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bedsin
Karst and karstificationin gypsiferous
Svalbard
Mathiesondalen,CentralSpitsbergen,
O , S A L V I G S E N .O , L A U R I T Z E N A N D J , M A N G E R U D
S a l v i g s e n . O . . L a u r i t z e n , O . & M a n g e r u d . J . 1 9 8 3 : K a r s t a n d k a r s t i f i c a t i o ni n g y p s i f e r o u sb e d s i n
Mathiesondalcn, Central Spitsbergen. Svalbard. Polar Research / n.s., 83_88. Oslo.
Rcccnt karst forms in gypsiferous bcds are reportcd from Mathicsondalen in Ccntral Spitsbergen. whcrc
sevcral sinkholcs (dolines) and swallow holes have been formed aftcr the deposition of Holocene raiscd
beach scdiments The bedrock of the area is mostl-vintcrbedded gypsunl/anhydrite and dolomites of the
Carhonifcrou. fbbadalcn Formalion.
Otto Saluigsen and Ornulf Lquritzen, Norsk Polarinstitutt, Rolfstangueien 12, 1330 Oslo Lufthaun; Jan
Mangerutl, Geologisk Institutt, Aud. B, LiniDersiteteti Bergen, 50ll Bergen, Norwav. June 1982 (reuised
Nouember 1982).
Introduction
In the area around Mathiesondalen in Btnsow
Land east of Billefjorden (Fig. 1). Carboniferous
and Permian beds dip gently to the south. The
outer part of the valley is covered by Holocene
raised beach sediments in the form of terraces
and beach ridges (Feyling-Hanssen1955; Lauritzen & Salvigsenin press). The valley floor itself
is occupied by a braided river system, and small
tributary streams have eroded gullies in the
unconsolidated sediments. The underlying rocks
are mostly interbedded evaporites and dolomites
of the Ebbadalen Formation (Cutbill & Challinor
1965),a formation describedin detail by Holliday
& Cutbill (1972) and Johannessen (1980). The
gypsiferous beds in the outer part of Mathiesondalen are downfaulted along local lineaments connectedwith the Billefjorden Fault Zone (Harland
et al. 1974) causing almost flat iying evaporites
to form the bedrock of the outer part of the valley
and on the sides of the mountains further east.
The post-depositional tectonic activity has caused
prominent cracks and fissuresin the bedrock, thus
allowing the percolation of surface water.
The geomorphological significanceof rock solution in limestone/dolomite areas in Spitsbergen
has been discussedby Corbel (1957, 1960) and
Helld6n (1974). Orvin (1944) described springs
in connection with the iimestone area near Hornsund in the southern part of Spitsbergen.Elsewhere karst forms ate most frequent and best
developed in limestone and dolomite, partly
becausethese rocks are more abundant than other
sotuble rock types (Sweeting 1968). Here we
describe karst phenomena in gypsum/anhydrite
beds in an area at the mouth of Mathiesondalen.
Observations
Large. closeddepressionsand other karst features
o c c u r i n t h e r a i s e db e a c h e si n t h e o u t e r p a r t o f
Mathiesondalen.They have a superficialsimilarity to kettles formed by melting of buried ice.
However, several of the depressionscontain a
drainage into underlying gypsiferousbeds. They
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Fig. 1. Location map.
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O. Saluigsen,@. Lauritzen & J. Mangerud
can therefore generallybe characterizedas sinkholes (dolines) with associatedforms. Six such
depressions(Locs. 1-6, Fig. 2) are described,
including apparent fossil sinkholes and presentday activesinkholes.Theseare:
(1) The highestlying depression,about70 metres
abovesealevel, is a lake on the beachterraceon
the south side of the valley, near the talus. This
appearsto be a fossil sinkhole.The total diameter
is about 100 metres, and surplus of water is
drained by a surfacestream.In late summer-time
the pond usuallyhas no visible drainage.Here,
the bedrockis not exposed.
Fig. 2. Vertical air photograph of the Mathiesondalenarea.
Kapp Ekholm in the foreground. The nmbers refer to the
karst depressionsdescribedin the text aslocalities1 to 6. Photo:
Norsk Polarinstitutt 561 2959 (23 August L961).
(2) A small circular sinkhole pond is found on
the terracenorth of the river bed (Fig. 3). The
height of the terrace is about 35 metresabovesea
level, and the sinkholeis probably a fossil one.
The pond has no visible outlets, and the water
depth varies throughout the year. Bedrock was
not exposed.
(3) The lowestlying depressionis locatedin the
Fig. 3. Localily 2. The small sinkhole pond without any surfaceoutlet. Figure in foreground as scale.
Karstifi.cationin gypsifurousbeds, Sualbard
85
river fan systemof Kapp Ekholm about 6 metres
above sea level. A small stream flows into the
pond, and the outlet is near the inlet. No difference between inflow and outflow could be seen.
The walls of the depressionshow evidence of
fresh slidesin unconsolidatedmaterial. Bedrock
was not exposed.
through it and disappearsinto a swallow hole in
a highly jointed and collapsed gypsiferouswall
(Fig. a) at a level of about 4 metres below the
pond level. The cave probably has a connection
to the lake previouslymentioned(locality 4). This
underground outlet has also been observed by
Balchin (1941).
(4) A lake near the southern edge of the delta
plain is remarkable. It has a length of about 300
metres and seemsto have a considerabledepth.
The lake is about 6 metres above sea level, and
the southern side has fresh slidesin terrace sand
and gravel. In late July the outlet of the lake was
a rapid flowing stream,which wasdifficult to cross
in rubber boots. Obvious sourcesof water were
not apparent and there were no streamsrunning
into the lake. We concludethat the lake must be
fed by subterranean tributaries, arising partly
from the sinkholes and swallow holes observed
in depressionsat localities 5 and 6.
