Article

Reconstruction of Holocene patterns of change in a High Arctic coastal landscape, Southern Sassenfjorden, Svalbard

Abstract and Figures

Abrupt shifts in sediment supply, relative sea level, permafrost regime, glacier state, snow cover and sea ice conditions associated with Holocene climate changes control processes operating on High Arctic coasts and make reconstructions of their past evolution a significant research challenge. This study attempts to describe the development of the coastal zone in southern Sassenfjorden, Svalbard, throughout the Holocene focusing on the styles of adjustment to major landscape changes. Five marine terraces (MT1-5) are identified and assessed. Spatial and chronological analysis suggests that the highest terrace, MT5, is pre-LGM (Last Glacial Maximum) and that MT4-3 underwent rapid uplift (151 and 11.4 mm/year, respectively) shortly prior to 11 061 ± 174 cal. yr BP and became fully terrestrial by 9100 years ago (as indicated by emergence rates) during the Holocene Thermal Maximum (HTM). Uplift rates for MT2-1 slowed to 5 and 2 mm/year, respectively, with suggested emergence between 7200 and 6800 cal. yr BP. A final 2 m uplift of the relict alluvial plain probably happened during the Medieval Warm Period (1200–950 cal. yr BP). Most recent coastal development (AD 1912–2012) is characterised by episodes of coastal erosion on the cliff and progradation of the Nøiselva delta. Interactions between sea ice, snow cover, permafrost, wind and wave regimes are assessed to understand their implications on future coastal development in a warming climate.
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Reconstruction of Holocene patterns of change in a High Arctic coastal
landscape, Southern Sassenfjorden, Svalbard
Evangeline G. Sessford
a,
, Mateusz C. Strzelecki
a,b
, Anne Hormes
a,1
a
Department of Arctic Geology, The University Centre in Svalbard, P.O. Box 156, N-9171 Longyearbyen, Norway
b
Department of Geomorphology, University of Wroclaw, pl. Uniwersytecki 1, 50-137 Wroclaw, Poland
abstractarticle info
Article history:
Received 15 March 2014
Received in revised form 6 December 2014
Accepted 10 December 2014
Available online 29 January 2015
Keywords:
Coastal evolutionsea-level change
Holocene climate
Svalbard
High Arctic
Abrupt shifts in sediment supply, relative sea level, permafrost regime, glacier state, snow cover and sea ice
conditions associated with Holocene climate changes control processes operating on High Arctic coasts and
make reconstructions of their past evolution a signicant research challenge. This study attempts to describe
the development of the coastal zone insouthern Sassenfjorden,Svalbard, throughout the Holocene focusing on
the styles of adjustment to major landscape changes. Five marine terraces (MT1-5) are identied and assessed.
Spatial and chronological analysis suggests that the highest terrace, MT5, is pre-LGM (Last Glacial Maximum)
and that MT4-3 underwent rapid uplift (151 and 11.4 mm/year, respectively) shortly prior to 11 061 ±
174 cal. yr BP and became fully terrestrial by 9100 years ago (as indicated by emergence rates) during the
Holocene Thermal Maximum (HTM). Uplift rates for MT2-1 slowed to 5 and 2 mm/year, respectively, with
suggestedemergence between7200 and 6800 cal. yr BP. A nal 2 m uplift of therelict alluvial plain probablyhap-
pened during the Medieval Warm Period (1200950 cal. yr BP). Most recent coastal development (AD 1912
2012) is characterised by episodes of coastal erosion on the cliff and progradation of the Nøiselva delta.
Interactions between sea ice, snow cover, permafrost, wind and wave regimes are assessed to understand their
implications on future coastal development in a warming climate.
© 2015 Elsevier B.V. All rights reserved.
1. Introduction
It has long been acknowledged that uplifted marine terraces are of
primary importance in regard to glacial reconstruction, and are con-
sidered isostatic ngerprints of past ice volume expansions in Svalbard
(Birkenmajer, 1960;Feyling-Hanssen, 1965; Boulton, 1979; Forman and
Miller, 1984; Salvigsen, 1984; Landvik et al., 1987; Salvigsen et al., 1990;
Ziaja and Salvigsen, 1995; Forman et al., 2004; Salvigsen and Høgvard,
2005; Ingólfsson, 2011; Long et al., 2012; Ingólfsson and Landvik,
2013). Extensive investigations of maximum elevations and marineter-
race locations in the Svalbard and Barents Sea region have led to the
consensus that the SvalbardBarents Sea Ice-Sheet (SBSIS) of the Last
Glacial Maximum (LGM) has experienced differential loading on the
land surface (Salvigsen and Slettemark, 1995; Ziaja and Salvigsen,
1995; Forman et al., 2004; Ingólfsson, 2011). Modern theory revolves
around a multi-domed SBSIS of varying ice thicknessesand thereby var-
iations in differential loading and isostatic rebound (Hogan et al., 2010;
Hormes et al., 2011; Long et al., 2012; Ingólfsson and Landvik, 2013).
Therefore, the marine limit of one area in Svalbard, for example, may
vary from one location to another within the same fjord.
Although the application of fossil shoreline records to estimate past
sea levels has recently been challenged by Pedoja et al. (2011) by
emphasising the key role of plate tectonics in controlling world-wide
Quaternary coastal uplift, careful investigations of Arctic uplifted
beaches combining sedimentological analyses and isotopic dating of
well-preserved material (e.g. whale bones, shells and driftwood) can
be used for reconstructions of the timing of deglaciation and the rate
of isostatic uplift for spatial and temporal comparison between shore-
lines. Collection of fossils from uplifted sediments of marine terraces,
provided they are contemporaneous with the geomorphology and
have remained in situ, may correspond with relative sea level (RSL)syn-
chronous with the time datable material was deposited. However, the
age of material can easily be over- or under-estimated due to reworking
and re-deposition by waves, rivers, glaciations and periglacial processes,
and must be taken into account in the analysis. Shoreline displacement
curves assist in the reconstruction of themagnitude and pattern of post-
glacial isostatic uplift such as that for Svalbard. They are created from
the mapping of marine terraces in association with dated material.
The Holocene shoreline displacement curve as described by Salvigsen
(1984) gives inner Isfjorden a displacement from approximately 70 m
a.s.l. to 15 m a.s.l. between 10,000 and 6000 cal. yr BP, suggesting an
Geomorphology 234 (2015) 98107
Corresponding authorat: P.O. Box 412, N-9171,Longyearbyen,Norway. Tel.: +47 400
69 884.
E-mail addresses: cayukshuk@gmail.com (E.G. Sessford), mat.strzelecki@gmail.com
(M.C. Strzelecki), anne.hormes@unis.no (A. Hormes).
1
University of Gothenburg, Department of Earth Sciences, Box 460, SE-405 30
Gothenburg, Sweden.
http://dx.doi.org/10.1016/j.geomorph.2014.12.046
0169-555X/© 2015 Elsevier B.V. All rights reserved.
Contents lists available at ScienceDirect
Geomorphology
journal homepage: www.elsevier.com/locate/geomorph
isostatic rebound of about 55 m during the Holocene Thermal Maxi-
mum (HTM). Isostatic rebound was of the order of 8 m during
Neoglacial cooling (ca.25kyrBP)(Werner et al., 2013), and 2 m during
the Medieval Warm Period (MWP) (Salvigsen, 1984; Miller et al. , 2010).
Therefore, it is apparent that glacier growth following the LGM was not
extensive enough to depress thesurface of Svalbard signicantly. It also
suggests that any terraces at elevations higher than 70 m a.s.l. should be
a result of glaciations prior to the LGM. This is supported by Feyling-
Hanssen (1965), where an 84.5 m terrace at Kapp Ekholm was dated
to be 24,945 ± 734 cal. yr BP.
By using ages of marine terraces in combination with surface topog-
raphy, it is possible to hypothesize about climate variations at the time
of uplift. Furthermore, changes in climatic forcing may be associated
with the development of the shoreline. This is a branch of study which
has only briey been touched upon (ller et al., 2002; Nichol, 2002).
Uplifted marine terraces should then be useful tools not only as indica-
tors of isostasy due to differential loading and unloading of ice sheets
and glaciations but also as clues into past shoreline development and
climatic forcing.
This study aims to improve our understanding of how High Arctic
coastal zones in Svalbard developed in response to Holocene climatic
changes and the interplay between global sea level and local glacio-
isostasy at Fredheim, southern Sassenfjorden. Understanding the
evolution of coastal systems in connection with climate change, rel-
ative sea-level rise, shifts in sediment supply and glacio -isostasy pro-
vides a crucial basis for constructing possible future scenarios for
High Arctic coastal environments (Overduin et al., 2014).
