Eiliv Larsen - Academia.edu (original) (raw)

Papers by Eiliv Larsen

Norsk Geologisk Tidsskrift, 1985

Based mainly on stratigraphical data and information on sea-leve! and cirque glacier erosion rate... more Based mainly on stratigraphical data and information on sea-leve! and cirque glacier erosion rates, the age and processes for the formation of the Norwegian strandflat are discussed. It is concluded that the main processes are frost-shattering in combination with sea-ice transportation and planation during glacial stages in the last 2.5 Ma.

Boreas, Oct 25, 2020

The volcanic island of Jan Mayen, remotely located in the Norwegian-Greenland Sea, was covered by... more The volcanic island of Jan Mayen, remotely located in the Norwegian-Greenland Sea, was covered by a contiguous ice cap during the Late Weichselian. Until now, it has been disputed whether parts of the island south of the presently glaciated Mount Beerenberg areawere ever glaciated. Based on extensive field mapping we demonstrate that an ice cap covered all land areas and likely also extended onto the shallow shelf areas southeast and east of the island. Chronological interpretations are based on K-Ar and 40 Ar/ 39 Ar dating of volcanic rocks, cosmogenic nuclide (36 Cl) surface exposure dating of bedrock and glacial erratics, and radiocarbon dating. We argue that ice growth started after 34 ka and that an initial deglaciation started some 21.5-19.5 ka in the southern and middle parts of the island. In the northern parts, closer to the present glaciers, the deglaciation might have started later, as evidenced by the establishment of vegetation 17-16 cal. ka BP. During full glaciation, the ice cap was likely thickest over the southern part of the island. This may explain a seemingly delayed deglaciation compared with the northern parts despite earlier initial deglaciation. In a broader context, the new knowledge of the Late Weichselian of the island contributes to the understanding of glaciations surrounding the North Atlantic and its climate history.

Journal of Biogeography, Jul 22, 2005

Aim We discuss the hypotheses proposed by Kullman [Geo‐Öko21 (2000) 141; Nordic Journal of Botan... more Aim We discuss the hypotheses proposed by Kullman [Geo‐Öko21 (2000) 141; Nordic Journal of Botany21 (2001) 39; Journal of Biogeography29 (2002) 1117] on the basis of radiocarbon‐dated megafossils of late‐glacial age from the central Swedish mountains that boreal trees survived the glaciation along the south‐west coast of Norway and subsequently migrated eastward early in the late‐glacial to early deglaciated parts of the central Swedish Scandes mountains.Methods We assess these hypotheses on the basis of glacial geological evidence and four lines of palaeoecological evidence, namely macrofossil records of the tree species, vegetation and climate reconstructions from plant evidence, independent climate reconstructions from other proxies for the late‐glacial environment of south‐west Norway, and the patterns of post‐glacial spread of the tree species.Location South and west Norway, central Swedish Scandes mountains (Jämtland).Results and conclusions South‐west Norway and the adjacent continental shelf were under ice at the last‐glacial maximum (LGM). The late‐glacial vegetation of south‐west Norway was treeless and summer temperatures were below the thermal limits for Betula pubescens Ehrh., Pinus sylvestris L. and Picea abies (L.) Karst. Instead of spreading immediately after the onset of Holocene warming, as might have been expected if local populations were surviving, B. pubescens showed a lag of local arrival of 600 to > 1000 years, Pinus lagged by 1500 to > 2000 years, and Picea only reached southern Norway c. 1500 years ago and has not colonized most of south‐west Norway west of the watershed. Glacial geological evidence shows the presence of an ice sheet in the Scandes at the LGM and in the Younger Dryas, which was cold‐based near or at the area where the late‐glacial‐dated megafossils were recovered by Kullman. We conclude that the samples dated by Kullman (2002) should be evaluated carefully for possible sources of contamination. All the available evidence shows that the biogeographical hypotheses, based on these radiocarbon dates taken at face value, of late‐glacial tree survival at the Norwegian coast and subsequent eastwards spread to the mountains, are unsupportable.

