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1.
Provenances for the lithogenic part of the sandy fraction of sediments on the Yermak Plateau are located in northern Eurasia. Based on the study of heavy minerals, new indicators are proposed for the ice-rafted material and main systems of surficial water circulation (gyres of the Beaufort Sea and Polar and Siberian currents of the Transpolar drift). Interpretation of the grain size distribution of sediments of warm and cold stages is based on difference in mechanisms of sedimentary material introduction into sea ice. Episodes of the influx of Atlantic warm and saline waters via the Fram Strait into the Arctic Ocean are reconstructed based on CaCO3 content. The relationship between sedimentary materials transported by icebergs and sea ice during the last 190 ka is given. Hypotheses of the history of surficial circulation in the Arctic Ocean and discharges of Siberian rivers during this period are presented.  相似文献   

2.
Heat flow taken between Svalbard and Greenland reveal three thermal provinces:
1. (1) the Molloy Ridge within the Spitsbergen Transform,
2. (2) the Yermak Plateau
3. (3) the northeastern margin of Svalbard (Nordaustlandet).
The Molloy Ridge is a short spreading segment and the average heat flow is much above the Sclater et al. (1971), cooling curve but agrees with values from the Norwegian-Greenland Sea. An additional zone of intrusion identified by heat flow lies to the northwest of the Molloy Ridge. It straddles both the visible fracture zone and part of the Yermak Plateau. A thermal boundary lies between the warm western segment of the Yermak Plateau and the shelf off Nordaustlandet. If the thermal subsidence of the western Yermak Plateau can be traced to the latest heating episode then it is likely that the crust is similar to oceanic in composition and not older than 13 m.y. (approximately 20 m.y. younger than the northeastern segment of the plateau). Plate rotation shows that there was no room for the western segment of the plateau prior to anomaly 7. We postulate that the original transform is associated with the Hornsund Fault zone. In response to deviatoric stress across the oblique ridge-transform system, the Nansen Ridge propagated southwestward aborting the old transform trace, and shifted to its present position.It is suggested that this propagation and migration of the ridge-transform system across a zone of extensional deviatoric stress allowed the massive intrusion of basalt forming the Western Yermak Plateau. The propagation phenomenon coincides with large-scale Tertiary volcanic activity on Svalbard.Readjustment and migration of the oblique transform is still taking place. As the transform-ridge system is liberated from continental constraints, the migration rate will diminish as orthogonality is approached.  相似文献   

3.
High-resolution bathymetric mapping of the fjords and continental shelf around the Svalbard archipelago shows an extensive pattern of large- and medium-scale submarine landforms formed by differences in ice-flow regimes. Mega-scale glacial lineations, lateral moraines, transverse ridges and glaciotectonic features are superimposed on the large-scale fjord, shelf and cross-shelf trough morphology of the margin. From these landforms we have inferred the flow and dynamics of the last ice sheet on Svalbard. Major fjords and their adjacent cross-shelf troughs have been identified as the main routes for ice streams draining the ice sheet. On the west coast of Svalbard major pathways existed along Bellsund, Isfjorden and Kongsfjorden. Along the northern Svalbard margin most of the ice drained through the Woodfjorden cross-shelf trough and Wijdefjorden-Hinlopen strait. Extensive areas with trough-parallel glacial lineations in the cross-shelf troughs suggest fast ice flow by palaeo-ice streams. Lateral ice-stream moraines, several tens of kilometres in length, have been mapped along the margins of some of the cross-shelf troughs, identifying the border zone between fast ice flow and stagnant or slow-flowing ice on intervening banks. Several general implications can be drawn from the interpretation of the glacier-derived submarine landforms around Svalbard. Firstly, the Late Weichselian ice sheet was partitioned into fast-flowing ice streams separated by slower moving ice. Secondly, our submarine morphological evidence supports earlier sedimentological, stratigraphical and chronological studies in implying that a large ice sheet reached the shelf edge around almost all of western and northern Svalbard in the Late Weichselian. The idea of a relatively restricted ice sheet over Svalbard, with ice-free conditions in some areas of the west coast at the Last Glacial Maximum, is therefore unlikely to be correct. Thirdly, the ice sheet appears to have retreated more rapidly from the cross-shelf troughs and outer fjords, although sometimes this occurred in a punctuated pattern indicated by grounding-zone wedges, and more slowly from the intervening shallower banks. In addition, a grounding zone for the ice sheet has been mapped at the shelf edge 10-20 km off the northwest coast of Svalbard, suggesting that ice did not reach the adjacent Yermak Plateau during the Late Weichselian.  相似文献   