(6) A jointed and collapsedbedrock in locality
5 continues to the end of a short blind valley
which branches out from the main river plain
(Figs. 5 & 6). Water from the main river in
Mathiesondalenfeedsa shallow lake in the blind
valley.The supplyof wateris highlyvariable,and
in the summer of 1981it was small becausethe
main river was on the opposite side of the river
plain. In 1981the water level in the lake varied
with the precipitation. Following healy rainfall
the water level roseabout 25 cm, and shoremarks
showedthe level to havebeen approximatelyone
meter higher than normal (see Fig. 5). At this
level the blind valley will be fllled with water, and
surface drainage will start to the river plain of
Mathiesondalen.This maximum level had probably beenreachedin the snowmeltingperiod. In
(5) A small sinkhole pond is found about
32 metresabovesealevel, 300metreseastof the
describedlake (localitv 4). A small stream flows
Fig. 4. Locahty 5. The swallow hole with stream flowing from left into the base of the white, tilted gypsiferousbeds and
disappearinginto the open fractures.Figure in the upper right corner as scale.
86
O. Saluigsen,@. Lauritzen & J. Mangerud
Flg' 5' Locality 6' The lake of the blind valley. Photo taken towardssouthwest.
The outlet into fractured gypsiferousbedsis seen
on the oppositeshore of the lake (seealso Fig. 6). Note the shore marks of higher
lake levels. Figure on shore as scale.
late July a great part of the blind valley was a
lacustrineplain coveredby fine sediment.The
lake was drained by subterraneanoutlets in the
blind valley. The bedrock is highly jointed and
severalcollapsedtunnelscan be seen(Fig. 6). In
many placesthe rock surfacehas small scalesolution features,and newly collapsedtunnelsalso
showthat karst processes
are still active.
flowinginto cavesin the gypsum/anhydrite
beds,
the one at locality 6 being a 5_6 metre deep
collapsedcave. It is thereforeobviousthat most
(probablyall) of thesedescribeddepressions
are
real karst forms, here developedby the solution
of gypsum,/anhydrite.
Their slopes,however,are
mouldedby thermokarsticprocesses
in the over_
lying sediments.
The sinkholesoccurin upliftedbeachsediments
One small scale stream from the main river which subsideinto the depressions.
Both the
plain was also observed to disappear before it structures and the
surface forms of the beach
reachedthe pond. It disappearedin a 5 metre sedimentsare crosscutby
sinkholes(seeFig. 2).
wide and 2 metre high tunnel in unconsolidated We have no observations
of fossil sinkhol,esor
materialnear the edgeof the river plain. During cracksin the bedrock filled with
till. Two main
a time spanof two weeks,about 10 metresof the conclusions can be drawn
from these
tunnel collapsed,but this did not affect the out- observations:
flow of the stream. No bedrock was seenin the
tunnel. The subsurfacedrainage from this area (1) The sinkholesare mainly
formed by collapse
probablyendsin the lake heredescribedaslocal- of subsurfacecaves.Where
the activepermafrost
ity 4.
reachesthe bedrock, downwardsolutionmav also
have taken place.
(2) The sinkholes are younger than the beach
sedimentsin which they occur. The caves and
At localities 5 and 6, water can be observed tunnels from which the sinkholes
were formed
Discussionand conclusion
Karsffication in gypsiferousbeds, Sualbard
Fig. 6. Locality 6. A collapsedgypsum cave near the subterranean outlet of the lake of the blind valley (see also Fig. 5).
Fisure above cave as scale.
87
However, a crucial factor in this connection is
that the subsurfaceconsistsof soluble evaporite
mineralsin a highly jointed bedrock. Freeze-thaw
action in bedrock cracks may allow water circulation in the rock and causesolution.
Liest@l(1977\ has discussedthe flow of water
m permafrost areasand shown that even narrow
passagesare held open all the year round in
connectionwith pingos and springs. The waterflow in Mathiesondalen,however,ceasesduring
the autumn, and subsurfacewaterflow will be at
a minimum until spring melting starts. Then percolation in the gypsiferousbedscan start, causing
the developmentof karst forms.
Gypsum or other evaporite rock fragmentsare
hardly ever seen in the Quaternarysediments,
except in the screeswhere they are very locally
derived,and evenhere the processof disintegration seemsmore activeto the evaporitesthan to
the interbeddedrocks,mostlydolomites.The rate
of solutionof largegypsumblockshasbeenstudied elsewhere,e.g.from Permianbedsin England
(James,Cooper & Holliday 1981),and factors
like water flow velocity, temperature,etc. have
beenconsidered.Here, however,we will not try
to calculate the rate of solution or the time
involved in the dissolutionprocessesbut will
rather stressthe fact that these processesare
active in high arctic areas where snow and ice
cover the ground most of the year.
Acknowledgementr. - We thank Dr. David L. Bruton for
improving the English text, Carl E. Dons and Yngve M. Nilsen
for assistance in the field, and Espen Kopperud for preparing
the figures for the press.
may be older, but they have collapsedafter the
formationof the strandlines.The strandlineshave
been formed more or less continuouslyfrom
approximately11,000yearsB.P. until the present
(Feyling-Hanssen
L965), and thus all sinkholes
are of Holocene age. The observed present
activity in the sinkholes is also indicative of a
young age.
The Svalbardareais subjectto permafrost,and
a normal model for groundwatercirculation cannot be used.The permafrostlayer normally acts
as a very efficient barrier to groundwater percolation. In the describedarea the active layer
has a maximum thickness of 2 metres; the
describedsubsurfacedrainageis well below this,
and thus in permanentlyfrozen ground. It is difficult to understandhow water can penetrate and
keep an open passagethrough the frozen layer.
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