The thickness of the Scandinavian Ice Sheet and its surface profile have long been disputed due t... more The thickness of the Scandinavian Ice Sheet and its surface profile have long been disputed due to divergent geologic evidence, especially in the mountainous areas of western Norway. It is essential to be able to reconstruct these parameters in addition to the relatively well known ice extent, because the dimensions and volume of the ice sheet strongly influenced global sea level and ocean and atmospheric circulation. We use a two-dimensional, time-dependent, thermomechanically coupled ice flow model along two E-W transects running at ca. 62°N and at ca. 66-67°N, respectively, in order to investigate the thickness evolution of the Scandinavian Ice Sheet. The model is mainly driven by temperature and precipitation. Estimates of LGM and later climate conditions in the area are taken from various GCM and regional climate model studies as well as paleoclimate reconstructions from proxy data. The GRIP d18O record has been adapted to the local data in order to provide us with a continuous...

Journal of Quaternary Science, 1987

Based on detailed stratigraphic investigations on a 200.6m long core (BGS borehole No. 81/26) fro... more Based on detailed stratigraphic investigations on a 200.6m long core (BGS borehole No. 81/26) from the Fladen Ground area (British sector), core material from the Sleipner field (Norwegian sector) and shallow seismic profiles between the core‐sites, the following conclusions are drawn: (1) The North Sea was glaciated sometime during th elaterpart of Matuyama reversed period. A complete glacial‐interglacial‐glacial cycle is recorded in these sediments. (2) In a period of marine sedimentation in the Middle Pleistocene, a transgression‐regression cycle under boreal‐arctic regime is recorded. (3) The Fladen area has subsided between 0.9 and 0.6 m/ka through the later parts of the Quaternary (4) A major glacial event dated at between 130 and 200 ka is recorded as a thick till unit in 81/26. This till, which was deposited by ice moving from the southwest (Scotland), probably represents a period when the Scandinavian and British ice sheets coalesced in the North Sea. (5) Based on the seism...

EGU General Assembly Conference Abstracts, Apr 1, 2019

Global and Planetary Change, Nov 1, 2001

The Arkhangelsk area lies in the region that was reached by the northeastern flank of the Scandin... more The Arkhangelsk area lies in the region that was reached by the northeastern flank of the Scandinavian ice sheet during the last glaciation. Investigations of Late Pleistocene sediments show interglacial terrestrial and marine conditions with sea level up to 52 m above the present level. An unconformity in the stratigraphy suggests a hiatus representing the Early Ž. Valdaian Weichselian and the beginning of the Middle Valdaian. This unconformity could be related to a low base level and isostatic depression of the area north of Arkhangelsk, either caused by ice masses advancing from the Kara and Barents ice sheets andror to Scandinavian ice over the Kola Peninsula. During Middle Valdaian, from c. 66 ka BP, until the advance of the Late Valdaian glacier, c. 17-16 ka BP, peat formation, and northward fluvial sedimentation occurred coexisting with permafrost conditions in a later phase. Before the glacier advance, the base level rose and thick vertical accumulations of fluvial sediments were formed. Associated with this glacier advance from the north-northwest, ice damming occurred. Fluvial drainage was opposite to the present drainage pattern and deposition appeared in glaciolacustrine ponds in the area outside the limit of the glaciation. After the deglaciation that started c. 15 ka BP, permafrost conditions and downwasting of buried stagnant glacier ice prevailed until at least 10.7 ka BP.

Quaternary science advances, Jul 1, 2022

Boreas, Apr 1, 2010

Mangerud, J., Gulliksen, S. & Larsen, E. 2009: 14C‐dated fluctuations of the western flank of... more Mangerud, J., Gulliksen, S. & Larsen, E. 2009: 14C‐dated fluctuations of the western flank of the Scandinavian Ice Sheet 45–25 kyr BP compared with Bølling–Younger Dryas fluctuations and Dansgaard–Oeschger events in Greenland. Boreas, 10.1111/j.1502‐3885.2009.00127.x. ISSN 0300‐9483.

