A detailed reconstruction of palaeo-ice flow configuration is lacking for the Kola Peninsula and ... more A detailed reconstruction of palaeo-ice flow configuration is lacking for the Kola Peninsula and Russian Lapland, northwest Arctic Russia. This study presents, for the first time, a 14-stage reconstruction of the last Fennoscandian Ice Sheet (FIS) flow configuration on the Kola Peninsula and Russian Lapland from build-up to complete deglaciation. Flowsets (n ¼ 102) and cross-cutting bedform assemblages identified from a high-resolution subglacial bedform record (subglacial lineations and subglacial ribs) are combined with subglacially streamlined bedrock data to define ice flow patterns, ice divides, ice margins, and glaciation styles of the last glaciation through relative time. The results demonstrate that the FIS flow configuration was not static. The FIS advanced eastwards across the region from Scandinavia, rather than expanding from local upland areas, and established a predominantly cold-based ice mass on the Kola Peninsula with an extensive adjacent warm-based ice lobe in the White Sea. An east-west aligned ice divide was located on the Kola Peninsula and Russian Lapland during the ice sheet build-up stages. However, this divide was short-lived as the White Sea lobe dominated ice flow on the peninsula during the local-Last Glacial Maximum, and ice predominantly flowed across the region from the main ice dispersal zone that was centred over the Gulf of Bothnia during deglaciation. Deglaciation on the peninsula was initially characterised by cold-based ice sheet retreat on the central eastern Kola Peninsula and warm-based ice lobe retreat in the White Sea. Continued deglaciation was characterised by ice sheet thinning, exposing mountain summits as nunataks behind the ice sheet margin, with topography constraining ice flow around upland areas. Ice streams in the region were drivers and consequences of continued ice sheet configuration change throughout glaciation. Four palaeo ice streams e (i) the Imandra Ice Stream; (ii) the Lovozero Ice Stream; (iii) the Kanozero Ice Stream; and (iv) the Kuusamo Ice Stream e and three possible palaeo-ice stream pathways are identified. We consider our ice flow configuration reconstruction to be the simplest palaeo-glaciological interpretation of the bedform record of the Kola Peninsula and Russian Lapland. The empirically-based reconstruction of ice flow geometry provides a regional framework and context for interpreting results from local-scale fieldwork, and is presented in a format that can be utilised by numerical ice sheet modellers to test and verify their models. The results underpin a new data-driven reconstruction of the last FIS in northwest Arctic Russia that we present in Part 2 of this study.
<p>Previous attempts to reconstruct the glacial history of the last Fennosc... more <p>Previous attempts to reconstruct the glacial history of the last Fennoscandian Ice sheet (FIS) in northwest Arctic Russia have resulted in various Last Glacial-Interglacial Transition (c. 20-10 ka) scenarios, suggesting that the Kola Peninsula was glaciated by the FIS, the Ponoy Ice Cap, or the Kara Sea Ice Sheet. The conflicting glacial interpretations have stemmed, in part, from the use of low-resolution geomorphological and geological maps. The advent of high-resolution remotely-sensed imagery warrants a new glacial reconstruction of ice sheet dynamics in northwest Arctic Russia: we therefore present initial glacial interpretations based on new high-resolution geomorphological mapping.</p><p>Geomorphological mapping using high-resolution ArcticDEM and PlanetScope imagery has identified >245,000 glacial landforms, significantly increasing the volume and detail of geomorphological data in the region. Over 66,000 subglacial bedforms (subglacial lineations and subglacial ribs) are used to construct flowsets, which demonstrate that ice flowed from the Scandinavian mountains in the west and across the shield terrain of the Kola Peninsula. Moreover, four possible palaeo-ice streams are identified in the region. Mapping individual moraine hummocks, rather than hummocky moraine spreads as in previous mapping attempts, reveals multiple ice margins across the Kola Peninsula. A noteworthy ~25 km wide belt of hummocky moraines aligned north-south across the Kola Peninsula is tentatively attributed to the Younger Dryas (c. 12.8-11.9 ka) ice marginal zone. The so-called “ring-and-ridge” hummock moraines that are predominantly observed within this ice marginal zone suggest down-wasting and stagnant ice margins. The meltwater landform record also reveals subglacial channel networks along the northern coastline that suggest warm-based conditions of the ice sheet may have been induced by warm currents in the Barents Sea during the last glacial-interglacial transition.</p><p>This research will provide crucial empirical data for validating numerical model simulations of the FIS, which in turn will further our understanding of ice sheet dynamics in other Arctic, Antarctic, and Alpine regions.</p>
