SOLIFLUCTION PROCESSES IN RECHERCHEFJORDEN (WESTERN SPITSBERGEN)

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1 Janina Repelewska-Pękalowa Kazimierz Pękala Institute of Earth Sciences Maria Curie-Sklodowska University Lublin, Poland Wyprawy Geograficzne na Spitsbergen UMCS, Lublin 1992 SOLIFLUCTION PROCESSES IN RECHERCHEFJORDEN (WESTERN SPITSBERGEN) REGION During the Geographical Expedition of the researchers from Maria Curie-Skłodowska University in the years there were carried out complex observations and measurements of periglacial phenomena in the north western part of Wedel Jarlsberg Land (Fig. 1). This region is situated in southern Bellsund where the main elements of relief are mountain ridges with steep rocky and rubbly sides, valley glaciated contemporarily and accumulative coastal plain raised by isosthatic movements (Szczęsny et al., 1989). The coastal plain Calypsostranda is a system of raised marine terraces of m a.s.l. high, mainly covered by Quaternary deposits of various genesis. These are Pleistocene boulder clays of glacial origin a series of marine sand and dust deposits and gravels. The upper leayer is made up by sands and gravels with rich fauna dating from Holocene. Eolic deposits can be found in some places (Troitski et al. 1979, Landvik et al. 1987, Stablein 1987, Pękala, Repelewska-Pękalowa 1990, Salvigsen et al. 1991). The coastal plain Calypsostranda since being raised above sea level has been formed by different morphogenetic processes such as erosion, vertical and horizontal ground movements connected with the permafrost active layer such as frost heave, ice segregation and solifluction (Pękala, Repelewska-Pękalowa, 1988). It can serve as a good example of relief formation and transformation in the Holocene periglacial conditions. The climate of the Bellsund region is characterized by thermal conditions which are result of this situation between the cold region of southern Spitsbergen (the average yearly air temperature -5.6 C) and warmer northern region (Isfjord -3.8 C according to Isfjord Radio). Contemporary meteorological elements in the studied area in the summer are characterized by great changeability in particular years (Tab. 1). Loose cover deposits, lack of compact vegetation and presence of permafrost and great changeability of weather promote active development of relief differentiated in kinds of forms and expansion. It makes estimation of particular phenomenon dynamics difficult. Therefore 73

2 a geomorphological mapping method and direct measurement method on some selected profiles and transects were applied in field studies. A morphodynamic map was prepared (Pękala, Repelewska-Pękalowa, 1988) and net of points for to geodesic measurements was installed. In the central part there were situate a meteorological station and measurements posts concerning thermal air currents and dynamics of permafrost active layer (Gluza, Repelewska-Pękalowa, 1988). There was found a correlation among processes shaping periglacial relief. There is a relation between development of tundra-poligons and erosion of.ablative waters coming from snow and permafrost as well as between solifluction and nivation. These processes shape young valley systems (Repelewska-Pękalowa 1987, Repelewska-Pękalowa, Pękala 1991). Existence of solifluction covers is related to development and dynamics of active layer whose thickness is differentiated on Calypsostranda and is from 45 cm under the compact tundra vegetation to over 170 cm within the dry spotted tundra and on slopes fed with water coming both from snow patches and permafrost degradation (Repelewska-Pękalowa, Gluza 1988, Repelewska-Pękalowa, Magierski 1989; Repelewska-Pękalowa, Paszczyk 1990; Paszczyk, Repelewska-Pękalowa 1991). The amount of solifluction creep was determined on the slopes of various expositions on which active layer dynamics was also studied. The slopes of similar geological structure and inclination (Quaternary deposits, inclination about 10 ) were selected for investigations. Bench-marks (points о geodetic measurements) were also placed on gently slopes at the bottom of frost cliffs, cryonival niches and cryoplanation steps. Traces of movement and active development of microrelief in the form of tongues, garland terraces and rubble-loamy belts were seen. There was no compact vegetation as a result of movement whose traces were cracks, small niches and mud flow. The size and rate of the movement were determined by the method consisting in driving steel pins into the ground. Movement rate was calculated from levelling measurements of ther positions. This method is used among others by: Jahn (1961), Czeppe (1966), Chandler (1972) and Akerman (1973). The values of average movement rate of solifluction were differentiated. This differentiation refers both to the exposition of the slope affected by the movement and its topography. The greatest rate is observed directly after snow cover recession in the first stage of ground thawing up to a depth of 20 cm. This movement is connected with intensive feed in water from melting snow, ground fluxing and its flow on the frozen ground. The second stage of movement is slower and it affects the layer of thickness greater than 50 cm. Then clay-rubble belts are formed. In the third stage with the moisture loss the rotary settlement 74

