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Durham Research Online Durham Research Online Deposited in DRO: 15 January 2016 Version of attached le: Published Version Peer-review status of attached le: Peer-reviewed Citation for published item: Streu, K. and Forwick, M. and Szczuci¡nski,W. and Andreassen, K. and O'Cofaigh, C. (2015) 'Submarine landform assemblages and sedimentary processes related to glacier surging in Kongsfjorden, Svalbard.', Arktos., 1 . p. 14. Further information on publisher's website: http://dx.doi.org/10.1007/s41063-015-0003-y Publisher's copyright statement: c The Author(s) 2015. This article is published with open access at Springerlink.com Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://crea tivecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Additional information: Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full DRO policy for further details. Durham University Library, Stockton Road, Durham DH1 3LY, United Kingdom Tel : +44 (0)191 334 3042 | Fax : +44 (0)191 334 2971 https://dro.dur.ac.uk Arktos DOI 10.1007/s41063-015-0003-y ORIGINAL ARTICLE Submarine landform assemblages and sedimentary processes related to glacier surging in Kongsfjorden, Svalbard 1,2 1 3 Katharina Streuff • Matthias Forwick • Witold Szczucin´ski • 1,4 2 Karin Andreassen • Colm O´ Cofaigh Ó The Author(s) 2015. This article is published with open access at Springerlink.com Abstract High-resolution swath-bathymetry data from cores reveal minimum sediment accumulation rates related inner Kongsfjorden, Svalbard, reveal characteristic land- to the Kongsvegen surge from 1948; these were 30 cm a-1 form assemblages formed during and after surges of tide- approximately 2.5 km beyond the glacier front shortly after water glaciers, and provide new insights into the dynamics surge termination, and rapidly dropped to an average rate of surging glaciers. Glacier front oscillations and overrid- of 1.8 cm a-1 in 1950, during glacier retreat. ing related to surge activity lead to the formation of overridden moraines, glacial lineations of two types, ter- Keywords Submarine landforms Á Glacier surges Á minal moraines, associated debris lobes and De Geer Tidewater glaciers Á Multibeam bathymetry Á Lithology Á moraines. In contrast to submarine landform assemblages Svalbard from other Svalbard fjords, the occurrence of two kinds of glacial lineations and the presence of De Geer moraines suggest variability in the landforms produced by surge-type Introduction tidewater glaciers. All the landforms in inner Kongsfjorden were deposited during the last c. 150 years. Lithological Glacier surges are cyclic switches between active and and acoustic data from the innermost fjord reveal that passive phases, during which the ice front may either suspension settling from meltwater plumes as well as ice advance rapidly (active), stagnate (transition), or retreat rafting are dominant sedimentary processes in the fjord, slowly (passive/quiescent phase; e.g. [16, 34, 60, 68, 71]). leading to the deposition of stratified glacimarine muds They generally occur independently of climate and are with variable numbers of clasts. Reworking of sediments triggered internally through, for example, changes in gla- by glacier surging results in the deposition of sediment cier hydrology or basal thermal regime [44, 60, 68, 72]. lobes containing massive glacimarine muds. Two sediment Surges are common on Svalbard, where they have a gen- erally longer duration than elsewhere, with active phases of between 4 and 10 years and quiescent phases of between & Katharina Streuff 50 and 500 years [5, 15, 61]. Many Svalbard glaciers have [email protected] been identified as surge-type (e.g. [15, 35, 53, 63, 66, 67]), with surges well-documented from the past c. 180 years, 1 Department of Geology, UiT-The Arctic University of but only two older examples (Paulabreen and Nathorstb- Norway, Postboks 6050, 9037 Langnes, Tromsø, Norway reen; [35, 36, 46, 49, 53]). 