Social Science Research Network, 2022

SEPM (Society for Sedimentary Geology) eBooks, 2019

Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, Oct 1, 2015

and Technology (NTNU) in Trondheim has a long history, dating back to the 1950s. Its relatively n... more and Technology (NTNU) in Trondheim has a long history, dating back to the 1950s. Its relatively new AMS facility is based on a 1 MV Tandetron from High Voltage Engineering Europa B.V. that is equipped with a hybrid solid/gas SO-110 ion source, a low energy spectrometer supporting sequential injection, a high energy analysis system consisting of a magnet and an electrostatic deflector, allowing insertion of an absorber foil for isobar suppression, and a two dimensional gas ionisation detector (E and DE). The system is at present capable of measuring 10 Be, 14 C, and 26 Al and can be easily modified to measure isotopes of higher masses. Acceptance tests results for 10 Be 1+ , 14 C 2+ , 26 Al 1+ , and 26 Al 3+ are presented. The laboratory measures only 14 C at present and the routine procedures are described. The system has demonstrated a very low background (70,000 14 C years BP or 2Á10 À16 on Alfa Aesar 40795 graphite powder, À200 mesh, 99.9995%) for 14 C when charge state 2+ is measured and the interference of Li ions in the detector is minimal. Some ion optical peculiarities of the system are also discussed.

Boreas, Jan 16, 2008

Abundant dinocysts in a high-resolution core from Voldafjorden, western Norway, reflect changes i... more Abundant dinocysts in a high-resolution core from Voldafjorden, western Norway, reflect changes in sea surface-water conditions during the last c. 11 300 BP. The period from c. 11 300 to 10 800 BP (Late Allerød) was characterized by cool temperate surface-waters, high annual temperature variation and relatively strong stratification of the water column, which is characteristic of fjord environments. Due to the stratification of the surface waters, the uppermost layer may have warmed considerably. This generated a principal difference in temperature conditions between land and sea, with slightly higher temperatures in the marine environments. The period from c. 10 800 to 10 000 BP is characterized by very harsh conditions, with sea surface-water temperatures close to freezing and long lasting seasonal sea-ice cover. Similar temperature changes at the beginning and end of the Younger Dryas are characteristic for NW Europe, but those in Voldafjorden differ from those in the open sea and in the Norwegian Channel by being significantly larger. The stratification of the water column during the Late Allerød was probably broken down because of incipient inflow of temperate normal saline waters, which caused a marked sea surface-water warming, at c. 10 000 BP. Surface-water conditions close to those of today were gradually established between c. 10 000 and 9500 BP. However, these interglacial conditions were abruptly interrupted by a significant drop in winter sea surface-water temperature and salinity occurring around 9700 BP. From c. 9500 to 7000 BP the influence of temperate normal saline water masses increased stepwise until full interglacial conditions were established around c. 7000 BP. The change in the dinocyst assemblage around 7000 BP in Voldafjorden was probably related to the onset of the modern Norwegian Coastal Current, previously documented in cores from the Skagerrak and the Mid-Norwegian Continental Shelf. The last c. 7000 BP is characterized by relatively stable surface-water conditions, possibly interrupted by periods of cooling or decreased inflow of temperate normal saline water. Like several other dinoflagellate cyst records from the Norwegian-Greenland Sea, O. centrocarpum peak values are between 4000 and 5000 BP, suggesting a regional-scale oceanographic change.

During the last decades, our understanding of the Weichselian glaciation history of southern Fenn... more During the last decades, our understanding of the Weichselian glaciation history of southern Fennoscandia has become progressively more complex as new data have become available, i.e. Larsen & Sejrup (1990), Houmark-Nielsen (1999), Sejrup et al. (2000), Olsen et al. (2001) and Mangerud (In press). Long and continuous records from the deep sea and from the Greenland Ice Sheet have been especially important in understanding the Weichselian climate changes in the North Atlantic region. Oxygen-isotope records from Greenland ice-cores indicate several rapid climate shifts during the Weichselian (Dansgaard et al. 1993). These oscillations have been correlated to changes recorded in North Atlantic marine sediments (Bond et al. 1993; Fronval et al. 1995; Haflidason et al. 1995; Elliot et al. 2001) and terrestrial sediments from western Norway (Olsen et al. 2001; Mangerud et al. 2003), suggesting a closely coupled ocean-atmosphere system in the Northern Atlantic region during the Weichselian.