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TitreConverging ice streams: a failed hypothesis for deposition of the Oak Ridges Moraine
AuteurSharpe, D R; Russell, H A J; Pugin, A J -M
SourceCANQUA-AMQUA Ottawa 2018, Joint Meeting of the Canadian and American Quaternary Associations, Crossing Borders in the Quaternary, program; 2018 p. 85
LiensOnline - En direct (complete volume - volume complet, pdf, 11.5 MB)
Année2018
Séries alt.Ressources naturelles Canada, Contribution externe 20180299
ÉditeurCANQUA-AMQUA
RéunionCANQUA-AMQUA 2018: Joint meeting of the Canadian and American Quaternary Associations; Ottawa, ON; CA; août 7-11, 2018
Documentlivre
Lang.anglais
Mediapapier; en ligne; numérique
Formatspdf
ProvinceOntario
SNRC30M/13; 30M/14; 31D/01; 31D/02; 31D/04; 31D/05; 31D/08; 31G/05; 40P/16
Sujetsantecedents glaciaires; glaciation; écoulement glaciaire; antecedents de sedimentation; milieu sédimentaire; dépôts glaciaires; moraines; topographie glaciaire; eskers; elements glaciaires; chenaux d'eau de fonte; Moraine d'Oak Ridges ; Till d'Halton ; directions d'écoulement glaciaire; courants glaciaires; chenaux-déversoirs; sédiments fluvioglaciaires; sédiments glaciolacustres; géologie des dépôts meubles/géomorphologie; stratigraphie; Phanérozoïque; Cénozoïque; Quaternaire
ProgrammeCaractéristiques d'aquifères et support cartographique, Géoscience des eaux souterraines
Diffusé2018 08 01
Résumé(disponible en anglais seulement)
The hypothesis that the Oak Ridges Moraine (ORM) formed between two converging (roughly NS) ice streams is tested based on readily available, high-resolution field data. These data include DEMs, geological mapping, shallow reflection seismic profiles, continuous core, and analysis of sediment type, architecture, and paleoflow. Combined these data refute the converging ice stream hypothesis for deposition of the ORM. Streamlined landforms, which are used to re-construct ice stream flow paths, are defined by surface mapping, seismic profiles and cored boreholes to trend beneath ORM; they illustrate that the streamlining event is older and has no direct bearing on the formation of ORM. Meltwater channels that truncate the streamlined landforms (linked to the ORM ice stream hypothesis) are inferred to represent (sub-aerial) spillways, which end at the north side of ORM. These NS meltwater channels truncate the streamlined forms and they also trend beneath ORM; they have eskers on their floors, and thus, are subglacial and not sub-aerial channels. Halton Till, the inferred southern, ice-stream bed, is not present in the areas of the predicted ice-stream flow path. Halton Till occurs in transition from ORM glaciofluvial sediment, and comprises interbedded diamicton and glaciolacustrine sediment, not the predicted ice-stream, deforming-bed sediment facies. ORM glaciofluvial to glaciolacustrine sediment has a clear east to west paleoflow in conflict with the ~NS sediment flux required by the converging ice stream hypothesis. In summary, the proposed ice stream hypothesis fails to explain the field data related to deposition of the ORM.
Résumé(Résumé en langage clair et simple, non publié)
Cet article montre que l'ORM n'a pas été formé par des courants glaciaires, car l'hypothèse n'est pas conforme aux données de terrain publiées sur le type de sédiment, la géométrie, la composition et les anciennes directions d'écoulement. ORM a été formé, plutôt, par la décharge d'eau de fonte glaciaire stockée à la fin du dernier épisode glaciaire. Sa composition en sable et en gravier en fait l'une des plus importantes ressources en eaux souterraines de la région de Toronto et du sud de l'Ontario.
GEOSCAN ID313103