Abstract The Kola Peninsula and Russian Lapland (Murmansk Oblast, northwest Arctic Russia) repres... more Abstract The Kola Peninsula and Russian Lapland (Murmansk Oblast, northwest Arctic Russia) represents a major sector of the Fennoscandian Ice Sheet (FIS) where empirical geomorphological, sedimentological, and chronological data are lacking and thus, where the pattern, style, and timing of glaciation is not well established. In this study, we present a critical review of published empirical data and interpretations of Late Weichselian (c. 40–10 ka) glaciation for the region. The review includes, for the first time, information published in Russian-language journal articles (n = 37), and is accompanied by a new Geographic Information System (GIS) numerical age database (spanning 472.3–6.2 ka) that collates known published numerical dates associated with the advance and retreat of the FIS in the study area. Our review suggests that an ice mass existed over the Kola Peninsula and Russian Lapland during the Early-Middle Weichselian (c. 115–40 ka), and likely retreated during the Alesund interstadial (c. 38–34 ka). During the Late Weichselian, it is likely that the FIS advanced eastwards across Russian Lapland and the Kola Peninsula, establishing the White Sea Ice Stream before the local-Last Glacial Maximum (c. 19–15 ka). Through an evaluation of the existing Last Glacial-Interglacial Transition (c. 20–10 ka) glaciation models for the region, we propose that the Kola Peninsula and Russian Lapland was deglaciated by the FIS, rather than the Ponoy Ice Cap or the Kara Sea Ice Sheet. In collating, discussing, and critically evaluating empirical data and interpretations, this paper provides a valuable resource to inform FIS dynamics at both a regional- and ice sheet-scale, and offers a framework through which numerical ice sheet models can be constrained. Precise FIS dynamics on the Kola Peninsula and Russian Lapland, including the position of the Younger Dryas ice marginal zone, remain unclear due to low-resolution geomorphological data. In concluding, we recommend that further work is needed in the form of a revised glacial reconstruction using high-resolution, peninsula-wide geomorphological data.
Icebergs are important as agents of deposition and seafloor reworking on glacier-influenced conti... more Icebergs are important as agents of deposition and seafloor reworking on glacier-influenced continental margins. When the keel of an iceberg exceeds water depth it ploughs through soft sediments producing scours/ploughmarks that can be kilometres long, hundreds of metres wide and sometimes tens of metres deep. Because the influence of iceberg keels on sediment is a critical factor when offshore structures (e.g. pipelines, power cables) are installed, the surface morphology of iceberg scours on the seafloor is relatively well-documented. Less however, is known about sub-scour deformation below the seafloor. This is particularly true of iceberg scoured diamicton (poorly sorted sediment comprising a variety of particle sizes), which is present in many high-latitude fjords and continental shelves. The aim of this research is to examine directly (macroscopically and microscopically, with thin sections) the style and intensity of deformation caused by the scouring action of iceberg keels in diamicton offshore of East Greenland. Results show that a distinctive suite of deformation structures (individual structures and overprinted structural patterns) dominated by planar shear, sediment mixing and high porewater, and dropstones characterises iceberg scoured diamicton. In addition, diamicton from areas of high-intensity iceberg scouring tends to show a wider variety, higher frequency and distribution, more abundant and better-developed deformation structures than diamicton from areas of intermediate-and low-intensity iceberg scouring. Characterising the effects of iceberg scour in diamicton is important more widely to inform: i) reconstruction of the geometry and dynamics of former ice sheets; and ii) installation and protection of offshore engineering structures in diamicton where iceberg scouring presents a geohazard. The value of micromorphology is significant especially in the absence of macroscopic sediment expo-sures/outcrops where the study of cores is necessary instead.