4.
A novel and promising biomarker proxy for reconstruction of Arctic sea ice conditions was developed and is based on the determination of a highly branched isoprenoid with 25 carbons (IP25). IP25 records have been restricted to the last 150 kyr BP. We present a biomarker record from Ocean Drilling Program (ODP) Site 912, going back to the Pliocene–Pleistocene boundary and indicating that sea ice of variable extent occurred in the Fram Strait/southern Yermak Plateau area at least since about 2.2 Ma. Furthermore, our data support the idea that a combination of IP25 and open water, phytoplankton biomarker data (“PIP25 index”) may give a more reliable and quantitative estimate of past sea ice cover (at least for the study area). The study reveals that the novel IP25/PIP25 biomarker approach has potential for semi-quantitative paleo-sea ice studies covering the entire Quaternary and could motivate further detailed high resolution research on ODP/IODP material using this proxy.  相似文献   

5.
A multiproxy analysis of Hole 911A (Ocean Drilling Program (ODP) Leg 151) drilled on the Yermak Plateau (eastern Arctic Ocean) is used to investigate the behaviour of the Svalbard/Barents Sea ice sheet (SBIS) during late Pliocene and early Pleistocene (~3.0-1.7 Ma) climate changes. Contemporary with the 'Mid-Pliocene (~3 Ma) global warmth' (MPGW), a warmer period lasting ~300 kyr with seasonally ice-free conditions in the marginal eastern Arctic Ocean is assumed to be an important regional moisture source, and possibly one decisive trigger for intensification of the Northern Hemisphere glaciation in the Svalbard/Barents Sea area at ~2.7 Ma. An abrupt pulse of ice-rafted debris (IRD) to the Yermak Plateau at ~2.7 Ma reflects distinct melting of sediment-laden icebergs derived from the SBIS and may indicate the protruding advance of the ice sheet onto the outer shelf. Spectral analysis of the total organic carbon (TOC) record being predominantly of terrigenous/fossil-reworked origin indicates SBIS and possibly Scandinavian Ice Sheet response to incoming solar radiation at obliquity and precession periodicities. The strong variance in frequencies near the 41 kyr obliquity cycle between 2.7 and 1.7 Ma indicates, for the first time in the Arctic Ocean, a close relationship of SBIS growth and decay patterns to the Earth's orbital obliquity amplitudes, which dominated global ice volume variations during late Pliocene/early Pleistocene climate changes.  相似文献   

6.
Investigation of eight deep-sea sediment cores from the Fram Strait provides evidence of two phases with an increased input of ice-rafted detritus (IRD) during the last 130,000 years. For the Middle and Late Weichselian events, east-west trends in accumulation rates and terrestrial organic matter content in the deep-sea sediments point to Svalbard as the source area of the IRD. Both phases are clearly correlated with glacier advances on Svalbard, allowing the application of marine stratigraphy to the terrestrial field sections. Since the dating of the terrestrial record of the Weichselian glacial history of Svalbard is still uncertain, this correlation will improve the age assignments to the individual glacial events.  相似文献   

7.
High‐resolution swath bathymetry and TOPAS sub‐bottom profiler acoustic data from the inner and middle continental shelf of north‐east Greenland record the presence of streamlined mega‐scale glacial lineations and other subglacial landforms that are formed in the surface of a continuous soft sediment layer. The best‐developed lineations are found in Westwind Trough, a bathymetric trough connecting Nioghalvfjerdsfjorden Gletscher and Zachariae Isstrøm to the continental shelf edge. The geomorphological and stratigraphical data indicate that the Greenland Ice Sheet covered the inner‐middle shelf in north‐east Greenland during the most recent ice advance of the Late Weichselian glaciation. Earlier sedimentological and chronological studies indicated that the last major delivery of glacigenic sediment to the shelf and Fram Strait was prior to the Holocene during Marine Isotope Stage 2, supporting our assertion that the subglacial landforms and ice sheet expansion in north‐east Greenland occurred during the Late Weichselian. Glacimarine sediment gravity flow deposits found on the north‐east Greenland continental slope imply that the ice sheet extended beyond the middle continental shelf, and supplied subglacial sediment direct to the shelf edge with subsequent remobilisation downslope. These marine geophysical data indicate that the flow of the Late Weichselian Greenland Ice Sheet through Westwind Trough was in the form of a fast‐flowing palaeo‐ice stream, and that it provides the first direct geomorphological evidence for the former presence of ice streams on the Greenland continental shelf. The presence of streamlined subglacially derived landforms and till layers on the shallow AWI Bank and Northwind Shoal indicates that ice sheet flow was not only channelled through the cross‐shelf bathymetric troughs but also occurred across the shallow intra‐trough regions of north‐east Greenland. Collectively these data record for the first time that ice streams were an important glacio‐dynamic feature that drained interior basins of the Late Weichselian Greenland Ice Sheet across the adjacent continental margin, and that the ice sheet was far more extensive in north‐east Greenland during the Last Glacial Maximum than the previous terrestrial–glacial reconstructions showed. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

