Subglacial till: the deforming glacier bed

Meer, J.J.M. van der; Menzies, John; Rose, James

doi:10.1016/s0277-3791(03)00141-0

Cited by 237 publications

(132 citation statements)

References 89 publications

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“…van der Meer et al, 2003;Menzies et al, 2006). The importance of its role increases where data from exposures is sparse such as in studies based on borehole cores (e.g.…”

Section: Introductionmentioning

confidence: 99%

Microstructures in subglacial and proglacial sediments: understanding faults, folds and fabrics, and the influence of water on the style of deformation

Phillips

Merritt

Auton

et al. 2007

Quaternary Science Reviews

104

120

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Macroscopic field and micromorphological studies have been carried out on subglacially and proglacially deformed glacigenic sequences at a number of sites throughout Scotland, UK. Examination of microstructures (folds, faults, hydrofractures, plasmic fabrics) aided understanding of the deformation histories preserved in the sediments, but a similar range of structures were developed in both subglacial and proglacial settings. Discrimination between subglacial and proglacial deformation was only possible when micromorphological data was used in conjunction with larger-scale field observations. Variations in lithology and water content were controlling factors influencing the style and apparent intensity of deformation recorded. Changes in pore-water content and pressure during deformation can lead to liquefaction and hydrofracturing, with early formed structures locally controlling the pattern of water-escape. Liquefaction can also lead to homogenisation of the sediments and the destruction of earlier deformation structures, even at relatively low strains. Beds or zones of liquefied sand and silt may form highly 'lubricated' detachments within the sediment pile, resulting in a marked reduction in the amount of shear transmitted to underlying units. A multidisciplinary approach, involving sedimentological, geomorphological, stratigraphical and structural field observations, combined with micromorphological analysis, is recommended to confidently unravel the glacitectonic history and depositional environment of most deformed glacigenic sedimentary sequences.

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“…van der Meer et al, 2003;Menzies et al, 2006). The importance of its role increases where data from exposures is sparse such as in studies based on borehole cores (e.g.…”

Section: Introductionmentioning

confidence: 99%

Microstructures in subglacial and proglacial sediments: understanding faults, folds and fabrics, and the influence of water on the style of deformation

Phillips

Merritt

Auton

et al. 2007

Quaternary Science Reviews

104

120

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“…In a later model, soft subglacial beds were pre sented as a mo saic of de form ing and sta ble spots; the in ten sity of de for ma tion var ied in both time and space . Con cepts of spa tially var ied glacier bed char ac ter is tics have been de scribed also by other authors (see Knight, 2002;Van der Meer et al, 2003;Larsen et al, , 2007Stokes et al, 2007;Narloch et al, 2012Narloch et al, , 2013Tylmann et al, 2013). The dif fer ences in as sess ment of the role and scale of subglacial de for ma tion are largely due to the dif ferent rhe o log i cal mod els for the be hav ior of basal till, i.e.…”

Section: Introductionmentioning

confidence: 72%

“…The mar ble-like struc ture of the clay close to the till base is a char ac ter is tic fea ture. Struc tures of this type are of ten rec ognized in till with a high con tent of clay (Hiemstra and Van der Meer, 1997; Van der Meer, 1997; Van der Meer et al, 2003). A net work of small frac tures was formed in the over loaded clay.…”

Section: Discussionmentioning

confidence: 99%

“…Ac cord ing to the "soft de form ing-bed" model, many re search ers as sume that in ar eas built of un con sol i dated sed i ments, the main mech a nism of gla cier mo tion was con tin u ous, per va sive de for ma tion of subglacial sed i ments (Boulton and Jones, 1979;Be get, 1986;Hicock et al, 1989;Hart et al, 1990;Al ley, 1991;Hart and Boulton, 1991;Boulton, 1996;Clark and Walder, 1994; Van der Meer et al, 2003;Ev ans et al, 2006;. How ever, this con cept does not al ways ap ply.…”

Section: Introductionmentioning

confidence: 99%

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Basal till and subglacial conditions at the base of the Upper Odra ice lobe (southern Poland) during the Odranian (Saalian) Glaciation

Salamon

2014

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Salamon, T., 2014. Basal till and subglacial con di tions at the base of the Up per Odra ice lobe (south ern Po land) dur ing the Odranian (Saalian) Gla ci ation. Geo log i cal Quar terly, 58 (4): 779-794, doi: 10.7306/gq.1176The ob jec tive of this con tri bu tion is de tail char ac ter is tics of the basal till and the con di tions at the base of the Up per Odra ice lobe. The lobe was formed in a foremountain area. Its cen tral part was a Niemodlin Plain and the W part of the Racibórz Basin, sur rounded by ar eas that have a much more var ied re lief. Par tic u lar at ten tion is paid to the con di tions at the ice sheet base, gen er at ing the dy nam ics of gla cier move ment. The study is based on anal y sis of the basal till. Three sites with basal till ly ing on dif fer ent types of sub stra tum (typ i cal for the study area) are pre sented. The basal till of the Up per Odra ice lobe is char ac ter ized by spa tial vari a tions. Dif fer ent in ten si ties of its de for ma tion in di cate that large lat eral dif fer ences in con di tions oc curred in the lobe sub stra tum. The li thol ogy con trolled the rate of basal wa ter pres sure, and thus the strength of both the subglacial sed i ments and the ice-bed cou pling. Var i ous strain rates in the till pro files in di cate that the con di tions at the ice sheet base also changed with time. The ice sheet was highly mo bile, even on the coarse-grained sub stra tum. The low perme abil ity of the Qua ter nary sub stra tum, and the rel a tively small thick ness of the Qua ter nary sands and grav els re sulted in a high wa ter pres sure at the ice sheet base. The move ment of the Up per Odra ice lobe was con cen trated in the basal zone of the ice sheet. The main mech a nisms of mo tion were slid ing and de for ma tion of the subglacial sed i ments. The de for ma tion oc curred in re stricted ar eas only, and did not have a per va sive char ac ter.

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“…Mar ble-bed and turbate struc tures are formed un der differ ent subglacial con di tions. In the opin ion of some re searchers, the zone of shear ing can change from the mar ble-bed config u ra tion to one that con sists of ro ta tional structures and a skelsepic plas mic fab ric (Van der Meer et al, 2003). There is also a view that mar ble-bed and turbate struc tures are formed in re verse or der.…”

Section: Unit Imentioning

confidence: 99%

Depositional environment of the glacigenic deposits from the Holy Cross Mountains (Poland) – interpretation based on macro- and microstructure analyses

Ludwikowska-Kędzia

Pawelec

2014

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Subglacial till: the deforming glacier bed

Cited by 237 publications

References 89 publications

Microstructures in subglacial and proglacial sediments: understanding faults, folds and fabrics, and the influence of water on the style of deformation

Microstructures in subglacial and proglacial sediments: understanding faults, folds and fabrics, and the influence of water on the style of deformation

Basal till and subglacial conditions at the base of the Upper Odra ice lobe (southern Poland) during the Odranian (Saalian) Glaciation

Depositional environment of the glacigenic deposits from the Holy Cross Mountains (Poland) – interpretation based on macro- and microstructure analyses

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