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IN THE WAKE OF DEGLACIATION - SEDIMENTARY SIGNATURES OF ICE-SHEET DECAY AND SEA-LEVEL CHANGE

Henrik Swärd

In the wake of deglaciation - sedimentary signatures of ice-sheet decay and sea-level change

Studies from south-central Sweden and the western Arctic Ocean

Henrik Swärd ©Henrik Swärd, Stockholm University 2018

ISBN print 978-91-7797-163-4 ISBN PDF 978-91-7797-164-1

Cover: Sólheimajökull, Iceland. Photo: Henrik Swärd Printed in Sweden by Universitetsservice US-AB, Stockholm 2018 Distributor: Department of Geological Sciences, Stockholm University S.D.G.

Abstract

Lacustrine and marine sedimentary archives help unravel details concerning the withdrawal of large ice sheets and resulting sea-level changes during the last deglaciation (22 -11 kyr). Despite being the most well-studied of Earth´s deglacial periods, considerable gaps in our knowledge of regional and local environmental responses to post-glacial warming still exist. These gaps limit our ability to resolve the forcing and feedback mechanisms operating in the global climate system during deglaciation. Filling these gaps requires correctly dating and interpreting the sedimentary changes captured in marine and lacustrine cores. In a series of four manuscripts, this PhD thesis investigates the sedimentological signatures from deglacial processes at three key locations in the northern hemisphere: (i) Lake Vättern (LV) in south-central Sweden, (ii) Herald Canyon (HC) in the western Chukchi Sea, and (iii) Mackenzie Trough (MT) on the westernmost edge of the Canadian Beaufort Shelf. Deglacial sedimentary signatures in one lacustrine (LV) and two marine (HC and MT) sediment cores were analyzed using a broad range of methods to describe the physical, chemical, mineralogical and biological characteristics, and used to construct paleoenvironmental interpretations.

The vast proglacial Baltic Ice Lake (BIL) drained catastrophically into the North Sea at least twice during the last deglaciation. While the final drainage of the BIL is recognized in regional geological archives by a distinct change in the sedimentary lithology, evidence of the first drainage is more elusive. The meltwater pulse from the first drainage was recently suggested to have caused rapid atmosphere-ocean circulation changes. Situated at the western rim of the BIL, LV is ideally located for capturing sedimentological changes associated with the drainages of the BIL. A broad suite of analytical methods including physical, chemical and biological analyses was performed on a 74 m deglacial sediment core from southern LV. Following the withdrawal of the Fennoscandian Ice Sheet, four major development stages are identified for LV. These stages document the connection between the LV Basin and the wider Baltic Sea development stages, i.e. the Baltic Ice Lake, the Yoldia Sea and the Ancylus Lake. The final isolation of LV is also captured in the sediment core; new radiocarbon dates indicate that this occurred at 9530±50 cal. yr BP. A sharp transition from a varved clay unit to a partly sulfide laminated clay unit marks the final drainage of the Baltic Ice Lake dated to 11 650 ±280 cal. yr BP. However, an earlier peak in pore water chlorinity identified in the sediment provides the most compelling evidence to date for an initial drainage of the Baltic Ice Lake (~12.8 cal. kyr BP) near the onset of the Younger Dryas cold event.

The second studied key region is HC, located downstream from where Pacific water flows into the Arctic through the Bering Strait. This inflow is important for regulating sea ice conditions in the western Arctic, and supplying nutrients that fuel primary productivity. Proxies for Pacific water inflow to the Arctic have primarily focused on the mineralogy of clay particles (smectite and chlorite) that are transported in the water column from the Bering to the Chukchi Sea. In the western Arctic, early Holocene sea level rise opened the Bering Strait ~11 cal. kyr BP, and allowed Pacific water to enter the Arctic Ocean, initially through the HC. Grain size data from a 6 m sediment core in the HC records a likely period of erosion during the initial flooding of the shelf. Biogenic silica increases after the opening of the Bering Strait, likely in response to elevated nutrient availability in surface waters. However, the clay mineralogy shows increased variability after the opening of the Bering Strait. This is interpreted as a combination of Pacific and East Siberian sources for bottom waters entering the HC. The notable absence of a clear Pacific water signature in the clay mineralogy highlights potential limitations to using this proxy in other records from the western Arctic.

A deglacial meltwater outburst into the Arctic Ocean, via the Mackenzie River corridor, remains a controversial hypothesis for the triggering of the Younger Dryas. Fluvial erosion along the Canadian Arctic coastline is the only geological evidence for this flooding event. Some far field studies from the Arctic have argued that Mackenzie River sediments in Younger Dryas age sediments can be recognized by a unique mineral and isotopic composition, but no detailed proximal study of Mackenzie River sediments exists to support this assertion. The mineral (XRD) and isotopic (Sr and Nd) studies presented in this thesis on samples from an 81.5-meter deep borehole from the third of the key regions, the MT, fills this gap. The results show that the mineral assemblage and ɛNd of fine fraction material delivered by the Mackenzie River remained relatively stable during the decay of the Laurentide Ice Sheet. An exception to this overall stability exists in a transitional sedimentary unit, deposited immediately after transgression at the drilling site, and might be related to meltwater pulses associated with the drainage of the Lake Agassiz. These results suggest that the modern mineral and isotopic signature of Mackenzie River sediments may not be a suitable proxy for deglacial meltwater events in far-field sedimentary records. Sammanfattning

Sediment från sjö- och havsbottnar utgör historiska arkiv över de stora inlandsisarnas reträtt och därtill hörande havsnivåförändringar. Den senaste isavsmältningen (22-11 kyr) är den mest kända avisningsperioden i jordens historia, men det finns fortfarande stora kunskapsluckor, bland annat avseende regionala och lokala effekter av den dåvarande globala uppvärmningen. Detta begränsar vår förståelse av de drivkrafter och feedback-mekanismer som styr tillbakadragandet av stora inlandsisar. Väldaterade sedimentkärnor med avtryck från händelser och skeenden under avisningsperioder utgör en viktig resurs för att utröna avisningens kronologi och effekter på det lokala/regionala planet. Denna avhandling undersöker sedimentära avtryck från avisningsprocesser vid tre områden på det norra halvklotet: (i) Sjön Vättern i centrala Sydsverige, (ii) Heralds kanjon belägen nordost om Wrangelön i östra delen av Tjukterhavet samt (iii) Mackenziesänkan i Beauforthavet utanför Kanadas nordvästra kust. En sedimentkärna från vardera område har analyserats med hjälp av ett brett spektrum av analysmetoder. Analyserna har genererat fysikaliska, kemiska, mineralogiska och biologiska data, som använts för att rekonstruera miljöförändringar under den senare delen av pleistocen och under holocen. Isavsmältningen över Skandinavien åtföljdes av åtminstone två katastrofala tappningar av den vidsträckta Baltiska issjön (BIL) ut i Nordsjön. Emedan den slutliga tappningen av BIL är väldokumenterad i en uppsjö av regionala sedimentkärnor så är bevisen för den första tappningen betydligt färre och av en mindre övertygande natur. Vättern utgjorde vid denna tid den västra utposten av BIL och torde därför innehålla sedimentära avtryck från de stora tappningarna. En 74 m lång sedimentkärna från södra Vättern har undersökts med avseende på fysikaliska, kemiska och biologiska förändringar. Sedimentkärnan uppvisar fyra utvecklingsstadier för Vätternsänkan efter den fennoskandiska inlandsisens tillbakadragande. Dessa stadier bekräftar Vätterns och Östersjöns delvis gemensamma utvecklingshistoria då tre av sedimentenheterna deponerats i Baltiska issjön, Yoldiahavet respektive Ancylussjön. Datering av makrofossil med hjälp av kol-14 metoden indikerar att Vättern isolerades 9530±50 BP cal (BP cal = kalenderår före 1950), d.v.s i tidig Littorinatid. Den slutliga tappningen av BIL är tydligt markerad genom en direkt övergång från varvig lera till en delvis sulfidlaminerad lera. Denna övergång är daterad till 11650 ±280 BP cal. Ett tydligt maximum i sedimentporvattnets kloridjonkoncentration utgör det hittills starkaste beviset på en första tappning av den Baltiska issjön (~12800 BP cal) i samband med inledningen av den köldperiod som går under benämningen Yngre Dryas. Heralds kanjon utgjorde den initiala vattenvägen för inströmmande stillahavsvatten när Bering Sund öppnades till följd av stigande globala havsnivåer under tidig holocen (~11000 BP cal). Inflödet av näringsrikt och tempererat vatten från Stilla havet till Arktiska oceanen är av stor betydelse för den biologiska produktionen och havsisförhållandena i Tjukterhavet. Ett sätta att mäta inflödet av stillhavsvatten har varit att bestämma lermineralsammansättningen (smektit- och kloritinnehållet) i de Arktiska sedimenten. Höga halter av dessa lermineral har tolkats som en tydlig stillahavsvattensignal. I den analyserade sedimentkärnan från Heralds kanjon indikerar kornstorleksförändringar en period av erosion i samband med öppningen av Berings Sund. Halten biogent kisel ökar markant i samband med öppningen av Berings Sund och tolkas som en respons på en ökad tillförsel av näringsrikt stillahavsvatten. Lermineralsammansättningen uppvisar en större variation efter öppningen av Berings Sund men den förväntade ökningen av smektit och klorit är inte övertygande. Detta tolkas som en ökad införsel av lermineral både från Stilla havet och från Östsibiriska havet. Det sistnämnda resultatet manar till viss försiktighet i användandet av specifika lermineral som s.k. proxies för stillhavsvatten. Tappningen av Lake Agassiz via Mackenzieflodens dalgång utgör alltjämt en kontroversiell hypotes för igångsättandet av Yngre Dryas köldperiod. Fluvial erosion kring Mackenzieflodens mynning utgör idag det enda geologiska beviset för att stora mängder smältvatten nådde Arktiska oceanen vid denna tid. Däremot förekommer sedimentstudier från centrala Arktis där man hävdar att sediment från Mackenziefloden kan kännas igen på grund av sin unika mineral- och isotopsammansättning. Det saknas dock fortarande sedimentstudier i närheten av Mackenzieflodens mynning som kan belägga dessa resultat. Studiet av mineral- och isotopsammansättning (Sr och Nd) av sediment från den 81,5 m långa sedimentkärnan i Mackenziesänkan avser att delvis fylla detta behov. Resultaten visar att mineralsammansättningen och ɛNd varit relative oförändrade under det stegvisa tillbakadragandet av den Laurentidiska inlandsisen. Undantag från denna stabila trend hittas dock i en sedimentsekvens som deponerats direkt efter den lokala marina transgressionen. Dessa undantag kan möjligen vara relaterade till smältvattenpulser från tappningen av Lake Agassiz. Sammanfattningsvis indikerar resultaten från denna studie att det är tveksamt att använda den moderna mineral och isotopsammansättningen i Mackenzieflodens sediment som proxy för möjliga tappningssediment i centrala Arktis. In the wake of deglaciation – sedimentary signatures of ice-sheet decay and sea-level change Studies from south-central Sweden and the western Arctic Ocean

Henrik Swärd

This thesis is comprised of a summarizing section accompanied with the following manuscripts. Paper I and II were reprinted with permission from Taylor and Francis and John Wiley and Sons respectively.

Paper I Swärd, H., O’Regan, M., Ampel, L., Ananyev, R., Chernykh, D., Flodén, T., Greenwood, S.L., Kylander, M.E., Mörth, C.-M., Pedro, P. & Jakobsson, M. (2016). Regional deglaciation and postglacial lake development as reflected in a 74 m sedimentary record from Lake Vättern, southern Sweden. GFF 138, 336–354. doi:10.1080/11035897.2015.1055510. Paper II Swärd, H., O’Regan, M., Björck, S., Greenwood, S.L., Kylander, M.E., Mörth, C.-M., Pearce, C. & Jakobsson, M. (2017). A chronology of environmental changes in the Lake Vättern basin from deglaciation to its final isolation. Boreas. https://doi.org/10.1111/bor.12288. Paper III Swärd, H., O’Regan, M., Pearce, C., Semiletov, I., Stranne, C., Tarras, H. & Jakobsson, M. (accepted for publication in αrktos). Sedimentary proxies for Pacific water inflow through the Herald Canyon, western Arctic Ocean. Paper IV Swärd, H., O´Regan, M., Hilton, R., Vogt, C. & Andersson, P. (manuscript). Mineral and isotopic (Nd, Sr) signature of fine-grained deglacial and Holocene sediments from the Mackenzie Trough, Arctic Canada.

H.S was the main contributor in terms of analyses and writing of all four manuscripts. All co-authors have commented on the manuscripts. The field work on Lake Vättern (Paper I and II) was led by M.J. with the assistance of T.F., M.O., H.S., S.L.G. and L.A. Ideas for Paper I were developed by M.J., M.O. and H.S. The ideas behind Paper II were developed jointly by M.O., S.B. and H.S. The ideas for Paper III and IV were conceived by M.O. and M.J. and developed and executed by H.S.

The following papers/manuscripts are not included as a part of this thesis but are an outcome of the 2012, 2013 and 2014 field campaigns on Lake Vättern. Greenwood, S.L., O’Regan, M., Swärd, H., Flodén, T., Ananyev, R., Chernykh, D. & Jakobsson, M. Multiple readvances of a Lake Vättern outlet glacier during Fennoscandian Ice Sheet retreat, south-central Sweden. Boreas 44, 619–637. doi:10.1111/bor.12132 Jakobsson, M., Björck, S., O’Regan, M., Flodén, T., Greenwood, S.L., Swärd, H., Lif, A., Ampel, L., Koyi, H., & Skelton, A. Major earthquake at the Pleistocene Holocene transition in Lake Vättern, southern Sweden. Geology 42, 379-382. doi:10.1130/G35499.1 O’Regan, M., Greenwood, S.L., Preto, P., Swärd, H., Jakobsson, M. Geotechnical and sedimentary evidence for thick grounded ice in southern Lake Vättern during deglaciation. GFF 138, 355–366. doi:10.1080/11035897.2015.1055511 Introduction reaching the Earth’s surface (Hays et al., 1976) as well various internal climate feedbacks Marine and lacustrine sediments record how including ice-driven cooling, enhanced local and regional climate has changed in the warming by greenhouse gases (CO2 and CH4), past. Information from individual archives variable rates of isostatic rebound and albedo contributes to a global paleoclimate ensemble, changes (Ruddiman, 2008). Studying which together allows us to investigate glacial/interglacial transitions enhances our processes and feedbacks during periods of past knowledge of local and regional climate change. Most commonly, these large- paleoenvironmental developments and scale investigations are conducted using increases our understanding of the broader models of varying complexity. An excellent processes affecting the earth’s climate system, example is the tremendous effort that has gone existing ice sheets and glacier systems. into unravelling the causes for abrupt climate changes at the end of the last glacial cycle (e.g. Quaternary glacial/interglacial stages are Ganopolski and Rahmstorf, 2001; Claussen et identified in many marine sediment cores by al., 2003; Hubbard et al., 2005; Tarasov and variations in the δ18O composition of benthic Peltier 2005; Condron and Winsor, 2012; foraminifera (Shackleton and Opdyke, 1973). Gregoire et al., 2012; Renssen et al., 2015). Glacial stages are marked by peaks in δ18O These modelling efforts are both guided by and composition while interglacials exhibit low evaluated against geologic data – and heavy oxygen isotope signals (Fig. 1a) ultimately depend upon our ability to identify (Shackleton and Opdyke, 1973; Lisiecki and and date sedimentary signatures of key Raymo, 2005). The general increase in global environmental change. The broad focus of this benthic foraminiferal δ18O between 3 to 1 Ma thesis is on identifying and interpreting implies a generally colder climate with larger sedimentological signatures related to critical proportions of the lighter oxygen isotopes events during deglaciation. The three study being bound in ice sheets (Fig. 1a). Glacial sites are located in the Northern Hemisphere, and interglacial periods identified in these in key regions dramatically affected by glacial records have been numbered, and are referred and periglacial processes during deglaciation – to as Marine Isotope Stages (MIS). Glacial but where considerable uncertainty exists in stages are denoted with an even number and either the timing, or the sedimentary response, interglacials with and odd number (Fig. 1b). of proposed events. In particular, the thesis Over the last ~5 Ma, δ18O cycles show the aims to identify the sedimentary response to highest amplitudes for the last 0.8 Ma, marine transgression and the opening of the reflecting the more prominent ice sheet growth Bering Strait in the Arctic Ocean; the drainage and accompanying sea-level variations during of the proglacial Baltic Ice Lake through the last eight glacial stages (Fig. 1b; Lisiecki southcentral Sweden; and the potential and Raymo, 2005; Miller et al., 2005). These drainage of the North American proglacial 100-kyr glacial cycles have a pronounced saw- Lake Agassiz into the Arctic Ocean. tooth pattern, with the gradual build-up of glacial ice, followed by rapid melting during Transitions between glacial and interglacial deglaciation (Fig. 1). However, within any of climate states of the Quaternary were these glacial cycles, there is ample evidence accompanied by the immense and dynamic for dynamic and rapid climate changes. For transfer of water between oceans and ice sheets example, high-resolution paleoclimate time- (Rohling et al., 2014). In the Northern series from terrestrial, marine and ice-core hemisphere, the largest ice sheets developed records reveal more than two dozen globally after the mid-Pleistocene transition, roughly recognized abrupt events during the last glacial 1.2-0.8 Ma (Clark et al., 2006; Elderfield et al., cycle and the accompanying deglaciation (e.g. 2010). This occurred partially in response to Blockley et al., 2014; Rasmussen et al., 2014). cyclic variations in Earth’s orbit that Of the eight 100-kyr glacial cycles since the influenced the amount of solar radiation mid-Pleistocene transition, the last glacial

1

global lowstand of -134 m at 21 kyr (Fig. 3). This is recorded in both sea-level equivalent reconstructions from marine δ18O records, and more directly in numerous coral reef records from tropical latitudes (Fairbanks 1989; Lambeck et al., 2014). However, regional and local sea-level variations differ significantly from this global estimate due to the influences of glacial isostatic adjustments.