8.
The precipitation fields of a palaeoatmospheric general circulation model are used to derive estimates of the geographical distribution, and flux, of icebergs from the Laurentide, Fennoscandinavian and eastern Siberian ice‐sheets at the Last Glacial Maximum (LGM). The atmospheric model fields from LGM simulations using CLIMAP or Peltier (ICE‐4G) ice orography were studied, to test the sensitivity of the predicted flux. The estimated Northern Hemispheric LGM iceberg flux is 3500–4000 km3 yr?1, of which about 60% issued directly into the North Atlantic. The iceberg flux from the St Lawrence area is of similar significance to that issuing from Hudson Strait in all estimates. Both the North Pacific and the Arctic received substantial iceberg fluxes (ca. 700 km3 yr?1), with relatively minor differences occurring between the two ice‐sheet reconstructions. Apparent discrepancies between Arctic deep‐sea core samples of ice‐rafted debris and our estimates of mean glacial iceberg flux may be ascribed to coastal trapping of bergs, the existence of floating ice tongues or a rapid exit of icebergs from the Arctic basin into the Greenland Sea through the Fram Strait. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

9.
Hormes, A., Akçar, N. & Kubik, P. W. 2011: Cosmogenic radionuclide dating indicates ice‐sheet configuration during MIS 2 on Nordaustlandet, Svalbard. Boreas, 10.1111/j.1502‐3885.2011.00215.x. ISSN 0300‐9483.0300‐9843 Glacial geological field surveys, aerial image interpretation and cosmogenic radionuclide (CRN) dating allowed us to reconstruct the ice‐sheet configuration on Nordaustlandet, the northernmost island of the European sector on the margin of the Arctic Ocean. The timing of deglaciation was investigated by determining the 26Al and 10Be ages of glacially scoured bedrock, weathered periglacial blockfields and glacial erratic boulders. Only 10Be ages were useful for our interpretations, because of unresolved analytical problems with 26Al. Fjords and lowlands on Nordaustlandet yielded Late Weichselian 10Be ages, indicating that actively erosive ice streams scoured the coastal fjord bathymetry during marine isotope stage (MIS) 2. In Murchisonfjorden, ground‐truthed air‐photograph interpretation and 10Be ages of boulders indicated a cold‐based glacier ice cover during MIS 2 on higher plateaus. 10Be ages and lithological studies of erratic boulders on higher and interior plateaus of Prins Oscars Land (>200–230 m a.s.l.) suggest that the Mid‐Weichselian glaciation (MIS 4) might have been more extensive than that during MIS 2.  相似文献   

10.
Expansion of fresh and sea‐ice loaded surface waters from the Arctic Ocean into the sub‐polar North Atlantic is suggested to modulate the northward heat transport within the North Atlantic Current (NAC). The Reykjanes Ridge south of Iceland is a suitable area to reconstruct changes in the mid‐ to late Holocene fresh and sea‐ice loaded surface water expansion, which is marked by the Subarctic Front (SAF). Here, shifts in the location of the SAF result from the interaction of freshwater expansion and inflow of warmer and saline (NAC) waters to the Ridge. Using planktic foraminiferal assemblage and concentration data from a marine sediment core on the eastern Reykjanes Ridge elucidates SAF location changes and thus, changes in the water‐mass composition (upper ˜200 m) during the last c. 5.8 ka BP. Our foraminifer data highlight a late Holocene shift (at c. 3.0 ka BP) in water‐mass composition at the Reykjanes Ridge, which reflects the occurrence of cooler and fresher surface waters when compared to the mid‐Holocene. We document two phases of SAF presence at the study site: from (i) c. 5.5 to 5.0 ka BP and (ii) c. 2.7 to 1.5 ka BP. Both phases are characterized by marked increases in the planktic foraminiferal concentration, which coincides with freshwater expansions and warm subsurface water conditions within the sub‐polar North Atlantic. We link the SAF changes, from c. 2.7 to 1.5 ka BP, to a strengthening of the East Greenland Current and a warming in the NAC, as identified by various studies underlying these two currents. From c. 1.5 ka BP onwards, we record a prominent subsurface cooling and continued occurrence of fresh and sea‐ice loaded surface waters at the study site. This implies that the SAF migrated to the southeast of our core site during the last millennium.  相似文献   