3 and deformation of slope profile through development of solifluction terraces and convexity in the frontal part of solifluction tongues take place. It should be stressed that solifluction movement proceeds stepwise. On slightly inclined slopes at the bottom of cryonival niches and within cryoplanation terraces in old terrace cliffs there were found very small horizontal shifts (1-2 cm/a year) of degradated covers but the vertical ground movements reaching 12 cm are related to the ground ice thawing and gravitational settlement. The rate and size of the movement were determined by the method measuring the range of eluvia relocated from frost cliffs and is on the average to 0.5 to 2 cm/a year. Deppression of topographic surface under the influence of solifluction can be determined in the present stage from transformations of marine terrace surface m a.s.l. Assuming its age to be about 8 thousand years BP (dates presented by various authors) among others is can be believed that depression of terrace surface in the zones of active solifluction is from 0.05 to 0.02 mm/a year. Translated by Maria Charmas REFERENCES Akerman J., 1973: Preliminare resultat undersoknigar av massrorelser vid Kapp Linne, Spitsbergen. Lunds. Univ. Nalurgeogr. Inst. Rapp. och Notiser 18, Lund. Chandler R. J., 1972: Periglacial mudslides in Vestspitsbergen and their bearing on the origin of fossil solifluction" shears in low angled slopes. The Quart. Journ. of Engineering Geology, vol. 5, 3. Czeppe Z., 1966: Przebieg głównych procesów morfogenetycznych w południowo-zachodnim Spitsbergenie. Zesz. Nauk. UJ, prace geogr. 13. Gluza A., Repelewska-Pękalowa J., Dąbrowski K., 1988: Thermic of permafrost active layer Spitsbergen. V International Conference on Permafrost in Trondheim, Norway, Proceedings vol. 1, John A., 1961: Quantitative analysis of some periglacial processes on Spitsbergen slopes. Geogr. Annal. ser. A, vol. 49. LandvikJ., MangerudJ., Salvigsen O., 1988: Glacial history and permafrost in the Svalbard area, V International Conference on Permafrost in Trondheim, Norway, Proceedings vol. 1, Paszczyk J., Repelewska-Pękalowa J., 1991: The phases of summer thawing on the coastal plain Calypsostranda (West Spitsbergen). Wyprawy Geograficzne na Spitsbergen, UMCS Lublin. Pękala К., Repelewska-Pękalowa J., 1988: Współczesne procesy morfogenetyczne w rejonie fiordu Recherche (Zachodni Spitsbergen). Wyprawy Geograficzne na Spitsbergen, UMCS Lublin. Pękala K Repelewska-Pękalowa J 1990: Relief and stratigraphy of Quaternary deposits in the region of Recherche Fiord and southern Bellsund (Western Spitsbergen). Wyprawy Geograficzne, UMCS Lublin. Repelewska-Pękalowa J., 1987: Rozwój równiny nadmorskiej pod wpływem procesów erozji (na przykładzie Calypsostrandy, rejon Bellsundu, Zachodni Spitsbergen). XIV Sympozjum Polarne, Lublin. Repelewska-Pękalowa J., Gluza A., 1988: Dynamics of permafrost active layer Spitsbergen. V International Conference on Permafrost, Trondheim, Norway, Proceedings vol