As solar insolation (65°N) began to increase, deglaciation of the Northern hemisphere (19- 11 kyr; Clark et al., 2012) was initiated (Fig. 3). The general warming trend is well constrained in δ18O ice core records (Fig. 3). In contrast to marine sediment cores, ice cores provide information on regional atmospheric signals at the time of deposition. The rapidly accumulated, annually layered ice cores also provide a robust chronology of detailed environmental changes in the late Pleistocene and Holocene (Walker, 2005) that are often difficult to acquire with less well dated, or slowly deposited marine and lacustrine sediments. This is especially true in many high latitude settings, where sediments are often devoid of calcareous microfossils used to generate both geochemical proxy records, and to develop age models (Alexanderson et al., Figure 1. Benthic δ18O record for the last 5 Ma 2014). indicating climatic fluctuations/sea-level changes (Lisiecki and Raymo, 2005). Peaks in δ18O corresponds to lowstands in global sea level estimate During the last deglaciation, Greenland ice (Miller et al., 2005). a) δ18O record for the last 5 Ma cores reveal two major stadials (GS-2 and GS- indicating a colder climate during the last 3 Ma that 1) that interrupted the general climate stabilizes at 0.8 Ma. The increasing amplitudes amelioration (Rasmussen et al., 2014). These indicates larger variations between colder and are commonly referred to as the Oldest Dryas warmer periods. b) Benthic δ18O record for the last (OD: >14.7 kyr BP) and Younger Dryas (YD: 0.8 Ma showing the last ~18 glacial cycles. Maxima ~12.9-11.7 kyr) respectively (Rasmussen et al., (glacials) are denoted with their marine isotope stage 2006; Fig. 3). Between these stadials the (MIS). Bølling-Allerød interstadial (GI-1: 14.7-12.9 kyr) is further divided into five substages (GI- cycle is the most well-studied, and arguably 1a to GI-1e) indicating minor climatic provides the most comprehensive view of the fluctuations within this warmer period processes and impacts associated with (Rasmussen et al., 2014). The enigmatic YD Quaternary glaciations. Vast areas in the stadial has long been considered a rather Northern Hemisphere were covered by ice or unique climate anomaly with no parallel during denudated during this glacial period (Fig. 2; the last three deglaciations (Petit et al., 1999). Ehlers and Gibbard, 2007). Sea level However, Broecker et al., (2010) suggest that reconstructions for the Last Glacial Maximum similar cold reversals may have occurred (LGM: 26.5-20 kyr; Clark et al., 2009) during previous terminations, based on equivalent to MIS2, indicate a maximum Bølling-Allerød and YD like events at the end

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Figure 2. Northern hemisphere ice sheets extension during Last Glacial Maximum (white shaded areas). White bathymetric contour is the 120 m isobath, suggesting the extent of exposed shelf areas around the LGM. The region from the Alaskan Peninsula to Eastern Siberia constituted Beringia. Yellow rectangles indicate study areas in this thesis. Manuscripts I & II = Lake Vättern, III = Herald Canyon, IV = Mackenzie Trough. Ice sheet limits based on reconstruction from Ehlers and Gibbard (2007), Jakobsson et al., (2014b), and Patton et al., (2016). of MIS8 (Termination III) recorded in relatively abrupt increase of glacier derived speleothem records from China (Chen et al., freshwater input to the North Atlantic, 2009). Still, the cause of the enigmatic YD resulting in a considerable slowdown of the cold event continuous to baffle Quaternary Atlantic Meridional Overturning Circulation scientists. How is it possible to have an abrupt (AMOC). A diminished AMOC would and major global reversal in warming when decrease the heat flux to the northern northern summer insolation is steadily hemisphere and thereby possibly trigger a increasing and ice sheets are melting? colder climate (Clark et al., 2001). Notably, the most prominent meltwater pulses during the The most accepted ideas concerning the cause last deglaciation (mwp1-a: 13.9 kyr and of the Younger Dryas cold reversal include a mwp1-b: 11.1 kyr) occurred without

3 subsequent cold events (Moore, 2005). Hence, prescribing disruptions of the AMOC by a general meltwater pulse is not straightforward. Although, massive melting of thick sea ice (Bradley and England, 2008) and excessive ice berg calving (Heinrich, 1988; Bond and Lotti, 1995) have been suggested as possible sources of freshwater, the sudden drainage of North American proglacial lakes into the North Atlantic is the more common explanation for triggering the YD (e.g. Broecker et al., 1989). Although similar dramatic outbursts of freshwater occurred from the Baltic Ice Lake (BIL), dating of this event has classically placed it at the end of the YD (Björck et al., 1996), and therefore it has not been considered as a potential triggering mechanism.

Drainage of the North American proglacial Lake Agassiz preceded the YD in time and has therefore been envisaged as a likely triggering mechanism (Broecker, 2006). The drainage routes for Lake Agassiz has remained a longstanding controversy, with possible routes via the Mississippi River to the South, the St Lawrence River to the East, and the Mackenzie River, draining to the North and into the Arctic Ocean (e.g. Broecker et al., 1989; Clark et al., 2001; Carlson et al., 2007). Numerous modelling studies have investigated the sensitivity of AMOC to freshwater input under these different scenarios (Tarasov and Peltier 2005, 2006; Peltier et al., 2006; Condron and Winsor, 2011; Condron and Winsor, 2012). These all tend to show that freshwater draining into the Arctic is the only way that drainage of the North American proglacial lakes could have directly affected the AMOC. Geologic Figure 3. Summer insolation at 65°N (Laskar et evidence for intense fluvial erosion across the al., 2004), global sea-level curve (Lambeck et al., Tuktoyaktuk Peninsula in Arctic Canada (close 2014) and NGRIP δ18O record (Rasmussen et al., to the Mackenzie River mouth) has been dated 2014) for the last deglacial period (27 - 0 ka BP). to the onset of the YD (Murton et al., 2010), but whether this freshwater pulse actually While captured in a plethora of global triggered the YD remains a very controversial paleoclimate and oceanographic time series, question. Furthermore, new evidence for an detailed regional and local geologic studies are earlier freshwater pulse exiting the proglacial required to test competing hypotheses for the Baltic Ice Lake (BIL) might also be related to proposed triggering mechanisms of the YD, the slowdown of the AMOC (Bodén et al., and more broadly to help resolve the intricate 1997; Muschitiello et al., 2015 and 2016). feedbacks between ice-sheets, sea level and Hence, a combination of factors causing the global climate. The dramatic processes slowdown of AMOC cannot be excluded.

4 isostatic rebound make these environments highly dynamic. The opening of new waterways reshape the proglacial lakes and, occasionally, allow them to drain completely into lower lying basins. This type of environment constitutes the first study site of this thesis, where the Scandinavian ice sheet and regional isostatic response, led to the damning of the Baltic Sea, and the development of the

massive proglacial Figure 4. Terminus on Icelandic glacier with loads of unsorted terrigenous Baltic Ice Lake. material (dirty ice). Sediment accumulates associated with deglaciation (i.e. vast ice sheet rapidly in proglacial decay, catastrophic drainage of proglacial lakes and often form seasonal layers with a lakes, significant sea-level rise, variations in thicker summer layer and a thinner winter sea-ice extension and reconfigurations of layer, together constituting a varve (De Geer, oceanic circulation) are imprinted in 1940). Varves formed close to the retreating sedimentary archives. The melting of ice margin are considerably thicker than varves continental ice sheets releases large amounts of formed in far-field locations indicating the encapsulated terrigenous material and can importance of the ice margin position to leave thick sedimentary deposits on local and sedimentation rates. In addition, well- regional scales. These processes have their developed varved clays have frequently been analogues in modern glaciated areas where used as a chronological marker since the early th glaciers terminating in marine and lacustrine 20 century (e.g. De Geer, 1908 and 1940). environments deposit considerable amounts of till and suspended sediment (Fig. 4). Due to During the last glacial cycle, the major the unique processes associated with Northern Hemisphere ice sheets all terminated entrainment and transport of terrigenous on the shelves of the Arctic Ocean (Jakobsson material in glacial environments, these et al., 2014b). Here they delivered vast sediments can have distinct mineral and amounts of sediment to the shelves and geochemical compositions compared local continental slopes, where ice streams drained sediments deposited under ice-free or ice-distal into the sea ice covered Ocean. Due to the conditions. many logistical difficulties associated with sediment coring and drilling in the Arctic In particular, the decay of an ice sheet releases Ocean (Polyak and Jakobsson, 2011) and in a slurry of mostly minerogenic particles of dating Arctic marine sediments (Alexanderson various sizes suspended in melt waters. In a et al., 2014), it remains challenging to piece terrestrial deglacial environment, this slurry is together the glacial history of the Arctic. The often trapped between the direct glacial Arctic Ocean has many unique features deposits (e.g. terminal moraines) and the including the limited exchange with other retreating ice margin, forming proglacial lakes oceanic basins, large and shallow continental (Fig. 5). Ice margin retreat and concomitant shelves that were exposed during glacial sea-

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Figure 5. Proglacial lake forming between a glacier margin (left) and moraine ridges (right) deposited by earlier ice margin standstill or readvance. Notable is the brown color of the water indicating a high content of suspended material. Skaftafjellsjökull, southeastern Iceland May 5th, 2011. Photo: Óðinn, https://commons.wikimedia.org/wiki/File:Skaftafellsj%C3%B6kull_panorama.jpg; Accessed 2017-12-20. level lowstands, and its perennial sea-ice cover proximal and far field sedimentary records (Stein, 2008). These features influence from the Arctic Ocean (Stein, 2008 and sediment transport and distribution. references therein). These studies, which tend to focus on the mineral composition and grain In this special environment, sediment size characteristics of marine sediments, need entrainment by sea-ice (Fig. 6) constitutes an to be anchored in well-defined end-member important process for redistribution of characteristics for sediments delivered by sediments from the broad shelves to the deep different transport mechanisms from the basins and isolated ridges that cover the Arctic geologically distinct provinces that surround Ocean floor (e.g. Stein and MacDonald 2004; Dethleff 2005; Eicken et al., 2005; Darby et al., 2011). The shallow regions (<50 m) of the Arctic shelves are the major sites of sea-ice entrainment, which are subsequently distributed via surface currents (i.e. the Beaufort Gyre and the Transpolar Drift; Fig. 7) to far-field areas in the central Arctic (e.g. Bischof and Darby, 1997). In addition, substantial amount of current transported ice rafted debris derive from the extensive calving of ocean terminating glaciers (e.g. Nørgaard- Pedersen et al., 1998; Phillips and Grantz 2001). During Glacial periods and deglaciation, there was likely a much more pronounced input of meltwater transported and iceberg rafted material into the Arctic Ocean Figure 6. Sediment entrainment in the lower (Polyak and Jakobsson, 2011). Considerable layers of sea-ice, Chukchi Sea. Photo: current research is focused on reconstructing Sandra Gdaniec. circum-Arctic ice sheet dynamics using

6 or ice-proximal sedimentation. Modern sedimentary plumes from river mouths evidence substantial transport of suspended material by coastal currents both along and distal from the river mouth (Fig. 8; MacNeill and Garrett, 1975; Giovando and Herlinveaux, 1981; Macdonald et al., 1999). Together, the four major Arctic rivers (Yenisei, Lena, Ob and Mackenzie; Fig. 7) deliver 1861 km3 freshwater and 165x106 ton suspended matter annually (Holmes et al., 2002). While the Russian rivers are the major contributors of freshwater, the suspended material from the Mackenzie River (MR) exceeds the sum of annual sediment input from all other Arctic rivers (Macdonald et al., 2004) making Figure 7. Map of the Arctic Ocean (IBCAO, Jakobsson et al., it the dominant circum-arctic riverine 2012) including the major rivers draining the circum-arctic sediment supplier. In contrast, coastal borderland (yellow arrows). White arrows indicate the erosion is thought to be more limited prevailing surface currents responsible for water and sea-ice along the Canadian Beaufort Sea transport from the shelves towards the central Arctic Ocean. coastline (Macdonald et al., 1998) Orange arrows indicate the main branches of Pacific water while it is a prominent sediment source entering the Arctic Ocean via the Bering Strait. MR = in other parts of the Arctic. For Mackenzie River, BS = Beaufort Shelf, CS = Chukchi Shelf, example, ratios of sediment supply CB = Canada basin, EB = Eurasian basin. Surface currents from coastal erosion to riverine input is adapted from Rudels et al., 2012. 2:1 in the Laptev Sea, Siberia (Rachold the Arctic Ocean (Stein, 2008). Two of the et al., 2000) and 6:1 in areas around the studies in this thesis focus on sediment cores Colville River mouth in Northern Alaska taken on the shelves (Beaufort Shelf and (Macdonald et al., 1998). Chukchi Shelf; Fig. 7) of the Arctic Ocean. In the wake of deglaciation, vast amounts of The deglacial history of these regions is sediment are distributed into sedimentary particularly pertinent to understanding the basins either directly as plumes of fine-grained transition from glacial to interglacial climate material or indirectly as ice rafted debris states. The Beaufort Sea contains sedimentary through calving ice sheets or sea-ice archives that can help constrain the possible entrainment. These sediments can have unique magnitude and timing of glacial meltwater mineralogic, grain size and geochemical outbursts routed through the Mackenzie River signatures. By studying the physical, chemical corridor. Sediments from the Chukchi Sea and biological imprints of dated deglacial provide an opportunity to investigate the sediment cores, we can decipher important timing and consequences for the inundation of local and regional interactions between the the Bering Sea and the inflow of Pacific waters waxing and waning of ice sheets, sea-level to the Arctic Ocean. changes and water mass exchange.

