Sedimentary and stratigraphic evidence for subglacial flooding, south-central Michigan, USA

Fisher, Timothy G.; Taylor, Lawrence D.

doi:10.1016/s1040-6182(01)00095-7

Cited by 51 publications

(28 citation statements)

References 55 publications

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“…The formation of subaqueous outwash fans associated with eskers can develop either, (i) subglacially within side cavities adjacent to the main tunnel formed in areas with high hydrostatic pressure (Gorrell and Shaw, 1991), (ii) near the ice margin, as ice-walled channel deposits, defined by the ratio of their length to their width and defined as long bead eskers by Warren and Ashley (1994), or (iii) at the ice margin snout as short bead eskers or ice marginal subaqueous fans (Warren and Ashley, 1994). Subglacial deposits are generally draped by a coating of diamicton (Fisher and Taylor, 2002). The esker ridge is dominated by poorly sorted cobble, boulder gravel (EX-A) overlain by diamicton.…”

Section: Discussionmentioning

confidence: 99%

Electrical resistivity and Ground Penetrating Radar for the characterisation of the internal architecture of Quaternary sediments in the Midlands of Ireland

Pellicer

Gibson

2011

Journal of Applied Geophysics

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a b s t r a c t a r t i c l e i n f oGeophysical techniques Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) supported by traditional field methods are used for the geological mapping, description and interpretation of Quaternary unconsolidated sediments in a site located in the Midlands of Ireland. The site comprises a broad range of glacial and postglacial sediments (diamicton, esker sand and gravel, glaciolacustrine sand, glaciolacustrine silt/clay and peat). Preliminary fieldwork comprising, geomorphological mapping, lithostratigraphic analysis of exposures and borehole drilling and laboratory testing encompassing particle size distribution analysis were carried out to broadly characterise the geology of the study area. These data aided locating the geophysical profiles and supported the geophysical data interpretation. Five GPR radargrams were collected and permitted depicting the subsurface internal architecture within low conductivity unconsolidated sediments and aided to the classification and characterisation of sedimentological and deformational structures. Four ERT profiles allowed the depth to bedrock to be determined and lithological classification of the sediments. The use of these geophysical techniques in combination with geotechnical and geological data allowed (i) the determination of the lithological composition and detailed internal architecture of the subsurface, (ii) the characterisation and description of the geology of the site and (iii) understanding the depositional processes acting in the area during ice withdrawal. Diamicton and esker gravels were deposited subglacially by an ice sheet withdrawing westwards; glaciolacustrine sediments located along the south margin of the esker ridge were laid down in an ice marginal environment as a subaqueous fan composed of silt, sand and gravel, and as distal deposits composed of silt and clay in the lower ground area between the fan and the esker ridge. Peat developed during postglacial times and was partially cut away by anthropogenic action at a later stage.

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Section: Discussionmentioning

confidence: 99%

Electrical resistivity and Ground Penetrating Radar for the characterisation of the internal architecture of Quaternary sediments in the Midlands of Ireland

Pellicer

Gibson

2011

Journal of Applied Geophysics

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“…11b). Outwash fans are particularly common in the Chippewa, Wisconsin, Langlade, Green Bay, Superior and Wadena lobes (see also Attig et al, 1989;Clayton et al, 1999;Cutler et al, 2002;Fisher and Taylor, 2002), and at the downstream end of the large bedrock tunnel valleys in Lake Superior (Regis …”

Section: Outwash Fansmentioning

confidence: 99%

Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation

Livingstone

Clark

2016

Earth Surf. Dynam.

