en place en réponse à des événements de fonte sous-glaciaire de 0705-7199 (imprimé) nature épisodique et catastrophique, et par des apports subséquents d’eau de 1492-143X (numérique) fonte saisonnière. La moraine s’est probablement formée lors de la ré-équilibration du système glacio-hydraulique en présence d’un inlandsis mince, en contact avec le substrat et alimentant un lac sous-glaciaire dans le Découvrir la revue bassin du lac Ontario. Citer cet article Russell, H. A., Arnott, R. W. & Sharpe, D. R. (2004). Stratigraphic Architecture and Sediment Facies of the Western Oak Ridges Moraine, Humber River Watershed, Southern Ontario. Géographie physique et Quaternaire, 58(2-3), 241–267. https://doi.org/10.7202/013141ar Tous droits réservés © Les Presses de l'Université de Montréal, 2006 Ce document est protégé par la loi sur le droit d’auteur. L’utilisation des services d’Érudit (y compris la reproduction) est assujettie à sa politique d’utilisation que vous pouvez consulter en ligne. https://apropos.erudit.org/fr/usagers/politique-dutilisation/ Cet article est diffusé et préservé par Érudit. Érudit est un consortium interuniversitaire sans but lucratif composé de l’Université de Montréal, l’Université Laval et l’Université du Québec à Montréal. Il a pour mission la promotion et la valorisation de la recherche. https://www.erudit.org/fr/ GPQ_58-2-3.qxd 20/06/06 09:55 Page 241 Géographie physique et Quaternaire, 2004, vol. 58, nos 2-3, p. 241-267, 19 fig., 3 tabl. STRATIGRAPHIC ARCHITECTURE AND SEDIMENT FACIES OF THE WESTERN OAK RIDGES MORAINE, HUMBER RIVER WATERSHED, SOUTHERN ONTARIO* Hazen A.J. RUSSELL**, Robert W.C. ARNOTT and David R. SHARPE; first and second authors: Department of Earth Sciences, University of Ottawa, Ontario K1N 6N5; first and third authors: Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8. ABSTRACT The Oak Ridges Moraine in southern Ontario is a RÉSUMÉ Architecture stratigraphique et faciès sédimentaire de la ca. 160 km long east-west trending ridge of sand and gravel situated moraine occidentale de Oak Ridges, bassin de la rivière Humber, sud north of Lake Ontario. Study of the Oak Ridges Moraine in the Humber de l’Ontario. La moraine de Oak Ridges, sud de l’Ontario, est une crête River watershed was undertaken to assess its role in the groundwa- de sable et de gravier orientée est-ouest d’une longueur de 160 km au ter system of the buried Laurentian Valley. The Oak Ridges Moraine nord du lac Ontario. L’étude de la moraine de Oak Ridges dans le bas- is interpreted to have been deposited in three stages. Stage I records sin de la rivière Humber permet de comprendre son rôle dans le sys- rapid deposition from hyperconcentrated flows where tunnel chan- tème de drainage de la vallée Laurentienne. La moraine de Oak Ridges nels discharged into a subglacial lake in the Lake Ontario basin. Low- a été édifiée en trois phases. La phase I consiste en une sédimenta- energy basin sedimentation of Stage II was in a subglacial and ice- tion rapide par hyperconcentration des écoulements, où les chenaux contact setting of a highly crevassed ice sheet. Stage III sedimentation en tunnel se déversent dans un lac sous-glaciaire du lac Ontario. Le is characterized by rapid facies changes associated with esker, sub- bassin de sédimentation de faible énergie de la phase II est sous-gla- aqueous fan, and basinal sedimentation. Detailed sediment analysis ciaire et touche à un inlandsis ayant d’importantes crevasses. La challenges the concept that the Oak Ridges Moraine was deposited phase III se caractérise par un changement de faciès très rapide, par principally from seasonal meltwater discharges, climatic modulated la présence d’eskers, de cônes aquatiques et de bassins sédimen- ice-marginal fluctuations, or in an interlobate position. Instead it is taires. Les analyses sédimentaires détaillées ébranlent l’hypothèse interpreted to have formed in response to late-glacial ice sheet events que la moraine de Oak Ridges ait été formée par la fonte des glaces associated with subglacial meltwater ponding, episodic