4 Repelewska-Pękalowa J., Magierski J.: Czynna warstwa zmarzliny: dynamika i właściwości chemiczne wód, Calypsostranda, sezon letnio-jesienny 1988 r. Wyprawy Geograficzne na Spitsbergen, UMCS Lublin. Repelewska-Pękalowa ]., Paszczyk J., 1990: Dynamics of permafrost active layer based on the statistical analysis. Wyprawy Geograficzne na Spitsbergen, UMCS Lublin. Repelewska-Pękalowa J., Pękala К., 1991: Periglacial morphogenesis of Recherche Fiord coastal plains (Spitsbergen). Wyprawy Geograficzne na Spitsbergen, UMCS Lublin. Siablein G., 1978: Extent and regional differentiation of glacio-isostatic shoreline variation in Spitsbergen. Polarforschung 1/2. Szczęsny R., Dzierżek J., Harasimiuk M., Nitychoruk J., Pękala К., Repelewska-Pękalowa J., 1989: Photogeological Map of the Renardbreen, Scottbreen and Blomlibreen Forefield (Wedel Jarlsberg Land, Spitsbergen) 1: Wyd. Geologiczne, Warszawa. Troilsky L., Punning J. M., Hiilt G., Rajamae R., 1979: Pleistocene glaciation chronology of Spitsbergen. Boreas vol. 8, no 4. STRESZCZENIE Podczas Wypraw Geograficznych Uniwersytetu Marii Curie-Skłodowskiej w latach prowadzono kompleksowe obserwacje i pomiary zjawisk peryglacjalnych w północnozachodniej części Ziemi Wedela Jarlsberga na Zachodnim Spitsbergenie (Fig. 1). Teren ten położony jest w strefie południowego obrzeżenia Bellsundu, a głównymi elementami rzeźby są grzbiety górskie o stromych skalisto-rumowiskowych stokach, doliny zlodowacone współcześnie i akumulacyjne równiny nadmorskie podniesione wskutek ruchów isostatycznych. Współczesne elementy meteorologiczne wykazują dużą zmienność w poszczególnych latach (Tab. 1). Obecność pokryw soliflukcyjnych wiąże się z rozwojem i dynamiką czynnej warstwy zmarzliny, której miąższość jest zróżnicowana. Wielkość ruchu soliflukcyjnego określano na stokach o różnej ekspozycji (Tab. 2). Największe tempo ruchu stwierdzono tuż po ustąpieniu pokrywy śnieżnej, w pierwszej fazie rozmarzania gruntu. Druga faza ruchu jest wolniejsza i podlega mu warstwa o miąższości większej niż 50 cm. Rozwijają się wtedy pasy gliniasto-gruzowe. W trzeciej fazie, w miarę utraty wilgoci następuje rotacyjne osiadanie i deformacja profilu stoku poprzez rozwój teras soliflukcyjnych i wypukłości w czołowych partiach jęzorów soliflukcyjnych. Praca wykonana w ramach realizacji projektu badawczego: (Grant KJBN) nr

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6 Tab. 1. Main meteorological elements on Calypsostranda (registered in the Expedition Meteorological Station in Calypsobyen) (summer seasons) Average air temperature e C Maximal average air temperature on height of 200 cm Minimal average air temperature on height of 200 cm Maximal average air temperature on height of 5 cm Minimal average air temperature on height of 5. cm Precipitation mm Number of days with precipitation fc 0.1 mm

7 Tab. 2. SoliDuction rate on the slopes with different exposition Bellsund Spitsbergen Slope Extreme movement Average movement Exposition Part cm/; rear N whole slope 4.0 S whole slope 6.5 E whole slope 4.6 V whole slope