| Title | Relating thick proglacial mud successions to processes at ice-stream margins: a tool for dating ice advances |
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| Author | 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  Open
Access |
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| Year | 2021 |
| Alt Series | Natural Resources Canada, Contribution Series 20210028 |
| Publisher | Atlantic Geoscience Society |
| Meeting | Atlantic Geoscience Society 47th Colloquium and Annual General Meeting 2021; February 5-6, 2021 |
| Document | serial |
| Lang. | English |
| Media | paper; digital; on-line |
| File format | pdf; html |
| Subjects | marine geology; surficial geology/geomorphology; sedimentology; Nature and Environment; Science and Technology; submarine features; submarine fans; glacial history; glaciation; ice flow; deglaciation;
ice retreat; ice margins; relative ages; marine sediments; muds; silts; debris flow deposits; sands; gravels; turbidites; glacial erosion; laminations; depositional history; sedimentation rates; debris flows; deformation; salinity; hydraulic head;
sediment transport; sediment dispersal; marine sediment cores; Laurentian Fan; ice streams; ice stream margins; glaciomarine sediments; Phanerozoic; Cenozoic; Quaternary |
| Program | Marine Geoscience for Marine Spatial Planning |
| Released | 2021 03 22 |
| Abstract | 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. |
| Summary | (Plain Language Summary, not published)
This presentation explores the use of deep-water sediment as an indicator of ice margins in the past |
| GEOSCAN ID | 328264 |
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