2. Study site
The study was conducted along the coast of Fredheim, a small cape
located on the southern coast of Sassenfjorden in central Spitsbergen
(Fig. 1). The study area included the present-day coastal zone in con-
nection with ve palaeo-coastlines, as delineated by uplifted marine
terraces. The tidal range in the area is ca. 1.5 m and the modern storm
ridges are formed at an altitude of between 1 and 0.7 m above mean
tide level (MTL). The total analysed area covered approximately
0.8 km
2
and incorporated a number of geomorphic features inuential
on coastal development including; the prograding Nøiselva delta, an
unconsolidated coastal cliff, active layer interow (sensu (Ballantyne,
1978)), snow-fed streams, rivers, and large snow drift accumulations
along the coastline which are often connected to the ice-foot during
winter. Snow cover around Fredheim is varied in distribution and thick-
ness. Alongthe coastal escarpment it tends to build up to between one
and two metres, however, higher up on the terraces snow depth ranges
from 0 to 45 cm (and possibly more), as has been observed during this
study.
Unlike most other Arctic regions which have a short open water
season of 34 months (Lantuit et al., 2012), Sassenfjorden and much
of western Spitsbergen have a longer season of approximately 56
months lasting from June through November and sometimes into
December (data collected between 1986 and 2012), produced by
Eliassen (2013). This is due to the warm Atlantic Waters that ow
past the western edge of Spitsbergen and enter into the fjord systems,
causing signicant inter-annual variability in fjord water temperatures
and sea ice content (Ådlandsvik and Loeng, 1991; Nilsen et al., 2008).
There have even been years, such as the case in 201112, where sea
ice was not present at Fredheim at all (Eliassen, 2013, and personal ob-
servation). There was, however, an ice-foot as well as large snowdrifts
that built up along the coastal escarpment.
Fjord water circulation in frontof Fredheim along the coast appears
to be toward the west, as seen from aerial images since 1977 (Fig. 2).
Dominant winter wind directions in Svalbard are from the southeast,
though local winds may vary from this, and measured wind data for
the region are lacking. An overall warming trend is seen where the av-
erage mean annual air temperature MAAT measurements at Svalbard
Airport rose from 6.7
0
Cto4.6
0
C for the periods 19611990 and
19812010, respectively (Førland et al., 2012).
Permafrost in Svalbard is approximately 100 m thick, with an ac-
tive layer thickness varying between 74 and 110 cm (Humlum et al.,
2003; Christiansen et al., 2010) in valleys close to sea level, such as is
thecaseinFredheim.Recentpermafrost temperatures at depth of
zero annual amplitude vary between 2.3 and 5.6 °C, however, a sig-
nicant warming of the order of 0.04 0.07 °C yr
1
has been ob-
served in Svalbard permafrost over the last decade (Christiansen
et al., 2010). The study by Christiansen and Etzelmüller (2010)
shows that Svalbard has the warmest permafrost so far north in the
northern hemisphere.
Fig. 1. A1) Thelocation of Svalbard within a global context, as indicatedby the white circle. A) Map of Svalbard indicatingthe study area in Isfjorden,central Spitsbergen. B) The eld site
location, Fredheim (1), as well as the locations for radiocarbon data used in the construction of the shoreline displacement curve: Erdmannya (2), Bohemanya (3), Gåsodden
(4), Mytilusbekken (5), Phantomvika (6), Kapp Ekholm (7), Ekholmvika (8), Teltfjellbekken (9) and Ebbadalen (10).
99E.G. Sessford et al. / Geomorphology 234 (2015) 98107
Fig. 2. Fredheim over the years from aerialphotographs from 1936, 1977, 1990 and 2009. Note the coastline retreat directly in front of Fredheim and the growth of the Nøiselva delta.
Fig. 3. Quaternary geological and geomorphological map of Fredheim indicating sample sites and geomorphological landforms mentioned throughout the text (after Sessford and
Hormes, 2013; reproduction with permission from the Norwegian Polar Institute Report Series).
100 E.G. Sessford et al. / Geomorphology 234 (2015) 98107
3. Methods
Spatial observations and mapping (Sessford and Hormes, 2013)of
the geomorphological beach characteristics of uplifted marine terraces
(MT1-5) were conducted during the summers of 2011 and 2012
(Fig. 3). Present-day coastal processes were studied using year-long
observations with time-lapse imagery on site and data modelled from
meteorological observations at the Longyearbyen Airport.
The sediments and their stratigraphy were logged at two sites on
marine terraces MT4 and MT3 (Fig. 4A, B). Sedimentary interpretations
are used in order to conrm and constrain glacial isostasy. An absolute
chronology has been established through collection of Mya truncata
shell halves and shell fragments found in marine terraces and dated
by radiocarbon techniques. Mollusc samples were collected 75 cm and
100 cm below the terrace surface (64.25 and 64 m a.s.l., respectively)
in MT4 (Fig. 4A). On MT3 mollusc samples were collected at 0.50 and
2.57 m below surface (50.5 and 48.40 m a.s.l.) (Fig. 4B).
Both mollusc fragments and shell halves were identied before
chemical preparation following techniques of Feyling-Hanssen (1965).
The radiocarbon analyses were determined using the Uppsala EN-
tandem accelerator after ultrasonic bathing and leaching of the samples
(Possnert, 1990). Radiocarbon ages are reported in Table 1 as conven-
tional ages with 1σstandard deviation and as calibrated ages. In the
text all radiocarbon ages are calibrated given as cal. yr BP(before pres-
ent: 1950 AD). The radiocarbon dates were calibrated to calendar ages
using a reservoir age of 440 ± 52 years. This is based on two different
recommendations using a marine reservoir effect of 450 ± 52 years
(Mangerud recommendation) and 438 ± 52 years (Bondevik and
Guliksen recommendation) for molluscs and foraminifera in Spitsber-
gen (Mangerud et al., 2006). The calibration is based on the Fairbanks
0107calibration curve with the online calibration software (http://
radiocarbon.ldeo.columbia.edu/research/radcarbcal.htm)(Fairbanks
et al., 2005) as this curve uses only coral U/Th dates.
The shoreline displacement curves for the locations other than
Fredheim are inferred from recalibrated, previously published radiocar-
bon dates as indicated in Table 1 (Feyling-Hanssen, 1965; Salvigsen,
1984; Salvigsen et al., 1990; Long et al., 2012) that they may be compa-
rable to thenew curve for Fredheimwhich is plotted on the same gure
(Fig. 5). Radiocarbondates are plotted against time inan idealized curve
with time on the x-axis showing zero asAD 1950. Sedimentological de-
scriptions from sections on the uplifted marine terraces corresponding
to the same locations asdated material are used to indicate minortrans-
gressions (locations marked in Fig. 3). Elevations are in metres above
mean tide level (m MTL) and used for all elevations, including the
map as shown in Fig. 3. Field observations showed that the crest of
modern storm ridges has an altitude of between 1 and 0.7 m above
mean tide level. Therefore in our palaeo-shoreline interpretations we
assumed that the elevation of a surface of a relict beach (storm ridge)
is within a metre above mean tide level at the time of ridge formation.
Uplift rates are inferred by the difference between the highest and
lowest elevations of each terrace in combination with age constraints
determined from the radiocarbon dates (Fig. 5).
Fig. 4. A) Sedimentological log of MT4 indicatingradiocarbon sample depths and changes in depositional environment. B) Sedimentological log of MT3 with radiocarbon sample depths
and indications of a transgression between Unit 2 and Unit 4.
101E.G. Sessford et al. / Geomorphology 234 (2015) 98107
4. Results and interpretation
4.1. Spatial observations
The relative chronology of Fredheim is established through observa-
tions of the Holocene landforms and sediments. By analysing how land-
forms have developed in relation to each other, the relative order of
events is determined (Fig. 3). Five uplifted marine terraces have been
identied, where four are of Holocene age and the fth may be pre-
LGM (Last Glacial Maximum) due to its high elevation between 70
and 80 m MTL (Forman et al., 2004; Ingólfsson and Landvik, 2013).
Post-glacial alluvial fans, i.e. alluvial fans that are not currently active,
deposited during the Holocene (marked as Fluvial material, pre-
recent,inFig. 3) have been deposited subsequently to beach develop-
ment and therefore overlie beach ridges on top of each terrace. Hum-
mocky sections and beach deformation by ice are also identied.
Landscape development is interpreted based on the Quaternary map
(Fig. 3) alongside shoreline displacement combined with radiocarbon
dates (Fig. 5) and sedimentary logs (Fig. 4).
