Clastic injection dynamics during ice front oscillations: A case example from Sólheimajökull (Iceland)

Ravier, Édouard; Buoncristiani, Jean‐François; Menzies, John; Guiraud, Michel; Portier, Éric

doi:10.1016/j.sedgeo.2015.04.013

Cited by 21 publications

(17 citation statements)

References 51 publications

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“…In the literature, sandstone dikes extending downward from source beds are more often than not interpreted as neptunian dikes (passive filling of open fractures by overlying sediments; Montenat et al, 2007), but it is worth mentioning that some authors have invoked downward injection of material to explain certain occurrences of downward-tapering intrusions (e.g. Parize et al, 2007;Ravier et al, 2015a). Downward injection of material remains a more unconventional mechanism, and is not considered a parsimonious explanation for the intrusions of the Tensleep Formation.…”

Section: Discussionmentioning

confidence: 99%

“…Vertical sedimentary intrusions are known from a wide range of environments: subglacial (Rijsdijk et al, 1999; Le Heron and Etienne, 2005;Ravier et al, 2015a), deep marine (Strachan, 2002;Duranti and Hurst, 2004;Parize et al, 2007), fluvio-lacustrine (Aspler and Donaldson, 1986;Li et al, 1996;Rodríguez-Pascua et al, 2000), and desert ergs (Huuse et al, 2005;Chan et al, 2007;Ross et al, 2014). Softsediment deformation structures are especially common-place in eolian depositional environments (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Basement influences on dolomite-hosted vertical sedimentary intrusions in marine erg-margin deposits from the Pennsylvanian of Northern Wyoming (USA)

Blanchard

Frank

Fielding

2016

Sedimentary Geology

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Understanding soft-sediment deformation structures and their triggers can help in assessing the influence of tectonics, climate, and diagenesis on the stratigraphic record. Such features commonly record processes that would not otherwise be preserved. The description of soft-sediment deformation in Pennsylvanian deposits of the western United States, characterized by orbitally-driven alternations between eolian sandstones, marine dolomites and shales, has been limited to contorted cross-beds. We document discordant, sheet-like sedimentary intrusions in three marine intervals over a 45 km-wide area. Intrusions consist of very well to moderately cemented, very-fine to fine-grained quartz sandstone. Body widths range from 5 to 50 cm, and heights up to 2 m. The orientations of 103 vertical bodies were measured. Based on upward-and downward-tapering, and the presence of deformed, microfractured fragments of host rocks, these intrusions are interpreted to result from seismically-induced fluidization of watersaturated sands. Their sheet-like morphology indicates injection through fractures. Two predominant directions (WNW-ESE and N-S) were recognized and interpreted as pre-injection fracture sets. Folding of surrounding layers around the intrusions suggests negligible compaction prior to injection, indicating penecontemporaneous or shallow burial fluidization. The intraplate location of Wyoming implies that seismicity did not originate at a plate boundary. The area within which intrusions are found is crossed by a zone characterized by localized development of thick eolian stories at the top of the formation,

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Basement influences on dolomite-hosted vertical sedimentary intrusions in marine erg-margin deposits from the Pennsylvanian of Northern Wyoming (USA)

Blanchard

Frank

Fielding

2016

Sedimentary Geology

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“…Therefore this basal zone is inconsistent with representing a primary (sedimentary) bedded sequence. Consequently, the most likely origin of this complex zone is as a series of cross-cutting sediment-filled hydrofractures, which formed as pressurised water exploited the basal detachment of the developing thrust-block moraine (see below) (Rijsdijk et al, 1999;van der Meer et al, 1999;Phillips and Merritt, 2008;van der Meer et al, 2009;Phillips et al, 2013a;Ravier et al, 2015). Their cross-cutting relationships show that the grain size of the sediments infilling the hydrofractures increased with time.…”

Section: Macroscale Description Of the Basal Detachmentmentioning

confidence: 99%

Micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in Melasveit, western Iceland