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Abstract. Tunnel valleys have been widely reported on the bed of former ice sheets and are considered an important expression of subglacial meltwater drainage. Although known to have been cut by erosive meltwater flow, the water source and development of channels has been widely debated; ranging between outburst flood events through to gradually occurring channel propagation. We have mapped and analysed the spatial pattern and morphometry of tunnel valleys and associated glacial landforms along the southern sector of the former Laurentide Ice Sheet from high-resolution digital elevation models. Around 2000 tunnel valleys have been mapped, revealing an organised pattern of sub-parallel, semi-regularly spaced valleys that form in distinctive clusters. The tunnel valleys are typically < 20 km long, and 0.5-3 km wide, although their width varies considerably down-valley. They preferentially terminate at moraines, which suggests that formation is time dependent; while we also observe some tunnel valleys that have grown headwards out of hill-hole pairs. Analysis of cross-cutting relationships between tunnel valleys, moraines and outwash fans permits reconstruction of channel development in relation to the retreating ice margin. This palaeo-drainage reconstruction demonstrates incremental growth of most valleys, with some used repeatedly or for long periods, during deglaciation, while others were abandoned shortly after their formation. Our data and interpretation support gradual (rather than a single-event) formation of most tunnel valleys with secondary contributions from flood drainage of subglacial and or supraglacially stored water down individual tunnel valleys. The distribution and morphology of tunnel valleys is shown to be sensitive to regional factors such as basal thermal regime, ice and bed topography, timing and climate.

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“…11 and 12. several differences: (1) the widespread abundance of meltwater channels on the ASE inner shelf suggests an important role for subglacial meltwater at times, when the ice sheet was more extensive, but the origin, flow rates, frequency, and duration of these flows is largely unknown at present ). In contrast, where meltwater landforms have been observed in northern hemisphere palaeo-ice sheets, the routing and function of meltwater is generally better understood (Fisher and Taylor, 2002;Evans et al, 2005b;Hä ttestrand and Clark, 2006). (2) Cross-cutting bedform sets, highlighting large switches in flow configuration in deglaciating ice sheets, are not apparent in the western ASE as they are in ice stream tracks across North America, the Canadian Shield, and offshore Norway (Stokes and Clark, 2001;Stokes et al, 2009).…”

Section: Comparisons To Other Landform Modelsmentioning

confidence: 99%

Bedform signature of a West Antarctic palaeo-ice stream reveals a multi-temporal record of flow and substrate control

Graham

Larter

Gohl

et al. 2009

Quaternary Science Reviews

172

173

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a b s t r a c tThe presence of a complex bedform arrangement on the sea floor of the continental shelf in the western Amundsen Sea Embayment, West Antarctica, indicates a multi-temporal record of flow related to the activity of one or more ice streams in the past. Mapping and division of the bedforms into distinct landform assemblages reveals their time-transgressive history, which implies that bedforms can neither be considered part of a single downflow continuum nor a direct proxy for palaeo-ice velocity, as suggested previously. A main control on the bedform imprint is the geology of the shelf, which is divided broadly between rough bedrock on the inner shelf, and smooth, dipping sedimentary strata on the middle to outer shelf. Inner shelf bedform variability is well preserved, revealing information about local, complex basal ice conditions, meltwater flow, and ice dynamics over time. These details, which are not apparent at the scale of regional morphological studies, indicate that past ice streams flowed across the entire shelf at times, and often had onset zones that lay within the interior of the Antarctic Ice Sheet today. In contrast, highly elongated subglacial bedforms on sedimentary strata of the middle to outer shelf represent a timeslice snapshot of the last activity of ice stream flow, and may be a truer representation of fast palaeo-ice flow in these locations. A revised model for ice streams on the shelf captures complicated multi-temporal bedform patterns associated with an Antarctic palaeo-ice stream for the first time, and confirms a strong substrate control on a major ice stream system that drained the West Antarctic Ice Sheet during the Late Quaternary.

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Sedimentary and stratigraphic evidence for subglacial flooding, south-central Michigan, USA

Cited by 51 publications

References 55 publications

Electrical resistivity and Ground Penetrating Radar for the characterisation of the internal architecture of Quaternary sediments in the Midlands of Ireland

Electrical resistivity and Ground Penetrating Radar for the characterisation of the internal architecture of Quaternary sediments in the Midlands of Ireland

Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation

Bedform signature of a West Antarctic palaeo-ice stream reveals a multi-temporal record of flow and substrate control

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