4.2. Sediment description and interpretation of marine terrace four (MT4)
(Fig. 4A)
4.2.1. Unit 1
The lowermost unit is a horizontally bedded and imbricated deposit
with rounded and sub-rounded pebbles. It is less sorted than units 3 and
4 and is interpreted as a storm beach deposit.
4.2.2. Unit 2
A gradational, conformable boundary separates thestorm beach de-
posit from a 10-cm thick sand layer that changes height over the prole.
This sand layer with shell fragments is interpreted to represent a pe-
riod of formation of a shallow embayment formed after RSL rise and
supplied by sandy sediments from uvial and slope sources. It con-
tains shell fragments (MT4 shell-1, Ua-44107) and was deposited
between 10,960 and 10,574 cal. yr BP (Table 1). The other dated
shell fragments indicate only a slightly older age of terrace MT4
that was dated to between 11,235 and 10,887 cal. yr BP (MT4 shell-
2, Ua-44108). These age overlaps can be interpreted to represent
rapid isostatic uplift and or reworking of older shell fragments by
coastal processes.
4.2.3. Units 3 and 4
The uppermost unit consists of imbricated, well sorted, sub-rounded
and rounded pebbles and represents a littoral environment duringuplift
of the site, and is indicative of a fair weather berm beach. The upper
20 cm of pebbles are frost shattered and carbonate precipitation pene-
trates to the same depth (Unit 4).
4.3. Sediment description and interpretation of marine terrace three (MT3)
(Fig. 4B)
4.3.1. Unit 1
The lowermost unit 1 of terrace MT3 is very compact, unsorted and
massive diamict with a yellowish silty clay matrix including smaller and
bigger clasts. The clasts are sub-rounded and sub-angular, and one clast
showing very clear striations was found. Therefore, this unit is
interpreted as a subglacial till. Another indicator for the glacial origin
of this unit is a rip-up clast of reddish clay that is incorporated within
the diamicton.
Table 1
Radiocarbon ages and associated information used in this study. Radiocarbon ages are reported as conventional dates with 1 standard deviation and as calibrated ages.
Reference Location Material ID m a.s.l
14
C yrs ±1σcal BP ±
Feyling-Hanssen (1965) Teltfjellbekken Mya truncata No. 358 Ua-132 56.0 9965 160 10,830 315
Feyling-Hanssen (1965) Phantomvika Mya truncata No. 349 Ua-128 50.7 10,105 150 11,032 294
Feyling-Hanssen (1965) Ekholmvika Astarte No. 350 Ua-124 42.0 9435 200 10,117 339
Feyling-Hanssen (1965) Ekholmvika Astarte U-203 9.7 4500 90 4553 204
Feyling-Hanssen (1965) Mytilusbekken Mytilus No. 343 Ua-126 5.2 3935 100 3770 196
Salvigsen (1984) Kapp Ekholm Larix occidentalis driftwood unknown 65.0 10,030 140 11,633 423
Salvigsen (1984) Gåsodden Mytilus edulis T-4628 18.1 6440 80 6841 167
Salvigsen et al. (1990) Erdmannya Shell fragments T-6287 47.0 10,160 110 11,113 225
Salvigsen et al. (1990) Erdmannya Hiatella arctica T-6282 26 (29) 10,120 110 11,060 234
Salvigsen et al. (1990) Erdmannya Mya t. and Hiatella a. T-6286 32 (41) 9940 100 7406 133
Salvigsen et al. (1990) Erdmannya Mytilus edulis T-6285 16.0 9410 110 10,098 228
Salvigsen et al. (1990) Erdmannya Modiolus modiolus T-6535 6.5 9110 90 9659 189
Salvigsen et al. (1990) Erdmannya Mytilus edulis T-6284 5.0 8650 90 9171 195
Salvigsen et al. (1990) Erdmannya Mytilus edulis T-6288 9.8 (11.6) 8500 100 8962 223
Salvigsen et al. (1990) Erdmannya Mya truncata T-8629 7.0 8370 100 8775 222
Salvigsen et al. (1990) Erdmannya Mytilus edulis T-6283 8.0 8120 90 8474 138
Salvigsen et al. (1990) Erdmannya Whale cranium T-6289 3.5 5590 80 5902 151
Salvigsen et al. (1990) Bohemanya Hiatella arctica Lu-2364 20.0 9950 90 10,808 235
Salvigsen et al. (1990) Bohemanya Mya truncata Lu-2363 01 9650 90 10,384 177
Salvigsen et al. (1990) Bohemanya Mya truncata Lu-2138 1820 9630 90 10,360 173
Salvigsen et al. (1990) Bohemanya Mya truncata Lu-2136 (in till) 9440 80 10,147 173
Salvigsen et al. (1990) Bohemanya Mytilus edulis Lu-2137 10.0 8130 80 8481 128
Salvigsen et al. (1990) Bohemanya Hiatella arctica Lu-2139 (in till) 4620 60 4722 157
This study Fredheim Mya truncata fragments Ua-44108 64.3 10,106 57 11,061 174
This study Fredheim Mya truncata fragments Ua-44107 64.0 9927 60 10,767 193
This study Fredheim Mya truncata half Ua-44106 50.5 9867 63 10,674 181
This study Fredheim Mya truncata fragments Ua-44105 48.4 9878 64 10,690 186
This study Fredheim Mya truncata fragments Ua-44104 48.4 9842 60 10,636 170
Long et al. (2012) Ebbadalen Astarte borealis, paired, juvenile SUERC-35206 1.24 3411 37 3144 135
Long et al. (2012) Ebbadalen Astarte borealis, paired, juvenile SUERC-33589 3.71 4188 37 4107 131
Long et al. (2012) Ebbadalen Astarte borealis, paired, juvenile SUERC-35209 5.01 4545 37 4618 145
Long et al. (2012) Ebbadalen Astarte borealis, paired, juvenile SUERC-35210 5.97 4930 37 5141 161
Long et al. (2012) Ebbadalen Astarte borealis, paired, juvenile SUERC-35211 11.73 6397 38 6784 110
Long et al. (2012) Ebbadalen Astarte borealis, paired, juvenile SUERC-35212 16.26 7292 39 7684 81
Long et al. (2012) Ebbadalen Astarte borealis, paired, juvenile SUERC-35213 20.5 8248 39 8591 112
Long et al. (2012) Ebbadalen Astarte borealis, paired, juvenile SUERC-35214 27.9 9125 39 9646 128
102 E.G. Sessford et al. / Geomorphology 234 (2015) 98107
4.3.2. Unit 2
This unit is composed of sub-rounded/rounded gravel and sand. A
bullet-shaped boulder was found at the bottom of this deposit that
might have been reworked from the underlying subglacial till. Half
a shell of M. truncata and shell fragments were found close to the
lowermost sharp boundary of the unit (MT3 shell-1, UA-44104;
MT3 shell-2, Ua-44105, respectively). The coarse sand and pebbles
are horizontally bedded and interpreted as beach deposit. According
to the radiocarbon ages, beach deposition started between 10,876
and 10,466 cal. yr BP (Table 1). The erosive boundary of the beach de-
posit on top of the diamict indicates a rather rapid sea-level rise at
the site.
4.3.3. Unit 3
A gradual boundary separates this medium to coarse sand con-
taining pebbles of local carbonate lithologies and quartzite, from the
beach deposit above. It is suggested that the gradual boundary can be
interpreted as a transgressional phase.
4.3.4. Unit 4
The beach deposits of Unit 4 are very loose and continued to cover
the lower part during logging; therefore, the boundary of Unit 4 to
Unit 3 could not be described. The top unit of the logging site shows
horizontally bedded, well sorted, well-rounded pebbles and sand. The
radiocarbon ages of the shell fragments (MT3 shell5, Ua-44106;
10,85510,493 cal. yr BP) that were found in this beach deposit overlap
with one standard deviation with the beach deposit of Unit 2.
4.4. Shoreline displacement
Results from sedimentological descriptions and radiocarbon dates
are used to produce the shoreline displacement curve for Fredheim
shown in Fig. 5. Deglaciation of Sassendalen began approximately
Fig. 5. Inferred shorelinedisplacement curvesas indicated by recalibrated radiocarbon datesfrom Feyling-Hanssen (1965),Salvigsen (1984), Salvigsen et al. (1990)Long et al. (2012) and
this study. Original datesand their recalibrations can be found in Table 1. Solid lines join sample dates; dashed lines are inferred extensions of the shoreline displacement. The squares
made up of dashedlines indicate the time range and elevation range used for emergence rates. Note: samples from Salvigsen et al. (1990) that had more than one sample depth were
not used in the curve.