2019

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Pressurised meltwater has a major impact on ice dynamics, as well as on sedimentary and deformational processes occurring below/in front of glaciers and ice sheets, but its role in glaciotectonic processes is yet to be fully understood. This study explores micro- and macroscale structures developed within décollements in two thrust-block moraines of Late Weichselian age in Melasveit, western Iceland. The aim is to investigate how pressurised subglacial meltwater can aid the dislocation and transport of large, unfrozen and unlithified sediment blocks by glaciers. A detailed model is constructed for the development of the thrust-block moraines and the microscale processes occurring along their detachments during thrusting. The detachments are characterized by relatively thin zones of crosscutting hydrofractures, which reflect fluctuating water pressures during glaciotectonism. Little evidence of shearing is observed along the leading edges of the thrusts in both moraines. This is supported by high water pressures along the detachments and indicates that the thrust blocks were initially decoupled from the underlying deposits. As the thrust moraines evolved, an increased amount of shear occurred in between events of sediment liquefaction, hydrofracturing, and fluid escape. This was followed by progressive locking up of the detachments and eventual cessation in the accretion of the thrust blocks.

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“…Hydraulic fracturing and fluidisation have been observed due to earthquakes (Audemard and de Santis, 1991;Rajendran et al, 2001;Audemard et al, 2005;Obermeier et al, 2005), but also in proglacial environments where the repeated advance and retreat of glaciers causes large fluctuations in pore-water pressure capable of forming dykes several metres long (Van der Meer et al, 2009;Ravier et al, 2015). According to Van Vliet-Lanoë et al (2004), dykes would only form in periglacial environments in unusual circumstances because pore-water pressures during ground freezing may remain low even in saturated conditions, due to the desiccation of sediment as water migrates towards the freezing front (Mackay, 1980).…”

Section: Genesis Of Involutions: a Reviewmentioning

confidence: 99%

Pleistocene Involutions and Patterned Ground in France: Examples and Analysis Using a GIS Database

Bertrán

Andrieux

Antoine

et al. 2017

Permafrost & Periglacial

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A georeferenced database is used to analyse the distribution of Quaternary soft‐sediment deformation structures across France. They include features visible in aerial photographs (soil stripes and cells) and features described in cross‐section (involutions). Overall, there is no clear relation between the distribution of features and the locations of known faults and earthquakes in available databases. In contrast, the distribution agrees with that of Pleistocene periglacial structures. Most of the soil stripes and cells are located north of 47.5°N, i.e. in the zone of ice‐wedge pseudomorphs, and can be interpreted as deformation structures of an active layer in permafrost terrain. The height of the involutions is influenced by the nature of the filling, the substrate and latitude. Deformation structures are larger in coarse material, reflecting the role of drainage and thermal conductivity. Their height increases northward to ca. 2 m at 48°N. This is thought to reflect the increase in thickness of the layer subjected to freeze–thaw cycles. Bowl‐shaped structures separated by coarse pillars, which correspond to soil stripes seen in section, have formed on slopes in settings unfavourable to the generation of high pore‐water pressure. Their genesis is probably related to differential frost heave. Ball‐and‐pillow structures and diapirs are common in flat and poorly drained terrain, and formed by liquefaction and sometimes fluidisation in a periglacial setting. Copyright © 2017 John Wiley & Sons, Ltd.

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Clastic injection dynamics during ice front oscillations: A case example from Sólheimajökull (Iceland)

Cited by 21 publications

References 51 publications

Basement influences on dolomite-hosted vertical sedimentary intrusions in marine erg-margin deposits from the Pennsylvanian of Northern Wyoming (USA)

Basement influences on dolomite-hosted vertical sedimentary intrusions in marine erg-margin deposits from the Pennsylvanian of Northern Wyoming (USA)

Micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in Melasveit, western Iceland

Pleistocene Involutions and Patterned Ground in France: Examples and Analysis Using a GIS Database

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