and cata- saisonnière, les fluctuations climatiques près des marges glaciaires, ou strophic subglacial meltwater discharge, and subsequent seasonal dans une position interlobaire. Notre interprétation indique plutôt qu’elle meltwater discharge. The moraine probably formed as the glacial- a été mise en place en réponse à des événements de fonte sous- hydraulic system re-equilibrated to the presence of a thinned, glaciaire de nature épisodique et catastrophique, et par des apports grounded ice shelf and a subglacial lake in the Lake Ontario basin. subséquents d’eau de fonte saisonnière. La moraine s’est probable- ment formée lors de la ré-équilibration du système glacio-hydraulique en présence d’un inlandsis mince, en contact avec le substrat et ali- mentant un lac sous-glaciaire dans le bassin du lac Ontario. Manuscrit reçu le 17 juin 2005 ; manuscrit révisé accepté le 2 mars 2006 (publié le 2e trimestre 2006) * Geological Survey of Canada contribution number 2005129 ** E-mail address: [email protected] GPQ_58-2-3.qxd 20/06/06 09:55 Page 242 242 H. A. J. RUSSELL, R. W. C. ARNOTT and D. R. SHARPE INTRODUCTION the Greater Toronto Area.It provides recharge to lower aquifers due to infill of deep valleys, with coarse sediment, that provide Moraines form a prominent element of the southern Ontario connecting to lower sediment (Sharpe et al., 2002). The ORM landscape. The location and distribution of the moraines was also provides abundant water to streams and to watershed outlined early in the 20th century by Taylor (1913). Subsequent ecosystems, in addition to a large domestic groundwater sup- work has refined the extent and form of these moraines ply (Sibul et al., 1977; Howard et al., 1995). Thus, improved (Barnett, 1992). Moraines in the area have been classified by information on sediment extent, composition and variability is Chapman and Putnam (1943) as either till or kame moraines needed to better manage these vital watershed activities. The (Fig. 1) and related to specific genetic processes. Kame Humber River watershed which includes the western extent of moraines have been inferred to be deposited at the margin of the ORM and underlying portions of the buried Laurentian Valley inactive ice, whereas, till moraines are inferred to be thrust is one such watershed worthy of study (Figs. 2-3). into position by advancing ice, and to mark the extent of ice- Moraine origin can be inferred from its sediment composi- advance (Chapman and Putnam, 1943). There have been few tion and architecture. The ORM has been interpreted as an studies of the sediment composition of either kame or till interlobate moraine deposited between converging flow of the moraines. Consequently, 60 years after Chapman and Putnam Lake Simcoe ice-lobe to the north and the Lake Ontario lobe work, understanding of many moraines in southern Ontario is to the south (Chapman and Putnam, 1984). The proposed incomplete. Two exceptions are the Waterloo and Oak Ridges inter-lobe re-entrant and increased meltwater and sediment moraines (Karrow and Paloschi, 1996). In particular, the flux in this reconstruction was attributed to climatic warming ca. 160 km long Oak Ridges Moraine (ORM) has been the during the Mackinaw Interstadial (Karrow, 1974; Duckworth, focus of extensive sedimentological study aimed at under- 1979). The proposed ice lobes and interstadial ice retreat standing the geological history of the landform (Barnett et al., implied sedimentary events, structures and depositional trends 1998; Sharpe et al., 2002). unique to each lobe. This classic interpretation for the origin of Many moraines in Ontario are important areas of ground- the ORM is at odds with accumulating evidence of large-scale water recharge. Moraine topography and internal sedimentary erosional and depositional meltwater events in the area and architecture controls the transmission of water from ground sur- formation of the ORM from short-lived flood discharge events face to groundwater and regional aquifers.
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