11.
We present the first multi-channel seismic reflection data ever collected from the Eurasian Basin of the Arctic Ocean. The 200 km data set was acquired by a 20 channel sonobuoy array deployed at U.S. ice drift station FRAM-IV and operated for 34 days about 370 km north of Svalbard in April–May 1982. Cross array drift and ice floe rotation which may constitute the most serious obstacle to the advantage of multi-channel data acquisition did only occur to a minor degree during the experiment and render most of the data set suitable for processing using common mid-point binning.A 0.7–1.4 s (two-way traveltime) thick sedimentary section has been deposited over oceanic crust of mid-Oligocene age below the Barents Abyssal Plain. In the deepest part, sediments are infilling topographic lows which indicate predominantly turbidite deposition. Erosional truncations are only locally present in the central part of the section. Conformable bedforms deposited over gentle basement highs indicate a relatively stable bottom current regime since mid-Oligocene time. Thus the establishment of a deep water connection between the Arctic Ocean and lower latitude water masses appear to have had only minor effect on Eurasian Basin bottom current circulation.Extensive submarine slide scars on the north slope of Yermak Plateau show that mass waste have been a sediment source to the Barents Abyssal Plain.  相似文献   

12.
Seismic reflection data reveal prominent bottom-simulating reflections (BSRs) within the relatively young (<0.78 Ma) sediments along the West Svalbard continental margin. The potential hydrate occurrence zone covers an area of c. 1600 km2. The hydrate accumulation zone is bound by structural/tectonic features (Knipovich Ridge, Molloy Transform Fault, Vestnesa Ridge) and the presence of glacigenic debris lobes inhibiting hydrate formation upslope. The thickness of the gas-zone underneath the BSR varies laterally, and reaches a maximum of c. 150 ms. Using the BSR as an in-situ temperature proxy, geothermal gradients increase gradually from 70 to 115 °C km−1 towards the Molloy Transform Fault. Anomalies only occur in the immediate vicinity of normal faults, where the BSR shoals, indicating near-vertical heat/fluid flow within the fault zones. Amplitude analyses suggest that sub-horizontal fluid migration also takes place along the stratigraphy. As the faults are related to the northwards propagation of the Knipovich Ridge, long-term disturbance of hydrate stability appears related to incipient rifting processes.  相似文献   

13.
Ice streams are the fast-flowing zones of ice sheets that can discharge a large flux of ice. The glaciated western Svalbard margin consists of several cross-shelf troughs which are the former ice stream drainage pathways during the Pliocene–Pleistocene glaciations. From an integrated analysis of high-resolution multibeam swath-bathymetric data and several high-resolution two-dimensional reflection seismic profiles across the western and northwestern Svalbard margin we infer the ice stream flow directions and the deposition centres of glacial debris that the ice streams deposited on the outer margin. Our results show that the northwestern margin of Svalbard experienced a switching of a major ice stream. Based on correlation with the regional seismic stratigraphy as well as the results from ODP 911 on Yermak Plateau and ODP 986 farther south on the western margin of Spitsbergen, off Van Mijenfjord, we find that first a northwestward flowing ice stream developed during initial northern hemispheric cooling (starting ～2.8–2.6 Ma). A switch in ice stream flow direction to the present-day Kongsfjorden cross-shelf trough took place during a glaciation at ～1.5 Ma or probably later during an intensive major glaciation phase known as the ‘Mid-Pleistocene Revolution’ starting at ～1.0 Ma. The seismic and bathymetric data suggest that the switch was abrupt rather than gradual and we attribute it to the reaching of a tipping point when growth of the Svalbard ice sheet had reached a critical thickness and the ice sheet could overcome a topographic barrier.  相似文献   

