Till kinematics in the Stargard drumlin field, NW Poland constrained by microstructural proxies

Hermanowski, Piotr; Piotrowski, Jan A.; Duda, Piotr

doi:10.1002/jqs.3233

Cited by 3 publications

(2 citation statements)

References 117 publications

(183 reference statements)

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“…Damsgaard et al, 2020; Evans et al, 2006; Menzies et al, 2016; van der Meer et al, 2003). The fold observed in trench T4 represents a shallow and spatially limited deformation, which is consistent with previous observations from other parts of the Stargard drumlin field (Hermanowski et al, 2019, 2020).…”

Section: Resultssupporting

confidence: 92%

“…Although the till fabrics in the GCLs and on the till plain broadly correspond with the orientation of drumlins and MSGLs, there is an offset of around 15 : the streamlined landforms are oriented NNW-SSE, whereas the till fabrics follow the NW-SE direction. This difference may indicate that the till in the area pre-dates the landscape streamlining, consistent with the lack of correspondence between the till microclast orientations and drumlin orientations elsewhere in the Stargard drumlin field (Hermanowski et al, 2020) and providing support for the erosional formation model of this drumlin field .…”

Section: Discussionmentioning

confidence: 61%

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Origin of glacial curvilineations by subglacial meltwater erosion: Evidence from the Stargard drumlin field, Poland

Hermanowski

Piotrowski

2022

Earth Surf Processes Landf

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Deciphering the origin of subglacial landforms is crucial for understanding processes operating under ice sheets. Due to the inaccessibility of the ice/bed interface limiting real-time observations, the origin of these landforms is typically interpreted from the morphological and sedimentological record exposed after ice retreat, which makes the conclusions conjectural. Here, we focus on a recently discovered new type of subglacial landform called glacial curvilineations (GCLs), whose formation generates some controversy. We use LiDAR imagery and geological data to constrain the origin of GCLs found in a tunnel valley in the Stargard drumlin field, Poland. The tunnel valley is about 3800 m long, 520 m wide, and it occupies about 2 km 2 . A total of 61 individual GCLs have been mapped there; they are up to 550 m long and typically 0.5-1.5 m high, but some reach a height of up to 5 m. The GCLs are composed of mostly massive till represented by either a single or several diamicton units occasionally separated by thin layers of meltwater sand. Till macrofabrics in the GCLs and in the nearby till plain are distinctly consistent, and have high and uniform clustering strengths. At all locations, the dominant till fabric direction broadly corresponds with the ice movement direction given by the drumlin orientations, but it is oblique to the orientation of the tunnel valley and independent of the orientations of the individual GCLs. The lack of correspondence between the orientation of the GCLs and the till fabrics in them suggests that the GCLs consist of an antecedent till deposited during the drumlinizing ice advance and subsequently carved by subglacial meltwater erosion in the tunnel valley. These results substantiate the hypothesis that GCLs are erosional features postdating the material constituting them, and emphasize the role of subglacial meltwater flows as a landforming agent.

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Section: Resultssupporting

confidence: 92%

Section: Discussionmentioning

confidence: 61%

Origin of glacial curvilineations by subglacial meltwater erosion: Evidence from the Stargard drumlin field, Poland

Hermanowski

Piotrowski

2022

Earth Surf Processes Landf

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Dynamics of the last Scandinavian Ice Sheet’s southernmost sector revealed by the pattern of ice streams

Szuman

Kalita

Ewertowski

et al. 2021

Boreas

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The Polish sectorof the last Scandinavian Ice Sheet is a key area for studying ice-sheet drainage and decay from its local Last Glacial Maximum (LGM) extent, as it is located at the terrestrial terminus of the large and dynamic Baltic Ice Stream Complex. Geomorphological mapping, based on a 0.4-m LiDAR digital elevation model, revealed about 940 streamlined bedforms, many of which are shown for the first time and consisting of mega-scale glacial lineations and drumlins. The lineation flowsets together with associated landforms were used to identify 17 ice streams, occupying 80% of the study area. We demonstrated that subtle topographic variations played an important role in influencing the ice-sheet dynamics. Variations in ice dynamicswere a response to external climatic forcing that controlled deglaciation at the ice-sheet scale as well as to internal reorganization due to the influence of topography, subglacial hydrology and glacier thermal regime. During the local LGM, the southern sector of the Scandinavian Ice Sheet in Poland was dominated by four simultaneously operating ice streams, likely active for several millennia, followed by fast active recession interrupted by three main periods of ice stream stagnation. Increased ice-flow dynamics during the period of the Young Baltic advances are suggested to be caused by variations in subglacial hydrology and the polythermal structure of the ice sheet.

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Subglacial tills: a process model based on microsedimentological clues

Menzies,

Paulen,

Reitner

et al. 2023

Journal of Sedimentary Research

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Subglacial sediments are subject to erosion, transport, and deposition in active, ephemeral, and spatially localized glacial environments. It is critical to determine how these mobilized sediments become immobilized in a time-transgressive process and can be frequently remobilized and reimmobilized. Microscopic sedimentary structural signatures provide invaluable information on subglacial processes and contribute to understanding till formation. Data were obtained from a series of field sites in Canada and Austria investigating the microsedimentological aspects of both alpine and continental glaciation tills to construct a conceptual model of subglacial deformation. Microstructures in these tills indicate rheological behaviors that can be summarized into a potential model for soft deforming subglacial sediments. Most microstructures noted in these subglacial till examples highlight the development of subglacial interface kinematics providing clues to till deposition mechanics, subglacial bedform development, and the processes involved in till provenance distributions. A conceptual process model of subglacial interface conditions in soft mobile sediments is developed that uses microsedimentological evidence and highlights how an active ice mass integrates with ongoing substrate deformation. In the model, interaction occurs between the ice and its sediment bed with internal sediment microstructures evolving where multiple transient shear deformation processes cause localized deformation linked to pervasive and nonpervasive sediment deformation.

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Till kinematics in the Stargard drumlin field, NW Poland constrained by microstructural proxies

Cited by 3 publications

References 117 publications

Origin of glacial curvilineations by subglacial meltwater erosion: Evidence from the Stargard drumlin field, Poland

Origin of glacial curvilineations by subglacial meltwater erosion: Evidence from the Stargard drumlin field, Poland

Dynamics of the last Scandinavian Ice Sheet’s southernmost sector revealed by the pattern of ice streams

Subglacial tills: a process model based on microsedimentological clues

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