| Titre | Relating thick proglacial mud successions to processes at ice-stream margins: a tool for dating ice advances |
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| Auteur | Piper, D J W |
| Source | Atlantic Geoscience Society, abstracts, 47th Colloquium & Annual General Meeting 2021; Atlantic Geology vol. 57, 2021 p. 128-129, https://doi.org/10.4138/atlgeol.2021.006  Accès
ouvert |
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| Année | 2021 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20210028 |
| Éditeur | Société géoscientifique de l'Atlantique |
| Réunion | Atlantic Geoscience Society 47th Colloquium and Annual General Meeting 2021; février 5-6, 2021 |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.4138/atlgeol.2021.006 |
| Media | papier; numérique; en ligne |
| Formats | pdf; html |
| Sujets | caractéristiques sous-marines; cônes sous-marins; antecedents glaciaires; glaciation; écoulement glaciaire; déglaciation; retrait de la glace; marges glaciaires; âges relatifs; sédiments marins; boues;
silts; dépôts de coulée de débris; sables; graviers; turbidites; erosion glaciaire; laminations; antecedents de sedimentation; débit de sedimentation; coulées de débris; déformation; salinité; charge hydraulique; transport des sediments; dispersion
des sédiments; carottes de sédiment marin; courants glaciaires; bordures de courants glaciaires; sédiments glaciomarins; géologie marine; géologie des dépôts meubles/géomorphologie; sédimentologie; Nature et environnement; Sciences et technologie;
Phanérozoïque; Cénozoïque; Quaternaire |
| Programme | Géosciences marines pour la planification spatiale marine |
| Diffusé | 2021 03 22 |
| Résumé | (disponible en anglais seulement)
Thick red mud successions many metres thick of late Pleistocene age on Laurentian Fan have attracted attention since the 1950s. Recent studies have shown that
they represent periods of high sediment supply on a centennial to millennial time scale, separated by intervals of hemipelagic sedimentation on a similar time scale. Comparison with independent evidence for ice margin positions suggests that the
distinctive red muds with silt laminae are not restricted to times when ice reached the top of the continental slope but may also be deposited after retreat of the ice stream within Laurentian Channel. Most red mud successions are not accompanied by
major plunging hyperpycnal flows of sand and gravel.
Seaward of Trinity Trough, muddy glacigenic debris flows (GDFs) are preserved on the low-gradient trough-mouth fan, providing evidence for the muddy composition of the basal deforming layer
beneath the Trinity Trough ice stream. The GDFs are cut by three erosional horizons corresponding to plunging sand and gravel flows. Such observations suggest that some of the thick mud successions on Laurentian Fan are the result of breakup on the
steep upper slope of GDFs derived from the basal deforming layer of the ice stream, involving rapid entrainment of ambient seawater.
Within Halibut Channel, a young erosional surface provides evidence for powerful meltwater flow seaward of the
Younger Dryas ice margin and corresponding proximal turbidites in Halibut Canyon demonstrate that meltwater flow was sufficiently prolonged to deposit multiple turbidites. Sand transported by glacial meltwater was not restricted to a single
catastrophic breaching event, but rather was a repetitive ice-margin process. 'Normal' meltwater flows with low salinity, driven by a hydraulic head of water in the ice sheet, apparently filled the transverse trough and transported sediment to the
shelf edge, where they probably evolved in a manner similar to that monitored in the Squamish Delta. Such a process provides an explanation for the youngest thick red mud successions on Laurentian Fan deposited after the ice stream had retreated from
the shelf edge.
Seaward of the Hudson Strait ice stream, cores suggest that thick mud successions and GDFs accumulated at the time of Heinrich layer H3 and probably H4, whereas in H1 and H2 little sediment was supplied to deep water. Concepts
developed at mid latitudes may be less applicable because the outer transverse trough is bounded by deeper water on either side, and there is less evidence for abundant meltwater. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Cette présentation orale explore l'utilisation des sédiments en eau profonde comme indicateur des marges de glace dans le passé |
| GEOSCAN ID | 328264 |
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