103E.G. Sessford et al. / Geomorphology 234 (2015) 98107
11,30011,200 cal. yr BP (Forwick et al., 2010) and glacier retreat was
signicant to allow marine ooding over all of Fredheim coastal plain.
The onset of uplift for upper marine terrace four (MT4) (7065 m
MTL.) began before lower MT4 (6560 m MTL.), as indicated by
M. truncata fragments sampled at 64 and 64.25 m MTL producing ages
of 11,061 ± 174 cal. yr BP and 10,767 ± 193 cal. yr BP, respectively.
MT3 underwent rapid uplift during the Holocene Thermal Maximum
(HTM) and became fully terrestrial by 9100 cal. yr BP. Uplift of MT2-1
were completed during a cooler period following the HTM and perhaps
into Neoglaciation.Suggested emergence for MT2 is between 7200 and
6800 cal. yrBP. Uplift of MT1 was completed by 3770 cal. yr BP, as sug-
gested by radiocarbon ages and curves from Feyling-Hanssen (1965),
Salvigsen (1984)andSalvigsen et al. (1990). Final uplift of the non-
active alluvial plain probably happened during the Medieval Warm Pe-
riod (MWP) (1200950 cal. yr BP). Other than the Fredheim curve, the
Holocene shoreline displacement curves shown in Fig. 5 are inferred
through recalibrated dates from Feyling-Hanssen (1965),Salvigsen
(1984), Salvigsen et al. (1990) and Long et al. (2012). Combined, the
curves suggest that in inner Isfjorden relative sea level (RSL) fell very
rapidly from ca. 65 m MTL to ca. 34 m MTL between 11,300 and
9000 cal. yr BP, by 3770 cal. yr BP it had reached 5.8 m MTL and by
3100 cal. yr BP it fell close to the elevation of the non-active alluvial
plain (ca. 1.2 m MTL.), suggesting an isostatic rebound of over 60 m dur-
ing the early and mid-Holocene.
With few radiocarbon data points at a single site or within a smallre-
gion, minor transgressions during uplift are often missed (Salvigsen,
1984). The sedimentary composition at Fredheim sheds light on these
minor changes and shows a gradual boundary between units 2 and 3
on MT3 (Fig. 4B), which is interpreted to be a small transgression. The
gradual boundary is between 48 and 50 m MTL and therefore occurred
approximately 10,500 cal. yr BP when plotted on the shoreline displace-
ment curve in relation to its elevation above current mean tide level. A
much larger transgression is noted by Salvigsen et al. (1990) on the
western coast of Isfjorden at 510 m MTL approximately 9000
8000 cal. yr BP. This is not seen in any of theother locations but cannot
be ruled out as existing. It is the only curve from the western side of
Isfjorden, and therefore may show differences to those further east
that are closer to the SBSIS domes. The results from Long et al. (2012)
show a similar stable, steady trend as those of Feyling-Hanssen (1965)
except that uplift occurs earlier. In northern Billefjorden region (eastern
coast of Petuniabukta), located 40 km from our study site, Long et al.
(2012) found the highest Holocene beaches, deposited shortly after
local deglaciation at ca. 10,000 cal. yr BP, at ca. 4045 m a.s.l. According
to Long et al. (2012), during the mid-Holocene RSL probably fell below
present level, and around 3100 cal. yr BP roseto reach within a metre of
present sea level.
5. Discussion
5.1. Landform development and uplift
The surface topography of marine terraces, i.e. beach ridge ampli-
tude and wavelength, and shore gradient, serves as indicators of pro-
cesses acting upon the shoreline during emergence and thereby
record vertical and horizontal movement of the shoreline, presence of
sea-ice cover as well as shifts in sediment supply to the coast. Due to
isostatic uplift the resulting beach plains will slope so that forelands
prograde and older beach ridges will be more elevated than those that
are younger. The slope gradient therefore depends upon the rate of
emergence and progradation of the shoreline, resulting in rapid (~N10
mm/year scale) or slow (~110 mm/year scale) displacement (inferred
from, Feyling-Hanssen and Olsson, 1960). At Fredheim, marine terrace
four (MT4) displays themost rapid uplift, as inferred by thedistance be-
tween the highest and lowest elevations of each terracein combination
with age constraints from the shell fragments, showing progradation of
approximately 15.1 mm/year between 11,235 and 10,574 cal. yr BP
(Table 1 and Fig. 5). The younger age overlaps at 1σwith the ages that
were yielded from terrace MT3. This overlap may suggest that the uplift
of MT4 to MT3 was fairly continuous and that the pause in uplift be-
tween the two was not long. It could also suggest that shell fragments
have been reworked after deposition, thereby showing older ages
than they ought to be on MT3. However,as we did not observe any car-
bonate precipitation on MT3, as we did on MT4, this observation might
be used as an additional argument that terrace MT4 has undergone
weathering processes for longer than MT3 and must therefore be rela-
tively older (Forman and Miller, 1984).
MT3 emerged quite rapidly, as is noted by the erosional boundary
between the glacial diamict and beach sediments, in addition to lack
of nes. Radiocarbon ages for MT3 suggest beach deposition started
shortly prior to 10,636 ± 170 and 10,690 ± 186 cal. yr BP (Table 1).
An emergence rate of 11.4 mm/year determined using the shoreline
emergence curves and surface topography, i.e. beach ridges, (between
10,855 and 9100 cal. yr BP) is suggested for MT3.
Emergence rates for marine terraces at Fredheim are supported by
those suggested by Salvigsen (1984) where average uplift rate between
10,000 and 8000 cal. yr BP is 19 mm/year and slowed down to 4.5mm/
year between 8000 and 4000 cal. yr BP. Uplift rates coincide with re-
constructions of deglaciation by Forwick et al. (2010) which suggest
step-wise retreat of the Sassendalen glacier, where glacial proximal
conditions were present during the mid-Holocene. It is likely that re-
bound also occurred in a step-wise fashion, as indicated by the steep
slopes between each terrace that may indicate periods of coastal erosion
in former terrace sediments during the slower sea-level fall.
Subsequent terraces MT2 and MT1 have not beendated as no mate-
rial suitable for dating was found during eldwork.Based on their eleva-
tions in comparison tothe local Isfjorden shoreline displacement curve
(Feyling-Hanssen, 1965; Salvigsen, 1984; Long et al., 2012), it is as-
sumed that MT2 and MT1 were most likely uplifted sometime between
7200 and 3574 cal. yr BP. Between 3200 cal. yr BP and during the Medi-
eval Warm Period (MWP), when sea-level was over 1 m higher than at
present, a large alluvial plain formed (Fig. 3). MT1 and MT2 appear to
have undergone much slower progradation of only 5 mm/year between
7200 and 6800 cal. yr BP, and 2.3 mm/year between 4200 and
3770 cal. yr BP, respectively. Forwick et al. (2010) propose that general
glacier growth in the area occurred between 4000 and 5000 cal. yr BP
(Neoglacial advance), which coincides well with the decrease in uplift
rate of MT1.
Anal period of uplift of the post-glacial alluvial plain, on which the
buildings at Fredheim have been built, likely occurred sometime during
the MWP between 1200 and 950 cal. yr BP, as indicated by the shoreline
displacement curve by Salvigsen (1984).
Since the uplift of the alluvial plain, both erosion and deposition
have been taking place at the coast. Aerial images show that between
1977 and 2009, the average rate of erosion on the coastal escarpment
made up of the alluvial plain has been 0.33 m/year and that average
growth of the modern delta is 3.6 m/year (Sessford, 2013).
Marine terraces 14(Fig. 5) support the rebound models for the
SvalbardBarents Sea Ice Sheet (SBSIS) by Ingólfsson and Landvik
(2013) who suggest that in central Spitsbergen (in the area of Fredheim
and Kapp Ekholm) an isobase for relative crustal rebound since around
7600 cal. yr BP is approximately 15 m above sea level, and that since
around 12,000 cal. yr BP isostatic rebound caused by isostatic depres-
sion has been approximately 5060 m (both of which correspond well
with the shoreline displacement curve in this paper) (Fig. 5). However,
MT5 at 7080 m a.s.l., which has not been thoroughly discussed, is too
high for the Holocene. Following previous models, MT5 may belong to
a pre-LGM (Last GlacialMaximum) terrace system. There are otherloca-
tions in Svalbard that are accepted to have been covered bynon-erosive
cold-based ice during LGM (Forman et al., 2004; Hormes et al., 2011;
Ingólfsson and Landvik, 2013), and therefore did not get reworked dur-
ing the LGM, and pre-existing terraces were left intact after retreat.