Contrasting with the more varied transport For this thesis, one lacustrine (Lake Vättern, mechanisms for deep-sea sediments, sediment south-central Sweden) and two marine delivery to the shelves mainly occurs via sediment cores (Herald Canyon and Mackenzie riverine input and coastal erosion (Stein, Trough, western Arctic Ocean) were 2008), or during glacial periods by subglacial investigated using a wide range of analytical 7 methods with the ultimate aim to identify, test, sedimentological evidence, an earlier drainage and/or interpret sedimentological proxies for event during the Late Alleröd (~12.8 cal. kyr important regional environmental changes BP), has only been suggested based on a during deglaciation. limited amount of geological evidence. This includes shore level displacements from the southern Baltic Sea, late glacial varve chronologies and drainage deposits, and the δ18O composition of foraminifera in a marine core from the North Sea (Bodén et al., 1997). In the Arctic Ocean, numerous studies have suggested mineralogic proxies for fingerprinting Pacific water inflow, but the robustness of these proxies has not been tested in well-dated and proximal records. Finally, the hypothesis for catastrophic outflow from glacial Lake Agassiz into the Arctic Ocean at the onset of the Younger Dryas has recently been argued based on sedimentary and isotopic signatures of sediments from the central Arctic Ocean and Fram Strait. However, no complementary Figure 8. Satellite image from the Mackenzie River data set exists from sites proximal to the mouth, Nov 11th, 2011. Notable is the prominent sediment Mackenzie River to define the end-member plume carried offshore and alongshore by surface currents composition of Mackenzie River sediments, before dispersing into the sea. Source: Chelys SRRS and how they may have changed during (Satellite Rapid Response System). deglaciation. In each of these regions, there is http://www.eosnap.com/tag/mackenzie-river/ Accessed a need to 1) better define the 2017-11-14. sedimentological signature of deglacial changes, and 2) more accurately date the Thesis objectives timing of these events. The objectives for this thesis are to use The detailed scientific objectives for each sedimentary properties to either refine our paper are outlined below. understanding, or improve our ability to reconstruct, deglacial to Holocene Papers I and II paleoenvironmental changes at three sites: Lake Vättern in south-central Sweden, Herald Swärd, H., O’Regan, M., Ampel, L., Ananyev, Canyon and the Mackenzie Trough, both in the R., Chernykh, D., Flodén, T., Greenwood, western Arctic Ocean. All of these regions S.L., Kylander, M.E., Mörth, C.-M., Pedro, P. have a unique place in discussions about global & Jakobsson, M. (2016). Regional deglaciation climate change during deglaciation – but and postglacial lake development as reflected considerable uncertainty exists in either the in a 74 m sedimentary record from Lake timing, or the sedimentary response, of Vättern, southern Sweden. GFF 138, 336–354. proposed events. doi:10.1080/11035897.2015.1055510. Far-field sedimentary records have been used Swärd, H., O’Regan, M., Björck, S., to infer the existence and timing of important Greenwood, S.L., Kylander, M.E., Mörth, C.- deglacial processes and events in each of the M., Pearce, C. & Jakobsson, M. (2017). A regions. For example, while the final drainage chronology of environmental changes in the of the Baltic Ice Lake has been constrained to Lake Vättern Basin from deglaciation to its 11.7 cal. kyr BP, based on a wide range of final isolation. Boreas. doi:10.1111/bor.12288. regional geomorphological and

8 Lake Vättern was deglaciated between ~14-11 can be identified by, the composition of marine kyr BP (Lundqvist, 2009) and was heavily sediment cores from the western Arctic Ocean. affected by the interplay between periodically Furthermore, this study aims to better constrain encapsulated meltwater from the decaying the depth (age) for the opening of the Bering Fennoscandian Ice Sheet and isostatic rebound Strait by using high-resolution grain size and following its retreat. The main objective for biogenic silica data as proxies for Pacific water Paper I is to investigate and describe the inflow. deglacial to Holocene development of the Paper IV Vättern Basin by establishing a lithostratigraphy of a 74 m sediment core Swärd, H., O´Regan, M., Hilton, R., Vogt, C. (VAT12) recovered at 95 m depth in southern & Andersson, P. (manuscript). Mineral and Lake Vättern. Changes in bulk density, shear isotopic (Nd, Sr) signature of fine-grained strength, magnetic susceptibility, elemental deglacial and Holocene sediments from the data, pore water chemistry, total organic Mackenzie Trough, Arctic Canada. carbon, total inorganic carbon, grain density and grain size distribution are used to While terrestrial studies have documented reconstruct the sequence of ice recession in the evidence of intense fluvial erosion in the Vättern Basin and to tie the stratigraphic region of the Mackenzie River at the onset of changes to major lake development stages. the Younger Dryas (Murton et al., 2010), complimentary proximal marine records do not The main objective for Paper II is to establish a yet exist to support this. Instead, there is a radiocarbon chronology for the key growing tendency to look for Mackenzie River sedimentary transitions identified in VAT12 in sedimentary signatures in far-field records order to date the major lake development from the central Arctic Ocean. However, very stages described in Paper I and possibly tie little information exists on the mineral or them to the general Baltic Sea development isotopic composition of deglacial and stages (i.e. Baltic Ice Lake, Yoldia Sea, Holocene sediments from the Mackenzie Ancylus Lake and Littorina Sea). In addition, a River. The primary research questions more detailed presentation of the mineralogy motivating this paper were: Is the MR a and elementary composition of VAT12 significant source of dolomite to the Arctic sediments is presented to further delineate ice Ocean? Does the provenance of sediments in recession in the Vättern Basin. the MT change from deglacial to Holocene deposits? Are there any provenance changes Paper III that may suggest sediment transport from Swärd, H., O’Regan, M., Pearce, C., freshwater outburst(s) of proglacial Lake Semiletov, I., Stranne, C., Tarras, H. & Agassiz? To address these questions the Jakobsson, M. (accepted for publication in mineralogy and Sr/Nd isotopic signatures of αrktos). Sedimentary proxies for Pacific water sediments are investigated from an 81.5 m inflow through the Herald Canyon, western deglacial to Holocene sedimentary sequence Arctic Ocean. (MTW01) recovered from the Mackenzie Trough (MT), Beaufort Shelf, Northwestern The Herald Canyon (HC) in the western Canada. Chukchi Sea was likely the initial waterway between the Pacific and Arctic Oceans as Background Beringia was flooded during global sea-level rise of the last deglaciation. Due to the shallow Lake Vättern nature of the Bering Strait sill, this important Lake Vättern (57°46’54’’-58°52’48’’ N, pathway for oceanic exchange was repeatedly 14°06’37’’-15°02’20’’ E) constitutes a striking shut-off during Quaternary glacial periods. landmark in southern central Sweden This study aims to better define how the inflow stretching 140 km in NNE-SSW direction with of nutrient rich Pacific water influences, and a maximum width of 30 km (Fig. 9). It is the

9 second largest lake in Sweden with an area of 1893 km2 and a volume of 77.6 km3. The Vättern Basin is a graben (Axberg and Wadstein, 1980) formed by successive faulting that largely ended by 290-240 Ma (Månsson, 1996). The graben structure is clearly visible in the landscape with pronounced relief on both sides of the elongated lake (Fig. 9) Furthermore, bathymetric measurements in the 1960s revealed a deep trough along the eastern coastline (Norrman, 1964; Fig. 9) that aligns with other local fault zones north and south of the lake (Bingen et al., 2008). The deepest parts of the lake are found south of Visingsö Island where depths up to ~120 m are recorded (Greenwood et al., 2015). Precambrian granites surround the lake but the underlying bedrock of the basin consists of a Neoproterozoic to Phanerozoic sequence of sedimentary rocks (i.e. sandstones and shales) called the Visingsö Group (Wik et al., 2006; Lundqvist et al., 2011). From a Quaternary perspective, the location of Lake Vättern makes it a focal point for deciphering patterns of ice recession during the last deglaciation. The surrounding terrestrial deglacial morphological features (e.g. end Figure 9. Lake Vättern a) location in southern central moraines, striae, drumlins, eskers, outwash Sweden b) geographic relief around the lake (Lantmäteriet) and bathymetry of the lake according to plains) have been used extensively for more Norrman (1964). The fault zone of the Vättern Basin is than a century to reconstruct the withdrawal reflected in the bathymetry by the deep trough along the of the Fennoscandian Ice Sheet (FIS) (e.g. De eastern shoreline but also in the steep relief, that Geer 1884; Munthe 1910; Nilsson 1968; surrounds the basin in the southern and western parts. Vi Berglund 1979; Lundqvist and Wohlfarth = Visingsö Island. The yellow star indicates the drill site 2000; Stroeven et al., 2016). Of these for VAT12. Map is modified from Swärd et al., 2015. features, the prominent end moraines of southwestern Sweden have been used to mark Vättern Basin between 13-14 kyr BP and the periods of significant standstill/readvance of ice margin left the northern parts at ~11.3 kyr the ice margin and correlated with episodes of BP (Fig. 10). Recently, Greenwood et al., cooling that occurred since LGM (Fig. 10). (2015) showed that up to three recession- Together with local clay varve chronologies readvance cycles are recorded in seismic (Strömberg, 1994; Brunnberg, 1995), these profiles from southern Lake Vättern before the glacial deposits have been used to construct ice readvance associated with the Levene ice theoretical ice recession lines that describe the marginal line (13 kyr BP; Fig. 2 in Paper II) general pattern and timing of ice recession indicating that the ice margin in the basin was across southern Sweden (e.g. Lundqvist and in part decoupled from the terrestrial ice Wohlfarth, 2000; Stroeven et al., 2016; Hughes margin movements. The deglacial et al., 2016). Following the ice marginal lines development of the Vättern Basin, including presented by Stroeven et al., (2016), the proglacial lake stages and accompanying northward retreat of the Fennoscandian Ice drainage routes, were thoroughly described by Sheet (FIS) uncovered the southern tip of the Erik Nilsson (1939, 1953, 1958, 1968) mainly

10 Wadstein, 1982; Greenwood et al., 2015). However, at present only one deep borehole has recovered sediments from the lake bottom (Paper I, II). Sedimentary investigations performed before drilling in 2012 (Paper I) were limited to grab samples or short gravity and piston cores (Ekman, 1914; Norrman, 1964; Norrman and Königsson, 1972; Björck et al., 2001). An extensive field campaign in southern and central Lake Vättern during 2012-2014 included multibeam echo sounding, sub-bottom and seismic reflection profiling, and the recovery of a 74 composite sediment core VAT12 (Fig. 9). The scientific outcomes of this Figure 10. Ice recession lines (white) from Stroeven et al., (2016) on top of campaign have highlighted end moraines of southern Sweden (yellow). Ages for ice recession lines are (i) Postglacial neo-tectonic given in kyr BP. The black ice recession line marks the ice margin at the onset activity in the Lake of YD (12.7 kyr BP). Map is modified from Stroeven et al., (2016). Vättern Basin and associated mass wasting through regional paleo-shoreline studies. These along the steep subaqueous slopes of Visingsö include (i) various stages of the proglacial (Jakobsson et al., 2014a; 2016), (ii) at least Lake Vättern (Fig. 11a), (ii) the incorporation four ice marginal retreat/readvance cycles of the proglacial lake Vättern into the growing since the initial deglaciation of the Vättern BIL, (iii) the drainage of BIL into the North Basin (Greenwood et al., 2015), (iii) Sea followed by rapid northward ice margin glaciotectonized sediments derived from a withdrawal and subsequent incursion of marine major ice margin readvance at ~13 kyr (O’Regan et al., 2016) and (iv) a marine waters (Fig. 11b), (iv) isostatic rebound and incursion contemporary with a first drainage of the formation of the Ancylus Lake (Fig. 11c) the BIL just before the YD cold period (Paper and eventually (v) the opening of the Danish I, II). Straits and a fully marine environment during the Littorina stage (Fig. 11d). While the details Mackenzie Trough of Nilsson’s various lake stages have been revised since the 1960s, the main ideas for the Northwest of the MR delta, the submarine deglacial development of the Vättern Basin Mackenzie Trough (MT; 69° 52’ 0’’ N, 138° being in close connection to the wider 10’ 0’’ W) stretches ~170 km offshore in a development of the Baltic Sea still remain northwest direction with a maximum width of relevant (Paper I, II). ~75 km (Shearer, 1971) (Fig. 12). Seismic profiles from the MT indicate up to 500 m of The sediments in Lake Vättern are a promising sediment including two subglacial till units paleoenvironmental archive, with up to 300 m interpreted as remnants of two major ice of unconsolidated deposits in the central and streams that likely excavated the trough during southern part of the basin (Axberg och the last glacial cycle (Batchelor et al., 2013).

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Figure 11. Development of the Vättern Basin according to Nilsson (1968). a) The proglacial Lake Tidan- Vättern captured between Mt Billingen to the west, the ice margin in the north and the southern Swedish highlands in the south. Drainage routes to the west and to the east (into the BIL) are denoted with small arrows. b) The Yoldia Sea stage following the final drainage of the BIL. The Vättern Basin was a part of the sea. c) The Ancylus Lake stage – the result of isostatic rebound in westerns Sweden that closed the major inlets and formed a closed Baltic basin. A preliminary stage of the present Lake Vättern is forming. d) The Littorina Sea – isostatic rebound and sea-level rise led to the isolation of Lake Vättern.

12 Stokes and Tarasov, 2010; Fritz et al., 2012; Peltier et al., 2015).

In 1984, the Geological Survey of Canada drilled an 81.5 m borehole (MTW01) in the landward end of the Mackenzie Trough. The borehole contains a deglacial progradational deltaic sequence, overlain by transgressive phase deposits that grade into a fully marine depositional environment (Moran et al., 1989; O’Regan et al., in review; Paper III). These three broad subdivisions are interpreted to be separated by disconformities. The sedimentary changes are primarily driven and explained by sea-level rise during deglaciation (Hill 1996). Regional studies confirm that sea level during deglaciation indeed increased from -117 m Figure 12. Northwestern Canada and the Mackenzie Trough (yellow star). after the LGM (Peltier et Ice recession lines for the withdrawal of the Laurentide Ice Sheet (LIS) with al., 2015) to -66 m in the ages denoted in kyr BP. Notable is the location of the Mackenzie Trough at Early Holocene (O’Regan the rim of the LIS at 18 kyr BP. Tu = Tuktoyaktuk peninsula. Ice recession et al., in review) but this lines after Stokes and Tarasov (2010) & Dyke (2004). process was heavily affected by rapid isostatic This idea is consistent with terrestrial data rebound until ~12 kyr BP indicating two ice margin advances from the (Peltier et al., 2015). However, due to poor Laurentide Ice Sheet (LIS) through the chronological constraints, it remains unclear if Mackenzie Valley during MIS 2-4 (Rampton, the origin of the erosional unconformities 1982; 1988). Situated at the northern rim of the between the delta deposits/transgressive LIS during the LGM, this region was strongly phase/shelf deposits may also have occurred affected by glacial and periglacial processes from pulses of meltwater from the Mackenzie during deglaciation (e.g. Fritz et al., 2012; Valley. Reworking of sediments prior to Jakobsson et al., 2014b). Although marine transgression at MTW01 was recently considerable debate exists concerning the suggested by Murton et al. (2010) and extent and timing of glacial ice in the Beaufort potentially correlated to morphological Sea (Jakobsson et al., 2014b), the modeled evidence for freshwater outbursts along the margin of the Laurentide Ice Sheet retreated Tuktoyaktuk Peninsula (Fig. 12; Murton et al., southeastwards from the MT between 18-16 2010). These finding are the first physical kyr BP (Fig. 12) but did not leave the MR evidence for a northern drainage route of catchment area until ~10 kyr BP (Dyke, 2004; proglacial Lake Agassiz. This route has been suggested to be the most likely one in terms of outburst waterways (Tarasov and Peltier, 2005)

13 and in terms of efficiency to slow down the a considerable effect on biological production AMOC enough to trigger the YD cold event in the surface waters of the Chukchi Sea (Condron and Winsor 2012). (Walsh et al., 1989). Furthermore, increased inflow of high temperate surface waters The only marine evidence put forward in through the Bering Strait is thought to be one support of a Mackenzie River meltwater of the major causes for the rapid decline of outburst preceding the YD was published by sea-ice in the Chukchi Sea since the 1970s Not and Hillaire-Marcel (2012). They (Serreze et al., 2016). In 2017, both the spring suggested that increased dolomite levels in and the autumn ice cover of Chukchi Sea cores from the central Arctic originated from a reached all time lows, suggested to be caused YD freshwater outburst via the Mackenzie by a combination of strong and prevailing Valley. As the sediment loaded freshwater northerly winds and increased southerly warm pulse reached the Arctic Ocean, fine-grained currents that allow for breaking and melting of sediments were entrained into sea ice and substantial amounts of sea-ice (Fig. 14). transported via the Beaufort Gyre into the central Arctic (Not and Hillaire-Marcel, 2012). Unlike large parts of the circum-Arctic This idea is based on the fact that Northern landmasses, the eastern parts of Siberia and the Canada is the only substantial circum-Arctic coastal regions of Alaska were not glaciated dolomite rich area (Stein, 2008). While the during the LGM (Fig. 2). This had profound Northern Canadian Archipelago has long been consequences for the distribution of life in envisaged as a major contributor of ice rafted these periglacial environments. In the 1930s, dolomites to the Arctic Ocean during deglacial the Swedish botanist Erik Hulthén (1937) periods (Bischof et al., 1996; Phillips and studied the distribution of arctic and boreal Grantz, 2001), Not and Hillaire-Marcel (2012) biota along the coastlines of Siberia and North argue that the MR catchment area is a America. Incorporating the growing dominant source for fine-grained, river knowledge of glacials/interglacials and transported dolomite. MTW01 provides a subsequent sea-level changes, he suggested valuable deglacial to Holocene record of that the distribution of biota was affected by a riverine input. While the chronology of the recurrent land bridge between Eurasian and borehole has recently been improved (O’Regan North America during and after glacial stages et al., in review), it remains too coarse to (Fig. 15). He called this land bridge Beringia exactly pinpoint Younger Dryas aged (Hultén, 1937). As paleo sea level data became sediments. Instead, the mineral and isotopic available, it was concluded that vast areas of composition of these sediments can be used to the present Siberian and Alaskan shelves were characterize the sedimentary signature of MR above sea level following the LGM (Fig. 2; sediments delivered to the Arctic Ocean, and e.g. McManus et al., 1983). The idea of a investigate how/if they have changed during deglacial land bridge over Bering Strait have deglaciation. later been used to partly explain human migration into North America during early Herald Canyon Holocene (Goebel et al., 2008), thus marking a crucial point in human history. Herald Canyon is a submarine valley located between Wrangel Island and the Herald Shoal During the SWERUS-C3 expedition in 2014, a in the western Chukchi Sea (Fig. 13). It unique sediment core (SWERUS-4-PC1) from stretches in a N-S direction from the Chukchi Herald Canyon was recovered that shed new Shelf where it deepens and merges into the light on the deglacial transgression of Beringia Chukchi Plain (Fig. 13). Herald Canyon (Jakobsson et al., 2017; Cronin et al., 2017). constitutes one of the two main waterways for The core was recovered in a drift deposit on Pacific waters into the Arctic Ocean, the other the eastern flank of the Herald Canyon at 120 is Barrow Canyon adjacent to the Alaskan m water depth (Fig. 13). SWERUS-4-PC1 coastline (Fig. 13). It has therefore been the captured the sedimentological transition focus of numerous physical oceanographic associated with the opening of Bering Strait studies (e.g. Pickart et al., 2010; Woodgate and and was dated to 11 cal kyr BP (Jakobsson et Aagaard, 2005). The inflowing nutrient-rich al., 2017). This date is later than previous and warm waters of Pacific Ocean origin have studies suggested (e.g. Elias et al., 1992;