2 Present Address: Department of Geography, Durham Glacier surges lead to the formation of characteristic University, Science Site, South Road, Durham DH13LE, UK landform assemblages, which are revealed when the gla- 3 Institute of Geology, Adam Mickiewicz University in ciers retreat (e.g. [10, 20, 22, 25, 63, 66, 71, 73]). Landforms Poznan´, Mako´w Polnych 16, 61-606 Poznan´, Poland related to glacier surges in submarine settings have been 4 Department of Geology, CAGE-Centre for Arctic Gas described from several Spitsbergen fjords [3, 10, 29, 63, 66, Hydrate, Environment and Climate, UiT-The Arctic University of Norway, Postboks 6050, 67]. The landform models suggested thus far include 9037 Langnes, Tromsø, Norway overridden recessional moraines, (mega-scale) glacial 123 Arktos lineations, terminal moraines with associated sediment during the Last Glacial Maximum (LGM), and (c) ice lobes on their distal slopes, eskers, annual push moraines retreat (see e.g. [19, 43, 50]). and crevasse-squeeze ridges, the latter suggested to be the During initial advance, ice extended beyond the pre- only feature diagnostic of a glacier surge [66, 71]. The high sent coastline, reaching the shelf break between 24,080 detail preserved in submarine environments offers invalu- Æ 150 and 23,550 Æ 185 cal a BP (calibrated years able insights into the processes controlling landform gene- before present; [43, 50]). Fast-flowing ice streams sis, and, together with lithological records from sediment drained the Svalbard-Barents Sea Ice-Sheet via the main cores, enables a better understanding of tidewater glacier fjord systems on Svalbard, including Kongsfjorden (e.g. sedimentation and dynamics (e.g. [10, 63, 66]). [40, 64, 65]). A terminal moraine at the shelf break in In this paper we present acoustic data (swath bathymetry southern Kongsfjordrenna was inferred to reflect maxi- and high-resolution seismic data) and lithological analyses mum ice extent during the Late Weichselian [65]. of two sediment cores from inner Kongsfjorden, Svalbard. Deglaciation of the shelf and fjords on west Spitsbergen We describe and interpret submarine landform assem- began around 20,500 Æ 500 cal a BP and was interrupted blages and deposits related to glacier surges and show that by multiple glacier halts and/or re-advances (e.g. [3, 31, such assemblages are more diverse than previously 32, 43, 46, 65]). The deglaciation of Kongsfjorden proper suggested. was documented as a two-stage recession initiated 13,000 cal a BP, leading to ice-free conditions by approximately 9000 cal a BP [52]. Recent findings by Study area Henriksen et al. [37], however, show that the ice stream in Kongsfjorden had retreated to the fjord mouth by Kongsfjorden is located on northwestern Spitsbergen, the 16,600 cal a BP, and that the deglaciation of the areas largest island of the Svalbard archipelago. It is the southern west of Blomstrandhalvøya was already complete before branch of the Kongsfjorden–Krossfjorden fjord system 14,400 (Æ300) cal a BP. (78500N, 11400E, and 79040N, 12400E; Fig. 1). Kongs- Asynchronous re-growth of Svalbard glaciers occurred fjorden and Krossfjorden merge towards the open sea, after c. 9000 cal a BP (e.g. [3, 30, 31, 33]). Maximum Late where a large submarine trough, Kongsfjordrenna, chan- Holocene glacier extents occurred either due to climatic nelled fast-flowing ice streams during the last glacial (e.g. cooling during the Little Ice Age or due to glacier surges [40, 64]). Kongsfjorden is approximately 20 km long and (e.g. [15, 35, 46, 53, 58, 63, 66, 67]). between 4 and 10 km wide. It covers an area of 210 km2, and has a volume of 29.4 km3 [41]. Water depths range from 350 m in the outer and central parts to\100 m in the Methods inner fjord. A detailed review on Kongsfjorden’s climate and oceanography was provided by Svendsen et al. [78]. Swath-bathymetry, sub-bottom profiler (chirp) data and Seven tidewater glaciers terminate in Kongsfjorden: sediment cores acquired in autumn 2010 with R/V Jan Løvlandbreen and Svansbreen form one tidewater front Mayen (now R/V Helmer Hanssen) from inner Kongs- with Blomstrandbreen in the north of the fjord (Fig. 1) and fjorden provide the basis for this study (Fig. 1). A Kongs- will be summarized by the term ‘‘Blomstrandbreen’’ berg Maritime Simrad EM 300 multibeam echo sounder throughout this paper. Conwaybreen, Kongsbreen and was used to acquire the bathymetry data (max. resolution Kronebreen dominate the east of the fjord with Kongsbreen of 5 m). The instrument operated at a frequency of terminating as two tidewater margins, one north and one approximately 30 kHz and was calibrated using p-wave south of Ossian Sarsfjellet (Fig. 1). Kongsvegen flows into velocities for the water column obtained from CTD (con- the fjord from the south-east, adjacent to Kronebreen ductivity, temperature, depth) measurements. The bathy- (Fig. 1). Three of these glaciers have been documented to metry data were supplemented with multibeam data from be of surge-type, with Kronebreen and Kongsvegen expe- the Norwegian Hydrographic Survey gridded to a max. riencing respective surges in 1869 and 1948, and Blom- resolution of 5 m and visualized and interpreted using the strandbreen surging in 1960 [35, 54].
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