Although none of the central Isfjorden higher elevation marine terraces
104 E.G. Sessford et al. / Geomorphology 234 (2015) 98107
(above 70 m a.s.l.) have beenthoroughly examined, evidence appearsto
support the presence of pre-LGM marine terraces. MT5 at Fredheim
needs to be more thoroughly examined so as to clarify if indeed it is
older than the LGM. If it is not, and belongs to the Holocene, it may be
that isostatic uplift curves need to be re-examined.
5.2. Geomorphic processes and climate
Site-specic factors such as exposure, wind direction, fjord circula-
tion, coastal plain gradient and sediment supply affect the formation
of Arctic beach accumulation and erosion processes (Møller et al.,
2002). Beach ridges are formed along the top of the forelands due to
dominant longshore drift, and represent either storm ridges (Feyling-
Hanssen, 1965) or fair weather berm ridges (Mason, 2010). A fair
weather beach might be characterised by low amplitude (b0.5 m)
beach crests with wavelengthsof approximately5 m and are at crested
(Mason, 2010; Long et al., 2012). Møller et al. (2002) identies ridges
having a steep seaward scarp and a marked landward swale to beindic-
ative of erosional stormy events in comparison to a gentle seaward
slope associated with fair weather. Although beach ridges were not
measured directly at Fredheim, one can see in Fig. 6A that, from marine
terrace three (MT3),beach ridges are relatively at crested, have an ap-
proximate amplitude of 3050 cm and wavelengths approximately 5
6 m. The same trend is exemplied on MT4 and MT1. Ridges on MT2
are however, difcult to assess due to geliuction and active layer
detachment sliding.
Modern surface water circulation in front of Fredheim is along
the coast toward the west, as indicated by aerial photographs since
1977 (Fig. 2). However, the delta is prograding eastward and wave-
generated beach ridges grow parallel with progradation. Wave activity
at Fredheim is largely limited to local wind waves as fetch distance is
minimal due to its location with the fjord system and the now present
Nøiselva delta protecting the shoreline. However, this is not the case
when winds are from the northeast through Sassenfjorden where
fetch distance is of the order of 14 km. Nonetheless, by broadening the
observation area, insight into dominant wind direction during the
Holocene is toward the southeast and beach ridges formed from sedi-
ment supplied from deltaic systems coming from Nøisdalen (Figs. 2,
3). Similar processes are described in Mason (2010) from northern
Greenland. Ridges imply a long-term easterly direction of littoral
sediment transport at Fredheim. Modern beach ridges to the west of
Fredheim and at the western edge of the Nøis delta follow this pattern,
and it is only directly in front of Fredheim that local winds seemto have
the most impact on beach development.
The surfaces of beach ridges in Arctic environments are often
disrupted and covered by hummocks and pits forming characteristic
pitted beach micro-relief (Nichols, 1961; Urdea, 2007; St-Hilaire-
Gravel et al.,2010). There appear to be three differentprocesses forming
pitted beach morphology at Fredheim: (i) melt-out of remnants of ice-
foots, ice oes, and icebergs buried in beach sediments which are
often referred to as sea-ice-kettles (found on the present beach, MT1
and MT2); (ii) ice deformation ridges and swales (found on the edges
of MT1 and MT3); and (iii) accumulationsof sediments around boulders
driven by wind wave action (found on the presentbeach and MT3).
The morphology of hummocks on MT1 and MT2 shows higher
ridges up-slope, a curved back-scarp and tend to run parallel to the
shore. Pits on these terraces tend to be behind the ridges (upslope)
and are elongated along the palaeo-shorelines. According to Lindner
and Marks (1989) larger pits found on raised beaches mark places of
iceberg stranding and may indicate periods of intensied calving and
iceberg production. When observing the present-day beach, hummocks
and pits appear in sites where the ice-foot forms during the winter sea-
son and show similar characteristics to those on MT1 and MT2 (Fig. 6C),
(Nichols, 1961; Urdea, 2007; Rodzik and Zagórski, 2009; St-Hilaire-
Gravel et al., 2010).
An increase in ice rafted debris in the area at 79305470 cal. yr BP
is attributed to enhanced sea ice formation (Baeten et al., 2010;
Rasmussen et al., 2013). Therefore, it is possible that these sea-ice-
kettles on MT12 have been produced by sea ice as an ice-foot and/or
grounded ice. These terraces were likely a product of uplift during cooler
times prior to or duringNeoglaciation,and it is possible that some ridges
may have formed from iceberg ride-up or pushing due to strong winds
(Møller et al., 2002; Urdea, 2007). A modern example of anice deforma-
tion ridge can be seen (Fig. 7A) where an ice oe had been pushed up
onshore, over the modern beach, thereby disrupting sediments and
crushing two boats on MT1 during an extreme event in 1999. It is un-
clear whether this was caused by ice ride-up, thrusting or by high
winds during a major storm event. They are also found just on the
steep erosional edge of MT3, suggesting that during the formation of
MT2 beach ice was thrust all the way up the escarpment onto MT3
(Fig. 7B).
The type iii hummocks are foundin the east on the modern beach as
well as on MT3. These hummocks and pits are present closer to the ex-
posed bedrock which has been affected by chemical and mechanical
weathering by water, though subsequently affected by periglacial and
Aeolian processes (Fig. 6B). It is possible that these hummocks are cre-
ated because of large boulders falling onto the shoreline through ero-
sion of the bedrock, followed by redistribution of sediments through
wind and wave action. Sediments would then not build smoothly as
ridges but around the boulders in hummocks. As MT3 was developed
during the Holocene Thermal Maximum (HTM) it seems unlikely that
sea ice was present due to higher sea level, air temperatures and
Fig. 6. A) Fair weather beach ridges on MT3. The black backpack dimensions are
approximately 60 by 20 cm. B) Hummocky beach on MT3 indicated within the
black dashed line area, note the rounded boulders from mechanical weathering
through wave action, and holes from chemical weathering. C) Modern beach ridges
as delineated by the solid line and hummocks outlines by the dashed line.
Photos: Sessford, June 2012.
105E.G. Sessford et al. / Geomorphology 234 (2015) 98107
increased inuence of Atlantic Water masses (Miller et al., 2010;
Rasmussen et al., 2013). This suggests that the hummocks are likely
formed through sediment redistribution around boulders that were
undergoing wave erosion.
6. Conclusions
This paper describes changes that occurred over the Holocene in the
coastal landscape of Fredheim, Southern Sassenfjorden. Our study sug-
gests that the analysed coastal system dynamically adjusted to shifts
in climate conditions, sediment supply and sea level over the Holocene.
Based upon the rates of uplift for marine terraces, development of
Holocene stratigraphy and detailed geomorphological mapping, we
conclude the following:
a) Spatial and chronological analysis suggests that uplifted marine ter-
races MT4 and MT3 underwent rapid uplift during the Holocene
Thermal Maximum starting shortly prior to 11,061 ±
174 cal. yr BP and becoming fully terrestrialby 9100 years ago. Uplift
of MT2 and MT1 were completed during the cooling period follow-
ing HTM and maybe into Neoglaciation, with suggested emergence
between 7200 and 6800 cal. yr BP for MT2 and 4200 and
3770 cal. yrBP for MT1. The last uplift of the relict alluvial plain prob-
ably happened during the MWP (1200950 cal. yr BP). Present
coastal erosion andprogradation of theNøiselva delta are recognised
as having taken place within the last 100 years.
b) MT5 may belong to a pre-LGM terrace system and needs to be more
thoroughly examined so as to clarify if indeed it is older than LGM.
c) The uplifted marine terraces are interpreted as having formed
during predominantly calm periods where sediment availability
and accommodation space were in ample supply, thereby causing
rapid accumulation.
d) Dominant wind direction during the Holocene was toward the
southeast, as indicated by the direction of beach ridge formation.
e) Hummocky and pitted beach sections on MT3 are interpreted to
have developed due to the presence of boulders disrupting clear
beach formation. However, on MT1 and MT2 sea-ice-kettles were
produced by the ice-foot and or ice-push as they were deposited
during cooler times.
The coastal zone of Fredheim provided a good opportunity to inves-
tigate High Arctic coastal response to Holocene sea-level and climate
changes and to observe various types of coastal adjustment to ongoing
environmental change. Our study suggests that Svalbard coastal sys-
tems responded abruptly to the Holocene landscape transformation.