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Figure 13. Herald Canyon in the Chukchi Sea including the location of 4PC-1. Inset highlights local bathymetry east of Wrangel Island including the Herald Canyon (HC), the Herald Shoal (Hs) and the Barrow Canyon (BC) adjacent to the Alaskan coastline. Bathymetry from IBCAO (Jakobsson et al., 2012). Keigwin et al., 2006; England and Furze, to have implications for climate stability in the 2008). The expected influence of nutrient rich Northern hemisphere (e.g. De Boer and Nof, water after the opening of the Bering Strait is 2004; Hu et al., 2012). Specifically, recovering nicely shown in a distinct increase in both the opening of the Bering Seaway in this δ13C, biogenic silica and a faunal change over record allowed an investigation into how the associated sedimentary transition sediment composition in a proximal sediment (Jakobsson et al., 2017; Cronin et al., 2017). core was influenced by the inflow of nutrient Studies of benthic foraminifera and ostracod rich Pacific waters, and whether a robust species in this core also refined the local sea- mineralogic proxy could be defined for Pacific level changes during the YD/Holocene water inflow. transition (Cronin et al., 2017). The sediments in SWERUS-4-PC1 from Herald Canyon Methodology provided an opportunity to enhance our knowledge of the timing and processes Methodologically, this thesis includes the associated with the opening of a Pacific-Arctic study of sediment cores using a broad range of waterway – an opening that has been suggested analytical techniques to obtain physical,

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Figure 14. Sea-ice distribution in the Chukchi Sea 2017 in a) May and b) November indicating strong effect of Pacific water inflow to the sea-ice extent in the region. Pink line indicate median ice edge 1981-2020. Sources: a) NOAA Climate.gov NWS Alaska Sea Ice Program, https://www.climate.gov/news- features/featured-images/low-sea-ice-chukchi-sea-alaska/ Accessed 20180106. b) National Snow and Ice Data Center, http://nsidc.org/arcticseaicenews/2017/12/record-low-extent-in-the-chukchi-sea/ Accessed 20180106. chemical, and biological proxies to interpret The Geological Survey of Canada drilled the paleoenvironmental changes. 81.5 m borehole from the Mackenzie Trough (MTW01) in 1984 from the drill rig Arctic Coring Kiggiak at a water depth of 45 m. Only specific The sediment cores analyzed in this PhD thesis intervals of the borehole were sampled, but an were recovered using two different techniques: adjacent piezocone penetrometer profile (i) drilling/rotary coring from a sea/lake based provided information to construct a full drill rig and (ii) piston coring from the side of a sedimentological sequence (Moran et al., ship/barge. The majority of analyzed sediment 1989). Samples from this borehole were cores from southern Lake Vättern were acquired from the GSC-Atlantic core obtained from a drilling platform (barge) repository in Canada. anchored at a water depth of 90-95 m. Five During the SWERUS-C3 expedition, core adjacent boreholes were drilled using an HQ SWERUS-L2-4-PC1 (hereafter referred to as wire line drilling system with HQ-3 plastic 4-PC1) was recovered using a 12 m piston liners (length 3 m, inner ׎ 63 mm and outer ׎ corer (Kullenberg, 1947) from the aft deck of 65 mm) where sediment from the lake floor IB Oden (Jakobsson et al., 2017). The core was down to 74 m below lake floor was recovered. retrieved in liners with an inner ׎ of 100 mm The recovered 3 m cores were cut into 1.5 m .and an outer ׎ of 110 mm sections and stored at +4°C. In addition, two 5 m piston cores were taken from the side of the Overview of analytical methods (Paper I, II, III barge allowing better recovery of the upper and IV) less compacted sediment. A composite core from the five boreholes was constructed using An extensive number of methods have been high-resolution physical property used to collect data for this thesis including measurements performed on the GEOTEK methods to determine the physical, Multi-Sensor Core Logger at Stockholm geochemical and mineralogical properties of University. sediments (Tab. 1). These include non- destructive and destructive methods. The non-

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Figure 15. The Bering Strait region with bathymetry as viewed by Hultén (1937). Although Hultén did not know the extent of sea-level rise during deglaciation, he assumed that large parts of the present sea floor were above sea-level - forming Beringia. He argued that this landmass existed for a substantial amount of time after the LGM, allowing easy transfer of plants and animals. The yellow star indicates the location of the Herald Canyon and sediment core 4-PC1. destructive and high-resolution methods Radiocarbon dating include (i) whole core analysis by a Multi Radiocarbon dating was initiated in the 1950s Sensor Core Logger (MSCL) used to generate by Willard Libby (Libby, 1952) and has since bulk density and magnetic susceptibility data become an invaluable standard routine for the and (ii) split core analysis including optical Quaternary research society. The method is imaging on the MSCL, X-ray fluorescence based upon the exponential radioactive decay (XRF) scanning using an ITRAX XRF core of 14 scanner to generate elemental data and X- ray C with a half-life of 5568 years. Originating in the upper atmosphere, 14C reacts 14 images for structure visualizations. Destructive with oxygen to form CO2 and is subsequently methods include sampling for grain size, grain transferred to the lower atmosphere and the density, total organic carbon (TOC), δ13C, 14C oceans where it is incorporated into living dating, mineralogy and Sr and Nd isotopic organisms via photosynthesis and marine composition. The shear strength measurements calcifiers. Thanks to the continuous resulted in mechanical impact on the sediment atmospheric input, the 14C content of living surface but without removal of any material. organisms is kept stable during its lifetime. However, following death the incorporation of Finally, the pore waters of VAT12 were new 14C atoms ends and radioactive decay acquired using Rhizon samplers (Dickens et solely affects the 14C content. Hence, a al., 2007) that have a minor destructive effect radiocarbon age (<~45 000 years) can be on the sediment cores. Of special interest to acquired by comparing the 14C of a particular this thesis are the radiocarbon dating and the sample with the normal 14C content in living X-ray diffraction methods both presented in organisms. more detail below.

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Table 1. Overview of methods used in this thesis.

Non-destructive Data Paper Method Equipment (N) generated /Destructive (D) Bulk density, Multi-Sensor Core I GEOTEK MSCL N Mag. Susc. Logging (MSCL) D Fall cone test Controls 22-T0029D and Shear (external force I and handheld Geotester pocket strength applied to penetrometer penetrometer sediment) D Helium displacement Micromeritics Accupyc I Grain density (sediment pycnometer 1340 sampling) Color, Visual core I stratigrapic Eyes of the lab workers N description features Inductively Coupled Thermo ICAP6500 Duo Plasma Optical ICP-OES Emission D Porewater and I Spectrometry (ICP- (Pore water chemistry Dionex IC20 OES) and sampling) connected to an AS22 Ion chromatography column (IC) I, II, D Laser III Grain size (sediment diffractometer/granul Malvern Mastersizer 3000 and composition sampling) ometry IV Carlo Erba NC2500 analyzer coupled with a D I and TOC and Mass spectometry Finnigan MAT (sediment II δ13C Delta V mass sampling) spectrometer Single Stage Accelerator D Accelerator Mass II 14C years Mass Spectrometer (Lund (sediment Spectrometry (AMS) University) sampling) I and Elemental X-ray fluorescence N ITRAX XRF core scanner II data (XRF) Thermic ionization D 87Sr/86Sr and Thermo Finnigan Triton III mass spectrometry (sediment ɛ TIMS Nd (TIMS) sampling) PANalytical X’Pert Pro diffractometer II, III and D Bulk X-ray diffraction and Bruker AXS D4 Endeavor (sediment mineralogy (XRD) IV X-ray diffractometer sampling) (Weatherford Laboratories) Bruker AXS D4 Endeavor D Clay X-ray diffraction X-ray diffractometer IV (sediment mineralogy (XRD) (Weatherford sampling) Laboratories)

18 In this thesis (Paper II), a radiocarbon chronology for VAT12 was established by wet sieving (>250 μm) sediment intervals in order to find terrestrial plant fragments (e.g. leaves, capsules) for radiocarbon dating. Using terrestrial plant fragments circumvents the problem with old glacier-derived carbon in the bulk sediment portion (Walker et al., 2001). After drying the samples, organic residues were picked using a microscope (Fig.16). In total, eight samples (0.1-0.6 mg) from the upper 28 m of VAT12 were sent to the Radiocarbon Dating Laboratory at the Department of Geology, Lund University. The samples were pretreated with hydrochloric acid before loaded into an Accelerator Mass Spectrometer (AMS). In contrast to an ordinary mass spectrometer, the AMS is equipped with a high energy (MeV) accelerator tube that make it possible to measure the extremely low isotopic abundance of 14C (1 out of 1010 carbon atoms; Walker, 2005). The precision of radiocarbon ages derived by AMS technique depends mainly on the size and quality of the sample (M. Rundgren, personal communication, November 2017). This is illustrated by a high precision (540±35 14C years) for the 0.6 mg sample in U1 (LuS 12288; Tab. 1 in Paper II) compared to the Figure 16. Example of organic macrofossils relatively low precision (9270±350 14C years) found in VAT12 and used for radiocarbon for a 0.1 mg sample in the organic-poor dating. a) Leaf found in the top of U3. b) Seed sediments of U2 (LuS 12294; Tab. 1 in Paper found in the upper part of U2. II). each depth interval in a sedimentary sequence Radiocarbon ages of terrestrial material cannot (e.g. Parnell et al., 2008; Muschitello and be directly translated into calendar years. This Wohlfarth, 2015). An age-depth model was is basically due to the instability of the constructed for the 15-28 mblf interval of atmospheric 14C levels over time (Goslar et al., VAT12 using a P-sequence (assuming 2000). However, using 14C dates of annually inherently random sedimentation) depositional layered biomaterial (e.g. tree rings, model in OxCal v4.2 (Bronk Ramsey 2008). speleothems and corals) allows for the X-ray diffraction (Paper II, III and IV) construction of calibration curves. The radiocarbon ages derived from VAT12 are X-ray diffraction (XRD) is a commonly used calibrated using the IntCal13 calibration curve method to obtain structural information of (Reimer et al., 2013) using the OxCal v4.2 solid matter. In a sedimentological context, software (Bronk Ramsey, 2008) and finally XRD allows you to determine and quantify the displayed as probability intervals (95% mineralogical composition of a sample. Hence, probability: 2σ). Based on the probability XRD analysis of surficial sediments as well as intervals of the radiocarbon samples, it is sediment cores is frequently used to decipher common to construct a Bayesian age-depth sediment sources and interpret patterns and model in order to assign representative ages to processes related to sediment transport. For

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Figure 17. Illustration of Bragg´s law. Constructive interference (diffraction) appears only when two different crystal layers with a distance that is an integer (n) of the wavelength (λ) reflect x-rays. example, sedimentary XRD data from the Bragg’s law states that constructive Arctic Ocean have been used extensively for interference (diffraction) appears only when x- provenance studies and related sea ice and rays are reflected by two different crystal iceberg transport (e.g. Vogt, 1997; Viscosi- layers with a distance that is an integer (n) of Shirley et al., 2003; Bazhenova, 2012; Fagel et the wavelength (λ) (Fig. 17). As distances al., 2014). In this thesis XRD was used in 3 of between the repeating atomic layers in a the 4 manuscripts, to assess the bulk and clay crystal is in the same region as x-ray mineralogy of sediments to investigate wavelengths (Friedrich et al., 1912), the basic temporal provenance changes coupled to ice concept of Bragg’s law has become very useful sheet retreat, sea-level changes and opening of to determine crystal structures of both new waterways. inorganic and organic compounds. The interaction between waves (x-rays) and In this thesis, two different X-ray matter (mineral structures) was described in diffractometers were used for mineralogical the early 1900s and formulated in Bragg’s law analysis of lacustrine and marine sediments. A (Bragg and Bragg, 1913): PANalytical X’Pert Pro diffractometer (Department of Geological Sciences, ʹ݀ݏ݅݊ߠ ൌ ݊ߣ Stockholm University) was used for where mineralogical determination of sediments from Lake Vättern and Mackenzie Trough (Paper II ߠൌ and III) while samples from Herald Canyon ,ݏݎݐ݈݈ܽܽݕ݁ݏݕݎݐܾܽ݊ܿ݁݁ݐݓ݁݁݊ܿݏ݅݀ ൌ ݀ ߣൌ (Paper IV) were analyzed at an external݀݊ܽݎݐܾ݈݁ܽ݉ܽ݊݃݁, ݊ൌ݅݊ݐ݁݃݁݊݁݀݅ܿ݊݅ ݓܽݒ݈݁݁݊݃ݐ݄

20 laboratory (Weatherford Laboratories, Stavanger) using a Bruker AXS D4 Endeavor diffractometer. The basic constituents of any diffractometer include an X-ray tube, an incident beam optical module, a sample stage, a goniometer, a diffracted beam optical module and a detector (Fig. 18). After leaving the X-ray tube, the x- ray beam is collimated and directed by a series of slits (i.e. divergence slit) in the incident beam optical module before hitting the sample mounted in the sample stage. A sample stage spinner rotates the sample during irradiation to avoid a non-representative diffraction. The goniometer moves the incident beam stepwise throughout the chosen interval (degrees θ) using a predefined step size (degree) and Figure 18. Schematic overview of an X-ray counting time. Diffracted beams pass through diffractometer. Modified from: U. S. Geological the diffracted beam optical module once again Survey Open-File Report 01-041 https://pubs.usgs.gov/of/2001/of01- (i.e. receiving slits) to focus the radiation 041/htmldocs/xrpd.htm/ Accessed 20171114. towards the detector. The X’Pert Pro diffractometer is equipped with a proportional 0.02° per step using a 0.3 mm variable point detector with Xenon gas that quantifies divergence slit and a silicon strip Lynx Eye the diffracted x-rays. In contrast, the Bruker High speed detector. AXS D4 Endeavor diffractometer uses a dynamic scintillation counter that strongly To extract the clay fraction, aqueous reduces the background noise and increase the suspensions of bulk samples were treated intensity of the diffraction signals. chemically (sodium hexametaphosphate) and physically (ultrasonification) before the Samples analyzed for bulk mineralogy (Paper suspension was centrifuged and the II and IV) were freeze-dried and subsequently supernatant (clay fraction) was vacuumed crushed/homogenized in a mortar before being filtered over a Millipore membrane. The mounted onto a cylindrical metal sample resulting oriented clay film was then treated holder (r=270 mm, h=2mm). The sediment with ethylene glycol vapor at 110 °C overnight samples were distributed into the sample and immediately scanned on the diffractometer holder using a glass slide providing a high from 2° 2θ to 30° 2θ at a step size of 0.02° degree of random orientation and a flat surface. using the same parameters as for the bulk Bulk analysis of sediment samples (~6g) from samples. Finally, the glycolated samples were the Herald Canyon (Paper III) included heated at 375°C for an hour and subsequently automatic milling using a micronizing mill rescanned. Ethylene glycol and heat treatment producing a slurry that was subsequently spray are necessary to determine the presence of dried in a spray dry oven. The spray dry expandable minerals (i.e. smectite and mixed- technique produces tiny sediment granules that layer clays). possess a completely random orientation of the minerals and therefore, significantly increases The outcome of an XRD analysis is presented the reproducibility (Hillier, 2002). The spray- in the form of an x-y plot called a dried powder was then placed onto the sample diffractogram. A diffractogram includes the holders and analyzed on a Bruker AXS D4 diffraction intensity (counts) on the y-axis and Endeavor X-ray diffractometer equipped with the corresponding angle (°2θ) on the x-axis. a Cu tube (Kα, λ=1.541). The samples were Using software (HighScore 3.0x for Paper II scanned from 5° 2θ to 70° 2θ at a step size of and IV) connected to a comprehensive

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Figure 19. Comparison of two similar X-ray diffractometers running the same sample. a) Diffractograms for 4PC-1_405.5 cmbsf run in two PANalytical X’Pert Pro diffractometers with different detectors. Blue line shows the diffraction signal from a multi-channel silicon strip detector (X’celerator) at the Swedish Museum of Natural History (NRM) run for 30 minutes. Red line shows the diffraction signal from a single point Xe detector at the Department of Geological Sciences, Stockholm University (IGV) run for 7 hours. Notable is the substantial difference in run time and signal intensity. b) For comparison, an adjacent sediment sample (4PC-1_407.5 cmbsf) run by Weatherford laboratories is shown. Although not directly comparable, it is clear that the high intensities allow a secure determination of minor peaks. reference diffractogram database (ICSD 3.2 Identification of mineral phases in 4PC-1 mineral database for Paper II and IV) it is (Paper III) follows the same procedure as for possible to identify peak patterns associated HighScore 3.0x although a different software with individual minerals in the bulk sediment was used (MDI Jade 9+ and ICDD PDF 4+ sample. The identification precedes by 2015 database). defining a baseline and height/width ratio in Three different methods of mineral order to only identify peaks that are quantification are used in this PhD thesis. In distinguished from the background noise. Paper II a semi-quantitative approach was

