Types of coasts of South Bellsund (West Spitsbergen) and

Types of coasts of South Bellsund (West Spitsbergen) and

Marian Harasimiuk,
Waldemar
Institute of Earth Sciences
Maria Curie-Sklodowska University
Lublin, Poland
Jezierski
Wyprawy Geograficzne na Spitsbergen
UMCS. Lublin 1991
TYPES OF COASTS OF SOUTH BELLSUND (WEST SPITSBERGEN)
AND TENDENCY OF THEIR EVOLUTION
During geographical expeditions Bellsund 1986 —1988 which were organized
by the Institute of Earth Sciences University of Maria Curie-Skłodowska, Lublin
the studies were carried out on the dynamics of the coasts of south Bellsund and
Fiord Recherche. The studies covered the coast section 52 km long. The types of
coasts with a close relation to the geological structure were mapped. Some
observations concering dynamics of coast processes were made. Based on the
observation of a drifting ice movement the directions of currents in the coastal
sea zone about 1 km wide were recorded.
GEOLOGY AND
GEOMORPHOLOGY
Bellsund is a wide bay in the southern part of Spitsbergen, opened to the West.
Two big fiords discharge to this'bay: Van Mijen and. Van Keulen, and the also
wide, short Fiord Recherche. The investigated section of the seashore is the
northern part of Wedel Jarlsberg Land. As for tectonics Wedel Jarlsberg Land
may be divided into three structural elements: a western block, a ten kilometer
wide ^one of folded deformations and central depression (Foreland) in the East
(Orvin 1940, Birkenmajer 1958). The whole investigated area is situated in the
western block. It is characterized by the prevalence of Proterozoic and Older
Paleozoic rocks which were took part in fold and block movements including
volcanic activity many times. As a result a very differentiated complex of rocks of
various range of metamorphisation was formed (called Hecla Hoek formation
after Orvin 1940). This area is built of rocks that can be included among the
youngest links of Hecla Hoek formations (called as Kapp Lyell Formation). It
consists of tillites, phyllites and sandstones. Craddock et al. (1985) consider these
sediments to be glacial, fluvioglacial and limnoglacial with various degrees of
metamorphisation. Nowadays, they form a flat, wide syncline with the North
— South direction of an axis. The western block is not of a homogeneous
character. It is divided with faults of a NNW to SSE and SW to NE directions. In
the north of Bellsund there is a long, narrow through called Forlandsundet which
also belongs to the western block. Fiord Recherche is a southern part of this
17
structure. It was filled with Paleocene deposits (mainly sandstones and shales
poorly cemented, inclined in the NE direction at an angle of 5° to 25°).
The center of the northern part of Wedel Jarlsberg Land is a glaciated
mountain area about 600 m to 830 m high (Fig. 1.). Small glaciers go down in
a N and NE directions across wide short valleys, however the usually do not
reach a sea shore. Their recent marginal zones are from 2 to 4 km from the coast.
Only the Renard Glacier (the biggest one) reaches a sea shore, forming in some
places an active ice cliff. On western and southern forelands of the mountain
massif there are coastal plains which are uplifted abrasive platforms with many
rock remnants, and locally with a cover of sandy gravels marine deposits
(Szczęsny et al. 1990). The width of these plains is from 3 km on western
Lognedalsflya and North-East (Calypsostranda) sides to 500 m (Dyrstadflya
and Lyellstranda). Within the shore plain one can distinguish the system of three
terraces, 5 m to 8 m, 17 m to 25 m and 30 m to 35 m high. One the slopes of
mountain ridges dipping on the coast zone there are 3 other terraces (45 m, 55 m
and 80 m) of the shape of narrow rock shelves. The biggest areas are occupied by
the terrace 17 m to 25 m. Generally, there are not glacial deposits on the surface
of these terraces. Only in the area of Calypsostranda terrace till deposits were
found and also the Young Pleistocene sea clays. The northern marginal of Wedel
Jarlsberg Land like most coasts of Spitsbergen are characterized by young
(recent) lifting movements with a clearly differentiated spatial tempo (Marcinkiewicz 1961, Stablein 1978, Stankowski 1982).
TYPES OF COASTS
The main factors which form coasts are the activity of waves, sea currents and
tidal (Hayes et al. 1980). The character and intensity of processes occurring in the
coast zone are modified by the local factors: lithology, tectonics, exposition to
sea currents. As a result sections of. coasts differentiated morphologically
developed (Harasimiuk, Jezierski 1988).
There were distinguished the following types of coasts:
1. Group of abrasion coasts (la. active cliff in Proterozoic rocks, lb. active
cliff in Paleocene rocks, lc. active cliff in Quaternary deposits, Id. ice cliff).