14.
Alexanderson, H., Landvik, J. Y. & Ryen, H. T. 2010: Chronology and styles of glaciation in an inter‐fjord setting, northwestern Svalbard. Boreas, 10.1111/j.1502‐3885.2010.00175.x. ISSN 0300‐9483. A 30‐m‐thick sedimentary succession at Leinstranda on the southwestern coast of Brøggerhalvøya, northwestern Svalbard, spans the two last glacial–interglacial cycles and reveals information on glacial dynamics, sea‐level changes and the timing of these events. We investigated the deposits using standard stratigraphical and sedimentological techniques, together with ground‐penetrating radar, and established an absolute chronology based mainly on optically stimulated luminescence dating. We identified facies associations that represent depositional settings related to advancing, overriding and retreating glaciers, marine and littoral conditions and periglacial surfaces. The environmental changes show an approximate cyclicity and reflect glaciations followed by high sea levels and later regression. The luminescence chronology places sea‐level highstands at 185 ± 8 ka, 129 ± 10 ka, 99 ± 8 ka and 36 ± 3 ka. These ages constrain the timing of recorded glaciations at Leinstranda to prior to c. 190 ka, between c. 170 and c. 140 ka (Late Saalian) and between c. 120 ka and c. 110 ka (Early Weichselian). The glaciations include phases with glaciers from three different source areas. There is no positive evidence for either Middle or Late Weichselian glaciations covering the site, but there are hiatuses at those stratigraphic levels. A high bedrock ridge separates Leinstranda from the palaeo‐ice stream in Kongsfjorden, and the deposits at Leinstranda reflect ice‐dynamic conditions related to ice‐sheet evolution in an inter‐fjord area. The environmental information and the absolute chronology derived from our data allow for an improved correlation with the marine record, and for inferences to be made about the interaction between land, ocean and ice during the last glacial–interglacial cycles.  相似文献   

15.
The Late Weichselian ice sheet of western Svalbard was characterized by ice streams and inter‐ice‐stream areas. To reconstruct its geometry and dynamics we investigated the glacial geology of two areas on the island of Prins Karls Forland and the Mitrahalvøya peninsula. Cosmogenic 10Be surface exposure dating of glacial erratics and bedrock was used to constrain past ice thickness, providing minimum estimates in both areas. Contrary to previous studies, we found that Prins Karls Forland experienced a westward ice flux from Spitsbergen. Ice thickness reached >470 m a.s.l., and warm‐based conditions occurred periodically. Local deglaciation took place between 16 and 13 ka. At Mitrahalvøya, glacier ice draining the Krossfjorden basin reached >300 m a.s.l., and local deglaciation occurred at c. 13 ka. We propose the following succession of events for the last deglaciation. After the maximum glacier extent, ice streams in the cross‐shelf troughs and fjords retreated, tributary ice streams formed in Forlandsundet and Krossfjorden, and, finally, local ice caps were isolated over both Prins Karls Forland and Mitrahalvøya and their adjacent shelves.  相似文献   

16.
The sediment core NP05‐71GC, retrieved from 360 m water depth south of Kvitøya, northwestern Barents Sea, was investigated for the distribution of benthic and planktic foraminifera, stable isotopes and sedimentological parameters to reconstruct palaeoceanographic changes and the growth and retreat of the Svalbard–Barents Sea Ice Sheet during the last ～16 000 years. The purpose is to gain better insight into the timing and variability of ocean circulation, climatic changes and ice‐sheet behaviour during the deglaciation and the Holocene. The results show that glaciomarine sedimentation commenced c. 16 000 a BP, indicating that the ice sheet had retreated from its maximum position at the shelf edge around Svalbard before that time. A strong subsurface influx of Atlantic‐derived bottom water occurred from 14 600 a BP during the Bølling and Allerød interstadials and lasted until the onset of the Younger Dryas cooling. In the Younger Dryas cold interval, the sea surface was covered by near‐permanent sea ice. The early Holocene, 11 700–11 000 a BP, was influenced by meltwater, followed by a strong inflow of highly saline and chilled Atlantic Water until c. 8600 a BP. From 8600 to 7600 a BP, faunal and isotopic evidence indicates cooling and a weaker flow of the Atlantic Water followed by a stronger influence of Atlantic Water until c. 6000 a BP. Thereafter, the environment generally deteriorated. Our results imply that (i) the deglaciation occurred earlier in this area than previously thought, and (ii) the Younger Dryas ice sheet was smaller than indicated by previous reconstructions.  相似文献   