22 applied that uses the height of the diagnostic and might therefore reveal minor peaks that are (major) quartz peak (26.6 °2θ; d = 3.34 Å) as a hidden in the noise of a diffractogram reference. By dividing heights of various generated by a point detector. To investigate diagnostic peaks of interest by the height of the this, a sediment sample from the 4-PC1 core quartz peak, relative abundances of specific (Herald Canyon, paper III) was analyzed on minerals can be compared between samples. two equivalent PANalytical X’Pert Pro Aiming for a quantitative estimate of the diffractometers, one equipped with a Xe Mackenzie River dolomite input to the Arctic proportional point detector and the other Ocean we applied the whole pattern Rietveld equipped with a multi-channel silicon strip refinement technique in Paper IV. This detector (X’celerator). The resulting technique is based on the comparison of a diffractograms differ in intensity by a factor 10 complete set of quantified reference for the major quartz peak (Fig. 19a). diffractograms for each identified mineral with Subsequent peak identification using the the actual diffractogram of the sample. The HighScore 3.0x software revealed identical reference diffractograms were collected from peaks in both diffractograms but with a minor the Crystallography Open Database hornblende signal only seen in the (http://www.crystallography.net) and uploaded diffractograms generated by the multi-channel into the MAUD software (Lutterotti et al., detector (Fig. 19a). This test suggests that the 2007) to run the refinement. All diffractograms dominant mineral components remain well- were processed in MAUD using five automatic captured by the lower intensity proportional iteration (refinement) cycles that resulted in gain detector, but that some of the minor weight percentage data for the included constituents may have been under-represented. mineral phases. For Paper III, the In the final manuscript, the mineralogy of the quantification is based on mineral intensity 4PC-1 was documented by high-intensity ratios (MIFs) derived from machine specific measurements produced by Weatherford XRD analysis of pure mineral standards mixed laboratories (Fig. 19b), and as such, no such with quartz. The diagnostic peaks of each concern about missing minor mineral mineral were compared to the corresponding components exists. peaks of the MIF standards and subsequently quantified. Separate bulk and clay mineralogy Summary of papers – Expectations, quantification allowed for a normalization of findings and implications individual clay minerals to the total amount of Paper I - Regional deglaciation and clay. The general low intensity (counts) of the postglacial lake development as reflected in a diffractograms obtained from the PANalytical 74 m sedimentary record from Lake Vättern, X´Pert Pro diffractometer at the department of southern Sweden Geological Sciences, Stockholm raised the question whether the relatively high Sediment cores from Lake Vättern are rare, background noise of these diffractograms and where existent tend to be short, recording might affect the peak identification. Settings only a compressed or truncated including long step time and short step size paleoenvironmental history. Consequently, will increase the intensity of the output signal knowledge of the deglacial and Holocene and give a more precise peak position; history of the Vättern Basin is principally however, time is often a limiting factor. based on local and regional terrestrial ice Another factor that affects the peak intensities recession data (i.e. varve chronology and is the type of detector used in the X-ray geomorphological features) and sea-level diffractometer. Compared to a point detector, approximations from paleoshoreline studies the use of a multi-channel (silicon strip) (e.g. Munthe,1935; Nilsson, 1968; Lundqvist detector significantly increases the peak and Wohlfarth, 2000). The recovery of a 74 m intensities and drastically shortens the time for composite sediment core (VAT12) in Lake each analysis. The use of multi-channel Vättern presented a unique opportunity to detectors also increases the signal to noise ratio

23 provide a more continuous and direct history and increased pore-water salinity indicated of lake development. brackish conditions in Lake Vättern at this time. Surprisingly, the peak in pore water Sediments in VAT12 were expected to contain chlorinity is located clearly below the U3/U2 deglacial to Holocene deposits and possibly sedimentological transition, and within the some subglacial sediments from the last varved glacial clay sediments, providing glaciation. In analyzing this sedimentary compelling evidence for an earlier drainage of sequence, the initial aims were to: (i) confirm the BIL that occurred prior to the YD (e.g. the general lake development stages that were Björck and Digerfeldt, 1984). Finally, the described in the literature, including various finding of micro-faulted sediments at the base periods of proglacial lake development, (ii) of U2 provided evidence for a period of post- constrain ice dynamics of the FIS in the glacial earthquakes that was primarily Vättern Basin and surrounding area, and (iii) interpreted from geophysical data in the reveal stage specific features including the Vättern Basin (Jakobsson et al., 2014a). final drainage of the BIL, brackish influence during the Yoldia Sea stage and isostatically Paper II - A chronology of environmental driven lake isolation. changes in the Lake Vättern Basin from deglaciation to its final isolation In the first manuscript, using a combination of non-destructive and destructive analytical In the 1st publication detailing the lithology of tools, the physical and chemical properties of VAT12 and its relation to the Baltic Sea sediment and pore water in VAT12 were stages, little concrete dating was presented to described. Furthermore, seismic profiling from constrain the chronology of environmental the southern parts of the lake were used to changes. For example, the lithologic transition extend the interpretations to a basin-wide level. between U3 and U2 was established through Three major sedimentary units (U1-U3) were visual correlation to a piston core from further identified in the 74 composite stratigraphy of North in Vättern where an assessment of the VAT12. The two lower ones (U2 and U3) pollen had been made. It was not until late show typical regional characteristics autumn of 2016 that an attempt was made to interpreted as deposits during the BIL and the find macrofossils in the sediments that could Yoldia Sea stage (e.g. Strömberg, 1994; be used for radiocarbon dating. The catalyst Andrén et al., 2002; Johnson et al., 2013) was Svante Björck who came up with the idea confirming the connection to the wider Baltic to search for terrestrial organic material at the Sea development stages. However, the upper U2/U1 transition with the ultimate aim to date unit (U1) is clearly distinguished from the the lake isolation; something that had not been lower ones by having a lower bulk density and done before. Knowing if Lake Vättern was grain density accompanied by higher water isolated during the Yoldia Sea stage, the content and organic carbon contents. This Ancylus Lake stage or the Littorina Sea stage sedimentary unit does not have an analogue in would increase our knowledge about the rate sediment cores from the Baltic Sea (e.g. of isostatic rebound and the interplay with Andrén et al., 2002). The preliminary regional sea-level changes. The search for interpretation was that U1 was deposited in the dateable organic material was extended below isolated Lake Vättern. Furthermore, the U2/U1 transition and into the top of U3, glaciotectonized sediments in U3 were where material was found to generate a identified and attributed to a major ice radiocarbon chronology covering the presumed readvance over the Vättern Basin BIL/Yoldia Sea transition and the isolation of contemporary to the terrestrial 13 kyr BP ice the Vättern Basin. Furthermore, δ13C data and recession line (Fig. 10). The widely recognized diatom abundance were used to further support color change from a reddish-brown to grey the lithological interpretation for lake isolation. clay associated with the final drainage of the A complete set of high-resolution elemental BIL is also clearly seen at the U3/U2 transition data together with discrete samples of in VAT12. In addition, a cm-thick sand layer mineralogic assemblages were used to further

24 constrain the paleoenvironmental changes the FIS margin north of the calcite bearing discussed in Paper I. Paper II also investigates bedrock areas in the northeastern part of the the varve characteristics with respect to basin. This observation is consistent with elemental and minerogenic composition, inferred patterns of ice recession that assign together with grain size data, in order to further the 11.6 cal. kyr BP ice margin position to just define sedimentological differences in these north of the limestone area (Stroeven et al., annually deposited proglacial sediments. A 2016). trend of higher relative intensities in the fine- Paper III - Sedimentary proxies for Pacific grained laminations of the varved clays in U3 water inflow through the Herald Canyon, is accompanied by high levels of Fe, K, Rb and western Arctic Ocean Ti while the corresponding coarse-grained laminations are enriched in Zr, Ca, Sr, Si but Due to the shallow nature of the Bering Sea exhibit reduced levels of clay minerals and (<53 m sill depth), the inflow of Pacific water feldspars. to the Arctic Ocean was heavily modified by changes in global and regional sea level across According to the radiocarbon age model, Lake Quaternary glacial cycles. Identifying a Vättern became isolated as late as 9530±50 cal. sedimentological proxy for Pacific water yrs BP indicating a closed lake forming during inflow is important for reconstructing its the Initial Littorina Sea stage (9.8-8.5 cal. kyr variability in the geologic past. Pacific water BP; Andrén et al., 2011). This date is far from masses are distinguished from Arctic waters in that proposed in the collected work of Nilsson terms of higher temperature and nutrient levels (1968) that implies an isolation of the Vättern and it is commonly argued that they carry Basin in the late Yoldia Sea/early Ancylus increased amounts of the clay-mineral chlorite Lake stage (Fig. 11 c). Also more recent in the suspended material (e.g. Beszczynska- publications have mapped the isolation of the Möller et al., 2011; Walsh et al., 1989; Naidu Vättern Basin in the Ancylus Lake stage, et al., 1995). With this in mind, the focus of although chronologically positioned towards this paper was to identify the sedimentological the final regressive phase of the Ancylus Lake imprint of the reopening of the shallow Bering stage (e.g. Björck 1995, 2008; Påsse & Strait following the last deglaciation (~11 cal. Andersson 2005; Andrén et al., 2011). kyr BP; Jakobsson et al., 2017) that re- Evidence for isolation at the U2/U1 transition established a net influx of Pacific water into includes a major change from minerogenic- the Arctic Ocean. dominated sediment to a distinct increase in the organic content of the sediments. This is Few existing records have captured this indicated by distinct changes in (i) deglacial transition. During the SWERUS-C3 minerogenic elements (decrease), (ii) diatom expedition on icebreaker Oden in 2014, a abundance (first appearance and up-core unique 6.1 m deglacial to Holocene sediment abundance increase) and (iii) δ13C (increase) at core (4PC-1) was recovered in the Herald the U2/U1 boundary. The U3/U2 transition is Canyon on the northern Chukchi shelf dated to 11 650±280 cal. yr BP and is (Jakobsson et al., 2017). Regional bathymetry contemporary with other regional dates for the as well as deglacial sea-level models (e.g. drainage of the BIL and the transition to the Manley 2002) suggest that the Herald Canyon Yoldia Sea stage (11 620±100 cal. yr BP; was the initial waterway for Pacific waters Stroeven et al., 2015). Thus, the during the flooding of Beringia, and as such, a lithostratigraphic boundary between U3 and key record for studying proxies of Pacific U2 is regarded as the sedimentological imprint water inflow into the Arctic Ocean. Using of the BIL drainage, as first suggested in Paper decreases in bulk density and magnetic I. susceptibility along with contemporary increase of biogenic silica and δ13C, the core Mineralogical and elemental data revealed a was divided into two main lithostratigraphic distinct decrease in calcite input at the U3/U2 units (B and A) deposited before and after the boundary likely indicating the withdrawal of

25 opening of the Bering Strait (Jakobsson et al., Sea. Both regions were flooded during 2017). The transition between these units was deglacial sea-level rise, and are important initially thought to be erosional, or condensed. sources for modern bottom waters in the This paper aimed to further constrain the Herald Canyon. opening of the Bering Strait by analyzing grain Paper IV - Mineral and isotopic (Nd, Sr) size, clay and bulk mineralogy, along with a signature of fine-grained deglacial and focused biogenic silica analysis across the 70 Holocene sediments from the Mackenzie cm B/A transition. Based on existing literature, Trough, Arctic Canada. the opening of the Bering Strait was expected to result in (i) an increase in the clay mineral Of all the world’s Oceans, the Arctic receives chlorite often associated with Pacific waters the largest proportional contribution from and (ii) a grain size effect related to marine riverine input. This is an important source of transgression and the first pulses of Pacific both freshwater and suspended sediment. The waters entering the HC and (iii) An increase in Mackenzie River is the largest contributor of biogenic silica originating from enhanced suspended material to the Arctic Ocean. It also surface water productivity as the nutrient rich drains the only significant circum-Arctic Pacific waters entered the Arctic. dolomite bedrock area, and would therefore imply that it is responsible for a considerable An abrupt increase in grain size, and portion of the total dolomite delivery into the subsequent fining upwards sequence was Arctic Ocean. These observations have been identified in the transitional interval at a core used to argue that the Mackenzie River was an depth of 412 cm. This suggests a period of important source of dolomite during the last elevated bottom current speeds and an deglaciation (Not and Hillaire-Marcel, 2012). erosional contact. The position is slightly In far field studies, relative increases in fine- lower (earlier) than the depth of 407 cm grained dolomite, and the Sr and Nd isotopic suggested by Jakobsson et al., (2017) for the ratios of sediments, are increasingly being used flooding of the Bering Strait. However, the as provenance indicators for Mackenzie River unknown local marine reservoir age constitutes transport. However, no proximal data on the a larger source of error for the age composition of deglacial and Holocene determination than the 5 cm difference in the sediments from the Mackenzie River exists. stratigraphic level associated with the Bering Strait opening. Hence, the results in this paper In order to address this gap in available data, do not refine the age for the opening of the and to test the assumption that the Mackenzie Bering Strait. River was a significant contributor of fine- grained dolomite to the Arctic Ocean, samples A clear increase in biogenic silica is not visible from an 81.5 m deglacial to Holocene borehole until above 400 cm, indicating that the grain (MTW01) from the Mackenzie Trough were size signal at 412 cm might be caused by analyzed. This borehole contained three major erosion or winnowing from the Arctic side of units including (i) a progradational unit the Herald Canyon. Surprisingly, a dramatic deposited in a deltaic environment when sea change in the bulk or clay mineralogy across levels was much lower than today, (ii) a the Unit B/A transition, associated with the transitional unit deposited in a transgressive onset of Pacific water inflow, was not found. phase and (iii) a marine unit deposited during After some data processing and statistical fully marine settings (Hill, 1996; O’Regan et testing, it was shown that the clay mineral al., in review). The fine-grained component of ratios did change across this transition, but that (<38 um) of 23 samples were investigated for more notably it was the variability in mineralogical (XRD) and isotopic composition mineralogy that changed with the opening of 143Nd/144Nd 87Sr/86Sr the Bering Sea. The data was interpreted to ( and ) and grain size reflect the mixing of two provenance sources, distribution in order to fingerprint the one from the East Siberian Sea (Wrangel Mackenzie River sediments delivered to the Island) area, and one from the Bering/Chukchi Mackenzie Trough.