A detailed reconstruction of palaeo-ice flow configuration is lacking for the Kola Peninsula and ... more A detailed reconstruction of palaeo-ice flow configuration is lacking for the Kola Peninsula and Russian Lapland, northwest Arctic Russia. This study presents, for the first time, a 14-stage reconstruction of the last Fennoscandian Ice Sheet (FIS) flow configuration on the Kola Peninsula and Russian Lapland from build-up to complete deglaciation. Flowsets (n ¼ 102) and cross-cutting bedform assemblages identified from a high-resolution subglacial bedform record (subglacial lineations and subglacial ribs) are combined with subglacially streamlined bedrock data to define ice flow patterns, ice divides, ice margins, and glaciation styles of the last glaciation through relative time. The results demonstrate that the FIS flow configuration was not static. The FIS advanced eastwards across the region from Scandinavia, rather than expanding from local upland areas, and established a predominantly cold-based ice mass on the Kola Peninsula with an extensive adjacent warm-based ice lobe in the White Sea. An east-west aligned ice divide was located on the Kola Peninsula and Russian Lapland during the ice sheet build-up stages. However, this divide was short-lived as the White Sea lobe dominated ice flow on the peninsula during the local-Last Glacial Maximum, and ice predominantly flowed across the region from the main ice dispersal zone that was centred over the Gulf of Bothnia during deglaciation. Deglaciation on the peninsula was initially characterised by cold-based ice sheet retreat on the central eastern Kola Peninsula and warm-based ice lobe retreat in the White Sea. Continued deglaciation was characterised by ice sheet thinning, exposing mountain summits as nunataks behind the ice sheet margin, with topography constraining ice flow around upland areas. Ice streams in the region were drivers and consequences of continued ice sheet configuration change throughout glaciation. Four palaeo ice streams e (i) the Imandra Ice Stream; (ii) the Lovozero Ice Stream; (iii) the Kanozero Ice Stream; and (iv) the Kuusamo Ice Stream e and three possible palaeo-ice stream pathways are identified. We consider our ice flow configuration reconstruction to be the simplest palaeo-glaciological interpretation of the bedform record of the Kola Peninsula and Russian Lapland. The empirically-based reconstruction of ice flow geometry provides a regional framework and context for interpreting results from local-scale fieldwork, and is presented in a format that can be utilised by numerical ice sheet modellers to test and verify their models. The results underpin a new data-driven reconstruction of the last FIS in northwest Arctic Russia that we present in Part 2 of this study.
<p>Previous attempts to reconstruct the glacial history of the last Fennosc... more <p>Previous attempts to reconstruct the glacial history of the last Fennoscandian Ice sheet (FIS) in northwest Arctic Russia have resulted in various Last Glacial-Interglacial Transition (c. 20-10 ka) scenarios, suggesting that the Kola Peninsula was glaciated by the FIS, the Ponoy Ice Cap, or the Kara Sea Ice Sheet. The conflicting glacial interpretations have stemmed, in part, from the use of low-resolution geomorphological and geological maps. The advent of high-resolution remotely-sensed imagery warrants a new glacial reconstruction of ice sheet dynamics in northwest Arctic Russia: we therefore present initial glacial interpretations based on new high-resolution geomorphological mapping.</p><p>Geomorphological mapping using high-resolution ArcticDEM and PlanetScope imagery has identified >245,000 glacial landforms, significantly increasing the volume and detail of geomorphological data in the region. Over 66,000 subglacial bedforms (subglacial lineations and subglacial ribs) are used to construct flowsets, which demonstrate that ice flowed from the Scandinavian mountains in the west and across the shield terrain of the Kola Peninsula. Moreover, four possible palaeo-ice streams are identified in the region. Mapping individual moraine hummocks, rather than hummocky moraine spreads as in previous mapping attempts, reveals multiple ice margins across the Kola Peninsula. A noteworthy ~25 km wide belt of hummocky moraines aligned north-south across the Kola Peninsula is tentatively attributed to the Younger Dryas (c. 12.8-11.9 ka) ice marginal zone. The so-called “ring-and-ridge” hummock moraines that are predominantly observed within this ice marginal zone suggest down-wasting and stagnant ice margins. The meltwater landform record also reveals subglacial channel networks along the northern coastline that suggest warm-based conditions of the ice sheet may have been induced by warm currents in the Barents Sea during the last glacial-interglacial transition.</p><p>This research will provide crucial empirical data for validating numerical model simulations of the FIS, which in turn will further our understanding of ice sheet dynamics in other Arctic, Antarctic, and Alpine regions.</p>