17.
New marine geological evidence provides a better understanding of ice-sheet dynamics along the western margin of the last Svalbard/Barents Sea Ice Sheet. A suite of glacial sediments in the Kongsfjordrenna cross-shelf trough can be traced southwards to the shelf west of Prins Karls Forland. A prominent moraine system on the shelf shows minimum Late Weichselian ice extent, indicating that glacial ice also covered the coastal lowlands of northwest Svalbard. Our results suggest that the cross-shelf trough was filled by a fast-flowing ice stream, with sharp boundaries to dynamically less active ice on the adjacent shelves and strandflats. The latter glacial mode favoured the preservation of older geological records adjacent to the main pathway of the Kongsfjorden glacial system. We suggest that the same model may apply to the Late Weichselian glacier drainage along other fjords of northwest Svalbard, as well as the western margin of the Barents Ice Sheet. Such differences in glacier regime may explain the apparent contradictions between the marine and land geological record, and may also serve as a model for glaciation dynamics in other fjord regions.  相似文献   

18.
Two cores from the southwestern shelf and slope of Storfjorden, Svalbard, taken at 389 m and 1485 m water depth have been analyzed for benthic and planktic foraminifera, oxygen isotopes, and ice-rafted debris. The results show that over the last 20,000 yr, Atlantic water has been continuously present on the southwestern Svalbard shelf. However, from 15,000 to 10,000 14C yr BP, comprising the Heinrich event H1 interval, the Bølling-Allerød interstades and the Younger Dryas stade, it flowed as a subsurface water mass below a layer of polar surface water. In the benthic environment, the shift to interglacial conditions occurred at 10,000 14C yr BP. Due to the presence of a thin upper layer of polar water, surface conditions remained cold until ca. 9000 14C yr BP, when the warm Atlantic water finally appeared at the surface. Neither extensive sea ice cover nor large inputs of meltwater stopped the inflow of Atlantic water. Its warm core was merely submerged below the cold polar surface water.  相似文献   

19.
Quantitative X‐ray diffraction analysis of the <2 mm sediment fraction was carried out on 1257 samples (from the seafloor and 16 cores) from the Iceland shelf west of 18° W. All but one core (B997‐347PC) were from transects along troughs on the NW to N‐central shelf, an area that in modern and historic times has been affected by drift ice. The paper focuses on the non‐clay mineralogy of the sediments (excluding calcite and volcanic glass). Quartz and potassium feldspars occupy similar positions in an R‐mode principal component analysis, and oligoclase feldspar tracks quartz; these minerals are used as a proxy for ice‐rafted detritus (IRD). Accordingly, the sum of these largely foreign minerals (Q&K) (to Icelandic bedrock) is used as a proxy for drift ice. A stacked, equi‐spaced 100 a record is developed which shows both low‐frequency trends and higher‐frequency events. The detrended stacked record compares well with the flux of quartz (mg cm?2 a?1) at MD99‐2269 off N Iceland. The multi‐taper method indicated that there are three significant frequencies at the 95% confidence level with periods of ca. 2500, 445 and 304 a. Regime shift analysis pinpoints intervals when there was a statistically significant shift in the average Q&K weight %, and identifies four IRD‐rich events separated by intervals with lower inputs. There is some association between peaks of IRD input, less dense surface waters (from δ18O data on planktonic foraminifera) and intervals of moraine building. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

20.
《Quaternary Science Reviews》2007,26(7-8):1016-1036
The Quaternary development offshore the Faroe Islands has been studied using high-resolution seismic and core data from the R/V DANA 2000 cruise and previous cruises. Several glacial-related features and deposits are observed, all bearing witness to former extensive glaciations of the Faroe area. On the shelves, overlaying a mid-Pleistocene glacial erosional surface, glacial and glacimarine deposits form a sheet geometry interrupted by ridges of sediment that are likely to represent ice-front deposits. An iceberg turbate north of the Faroe Islands provides evidence of large-scale drift of ultra-deep draft (>600 m) icebergs in the Nordic Seas at pre-Weichselian glacial stage(s). Marginal and transverse troughs found on the eastern and western shelf are suggested to have formed during the same glacial period(s) as the iceberg turbate. Iceberg plough-marks and abundant ice rafted material of non-Faroese origin, together with the relict moraine ridges encircling the Faroe Islands at around the 100 and 200 m water depth contours, indicate that the outer shelf was probably ice free during the Weichselian ice age. On the slopes and basinal parts, the formation of fine-grained contourites was favoured during (Weichselian) glacial stages when bottom currents were reduced. Sediment overloading during these glacial stages resulted in repeated slope instability, causing mass failures of the contourite deposits.  相似文献   

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