26 We expected to see changes in the amount of straightforward. It requires an understanding of dolomite and the isotopic signal throughout the the road from weathering via transport to final deglacial and Holocene sequence, reflecting deposition - in an environment that changes the withdrawal of the Laurentide Ice Sheet over time. A detailed knowledge of the from the Mackenzie River drainage area (Fig. regional paleoclimatic and geologic setting is 12). Furthermore, we hoped to see isotopic or almost a prerequisite for identifying these minerogenic imprints of the suggested northern events. Large and permanent changes to the drainage route of proglacial Lake Agassiz depositional environment, like the isolation of related to the YD and the 8.1 kyr BP climate Lake Vättern and transgression of the Arctic events (Murton et al., 2010). shelves, are clearly reflected in the lithology and sedimentary characteristics. However, The XRD results indicate that the Mackenzie other more ephemeral, or purely hydrologic River does deliver relatively large amounts of changes, are difficult to recognise. These dolomite to the Arctic (~ 8 wt%), but include the early drainage of the Baltic Ice surprisingly this remained relatively stable Lake through Lake Vättern, the mineralogic during deglaciation and the Holocene. This imprint of Pacific water in the Herald Canyon, was also seen in the Nd isotopic signals and changes in provenance of Mackenzie River (presented as ε ). The Nd isotopic signal in Nd sediments during deglaciation. The loss of the top and bottom unit (ε = -13.6 to -12.8) Nd calcite in the mineral assemblage from Lake resembles a modern Mackenzie River Vättern, interpreted as the final withdrawal of mainstream signal (e.g. Vonk et al., 2015). the ice sheet from the lake basin, is one Larger variations in the transitional unit (2 data example where the mineral proxies seem to points) might reflect pulses of water from other work well. In other instances, like the Herald sources - including potential proglacial lake Canyon, the lack of a clear Pacific water signal outbursts. However, more data points and a appears to be related to the more complex local firm chronology for the transitional unit is oceanography. needed to constrain this course of events. The Isotopic data appear to be an extremely results indicate an important distinction valuable addition to mineral assemblage between the background mineralogic and analyses. This is exemplified in the Mackenzie isotopic composition of Mackenzie River Trough where mineral assemblages clearly sediments, and the fingerprint of thise change during transgression, but it is the associated with a meltwater outburst from isotopic data that most strongly supports the further inland. This distinction has not been interpretation of a stable background sediment considered in existing literature. provenance during deglaciation and the The 87Sr/86Sr was notably larger in the marine Holocene – with a possible exotic provenance unit. However, upon further analysis, this briefly appearing during transgression. increase was linked to an increase in illite, Even in Lake Vättern, the mineral assemblage which is known to have an effect on the Sr changes during the drainage phases of the BIL isotopic ratio via its high content of radioactive are not extremely pronounced. Interpreting Rb that decays to 87Sr (Meyer et al., 2010). them relies on prior knowledge developed over Hence, the Sr signal does not seem to provide a centuries of Quaternary research in the region. robust proxy for sediment provenance in this The final drainage of the BIL marked a system. permanent transition in the depositional Future work environment and can be identified by a clear lithologic change. The earlier drainage event is Overall impressions really only recognised in the porewater chemistry, that reveals an influx of saline Recognising and interpreting sedimentological waters during the deposition of the varved imprints associated with regional hydrologic glacial clays. changes during deglaciation is not

27

Changes in biological proxies (TOC, δ13C, The Swedish Time Scale (STS) is and biogenic silica, diatom and foraminiferal independent chronology based on local clay abundance and assemblages) are clearly varve chronologies (e.g. Kristiansson, 1986; sensitive indicators of hydrologic changes. Strömberg, 1994; Brunnberg, 1995; Wohlfarth This is seen during the isolation of Lake et al., 1998) covering the time span 12340 to Vättern, the opening of the Bering Strait, and 9950 cal yrs BP (Stroeven et al., 2016). Of in the transgression of the Arctic shelves. special interest is the YD and early Holocene However, in many environments where we clay varve chronology in the areas on both want to identify hydrologic changes during sides of northern Lake Vättern (Fig. X; deglaciation, biologic remains are non-existent Strömberg, 1994). By anchoring the clay – and we must rely on mineral and isotopic varves of VAT12 to the records of Strömberg proxies. This includes the early drainage of the (1994), it would be possible to significantly BIL in Lake Vättern, and the identification of refine the timing of environmental changes meltwater related provenance changes in associated with the late stages of the proglacial sediments from the Mackenzie Trough. There Lake Vättern. is also a need to identify mineral and isotopic Traditionally, varves have been determined proxies that can be used to trace and identify macroscopically (e.g. De Geer, 1912). these hydrologic events in far-field records – However, the development of new analytical where biologic proxies either do not exist, or techniques provides novel ways to quantify would not be expected to work. For example, varve numbers and thickness (Zolitschka et al., in identifying periods of enhanced Mackenzie 2015). In VAT12, varves were identified by River outflow in marine sediments from the rhythmic variations in bulk density, x- outer shelf, or central Arctic Ocean. radiographic density and elemental Lake Vättern composition (Paper I and II). These techniques were able to clearly identify varves that were Existing work has dated both the final drainage not apparent to the naked eye, and constitute a of the BIL and the isolation of Lake Vättern promising complement to traditional but there is still considerable scope for descriptive techniques (Paper I and II). expanding the chronology of VAT12. Dateable amounts of macrofossils were found in the Herald Canyon varved proglacial clays in the upper part of U3 As the mineralogical signal of the Bering Strait (28 mblf). It may be possible to extend the opening was less pronounced in 4-PC1 (Paper radiocarbon chronology further downcore and III) than expected, it would be beneficial to to better constrain the inferred date of ~13.6 find a more robust and straightforward proxy kyr BP for the withdrawal of the FIS margin of Pacific water inflow. Sedimentary (Paper 1). An extended radiocarbon radiogenic neodymium (ε ) is a promising chronology would also be of specific interest Nd candidate. The isotopic Nd signal in the oceans in order to date the chlorinity peak in the pore varies due to the age of the surrounding waters at 33 mblf (Paper I). A firmer date on bedrock (Faure, 1986). Reflecting the younger this event would help resolve the timing for the volcanic bedrocks of North Pacific, the ε first drainage of the BIL (12 867 ± 66 cal. yr Nd values are significantly higher than ε in the BP; Muschitiello et al., 2016), and its possible Nd Arctic Ocean (Amakawa et al., 2004; Porcelli contribution to surface water freshening in the et al., 2009). Thus, inflow of Pacific water Norwegian-Greenland Sea prior to the through the Bering Strait is likely reflected by Younger Dryas. an increase in εNd. Signals of εNd in the water To further enhance the chronological precision column is preserved in Fe-Mn coatings on it would be of interest to incorporate the well- detrital and biogenic sediment grains at the developed varves of U3 (Paper I) into the sediment-water interface and subsequently existing clay varve chronology of southern preserved during burial (Rutberg et al., 2000). Sweden (Swedish Time Scale; Cato, 1987). The conservative behavior of Nd in sediment

28 (i.e. not altered by biological processes) allow age by targeting larger (mm-sized) peat and for preservation of the original water mass wood fragments in these sediments. signal (Tachikawa et al., 2003). Various Alternatively, a similar study could be leaching processes are needed to obtain the conducted on shorter, lower sedimentation rate authigenic Nd signal from sediments (e.g. cores, acquired from seaward areas of the Bayon et al., 2002; Gutjahr et al., 2003). The Mackenzie Trough, although no records are leachate is then analyzed using mass currently known to exist that capture the spectrometric techniques. Younger Dryas. The effect of Pacific water inflow through the The general use of Nd as a provenance tracer Bering Strait is reflected in the increase of for glacial lake outbursts from the Mackenzie biogenic silica in 4-PC, occurring above the River would benefit from a more complete Unit B/Unit A boundary. It is therefore likely dataset on the radiogenic Nd isotopes in the that another water mass signal (εNd) existed bedrock of the drainage basin. Together, these prior to this transition. Analyzing sediments data would greatly enhance the possibility to from 4-PC1 with respect to radiogenic Nd unravel a Lake Agassiz drainage signal in would be an excellent way to test its robustness MTW01, and other far-field records from the as a Pacific water proxy. Arctic Ocean. Mackenzie Trough Acknowledgements

The εNd of MTW01 also seems to be a I would like to express my deep gratitude to promising proxy for sediment provenance in my supervisors Matt O’Regan and Martin the MR catchment area (Paper IV). Of special Jakobsson. interest are the two εNd data points in Unit B, which suggest sediment sources significantly Matt – thank you for your invaluable support different from the one containing the common throughout my PhD years and for creating a friendly and inspiring working environment. background εNd signal seen in Units A and Unit C-E. These anomalies might reflect pulses of Martin – thank you for giving me the suspended load carried by water from the opportunity to do research and for being the drainage of Lake Agassiz via the Mackenzie true senior advisor always there when needed. valley. To further test these ideas there is a need for: (i) Increased resolution of the Sarah Greenwood and Malin Kylander have radiogenic Nd data points in Unit B, (ii) a more willingly shared their knowledge in reliable chronology for Unit B and (iii) paleoglaciology and paleolimnology increased knowledge concerning the variation respectively. Thank you very much for your of εNd values in bedrock of the MR catchment help and for being nice to a simple PhD area. The first of these could easily be student. Thank you Svante Björck for your achieved by a increasing the sampling density advice and fresh input of ideas, which led to an across the transitional unit. The age model for important breakthrough for Paper II. Per the transitional sediments relies on radiocarbon Andersson is hereby acknowledged for dates of carbonate marine microfossils (benthic providing the opportunity to use the isotope foraminifera) and mollusk shell fragments. laboratory at the Swedish Museum of Natural They were only found at the top of the History. transitional unit. Dating at the base of the unit Modern geoscience is depending on support was limited to bulk particulate carbon analyses from outstanding laboratory technicians such on the >63 um size fraction (O’Regan et al., in as Carina Johansson, Heike Siegmund, Pär review). These measurements were clearly Hjelmqvist, Karin Wallner och Hans Schöberg. biased by the incorporation of older reworked Thank you all for making this thesis possible. organic material and are only maximum limiting ages. It may be possible to obtain I also want to thank my office mates during better results for the maximum depositional these years for creating a refuge in a

29 sometimes harsh research world: Margareta, Sea. Boreas 31, 226–238. doi:10.1111/j.1502- Linda, Linda, Tommy, Camilla, Jenny, Natalia, 3885.2002.tb01069.x Sandra, Gabriel, Alba and Liselott. It has been Andrén, T., Björck, S., Andrén, E., Conley, D., a pleasure! Zillén, L. & Anjar, J. (2011). The development Forskarskolan för lärare blev inkörsporten till of the Baltic Seabasin during the last 130 ka. In doktorandåren och därför står jag i Harff, J., Björck, S. & Hooth, P. (eds.): The tacksamhetsskuld till Ove Tunhav, f.d. rektor Baltic Sea Basin, 75–98. Springer-Verlag, vid Per Brahegymnasiet. Utan hans välvilliga Berlin and Heidelberg. inställning till lärarfortbildning hade detta Axberg, S. & Wadstein, P. (1980). Distribution kapitel i mitt arbetsliv aldrig påbörjats. Här vill of the sedimentary bedrock in Lake Vättern, jag också passa på att tacka mina kollegor vid southern Sweden. Stockholm contributions in Per Brahegymnasiet för support och geology, Acta Universitatis Stockholmiensis engagemang i universitetsnära samarbeten 34, 15–26. under årens lopp. Ett särskilt tack till min kemilärarkollega Per Persson som, utan knot, Batchelor, C.L., Dowdeswell, J.A., Pietras, J.T. ryckt in som vikarie för mig under mina (2013). Seismic stratigraphy, sedimentary fortbildningsperioder. architecture and palaeo-glaciology of the Mackenzie Trough: evidence for two Tack släkt och vänner för visat intresse och Quaternary ice advances and limited fan omsorg under doktorandåren. Tack mor, far development on the western Canadian och svärmor för gott stöd i med och motgång. Beaufort Sea margin. Quaternary Science Thea, Sigvard och Ally – tack för ert tålamod Reviews 65, 73-87. med forskarpappan. Ett särskilt tack till doi:10.1016/j.quascirev.2013.01.021 Sigvard som lånat ut sitt skrivbord under nästan två års tid. Bayon, G., German, C., Boella, R., Milton, J., Elin – tack för allt. Nu är det din tur  Taylor, R. & Nesbitt, R. (2002). An improved method for extracting marine sediment An additional acknowledgement to Ådi for fractions and its application to Sr and Nd being a lazy and quiet dog. isotopic analysis. Chemical Geology 187, 179- 199. doi:10.1016/S0009-2541(01)00416-8 References Bazhenova, E.A. (2012). Reconstruction of Alexanderson, H., Backman, J., Cronin, T.M., late Quaternary sedimentary environments at Funder, S., Ingólfsson, Ó., Jakobsson, M., & ... the southern Mendeleev Ridge (Arctic Ocean). Spielhagen, R.F. (2014). Invited review: An PhD Thesis, University of Bremen, Germany, Arctic perspective on dating Mid-Late 83 pp. Pleistocene environmental history. Quaternary Science Reviews 92, 9-31. Berglund, B.E. (1979). The deglaciation of doi:10.1016/j.quascirev.2013.09.023 southern Sweden 13,000-10,000 B.P. Boreas 8, 89-117. Amakawa, H., Nozaki, Y., Alibo, D.S., Zhang, J., Fukugawa, K., & Nagai, H. (2004) Beszczynska-Möller, A., Woodgate, R.A., Lee, Neodymium isotopic variations in Northwest C., Melling, H. & Karcher, M. (2011). A Pacific waters. Geochimica et Cosmochimica Synthesis of Exchanges through the Main Acta 68, 715-727. doi:10.1016/S0016- Oceanic Gateways to the Arctic Ocean. 7037(03)00501-5 Oceanography 3, 82-99. Andrén, T., Lindeberg, G. & Andrén, E. Bingen, B., Andersson, J., Söderlund, U. & (2002). Evidence of the final drainage of the Möller, C. (2008). The Mesoproterozoic in the Baltic Ice Lake and the brackish phase of the Nordic countries. Episodes 31, 29–34. Yolida Sea in glacial varved from the Baltic Bodén, P., Fairbanks, R.G., Wright, J.D. & Burckle, L.H. (1997). High-resolution stable

30 isotope records from southwest Sweden: The Glaciation. Science 267 (5200), 1005–1010. drainage of the Baltic Ice Lake and Younger doi:10.1126/science.267.5200.1005 Dryas ice margin oscillations. Bradley, R. & England, J. (2008). The Paleoceanography 12, 39-49. Younger Dryas and the Sea of ancient ice. Björck, S. (1995). A review of the history of Quaternary Research 70(1), 1-10. the Baltic Sea, 13.0-8.0 ka BP. Quaternary doi:10.1016/j.yqres.2008.03.002 International 27, 19-40. doi:10.1016/1040- Bragg, W.H. & Bragg, W.L. (1913). The 6182(94)00057-C reflection of X-rays by crystals. Proceedings of Björck, S. (2008). The late Quaternary the Royal Society of London A88, 428-438. development of the Baltic Sea basin. In Broecker, W.S., Flower, B.P., Keller, J.T., Assessment of climate change for the Baltic Trumbore, S., Bonani, G. & Wolfli, W. (1989). Sea Basin Edited by: The BACC Author Team, Routing of meltwater from the Laurentide Ice 398–407. Springer-Verlag, Berlin and Sheet during the Younger Dryas cold episode. Heidelberg. Nature 341, 318–321. doi:10.1038/341318a0 Björck, S. & Digerfeldt, G. (1984). Climatic Broecker, W.S. (2006). Was the Younger changes at Pleistocene/Holocene boundary in Dryas Triggered by a Flood? Science the Middle Swedish endmoraine zone, mainly 312(5777), 1146-1148. inferred from stratigraphic indications. In N.- doi:10.1126/science.1123253 A. Mörner & W. Karlén (eds.): Climatic changes on a yearly to millenial basis, 37–56. Broecker, W., Denton, G., Edwards, R., Reidel, Dordrecht. Cheng, H., Alley, R., & Putnam, A. (2010). Putting the Younger Dryas cold event into Björck, S, Rasmussen, T, Kromer, B, Johnsen, context. Quaternary Science Reviews 29, S, Hammer, C, Bennike, O, Hammarlund, D, 1078-1081. Lemdahl, G, Wohlfarth, B, Possnert, G, & doi:10.1016/j.quascirev.2010.02.019 Spurk, M. (1996). Synchronized terrestrial- atmospheric deglacial records around the Bronk Ramsey, C. (2008). Deposition models North Atlantic, Science 274(5290), 1155-1160. for chronological records. Quaternary Science doi:10.1126/science.274.5290.1155 Reviews 27, 42–60. doi:10.1016/j.quascirev.2007.01.019 Blockley, S.P., Bourne, A.J., Brauer, A., Davies, S.M., Hardiman, M., Harding, P.R., & Brunnberg, L. (1995). Clay-varve chronology ... Zanchetta, G. (2014). Tephrochronology and and deglaciation during the Younger Dryas and the extended intimate (integration of ice-core, Preboreal in the easternmost part of the Middle marine and terrestrial records) event Swedish Ice Marginal Zone. PhD thesis, stratigraphy 8–128 ka b2k. Quaternary Science Quaternaria, Stockholm University, Stockholm Reviews 106, 88-100. 94 pp. doi:10.1016/j.quascirev.2014.11.002 Bischof, J., Clark, D.L. & Vincent, J.S., Bodén, P., Fairbanks, R.G., Wright, J.D. & (1996). Origin of ice-rafted debris: Pleistocene Burckle, L.H. (1997). High-resolution stable paleoceanography in the western Arctic Ocean. isotope records from southwest Sweden: The Paleoceanography 11, 743–756. drainage of the Baltic Ice Lake and Younger Dryas Ice Margin Oscillations. Bischof, J.F. & Darby, D.A. (1997). Mid to Paleoceanography 12(1), 39–49. Late Pleistocene ice drift in the western Arctic doi:10.1029/96PA02879. Ocean: evidence for a different circulation in the past. Science, 277, 74–78. doi: Bond, G.C. & Lotti, R. (1995). Iceberg 10.1126/science.277.5322.74 Discharges into the North Atlantic on Millennial Time Scales During the Last Carlson, A.E., Clark, P.U., Haley, B.A., Klinkhammer, G.P., Simmons, K., Brook, E.J.