Acknowledgments
We thank Jens Morten Hansen and one anonymous reviewer of this
paper for helpful suggestions. Thanks are also attributed to Andrew
Plater for the nal editorial review.
Matt Strzelecki is supported by National Science Centre Postdoctoral
Fellowship (Project: Model of the interaction of paraglacial and periglacial
processes in the coastal zone and their inuence on the development of
Arctic littoral relief' award no. 2013/08/S/ST10/00585) and Foundation
for Polish Science HOMING PLUS (grant no. 2013-8/12) and START
grant.
This paper is a contribution to the Palaeo-Arctic Spatial and
Temporal Gateways Programme and the IAG Sediment Budgets in
Cold Environments Working Group.
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107E.G. Sessford et al. / Geomorphology 234 (2015) 98107
... In periglacial environments the active layer, (sediment that overlays the permafrost which undergoes annual freeze and thaw cycles) is thickening which results in enhanced solifluction (Åkerman, 2005;Biskaborn et al., 2019). Furthermore, coastal regions will likely experience increased instability due to enhanced erosional processes (Lantuit et al., 2012;Sessford et al., 2015;Nicu et al., 2020). During the Last Glacial Maximum (LGM), the Svalbard Barents-Sea Ice Sheet covered the archipelago and ice streamed through the fjords and troughs, extending all the way to the shelf edge Ingólfsson, 2011;. ...
... High-resolution overview maps of the peri-and paraglacial processes influencing the terrestrial geomorphology exist from southern, central and western Svalbard (e.g., Åkerman, 1987;Karczewski et al., 1990;Tolgensbakk et al., 2001;Zwoliński et al., 2013;Miccadei et al., 2016;Rubensdotter et al., 2015a,b;2016;Lyså et al., 2018;Rouyet et al., 2019;Berthling et al., 2020; Fig. 1). Studies and geomorphological maps focusing on coastal processes exist from central and northern Svalbard (e.g., Brückner and Schellman, 2003;Sessford et al., 2015;Borriquen et al., 2018), and a highly detailed geomorphological map of an alluvial fan system exists from central Spitsbergen (Tomczyk et al., 2019; Fig. 1). Geomorphological studies and mapped areas have tended to cluster around research stations or settlements, where the landscape can be relatively easy accessed. ...
... These works have indirectly summarized chronological shoreline development through the Holocene (e.g. Salvigsen, 1981;Forman, 1990;Forman et al., 2004;Bondevik et al., 1995;Forman et al., 2004;Sessford et al., 2015;. ...
Thesis
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The Arctic regions are affected by the modern climate change to a greater extent than the global average. This effect is called the Arctic amplification and is reflected in air temperatures rising with double rate and increased precipitation compared to the global average. The climate of Svalbard is strongly related to variations in the atmospheric and oceanic circulation patterns, and the archipelago is, therefore, ideal location to study the climate sensitivity of the Arctic. This dissertation presents research on the Late Pleistocene and Holocene glacial history of Svalbard. Marine, lacustrine and terrestrial archives are assessed in a confined geographical area in northern Wijdefjorden, northern Spitsbergen, and the regional timing of the deglaciation, Holocene Thermal Maximum, Holocene Glacial Minimum as well as the onset of the Neoglacial are identified (Papers I-III). The research focus is on Wijdefjorden, Femmilsjøen and the NW part of the Åsgardfonna ice cap. The results are placed in a regional context and compared to studies across Svalbard. A review of the Holocene glacial history of Svalbard is presented in Paper IV, where all Holocene chronological data from Svalbard are re-calibrated or calculated and gathered in one database. The landforms in the fjord (Paper I) and the lowermost acoustic and sedimentary facies (Papers I-II) are interpreted to be indicative of grounded, warm-based ice occupied the fjord during the Last Glacial. By contrast, Paper III speculates that parts of the terrestrial terrain are similar to forelands of cold-based glaciers in Antarctica, which may have been covered by cold-based and little erosive glacier ice during the Last Glacial. Among the findings are that northern Svalbard deglaciated early. Wijdefjorden is inferred to deglaciate at least prior to 12.4 ± 0.3 cal. ka BP and potentially prior to 14.5 ± 0.3 cal. ka BP. Femmilsjøen deglaciated potentially prior to 16.1 ± 0.3 cal. ka BP. Deglaciation occurred in a stepwise manner and was characterised by fluctuating water temperatures and sea ice cover. Overarching, the Svalbard fjords deglaciated rapidly during the first half of the Early Holocene, however the overall retreat was punctuated by dynamic ice-advances of smaller tributary glaciers. Femmilsjøen was isolated from the marine environment c. 11.4 cal. ka BP. The regional Holocene glacial minimum coincided with the Holocene thermal maximum (between 10.1 ± 0.4 and 3.2 ± 0.2 cal. ka BP), during which time the ice cap Åsgardfonna was small or close to absent. Collectively in Svalbard, the Holocene glacial minimum most likely occurred between 8.0 and 6.0 cal. ka BP. Thus, the Holocene thermal maximum and Holocene glacial minimum in northern Wijdefjorden seems extended compared to the rest of Svalbard. In the fjord, seawater temperatures show a gentle decrease and the sea-ice proxy a gentle increase from c. 6.0 cal. ka BP, but values do not accelerate until c. 0.5 cal. ka BP. In Svalbard, Neoglacial glacier advances occurred generally from 4.0 to 0.5 cal. ka BP and with the Little Ice Age representing the last cold-spell of the Neoglacial. In Femmilsjøen, glacial influence recommenced from 3.2 ± 0.2 cal. ka BP, and glaciers in the catchment reached sizes no smaller than their current extent within c. 1.0 ka. The Holocene climate and glacial variability of Svalbard are strongly coupled to atmospheric and oceanic forcings.
... The bedrock geology is characterized by Carboniferous-Permian carbonate rocks, evaporates and clastic sedimentary rocks (Dallman 2015). While no relative sea level curve has been established specifically for Bjonasletta, a Holocene uplift curve has been developed from a series of raised beaches at Fredheim, 5 km to the SE (Sessford et al., 2015). The region is suggested to have undergone at least 70 m of uplift relative to sea level over the last c. ...
... 11 ka. (Fig. 2; Sessford et al., 2015). ...
... We present descriptions, occurrence, elevation and major elemental geochemistry of ocean-rafted pumice for three regions in Svalbard, Lady Franklinfjorden, Palanderbukta and Bjonahamna. Our data are presented alongside previously published relative sea level curves respective to each region according to Blake (1961a), Schomacker et al. (2019) and Sessford et al. (2015 ; Table 1). Radiocarbon ages constraining relative sea level curves have all been (re-) calibrated and corrected for synchronizing the RSL curves according the SVALHOLA database (Table A1; . ...
Article
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Distally deposited tephra from explosive volcanic eruptions can be a powerful tool for precise dating and correlation of sedimentary archives and landforms. However, the morphostratigraphic and chronological potential of ocean-rafted pumice has been under-utilized considering its long observational history and widespread distribution on modern and palaeo-shorelines around the world. Here we analyze the geochemical composition and elevation data of 60 samples of ocean-rafted pumice collected since 1958 from raised beaches on Svalbard. Comparison of pumice data with postglacial relative sea-level history suggests eight distinct pumice rafting events throughout the North Atlantic during the Middle and Late Holocene. Analyzed ocean-rafted pumice exhibit consistent silicic composition characteristic of deposits from Iceland’s volcanic system, Katla. Eruption-triggered jökulhlaups are key drivers of the transport of pumice from the Katla caldera to beyond the coast of Iceland and into the surface currents of the North Atlantic Ocean. Thus, the correlation of distinct, high-concentration pumice horizons from Katla deposited along raised Middle Holocene beach ridges in Svalbard further advocates for the persistence of the Mýrdalsjökull ice cap through the Holocene thermal maximum.
... These works have indirectly summarized chronological shoreline development through the Holocene (e.g. Salvigsen, 1981;Forman, 1990;Forman et al., 2004;Bondevik et al., 1995;Forman et al., 2004;Sessford et al., 2015;Schomacker et al., 2019). ...
... Through the Late Holocene, dated raised marine shorelines indicate a further decrease in relative uplift rates . Generally, it is believed Late Holocene relative sea level was regressive around Svalbard Forman et al., 2004;Sessford et al., 2015). It is unknown to what extent Neoglacial glacier expansion influenced relative sea level in Svalbard during the Late Holocene as eustatic sea level is suggested to have out-paced relative land uplift along Spitsbergen's western coast Fjeldskaar et al., 2018). ...