Abstract The Kola Peninsula and Russian Lapland (Murmansk Oblast, northwest Arctic Russia) repres... more Abstract The Kola Peninsula and Russian Lapland (Murmansk Oblast, northwest Arctic Russia) represents a major sector of the Fennoscandian Ice Sheet (FIS) where empirical geomorphological, sedimentological, and chronological data are lacking and thus, where the pattern, style, and timing of glaciation is not well established. In this study, we present a critical review of published empirical data and interpretations of Late Weichselian (c. 40–10 ka) glaciation for the region. The review includes, for the first time, information published in Russian-language journal articles (n = 37), and is accompanied by a new Geographic Information System (GIS) numerical age database (spanning 472.3–6.2 ka) that collates known published numerical dates associated with the advance and retreat of the FIS in the study area. Our review suggests that an ice mass existed over the Kola Peninsula and Russian Lapland during the Early-Middle Weichselian (c. 115–40 ka), and likely retreated during the Alesund interstadial (c. 38–34 ka). During the Late Weichselian, it is likely that the FIS advanced eastwards across Russian Lapland and the Kola Peninsula, establishing the White Sea Ice Stream before the local-Last Glacial Maximum (c. 19–15 ka). Through an evaluation of the existing Last Glacial-Interglacial Transition (c. 20–10 ka) glaciation models for the region, we propose that the Kola Peninsula and Russian Lapland was deglaciated by the FIS, rather than the Ponoy Ice Cap or the Kara Sea Ice Sheet. In collating, discussing, and critically evaluating empirical data and interpretations, this paper provides a valuable resource to inform FIS dynamics at both a regional- and ice sheet-scale, and offers a framework through which numerical ice sheet models can be constrained. Precise FIS dynamics on the Kola Peninsula and Russian Lapland, including the position of the Younger Dryas ice marginal zone, remain unclear due to low-resolution geomorphological data. In concluding, we recommend that further work is needed in the form of a revised glacial reconstruction using high-resolution, peninsula-wide geomorphological data.
Icebergs are important as agents of deposition and seafloor reworking on glacier-influenced conti... more Icebergs are important as agents of deposition and seafloor reworking on glacier-influenced continental margins. When the keel of an iceberg exceeds water depth it ploughs through soft sediments producing scours/ploughmarks that can be kilometres long, hundreds of metres wide and sometimes tens of metres deep. Because the influence of iceberg keels on sediment is a critical factor when offshore structures (e.g. pipelines, power cables) are installed, the surface morphology of iceberg scours on the seafloor is relatively well-documented. Less however, is known about sub-scour deformation below the seafloor. This is particularly true of iceberg scoured diamicton (poorly sorted sediment comprising a variety of particle sizes), which is present in many high-latitude fjords and continental shelves. The aim of this research is to examine directly (macroscopically and microscopically, with thin sections) the style and intensity of deformation caused by the scouring action of iceberg keels in diamicton offshore of East Greenland. Results show that a distinctive suite of deformation structures (individual structures and overprinted structural patterns) dominated by planar shear, sediment mixing and high porewater, and dropstones characterises iceberg scoured diamicton. In addition, diamicton from areas of high-intensity iceberg scouring tends to show a wider variety, higher frequency and distribution, more abundant and better-developed deformation structures than diamicton from areas of intermediate-and low-intensity iceberg scouring. Characterising the effects of iceberg scour in diamicton is important more widely to inform: i) reconstruction of the geometry and dynamics of former ice sheets; and ii) installation and protection of offshore engineering structures in diamicton where iceberg scouring presents a geohazard. The value of micromorphology is significant especially in the absence of macroscopic sediment expo-sures/outcrops where the study of cores is necessary instead.
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