31

& Meissner, K.J. (2007). Geochemical proxies Cronin, T.M., O'Regan, M., Pearce, C., of North American freshwater routing during Gemery, L., Toomey, M., Semiletov, I. & the Younger Dryas cold event. PNAS 104, Jakobsson, M. (2017). Deglacial sea-level 6556-6561. doi:10.1073/pnas.0611313104 history of the East Siberian Sea Margin. Climate of the Past 13, 1097-1110. Cato, I. (1987). On the definitive connection of doi:10.5194/cp-13-1097-2017 the Swedish Time Scale with the present. Geological Survey of Sweden. Ca 68, 1-55. Darby, D.A., Myers, W.B., Jakobson, M. & Rigor, I. (2011). Modern dirty sea ice Clark, P.U., Archer, D., Pollard, D., Blum, characteristics and sources: The role of anchor J.D., Rial, J.A., Brovkin, V., & ... Roy, M. ice. Journal of Geophysical Research 116, (2006). The middle Pleistocene transition: C09008 doi:10.1029/2010JC006675 characteristics, mechanisms, and implications for long-term changes in atmospheric pCO2. De Boer, A.M. & Nof, D. (2004). The Bering Quaternary Science Reviews 25, 3150-3184. Strait’s grip on the northern hemisphere doi:10.1016/j.quascirev.2006.07. climate, Deep-Sea Res. Pt. I, 51, 1347–1366. doi: 10.1016/j.dsr.2004.05.003 Clark, P.U., Dyke, A.S., Shakun, J.D., Carlson, A.E., Clark J., Wohlfarth, B., Mitrovica J.X., De Geer, G. (1884). Om den skandinaviska Hostetler, S.W. & McCabe, A.M. (2009). The landisens andra utbredning, Geologiska Last Glacial Maximum. Science 325, 710-714. Föreningen i Stockholm Förhandlingar 7:7, doi:10.1126/science.1172873 436-466. doi: 10.1080/11035898409443544 Clark, P., Marshall, S., Clarke, G., Hostetler, De Geer, G. (1908). On late-Quaternary time S., Licciardi, J., & Teller, J. (2001). Freshwater and climate. Geologiska Föreningens i forcing of abrupt climate change during the Stockholm Förhandlingar 30, 459–464. last glaciation. Science 293, 283-287 doi:10.1038/20859 De Geer, G. (1912). A geochronology of the last 12 000 years. In Proceedings of the 11th Clark, P.U., Shakun, J.D., Baker, P.A., International Geological Congress 1910, Bartlein, P.J., Brewer, S., Brook, E., & ... Stockholm, 243-253. Williams, J.W. (2012). Global climate De Geer, G. (1940). Geochronologia Suecica evolution during the last deglaciation. Principles. Kungliga Svenska Proceedings Of The National Academy Of Vetenskapsakademiens handlingar Ser III 18 Sciences Of The United States Of America (6). 109, E1134-E1142. doi:10.1073/pnas.1116619109 Dethleff, D. (2005). Entrainment and export of Laptev Sea ice sediments, Siberian Arctic. Claussen, M., Ganopolski, A., Brovkin, V., Journal of Geophysical Research 110, C07009. Gerstengarbe, F., & Werner, P. (2003). doi: 10.1029/2004JC002740. Simulated global-scale response of the climate system to Dansgaard/Oeschger and Heinrich Dickens, G.R., Kölling, M., Smith, D. C., events. Climate dynamics 21, 361-370. Schnieders, L., & the IODP Expedition 302. (2007). Rhizon Sampling of Pore Waters on Condron, A. & Winsor, P. (2011). A Scientific Drilling Expeditions: An Example subtropical fate awaited freshwater discharged from the IODP Expedition 302, Arctic Coring from glacial Lake Agassiz. Geophysical Expedition (ACEX). Scientific Drilling 4, 22- Research Letters 38(3). 25. doi:10.5194/sd-4-22-2007 doi:10.1029/2010GL046011 Dyke, A.S. (2004). An outline of North Condron, A. & Winsor, P. (2012). Meltwater American deglaciation with emphasis on routing and the Younger Dryas. Proceedings central and northern Canada In Quaternary Of The National Academy Of Sciences Of The United States Of America 109, 19928-19933 Glaciations - Extent and Chronology, Part II

32 Editors J. Ehlers and P.L. Gibbard Amsterdam. melting rates on the Younger Dryas event and Elsevier. 380 p. deep-ocean circulation. Nature 342, 637-642. doi:10.1038/342637a0 Ehlers, J. & Gibbard, P.L. (2007). The extent and chronology of Cenozoic global glaciation. Faure, G. (1986). Principles of Isotope Quaternary International 164-165, 6-20. Geology, John Wiley, Hoboken, N. J. doi:10.1016/j.quaint.2006.10.008 Friedrich, W., Knipping, P. & Laue, M. Eicken, H., Gradinger, R., Gaylord, A., (1912). Interferenz-Erscheinungen bei Mahoney, A., Rigor, I., & Melling, H. (2005). Röntgen-strahlen. Sitzungsberichte der Sediment transport by sea ice in the Chukchi Königlichen Bayerische Akademie der and Beaufort Seas: Increasing importance due Wissenschaften, 303-322. to changing ice conditions? Deep-Sea Fritz, M., Wetterich, S., Schirrmesidter, L., Research Part II, 52, 3281-3302. doi: 10.1016/j.dsr2.2005.10.006 Meyer, H., Lantuit, H., Preusser, F., & Pollard, W.H. (2012). Eastern Beringia and beyond: Ekman, S. (1914). Sedimentering, Late Wisconsinan and Holocene landscape omsedimentering och vattenströmningar i dynamics along the Yukon Coastal Plain, Vättern. Ymer 34, Stockholm. Canada. Palaeogeography, Palaeoclimatology, Palaeoecology 319-320, 28-45. Elderfield, H., Greaves, M., Barker, S., Hall, doi:10.1016/j.palaeo.2011.12.015 I.R., Tripati, A.K., Ferretti, P., Crowhurst, S.J., Booth, L. & Daunt, C. (2010). A record of Ganopolski, A. & Rahmstorf, S. (2001). Rapid bottom water temperature and seawater d18O changes of glacial climate simulated in a for the Southern Ocean over the past 440kyr coupled climate model. Nature 409, 153-158. based on Mg/Ca of benthic foraminiferal doi:10.1038/35051500 Uvigerina spp. Quaternary Science Reviews Giovando, L.F. & Herlinveaux, R.H. (1981). A 29, 160-169. discussion of factors influencing dispersion of doi:10.1016/j.quascirev.2009.07.013 pollutants in the Beaufort Sea. Pacific Marine Elias, S.A., Short, S.K. & Phillips, R.L. (1992). Science Report 81-4, Institute of Ocean Paleoecology of late-glacial peats from the Sciences, Sidney, BC, Canada. Bering land bridge, Chukchi Sea shelf region, Goslar, T., Arnold, M., Tisnerat-Laborde, N., northwestern Alaska, Quaternary Research 38, Czernik, J. & Wiȩckowski, K. (2000). 371–378. doi:10.1016/0033-5894(92)90045-K Variations of Younger Dryas atmospheric England, J.H. & Furze, M.F.A. (2008). New radiocarbon explicable without ocean evidence from the western Canadian Arctic circulation changes. Nature 403, 877. Archipelago for the resubmergence of Bering doi:10.1038/35002547 Strait, Quaternary Research 70, 60–67. Goebel, T., Waters, M.R., & Rourke, D.H. doi:10.1016/j.yqres.2008.03.001, 2008. (2008). The Late Pleistocene Dispersal of Fagel, N., Not, C., Gueibe, J., Mattielli, N. & Modern Humans in the Americas. Science 319, Bazhenova, E. (2014). Late Quaternary 1497–1502. doi:10.1126/science.1153569. evolution of sediment provenances in the Greenwood, S.L., O’Regan, M., Swärd, H., Central Arctic Ocean: mineral assemblage, Floden, T., Ananyev, R., Chernykh, D. & trace element composition and Nd and Pb Jakobsson, M. (2015). Multiple re-advances of isotope fingerprints of detrital fraction from the a Lake Vättern outlet glacier during Northern Mendeleev Ridge, Quaternary Fennoscandian Ice Sheet retreat, southcentral Science Reviews 92, 140-154. Sweden. Boreas 44, 619–637. doi:10.1016/j.quascirev.2013.12.011. doi:10.1111/bor.12132 Fairbanks, R.G. (1989). A 17,000-year glacio- Gregoire, L.J., Payne, A.J. & Valdes, P.J. eustatic sea level record: influence of glacial (2012). Deglacial rapid sea level rises caused

33 by ice-sheet saddle collapses. Nature 487, 219– vicinity of the northern Patagonian icefield, 222. doi:10.1038/nature11257 South America, Geografiska annaler series A (2). 375-391. Gutjahr, M., Frank, M., Stirling, C., Klemm, V., van de Flierdt, T. & Halliday, A. (2007). Hughes, A.L.C., Gyllencreutz, R., Lohne, Ø.S., Reliable extraction of a deepwater trace metal Mangerud, J. &Svendsen, J.I. (2016). The last isotope signal from Fe-Mn oxyhydroxide Eurasian ice sheets – a chronological database coatings of marine sediments. Chemical and time-slice reconstruction, DATED-1. Geology 242, 351-370. Boreas 45, 1–45. doi:10.1111/bor.12142 Hays, J.D., Imbrie, J. & Shackleton, N.J. Hultén, E. (1937). Outline of the history of (1976). Variations in the Earth’s orbit: arctic and boreal biota during the Quaternary pacemaker of the ice ages. Science 194, 1121- Period: their evolution during and after the 1132. doi:10.1126/science.194.4270.1121 glacial period as indicated by the equiformal progressive areas of present plant species. Heinrich, H. (1988). Origin and consequences Bokförlagsaktiebolaget Thule, Stockholm. of cyclic rafting in the northeast Atlantic Ocean during the past 130,000 years. Jakobsson, M., Mayer, L.A., Coakley, B., Quaternary Research 29, 142–152. Dowdeswell, J.A., Forbes, S., Fridman, B., doi:10.1016/0033-5894(88)90057-9 Hodnesdal, H., Noormets, R., Pedersen, R., Rebesco, M., Schenke, H.-W., Zarayskaya, Y., Hill, P.R. (1996). Late Quaternary sequence Accetella, D., Armstrong, A., Anderson, R.M., stratigraphy of the Mackenzie Delta. Canadian Bienhoff, P., Camerlenghi, A., Church, I., Journal of Earth Sciences 33, 1064-1074. Edwards, M., Gardner, J.V., Hall, J.K., Hell, doi:10.1139/e96-081 B., Hestvik, O.B., Kristoffersen, Y., Hillier, S. (2002). Spray Drying for X-ray Marcussen, C., Mohammad, R., Mosher, D., Powder Diffraction Specimen Preparation. Ngheim, S.V., Pedrosa, M.T., Travaglini, P.G. International union of Crystallography 27, 7-9. & Weatherhall, P. (2012). The International doi:10.1180/000985599545984 Bathymetric Chart of the Arctic Ocean (IBCAO) Version 3.0, Geophysical Research Holmes, R.M., McClelland, J.W., Peterson, Letters, doi: 10.1029/2012GL052219. B.J., Shiklomanov, A.I., Zhulidov, A.V., Gordeev, V.V. & Bobrovitskaya, N. (2002). A Jakobsson, M., Björck, S., O´Regan, M., circumpolar perspective on fluvial sediment Flodén, T., Greenwood, S.L., Swärd, H., Lif, flux to the Arctic Ocean. Global A., Ampel, L., Koyi, H. & Skelton, A. (2014a). Biogeochemical Cycles, 16/4. doi: Major earthquakes at the Pleistocene-Holocene 10.1029/2002GB001920 transition in Lake Vättern, southern Sweden. Geology 42, 379-382. Hu, A., Meehl, G.A., Han, W., Timmermann, A., Otto-Bliesner, B., Liu, Z., Washington, Jakobsson, M., Andreassen, K., Bjarnadóttir, W.M., Large, W., Abe-Ouchi, A., Kimoto, M., L. R., Dove, D., Dowdeswell, J. A., England, J. Lambeck, K. & Wu, B. (2012). Role of the H., Funder, S., Hogan, K., Ingólfsson, Ó., Bering Strait on the hysteresis of the ocean Jennings, A., Larsen, N. K., Kirchner, N., conveyor belt circulation and glacial climate Landvik, J. Y., Mayer, L., Mikkelsen, N., stability, Proceedings of The National Möller, P., Niessen, F., Nilsson, J., O’Regan, Academy of Sciences of The United States of M., Polyak, L., Nørgaard-Pedersen, N., Stein, America 109, 6417– 6422, R. (2014b). Arctic Ocean glacial history. doi:10.1073/pnas.1116014109 Quaternary Science Reviews, 92, 40-67. http://dx.doi.org/10.1016/j.quascirev.2013.07.0 Hubbard, A., Hein, A.S., Kaplan, M.R., 33 Hulton, N.R. & Glasser, N. (2005). A modelling reconstruction of the last glacial Jakobsson, M., O'Regan, M., Greenwood, S. maximum ice sheet and its deglaciation in the L., Flodén, T., Swärd, H., Björck, S. &Skelton,

34 A. (2016). Postglacial tectonic structures and Libby, W.F. (1952) Radiocarbon dating. mass wasting in Lake Vättern, southern University of Chicago press, Chicago. Sweden. Geological Society, London, Lisiecki, L.E. & Raymo M.E. (2005), A Memoirs: v. 46, no. 1, p. 119–120. Pliocene-Pleistocene stack of 57 globally doi:10.1144/M46.58 distributed benthic δ18O records, Jakobsson, M., Pearce, C., Backman, J., Paleoceanography 20, PA1003, doi: Barrientos, N., Coxall, H., De Boer, A., Mörth, 10.1029/2004PA001071. C.M., Rattray, J.E., Stranne, C., O'Regan, M., Lundqvist, J. (2009). Weichsel-istidens Cronin, T.M., Anderson, L.G., Björk, G., huvudfas. In: Fredén, C., (ed.), Berg och Jord, Mayer, L.A., Nilsson, J., Semiletov, I. (2017). 124-135, Sveriges Nationalatlas. Norstedts Post-glacial flooding of the Bering Land kartor. Bromma Bridge dated to 11 cal ka BP based on new geophysical and sediment records. Clim Past Lundqvist, J. & Wohlfarth, B., (2000). Timing 13:991-1005. doi:10.5194/cp-13-991-2017 and east–west correlation of south Swedish ice marginal lines during the Late Weichselian. Johnson, M.D., Kylander, M.E., Casserstedt, Quaternary Science Reviews 20, 1127–1148. L., Wiborgh, H. & Björck, S. (2013). Varved doi:10.1016/S0277-3791(00)00142-6. glaciomarine clay in central Sweden before and after the Baltic Ice Lake drainage: a further Lundqvist, J., Lundqvist, T., Lindström, M., clue to the drainage events at Mt Billingen. Calner, M., Sivhed, U., 2011. Sveriges geologi GFF 135, 293–307. från urtid till nutid, 3rd ed. Studentlitteratur, doi:10.1080/11035897.2013 628 pp. Keigwin, L. D., Donnelly, J. P., Cook, M. S., Lutterotti, L., Bortolotti, M., Ischia, G., Driscoll, N. W. & Brigham-Grette, J. 2006. Lonardelli, I. & Wenk, H.-R. 2007. Rietveld Rapid sea-level rise and Holocene climate in texture analysis from diffraction images, the Chukchi Sea, Geology 34, 861–864, Zeitschrift Kristallographie, Supplement. 26, https://doi.org/10.1130/g22712.1, 2006. 125-130. Kristiansson, J. (1986). The ice recession in the Macdonald, R. W., Solomon, S. M., Cranston, south-eastern part of Sweden. A varve- R. E., Welch, H. E., Yunker, M. B. & Gobeil, chronological time scale for the latest part of C. (1998). A sediment and organic carbon the Late Weichselian. University of budget for the Canadian Beaufort Shelf. Stockholm, Department of Quaternary Marine Geology 144, 255–273. Research, Report 7, 149 pp. Macdonald, R.W., Carmack, E.C., Kullenberg, B. (1947) The piston corer. Sv. McLaughlin, F.A., Falkner, K.K. & Swift, Hydr. Biol. Komms. Skrifter, 1 (No. 2) J.H., (1999). Connections among ice, runoff and atmospheric forcing in the Beaufort Gyre. Lambeck, K., Rouby, H., Purcell, A., Geophysical Research Letters 26, 2223–2226. Sambridge, M. & Sun, Y. (2014). Sea level and global ice volumes from the Last Glacial Macdonald, R.W., Sakshaug, E., Stein, R., Maximum to the Holocene. Proceedings of 2004. Modern hydrography and sea-ice cover The National Academy of Sciences of The of the Arctic Ocean. In: Stein, R., Macdonald, United States of America 111, 15296-15303. R.W. (Eds.), The organic carbon cycle in the doi:10.1073/pnas.1411762111 Arctic Ocean. Springer, Berlin. Laskar, J., Robutel, P., Joutel, F., Gastineau, MacNeill, M.R. & Garrett, J.F., (1975). Open M., Correia, A.C.M. & Levrard, B. 2004. A water surface currents. Beaufort Sea Technical long-term numerical solution for the insolation Report 17, 113. quantities of the Earth. Astronomy and Astrophysics 428, no. 1: 261 Manley, W.F. (2002). Postglacial Flooding of the Bering Land Bridge: A Geospatial