... Occurrence and diversity of thermophilous plant species like Empetrum nigrum, Arnica angustifolia and Arabis alpine indicate that during the Early Holocene, the ice-free terrestrial realm on Svalbard was warmer than present. Although the majority of the terrestrial landscape is presumed to still be evacuating (Forman et al., 2004 and references therein;Sessford et al., 2015;Schomacker et al., 2019). Five relative sea level curves have been highlighted in bold, selected from different key sites around Svalbard, exhibiting unique variability in postglacial sea level; P = Prins Karls Forland, H = Hornsund, B = Bangenhuk, E = Edgeøya (Humla) and K = Kong Karls Land. ...
Article
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We synthesize the current understanding of glacier activity on Svalbard from the end of the Late Pleistocene (12,000 yrs. before present) to the end of the Little Ice Age (c. 1920 AD). Our glacier history is derived from the SVALHOLA database, the first compilation of Holocene geochronology for Svalbard and the surrounding waters, including over 1,800 radiocarbon, terrestrial cosmogenic nuclide and optically stimulated luminescence ages. Data have been categorized by geological setting, uniformly (re-)calibrated, quality assessed and ultimately used to constrain glacier fluctuations (deglaciation, ice free conditions, glacier re-advances and ice marginal positions). We advance existing knowledge by mapping the extent and distribution of ice-cover during the Holocene glacial maximum and the glacial minimum, as well as present retreat rates (and percentages) within Early Holocene fjord-systems. We discuss the complexities of glacier systems and their dynamics in response to changes in climate. This review provides a holistic state of the art of Holocene glaciers on Svalbard, suitable for orienting future works which address gaps in our current knowledge.
... Glacio-isostatic processes are at present considered as insignificant; however, they were of great importance at the beginning of Holocene when the uplift was estimated to reach more than 20 mm/year (Salvigsen 1978). During the Medieval warm period an isostatic rebound of about 2 m (Sessford, Strzelecki, and Hormes 2015) took place in the region. Changes in climate led to further reaction of local glaciers. ...
... escarpment made up of the alluvial plain has been 0.33 m/year and that average growth of the modern delta is 3.6 m/year (Sessford, Strzelecki, and Hormes 2015). This is however one order lower than the highest progradation rate found in Southern Svalbard in Sørkappland where 20 m/year was recorded from 1990 to 2005 (Ziaja, Maciejowski, and Ostafin 2009). ...
Article
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Changes in the position of the shore in the vicinity of Kapp Napier in central Svalbard was described. The overall advance of the shore was probably related to high input of the sediment material originating from erosion of the coastal areas south of the Kapp Napier locality and high input of material from adjacent glacifluvial system of Nordenskiöld glacier with its marginal water streams. Fast evolution of glacier retreat related processes after the Little Ice Age was a secondary driver of the dynamic changes in the central Svalbard coastal areas especially in the first half of the 20th century. The highly dynamic longshore currents in the area altogether with still ongoing glacio-isostatic uplift played an important role in the process as well. The most active parts of the shore experienced advance of almost 100 meters since 1908 to 2009. On the other hand, a small part of the coast retreated of about 20 meters. Most of the study area experienced aggradation (65%), 30% of the coast was stable and about 5% of the coast has undergone minor retreat. The maximum aggradation rate of 0.96 m/year corresponds well with similar sites in the vicinity.
... Coastal areas in Svalbard display pronounced geomorphic changes since the termination of the Little Ice Age (LIA) (Małecki, 2016;Martín-Moreno et al., 2017;Strzelecki et al., 2018Strzelecki et al., , 2020Kavan, 2019). Progradation prevailed in the coastal areas fed by glaciofluvial rivers (Mercier and Laffly, 2005;Sessford et al., 2015b;Bourriquen et al., 2016;Joo et al., 2019), resulting from increasing runoff and sediment discharge (Zajączkowski et al., 2004;Szczuciński et al., 2009). The progradation led to expansive tidal flats where sedimentation rates exceed tens of millimeters per year (Szczuciński et al., 2009). ...
Article
Recent global warming triggered pronounced geomorphic changes such as coastal retreat and delta progradation along the coastlines of the Arctic regions. Coastal morphodynamics and associated sediment transport at the Arctic fjord head remain relatively unexplored due to the logistically limited accessibility to the field area, especially at short-term temporal scales. A repeat survey using an unmanned aerial vehicle (UAV)-assisted photogrammetry was conducted to quantify the annual morphodynamics of gravel spit complexes developed on the tidal delta plain of the deglaciated Dicksonfjorden, Svalbard of Arctic. Results show that the spit morphodynamics varies in time and space with an overall downfjord increase in the growth and migration rate of the spits. The youngest spits elongated 22 m yr⁻¹ and migrated landward 4.3 m yr⁻¹ between 2015 and 2019, marking the most pronounced spit morphodynamics documented to date in the Svalbard fjord systems. The spit morphodynamics is driven primarily by longshore drift and to a lesser degree by overwash processes. Gravels constituting the spits originate from the unconsolidated debris-flow deposits of old alluvial fans, which locally retreat 0.5 m yr⁻¹. The growth of the spit complexes is also fed by snow meltwater discharge on the alluvial fans, accounting for a downfjord imbrication of angular gravel layers that are intercalated with interlaminated sands and muds on the landward sides of the spits. The breached spits at the most upfjord location have remained stationary during the study period and presumably since the 1930s. Rapid delta progradation combined with an isostatic rebound after the Little Ice Age (LIA) has decreased spit morphodynamics on the tidal delta plain upfjord in Dicksonfjorden with infrequent and insignificant wave influence. Sparse distribution of the isolated spits signifies the intermittent spit development, which is constrained by the proximity to the protruded alluvial fans. The spit complexes in Dicksonfjorden highlight that climate change accelerates coastal geomorphic changes at the fjord head by enhancing wave intensity and regulating episodic sediment delivery that led to the downfjord shift in the locus of wave shoaling.
... Detailed local scale field studies show that the coastlines of the Svalbard archipelago are highly dynamic. Key processes that control local and regional changes in shoreline morphology include changes in sediment supply (from terrigenous and marine sources), variations in nearshore wave climate caused by storms, temperature changes that influence sea-ice extent, as well as local changes in relative sea-level (e.g., Niewiarowski and Myzyk 1983;Laffly and Mercier 2002;Mercier and Laffly 2005;Kowalska and Sroka 2008;Sessford, Baeverford, and Hormes 2015;Sessford, Strzelecki, and Hormes 2015;Strzelecki, Małecki, and Zag orski 2015;Zag orski et al. 2015;Bourriquen et al. 2016Bourriquen et al. , 2018Strzelecki 2017, 2018;Strzelecki, Long, and Lloyd 2017;Strzelecki et al. 2018;Kavan 2019). ...
Article
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Arctic coasts are sensitive indicators of polar environment change. Here we present the results of a study that examines the coastal morphodynamics of the Calypsostranda coastline in Svalbard (High Arctic) between 2007 to 2017 and compare these short-term changes to previous studies for the period 1936–2007. During the 2007-2017 study period, the study area lost ca. 10 710 m2, at a mean Net Shoreline Movement (NSM) of -1.86 m and End Point Rate (EPR) -0.19 m/yr. Erosion also dominated between 1936–2007, -28800 m2, at a mean NSM of -4.99 m and EPR -0.07 m/yr. Using EPR and Linear Regression Rate (LRR) parameters, we divide the Calypsostranda coastline into eroding and aggrading zones. The overall pattern of coastline change during the two study periods is similar, but the rate of erosion is higher in the recent interval, reflecting stronger climate-driven processes. Recent climate warming in the study area has been accompanied by an intensification of extreme events such as storms (e.g. ocean swell). The situation is becoming more pronounced due to the progressively reduced period of winter shore ice. Depending on the anemometric conditions, the Calypsostranda coast is modified by wind waves, and consequently longshore currents and associated sediment movement.
... This palaeo-notch opens towards the sea and has a smooth bottom of limestone. This palaeonotch was formed by the erosion of ocean wave, and then became exposed and started to receive deposit after terrace uplift from the rapid isostatic rebound around 11000 yr BP (Sessford et al. 2015) or due to sea level decrease (Forman et al. 1987). ...
