Till mélange at Amsdorf, central Germany: sediment erosion, transport and deposition in a complex, soft-bedded subglacial system

Development of a subglacial drainage system and its effect on glacitectonism within the polydeformed Middle Pleistocene (Anglian) glacigenic sequence of north Norfolk, Eastern England

“…This thick (up to 30 m thick) laterally extensive subglacial shear zone is composed of a complex, anastomosing system of shallowly to moderately west-dipping thrusts and broader ductile shear zones wrapping around apparently lower strain areas (Lee and Phillips, 2008;Phillips et al, 2008), and is responsible for much of the deformation seen in the Sheringham to Weybourne coastal cliff sections. This shifting (spatial and temporal) pattern of deformation partitioning recorded by the BGT is consistent with the model proposed 14 by Piotrowski and Kraus (1997) (also see Evans et al, 2006;Lee and Phillips, 2008) for the development of actively deforming and stable (non-deforming) zones within the subglacial deforming bed in response to either water-induced decoupling at the ice-bed-interface (Hoffman and Piotrowski, 2001), or the ability of the subglacial bed to drain inter-granular pore water (Piotrowski et al, 2004). Lee and Phillips (2008) and Phillips et al (2008), using macroscopic structural evidence from Bacton Green and West Runton (respectively), argued that during the earlier stages of subglacial deformation, shear stress imposed by the overriding glacier ice was being transmitted throughout the entire bed resulting in the pervasive deformation of the BGT (cf.…”

Mechanisms and processes of stratal disruption and mixing in the development of mélanges and broken formations: Redefining and classifying mélanges

“…It also excludes other sedimentary deposits such as turbidites. Glacial till (e.g., Hoffmann and Piotrowski, 2001) or the Martian chaos (e.g., Kargel et al, 2007) may be included in this definition of mélange because they, too, form by mixing of different blocks as a result of slope failure, mass-transport processes, gas outburst by clathrate dissociation, mud volcanism, and bolide impacts on the surface of the planet.…”

“…Some may also form when accretion is replaced by tectonic erosion at a convergent margin (e.g., von Huene and Lallemand, 1990;Ranero and von Huene, 2000;von Huene et al, 2004;Remitti et al, 2011). Sedimentary processes might also have been responsible for the formation of different types of sub-aerial mélanges (Type 7a in Tab. 2), such as debris flow and avalanches, alluvial fan deposits, talus breccias (scree deposits) and megabreccias, block falls, and glacial till (see Hoffmann and Piotrowski, 2001). …”

A multiproxy study of a basal till: a time‐transgressive accretion and deformation hypothesis

“…It has been suggested that the massive appearance may be linked to particle dispersion when sediment is subjected to pervasive subglacial deformation (Alley, 1991;Boulton, 1996;Benn and Evans, 1996;van der Meer, 1997;Boyce and Eyles, 2000) or to the entrainment mechanisms and the mode of glacial transport and deposition (Rappol and Stoltenberg, 1985;Clark, 1987;Shaw, 1985;Hildes, 2001;Fisher and Taylor, 2002). In many instances massive tills contain clasts of fragile materials consisting of sorted sediments with preserved sedimentary structures (Berthelsen, 1979;Clayton et al, 1989;Hicock et al, 1989;Menzies, 1990;Hoffmann and Piotrowski, 2001), heavily weathered boulders (Shilts, 1978), organic remnants (Punkari and Forsströ m, 1995), or almost intact fossils Tulaczyk et al, 2001). Preservation of these fragile inclusions in sediments interpreted as tills subjected to high strains raises some controversies (Boulton et al, 2001;Piotrowski et al, 2001Piotrowski et al, , 2002.…”