35

Animation: INSTAAR, University of Stockholm Förhandlingar 57, 29-46. doi: Colorado, v1, 10.1080/11035893509444912 http://instaar.colorado.edu/QGISL/bering_land Murton, J. B., Bateman, M. D., Dallimore, S. _bridge. Accessed 11 October 2017 R., Teller, J. T. & Yang, Z. (2010). McManus, D.A., Creager, J.S., Echols, R.J. & Identification of Younger Dryas outburst flood Holmes, M. L. (1983). The Holocene path from Lake Agassiz to the Arctic Ocean. transgression of the flank of Beringia: Chukchi Nature 464, 740–743. valley to Chukchi estuary to Chukchi Sea, in: Muschitiello, F., Smittenberg, R., Wohlfarth, Masters, P.M. & Flemming, N.C., (Eds.), B., Pausata, F., Salih, A., Watson, J., Quaternary Coastlines and Marine Whitehouse, N., Brooks, S. & Karlatou- Archaeology: Towards the Prehistory of Land Charalampopoulou, A. (2015). Fennoscandian Bridges and Continental Shelves Masters. N. freshwater control on Greenland hydroclimate C., Academic Press London. shifts at the onset of the Younger Dryas. Meyer, I., Davies, G., & Stuut, J. (2010). Grain Nature Communications, 6:8939. doi: size control on Sr-Nd isotope provenance 10.1038/ncomms9939 studies and impact on paleoclimate Muschitiello, F., Greenwood, S., Wohlfarth, reconstructions: An example from deep-sea B., Lea, J., Brunnberg, L., Nick, F. & Macleod, sediments offshore NW Africa. Geochemistry A. (2016). Timing of the first drainage of the Geophysics Geosystems 12. Baltic Ice Lake synchronous with the onset of Miller, K., Kominz, M., Browning, J., Wright, Greenland Stadial 1. Boreas 45, 322-334. J., Mountain, G., Katz, M., Sugarman, P., doi:10.1111/bor.12155 Cramer, B., Christie-Blick, N. & Pekar, S. Månsson, A.G.M. (1996). Brittle reactivation (2005) The Phanerozoic Record of Global Sea- of ductile basement structures; a tectonic Level Change. Science 310, 1293-1298. doi: model for the lake Vättern Basin, southern 10.1126/science.1116412 Sweden. Geologiska Föreningen i Stockholm Moore D.M. & Reynolds R.C. (1997). X-ray Förhandlingar 118, 19. diffraction and the identification and analysis Naidu, A., Wajda, W., Han, M., Mowatt, T. of clay minerals 2nd ed. Oxford University (1995). Clay minerals as indicators of sources Press. Oxford New York, 378 pp. of terrigenous sediments, their transportation Moore, T.C., Jr. (2005). The Younger Dryas: and deposition: Bering Basin, Russian-Alaskan From whence the fresh water? Arctic. Marine Geology 127:87-104. Paleoceanography 20, PA4021. doi:10.1016/0025-3227(95)00053-2 doi:10.1029/2005PA001170. Nilsson, E. (1939). Huvuddragen av Moran, K., Hill. P.R., & Blasco, S.M., (1989). Vättertraktens geografiska utveckling under Interpretation of piezocone penetrometer senkvartär tid. Mäster Gudmunds gilles årsbok, profiles in sediment from the Mackenzie 11-38, Jönköping. Trough, Canadian Beaufort Sea. Journal of Sedimentary Petrology 59, 88 - 97. Nilsson, E. (1953). Om södra Sveriges senkvartära historia. Geologiska Föreningen i Munthe, H. (1910). Studies in the Late- Stockholm Förhandlingar 75, 155-246. Quaternary history of Southern Sweden, Geologiska Föreningen i Stockholm Nilsson, E. (1958). Issjöstudier i södra Sverige, Förhandlingar 32, 1197-1293. Geologiska Föreningen i Stockholm doi:10.1080/11035891009442326 Förhandlingar 80, 166-185.

Munthe, H. (1935). Till frågan om Vätterns Nilsson, E. (1968). Södra Sveriges senkvartära senkvartära historia, Geologiska Föreningen i historia. Geokronologi, issjöar och landhöjning. Kungliga Svenska

36 Vetenskapsakademiens Handlingar, Fjärde Peltier, W.R, Vettoretti, G. & Stastna, M. Serien. Bd. 12:1. 117 pp. (2006). Atlantic meridional overturning and climate response to Arctic Ocean freshening. Norrman, J.O. (1964). Lake Vättern: Geophysical Research Letters 33, L06713. investigations on shore and bottom morphology (PhD thesis), Uppsala University, Peltier, W.R., Argus, D.F. & Drummond, R. Uppsala, Sweden 238. (2015). Space geodesy constrains ice age terminal deglaciation: The global ICE-6G_C Norrman, J.O. & Königsson, L.-K. (1972). The (VM5a) model. Journal of Geophysical Sediment Distribution in Lake Vättern and Research: Solid Earth 120, 450–487. some Analyses of Cores from its Southern doi:10.1002/2014JB011176 Basin. Geologiska Föreningen i Stockholm Förhandlingar 94, 489–513. Petit, J., Jouzel, J., Raynaud, D., Barkov, N., Barnola, J., Basile, I., Benders, M., Not, C. & Hillaire-Marcel, C. (2012). Chappellaz, J., Davis, M., Delaygue, G., Enhanced sea-ice export from the Arctic Delmotte, M., Kotlyakov, V., Legrand, M., during the Younger Dryas, Nature Lipenkov, V., Lorius, C., Pepin, L., Ritz, C., Communications 3:647, Saltzman, E. & Stievenard, M. (1999). Climate http://dx.doi:10.1038/ncomms1658 and atmospheric history of the past 420,000 Nørgaard-Pedersen, N., Spielhagen, R.F., years from the Vostok ice core, Antarctica. Thied, J., Kassens, H. (1998). Central Arctic Nature 399, 429-436. surface ocean environment during the past Phillips, R. L. & Grantz, A. (2001). Regional 80,000 years. Paleoceanography 13, 193–204. variations in provenance and abundance of ice- O’Regan, M., Greenwood, S., Preto, P., Swärd, rafted clasts in Arctic Ocean sediments: H. & Jakobsson, M. (2016). Geotechnical and Implications for the configuration of Late sedimentary evidence for thick-grounded ice in Quaternary oceanic and atmospheric Southern Lake Vättern during deglaciation. circulation in the Arctic. Marine Geology 172, GFF 138, 355–366. 91–115. O’Regan, M., Coxall, H., Hill, P., Hilton, R., Pickart, R.S., Pratt, L.J., Torres, D.J., Muschitiello, F. & Swärd, H. (in review). Early Whitledge, T.E., Proshutinsky, A.Y., Aagaard, Holocene sea-level in the Canadian Beaufort K., Agnew, T.A., Moore, G.W.K., and Dail, Sea constrained by radiocarbon dates from a H.J.: Evolution and dynamics of the flow deep borehole in the Mackenzie Trough, Arctic through Herald Canyon in the western Chukchi Canada. Boreas XX p. X-XX. Sea. (2010). Deep-Sea Research Part II 57, 5– 26. https://doi.org/10.1016/j.dsr2.2009.08.002, Parnell, A., Haslett, J., Allen, J., Buck, C. & 2010. Huntley, B. (2008). A flexible approach to assessing synchroneity of past events using Polyak, L. & Jakobsson, M. (2011). Bayesian reconstructions of sedimentation Quaternary sedimentation in the Arctic Ocean: history. Quaternary Science Reviews 27, 1872- Recent advances and further challenges. 1885. doi:10.1016/j.quascirev.2008.07.009 Oceanography 24, 52–64. doi:10.5670/oceanog.2011.55. Patton, H., Hubbard, A., Andreassen, K., Winsborrow, M. & Stroeven, A.P. (2016). The Porcelli, D., Andersson, P.S., Baskaran, M., build-up, configuration, and dynamical Frank, M., Björk, G. & Semiletov, I. (2009). sensitivity of the Eurasian ice-sheet complex to The distribution of neodymium isotopes in Late Weichselian climatic and oceanic forcing. Arctic Ocean basins. Geochimica et Quaternary Science Reviews 153, Cosmochimica Acta, 732645-2659. http://dx.doi.org/10.1016/j.quascirev.2016.10.0 doi:10.1016/j.gca.2008.11.046 09

37

Påsse, T. & Andersson, L. (2005). Shore-level Renssen, H., Mairesse, A.I., Goosse, H., displacement in Fennoscandia calculated from Mathiot, P., Heiri, O., Roche, D.M., & ... empirical data. GFF 127, 253–268. Valdes, P.J. (2015). Multiple causes of the Younger Dryas cold period. Nature Geoscience Rachold, V., Grigoriev, M.N., Are, F.E., 8, 946-949. doi:10.1038/ngeo2557 Solomon, S., Reimnitz, E., Kassens, H. & Antonow, M. (2000). Coastal erosion vs Rohling, E.J., Foster, G.L., Grant, K.M., riverine sediment discharge in the Arctic shelf Marino, G., Roberts, A.P., Tamisiea, M.E. & seas. International Journal of Earth Science, Williams, F. (2014). Sea-level and deep-sea- 89, 450–460. temperature variability over the past 5.3 million years. Nature 508, 477–482. Rampton, V.N. (1982). Quaternary geology of the Yukon Coastal Plain. Geological Survey of Ruddiman, W.F. (2008) Earth’s climate: past Canada, Bulletin 317. and future. 2nd edition. W.H. Freeman and Company, New York. 388 p. Rampton, V.N. (1988). Quaternary geology of the Tuktoyaktuk Coastlands, Northwest Rudels, B., Andersson, L., Eriksson, P., Territories. Geological Survey of Canada, Fahrbach, E., Jakobsson, M., Jones, E.P., Memoir 423. Melling, H., Prinsenberg, S., Schauer, U. & Yao, T. (2012). Observations in the ocean. In: Rasmussen, S.O., Andersen, K.K., Svensson, Lemke, P. & Jacobi, H.-W. (eds.), Arctic A.M., Steffensen, J.P., Vinther, B. M., Climate Change: The ACSYS Decade and Clausen, H.B., Siggaard-Andersen, M.L., Beyond, Atmospheric and Oceanographic Johnsen, S.J., Larsen, L.B., Dahl-Jensen, D., Sciences Library 43, Springer Science, Bigler, M., Röthlisberger, R., Fischer, H., Business Media B.V., p. 81. Goto-Azuma, K., Hansson, M.E. & Ruth, U. (2006). A new Greenland ice core chronology Rutberg, R. L., Hemming, S. R., & Goldstein, for the last glacial termination. Journal of S. L. (2000). Reduced North Atlantic Deep Geophysical Research 111, D06102. Water flux to the glacial Southern Ocean doi:10.1029/2005JD006079. inferred from neodymium isotope ratios. Nature 405, 935-938. Rasmussen, S.O., Bigler, M., Blockley, S.P., Blunier, T., Buchardt, S.L., Clausen, H.B., Serreze, M., Crawford, A., Stroeve, J., Barrett, Cvijanovic, I., Dahl-Jensen, D., Johnsen, S.J., A. & Woodgate, R. (2016). Variability, trends, Fischer, H., Gkinis, V., Guillevic, M., Hoek, and predictability of seasonal sea ice retreat W.Z., Lowe, J.J., Pedro, J.B., Popp, T., and advance in the Chukchi Sea. Journal of Seierstad, I.K., Steffensen, J.P., Svensson, Geophysical Research: Oceans, 121(10), 7308- A.M., Vallelonga, P., Vinther, B.M., Walker, 7325. doi:10.1002/2016JC011977 M.J., Wheatley, J.J. & Winstrup, M. (2014). A Shackleton, N.J. & Opdyke, N.D. (1973). stratigraphic framework for abrupt climatic Oxygen isotope and paleomagnetic changes during the Last Glacial period based stratigraphy of equatorial Pacific Core V28- on three synchronized Greenland ice-core 238: oxygen isotope temperatures and ice records: refining and extending the volume on a 105 year and 106 year scale. INTIMATE event stratigraphy. Quaternary Quaternary Research, 3, 39-55, Science Reviews 106, 14-28. doi:10.1016/0033-5894(73)90052-5 Reimer, P., Reimer, R., Bard, E., Bayliss, A., Shearer, J.M. (1971). Preliminary Beck, J., Blackwell, P., ... & van der Plicht, J. interpretation of shallow seismic reflection (2013). IntCal13 and Marine13 radiocarbon profiles from the west side of Mackenzie Bay, age calibration curves 0-50,000 years cal BP. Beaufort Sea. In: Report of Activities. Part B, Radiocarbon 55, 1869-1887. doi:10.2458/azu_js_rc.55.16947 Geological Survey of Canada, Paper 71-1, pp. 131-138.

38 Stein, R. (2008) Arctic Ocean Sediments: the North American continent: evidence of an Processes, Proxies, and Paleoenvironment. Arctic trigger for the Younger Dryas. Elsevier, Amsterdam. Quaternary Science Reviews 25, 659-688. Stein, R., & Macdonald, R. W. (2004). Organic Viscosi-Shirley, C., Mammone, K., Pisias, N. carbon budget: Arctic Ocean vs. Global Ocean. & Dymond, J. (2003). Clay mineralogy and In: Stein, R. & Macdonald, R. W. (eds.). The multi-element chemistry of surface sediments organic carbon cycle in the Arctic Ocean (pp. on the Siberian-Arctic shelf: implications for 315–322). Heidelberg: Springer-Verlag. sediment provenance and grain size sorting. Continental Shelf Research 23, 1175-1200. Stokes, C.R. & Tarasov, L. (2010). Ice doi:10.1016/S0278-4343(03)00091-8 streaming in the Laurentide Ice Sheet: A first comparison between data-calibrated numerical Vogt, C. (1997). Regional and temporal model output and geological evidence, variations of mineral assemblages in Arctic Geophys. Res. Lett., 37, L01501, Ocean sediments as climatic indicator during doi:10.1029/2009GL040990. glacial/interglacial changes. Reps. Pol. Res., 251, 309 pp. Stroeven, A.P., Heyman, J., Fabel, D., Björck, S., Caffee, M.W., Fredin, O. & Harbor, J.M. Vonk, J.E., Giosan, L., Blusztajn, J., (2015). A new Scandinavian reference 10Be Montlucon, D., Graf Pannatier, E., McIntyre, production rate. Quaternary Geochronology C., ... & Eglinton, T.I. (2015). Spatial 29, 104–115. variations in geochemical characteristics of the modern Mackenzie Delta sedimentary system. Stroeven, A.P., Hättestrand, C., Kleman, J., Geochimica et Cosmochimica Acta 171, 100- Heyman, J., Fabel, D., Fredin, O., Goodfellow, 120. doi:10.1016/j.gca.2015.08.005 B.W., Harbor, J.M., Jansen, J.D., Olsen, L., Caffee, M.W., Fink, D., Lundqvist, J., Wohlfarth, B., Björck, S., Possnert, G. & Rosqvist, G.C., Strömberg, B. & Jansson, K.N. Holmquist, B. (1998). An 800-year long, (2016). Deglaciation of Fennoscandia. radiocarbon-dated varve chronology from Quaternary Science Reviews 147, 91–121. south-eastern Sweden. Boreas 27, 243-257. Strömberg, B. (1994). Younger Dryas Walker, M., Bryant, C., Coope, G.R., deglaciation at Mt. Billingen, and clay varve Harkness, D.D., Lowe, J.J. & Scott, E.M. dating of the Younger Dryas/Preboreal (2001). Towards a radiocarbon chronology for transition. Boreas 23, 177-193. the Lateglacial: sample selection strategies. Radiocarbon 43, 1007-1020. Swärd, H. (2015). The deglaciation of southern central Sweden reflected in the seismic and Walker, M. (2005). Quaternary Dating sedimentary stratigraphy of southern Lake Methods. John Wiley & Sons Ltd. West Vättern. Department of Geological Sciences, Sussex, England. p 286. Stockholm University, Stockholm, p. 28. Walsh, J.J., McRoy, C.P., Blackburn, T.H., Tachikawa, K., Athias, V. & Jeandel, C. Coachman, L.K., Goering, J.J., Henriksen, K., (2003). Neodymium budget in the modern Andersen, P., Nihoul, J.J., Parker, P.L. & ocean and paleo-oceanographic implications. Springer, A.M. (1989). The role of Bering Journal of Geophysical Research: Oceans 108, Strait in the carbon/nitrogen fluxes of polar 1-13. marine ecosystems. In: Rey, L. & Alexander, V. (eds.). Proceedings of the Sixth Conference Tarasov, L. & Peltier, W.R. (2005). Arctic of the Comité Arctique International. E.J.Brill, freshwater forcing of the Younger Dryas cold Leiden, pp 90-120 reversal. Nature 435, 662-665. doi:10.1038/nature03617 Wik, N-G., Andersson, J., Bergström, U., Claeson, D., Juhojuntti, N., Kero, L., Tarasov, L. & Peltier, W.R. (2006). A Lundqvist, L., Möller, C., Sukotjo, S. & calibrated deglacial drainage chronology for

39

Wikman, H. (2006). Beskrivning till regional Letters 32, L02602, berggrundskarta över Jönköpings län. SGU, K doi:10.1029/2004GL021747. 61, 60 pp. Zolitschka, B., Francus, P., Ojala, A.E.K. & Woodgate, R.A. & Aagaard, K. (2005). Schimmelmann, A. (2015). Varves in lake Revising the Bering Strait freshwater flux into sediments - a review. Quaternary Science the Arctic Ocean, Geophysical Research Reviews 117, 1–41.

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