2. Group of accumulation coasts (2a. beaches with a fully developed profile,
2b. sand bar, 2c. tidal flat or delta). 3. The plain coasts with a leveled
accumulation — abrassion shape with undeveloped beaches (3a. shaped on
metamorphic rocks and 3b. shaped on Quaternary deposits).
Active cliff in Proterozoic rocks. Irregular cliffs cut in a series of tillites and
sandstones with different resistance and also with a complicated system of faults
and joints. These are many arched incisions with a character of small bays of
different radii (from 100 m to 1 km). On the prolongation of the capes between
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arches there are numerous stacks. The maximal height of the cliff cut in
Proterozoic rocks is 25 m. In the bays narrow undeveloped beaches were formed
— dependent on the dynamics of processes they are built of sand, gravels or
boulders. The coasts of such a character occupy about 30% of the investigated
coast line.
Active cliff in Paleocene rocks. This type of coast occurs only in Skilvika Bay
and it makes about 2% of the coast line (Fig. 1) Nonresistant rocks (mainly
poorly cemented sandstones and mudstones) cause quick retreating of the cliff in
SE direction. Abrasion processes are excellently legible here. A narrow gravel
beach of incomplete profile formed at the foot of the cliff. Thermodenudation
processes are also very important in developing the cliff of this type.
Active cliff in Quaternary deposits. Quaternary deposits occur in the eastern
zone of the coast. They are the covers of slope deposits, fluvioglacial gravels and
sands, glacial and marine deposits. In the eastern part of the investigated area
(Recherche Fiord) there are cliffs cut in slope and moraines deposits with
differentiated heights — from 1 m to 5 m. In the northern part there are cliffs cut
in beach gravels building the older marine terrace. On the cliffs cut in moraines
and marine clays landslides and solifluction processes play a significant role in
modelling cliffs. There also quickly retreating cliffs.
Ice cliff. As the result of progressing deglaciation of the area the zone of the
contact of glacier ice and sea is still being reduced. Nowadays, the majority of the
ice cliffs consists of a part of Recherche Glacier. This cliff is about 15-20 m a high.
Flat sea shores are formed in the places where ice cliff regresses.
Full developed beaches. The are formed in the strong shore currents zone with
additional balance of sediments transport. They appear in the places were
intensive processes of accumulation take place, as the result of currents
convergention with a great transport of sandy gravel materials along the
seashore. The beach there is about 350 m wide.
Parallel sandy gravel bars. Bars appear only in Recherche Fiord. The develop
in the proximal side of fluvioglacial fans or by small alluvial fans (deltas) that are
formed at the mouths of the streams.
Tidal accumulation flats or delta. The tidal accumulation flat was formed in
a big structurally conditioned bay of Recherche Fiord at the mouth Chamberlin
River, where currents parallel to the coast do not appear, and where tides
amplitude is about 1.5 m. The flat watt surfaces reaches about 1 km 2 . This zone is
dissected by a composite system of transit channels of fluvio-glacial waters. The
surface of the tidal flat is made of silts in the lower part and silty sands in the
upper part. There are not storm ridges on this tidal flat because the whole bay is
screened from the storm winds.
The plain coasts with leveled accumulation — abrasion shape with undeveloped
beaches. These kinds of coasts make up about 30% of the investigated shore line.
In the western part (Lognedalsflya) there is a wide mesotidal abrasive plain (tidal
19
range is about 2 m) with small storm accumulation ridges (Fig. 1). This type of
coast was formed on gently sloped metamorphic rocks. In the eastern part
(Recherche Fiord) this type of coast was formed in Quaternary deposits (mainly
glacial tills and solifluction covers), (Pękala, Repelewska-Pękalowa 1988).
CONCLUSIONS
The results of the investigations carried out in different areas of Wedel
Jarlsberg Land enable comparisons of processes and forms in the segments of
coast characterized by environmental parameters.
The eastern part (particularly the coast of Recherche Fiord) represents the
coasts of low wave energy conditions with prevailing accretion processes.
The northern and western parts of the coast are zones of high wave energy
conditions, with prevailing abrasion processes. The most important waves to
operate in these parts of the coast are generated by strong winds from the West
(large oceanic waves).
Detailed investigations will be carried out during next expeditions.
REFERENCES
Birkenmajer K., 1958: Z badań nad stratygrafią i tektoniką formacji Hecla Hoek w Ziemi
Wedel-Jarlsberg (sprawozdanie wstępne) Prz. Geofiz. R. 3 (11) z. 2
Craddock C., Hauser E.,Maher M. D., Sun A.Y., Zhu-Guo-Qiang,
1985: Tectonic evolution of the
West Spitsbergen fold belt. Tectophysics, 114.