Article
The glaciers act as an important proxy of climate changes; however, little is known about the glacial activities in Ny-Alesund during the Little Ice Age (LIA). In the present study, we studied a 118-cm-high palaeo-notch sediment profile YN in Ny-Alesund which is divided into three units: upper unit (0–10 cm), middle unit (10–70 cm) and lower unit (70–118 cm). The middle unit contains many gravels and lacks regular lamination, and most of the gravels have striations and extrusion pits on the surface. The middle unit has the grain size characteristics and origin of organic matter distinct from other units, and it is likely the glacial till. The LIA in Svalbard took place between 1500 and 1900 AD, the middle unit is deposited between 2219 yr BP and AD 1900, and thus the middle unit is most likely caused by glacier advance during the LIA. Glaciers during the LIA likely overran the sampling site, removed part of the pre-existing sediments, and contributed to the formation of diamicton in the middle unit. This study provides evidence for glacial deposits during the LIA in Ny-Alesund and improves our understanding about historical glacier dynamics and ice-sheet margins during the LIA in western Spitsbergen.
... The changes taking place on the Arctic coasts were presented by many authors (John and Sugden 1975;Forbes et al. 2011;Overduin et al. 2014). The research was mostly carried out on the shores of Alaska (Jones et al. 2009;Wobus et al. 2011;Gibbs and Richmond 2015), Canada (McCann and Owens 1969;Solomon 2005;St-Hilaire-Gravel et al. 2010Atkinson et al. 2016), Greenland (Kroon et al. 2010;, Spitsbergen (Mercier and Laffly 2005;Sessford et al. 2015b;Strzelecki et al. 2017a;Zagórski et al. 2015) and Siberia Ogorodov 2011;Ogorodov et al. 2013). Most of these investigations concerned areas characterized by the presence of permafrost. ...
Article
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The objective of this research is to determine the impact of waves on the segregation of sediment within the area of its supply in the context of meteorological conditions. The research was conducted on a 4 km section of the shore of Calypsostranda (Bellsund, West Spitsbergen), shaped by waves such as swell, wind waves, and tides. Particular attention was paid to the diversity and variability of the surface texture within the intertidal zone. Meteorological measurements, recording of wave climate, as well as analysis of the grain-size distribution of the beach sediments were performed. Nearshore bathymetry, longshore drifts, episodic sediment delivery from land, as well as resistance of the shore to coastal erosion and direction of transport of sediments in the shore zone are important factors controlling shore development. Data show that wind waves contribute to erosion and discharge of material from the nearshore and intertidal zone. The research also shows that oceanic swell, altered by diffraction, reaching the shore of Calypsostranda contributes to better sorting of sediment deposited on the shore through washing it out from among gravels, and longshore transport of its finest fraction. The grain size distribution of shore sediments is significantly changed already during one tidal cycle. The degree of this modification depends not only on wave height and period but on the direction of wave impact. The shore of Calypsostranda can be regarded as transitional between high and low energy coasts.
... In general, over the last decade, Svalbard coastal studies have been concentrated on the coastal zone response to shifts in sediment supply associated with changes in local ice masses and paraglaciation (e.g., Bourriquen et al., 2016;Mercier & Laffly, 2005;Sessford, Strzelecki, & Hormes, 2015;Strzelecki et al., 2018;Zagórski, 2011); ephemeric pulses of sediments from snow-fed streams (Lønne & Nemec, 2004;Strzelecki, Long, & Lloyd, 2017); or the controls of coastal permafrost development . Recent years had also brought some advances in local rocky coast systems that dominate over coastal landscape in numerous Svalbard fjords (e.g., Kasprzak et al., 2017;Strzelecki, 2011;Strzelecki, 2017;Strzelecki et al., 2017;Świrad, Migoń, & Strzelecki, 2017). ...
Article
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Longyearbyen is the major administrative, touristic and scientific centre in Svalbard and so‐called ‘European Gateway’ to the Arctic. The number of inhabitants and tourists as well as community infrastructure has significantly expanded over the recent decade and present‐day community faces development thresholds associated with climate warming and disturbance of cold region landscape. Coastal zone is a key interface where severe environmental changes impact directly on Longyearbyen infrastructure. We applied the combination of environmental assessment methods (Leopold Matrix; Coastal Vulnerability Index) and GIS analyses (Digital Shoreline Analysis Systems) together with field mapping to investigate the scale of degradation of coastal zone in Longyearbyen and examine the impact of coastal hazards on major elements of community infrastructure. Rate of observed coastal changes, the diversity of natural and man‐made hazards mapped along the coast as well as observed damages in infrastructure suggest a need for coastal change monitoring in Longyearbyen. The part of the Longyearbyen coast that should be monitored and protected are sections spreading between new port and surroundings of Longyearelva delta significantly modified by coastal erosion and landsliding. In order to improve coastal zone protection and safety of town development we present arguments supporting the incorporation of Longyearbyen into recently established Circum‐Arctic Coastal Communities Knowledge Network.
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Deglaciation in Svalbard was followed-up by seawater ingression and the deposition of marine (deltaic) sediments in fjord valleys, while elastic rebound resulted in fast land uplift and the exposure of these sediment to the atmosphere, therefore the formation of epigenetic permafrost. This was then followed by the accumulation of aeolian sediments, which froze syngenetically. The permafrost was drilled in the east Adventdalen valley, Svalbard, 3–4 km from the maximum up-valley reach of post-deglaciation seawater ingression, and its ground ice was measured for chemistry. While ground ice in the syngenetic part is basically fresh the epigenetic part reveals a frozen fresh-saline water interface (FSI), with chloride concentrations increasing from the top of the epigenetic part (depth of 5.5 m) to about 15 % that of seawater at 11 m. We applied a one-dimensional freezing model in order to examine the rate of top-down permafrost aggradation, which could accommodate with the observed frozen FSI. The model examined permafrost development under different scenarios of mean average air temperature, water-freezing temperature and the degree of pore-water freezing. We found that even at the relatively high temperatures of the Early to mid-Holocene, permafrost could aggrade quite fast, e.g. down to 15 to 33 m in 200 years, therefore allowing freezing of the fresh-saline water interface despite of the relatively fast rebound rate and the resultant increase in topographic gradients toward the sea. This could be aided by non-complete pore water freezing, which possibly lead to slightly faster aggradation, resulting in the freezing of the entire marine section at that location (23 m) within less than 200 years. We conclude that freezing should have occurred immediately after the exposure of the marine sediment to atmospheric conditions.
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Three well-developed raised marine shorelines along Nordenskioldkysten have been studied and correlated with the shoreline displacement since the last deglaciation. The marine limit of 64 m in the area is of Late Weichselian age and has been dated to 10,900- I1,OOO years B.P. An intermediate level at 50 m is estimated to be 10,600-10,000 years old and demonstrates a sea level stagnation probably caused by a glacier readvance in eastern Svalbard during the Younger Dryas. A Holocene transgression culminating shortly after 6,000 years B.P. has been stratigraphically demonstrated, and it probably correlates with the Tapes transgression of Scandinavia. No pre-Late Weichselian marine levels are found, and the large rebound can be attributed only to a Late Weichselian glaciation.
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Finds of pumice on raised beaches in the inner Isfjorden area are reported. Pumice is abundant in two zones, and four levels can be distinguished in some areas. The highest lying level has the greatest concentration of pumice and is dated to a maximum of 6,500 years B.P. Tentative correlations with pumice levels from other places in Svalbard indicate approximate ages of 6,000, 4,100, and 3,100 years for the lower levels in inner Isfjorden. A shoreline displacement curve based on the pumice levels and on 10,OOO year old driftwood is presented.
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Age determinations of bivalve shells indicate that Bockfjorden, a fjord in north-western Spitsbergen, Svalbard, was deglaciated shortly before 10 Kya, and that the upper marine limit in this area, with an altitude of about 50 m a.s.l., has the same age. During most of the Holocene, the glaciers in Bockfjorden were less extensive than they are today. Their maximum Holocene extension occurred during the Little Ice Age. The initial shoreline emergence after the deglaciation was rapid, and former shorelines younger than 8.5 Ky are below the present sea level. A mid- Holocene transgression of the sea is traced as well as a transgression during the last thousand years.
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This paper presents results of a morphological, sedimentological, and stratigraphical study of relict beach ridges formed on a prograded coastal barrier in Bream Bay, North Island New Zealand. Bream Bay is situated on a low mesotidal coast, influenced by low to moderate and refracted wave energy. Sediment supply for coastal progradation is dominated by marine deposits of reworked volcaniclastic sediment. The type section for beach ridge stratigraphy is exposed at One Tree Point where surveys of the contact between beach and foredune deposits (+4-5 m), and thermoluminescence dating indicate deposition of the beach ridges during the Last Interglacial sea-level highstand (isotope sub-stage 5e to 5a). Outcrop mapping, supplemented with ground penetrating radar data suggest that swash processes are important in the formation of these particular beach ridges. A model for the development and preservation of the One Tree Point beach-ridge system is presented with a focus on the role of relative sea level.