Harasimiuk M., Jezierski W., 1988: Typy wybrzeży południowego Bellsundu. Wyprawy
Geograficzne na Spitsbergen. UMCS Lublin,
Hayes M., Owens E. H., Hubbard D. K., Abele R. W., 1980: The investigation of form and
processes in the coastal zone. Coastal Geomorphology.
Marcinkiewicz A., 1961: Podniesione terasy morskie południowego wybrzeża Bellsundu i fiordu
Van Keulena między lodowcami Recherche i Hessa (Zachodni Spitsbergen) Biul. Geol. t. 1 cz. 1.
Orvin A. K., 1940: Outline of the geological history of Spitsbergen. Shrifter om Svalbard og
ishavet nr 78.
Stablein G., 1970: Untersuchung der Auftauschicht iiber Dauerfrost in Spitsbergen. Eiszeitalter u.
Gegenwart, 21, Obringen.
Siankowski W., 1982: The role of marine processes in the morphogenesis of the Lisbetdalen (NW
Sórkapp Land, Spitsbergen) Questiones Geographicae 8.
Szczęsny R., Nitychoruk
J., Dzierżek J., Harasimiuk
M., Pękala К., Repelewska-Pękalowa
J.,
1989: Photogeological map of the Renardbreen, Scottbreen and Blomlibreen forefield (Wedel
Jarlsberg Land, Spitsbergen) 1:10 000. Wydawnictwa Geologiczne.
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STRESZCZENIE
Podczas geograficznych ekspedycji „Bellsund 1986 — 1988" organizowanych przez Instytut
Nauk o Ziemi Uniwersytetu Marii Curie Skłodowskiej z Lublina prowadzone były badania nad
typami wybrzeży i dynamiką procesów w strefie brzegowej w północnej części Ziemi Wedel
Jarlsberga.
Głównym czynnikiem modelującym badany odcinek wybrzeża o długości 52 km jest działalność
fal, przy współudziale prądów morskich i pływów. Procesy soliflukcyjne i termoabrazja odgrywają
znikomą rolę. Charakter i natężenie procesów zachodzących w strefie wybrzeża modyfikują czynniki
lokalne: litologia skał, tektonika, ekspozycja w stosunku do przeważającego kierunku ruchu fal.
W konsekwencji powstały wyraźnie zróżnicowane pod względem morfologicznym odcinki wybrzeża.
Wyróżniono następujące typy wybrzeża: 1. wybrzeża abrazyjne (la. aktywne klify w skałach
proterozoicznych, lb. aktywne klify w skałach paleoceńskich, lc. aktywne klify w osadach
czwartorzędowych, ld. klify lodowe). 2. Wybrzeża akumulacyjne (2a. plaże o pełnym profilu, 2b.
wybrzeża mierzejowe, 2c. równiny pływowe — delty). 3. Abrazyjne równiny nadmorskie z plażami
o niepełnym profilu.
We wschodniej części badanego obszaru (fiord Recherche) przeważają wybrzeża kształtowane
przez fale o małej energii, z dominacją procesów akrecji. Północna i zachodnia część badanego
wybrzeża kształtowana jest przez fale oceaniczne o wysokiej energii za zdecydowaną przewagą
procesów abrazji.
21
COAST TYPES OF
SOUTH BELLSUND
ы
to
ABRASION FORMS
JVWM
•л*
SVALBARO
Archipelago
mm
2
Ц
5
6
Ш-
7
ACCUMULATION FORMS
Q
9
JOSEPHBUKTA
10
FLAT, ABRASIVE ANO
ACCUMULATIVE COAST
"П
•«••• 12
/
TTOMTOOOEN
FAGERBUKTA
DIRECTION OF SEA CURRENT
< = = 13
- — 14
—
15
KVITFISKPYNTEN
DUNDERBUKTA
Fig. 1. Types of coasts of south Bellsund. Abrasion forms: 1 — active cliff in Proterozoic rocks,
2 — active cliff in Tertiary rocks, 3 — cliff in sea gravels, 4 — cliff in moraine, 5 — ice cliff, 6 — old
cliff, 7 — abrasive remnants. Accumulation forms: 8 — beaches of the developed profile, 9 — tidal
flat or delta accumulation, 10 — old shore ridges. Flat, abrasive and accumulative coast: 11 — on the
Proterozoic rocks, 12 — on the Quaternary deposits. Direction of sea current: 13 — oceanic drift
(high ware energy), 14 — foehn wind drift (low wave energy), 15 — local near shore drift. 16 — points
of abrasion measurements.