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Chronology and styles of glaciation in an inter-fjord setting, northwesternSvalbard

HELENA ALEXANDERSON, JON Y. LANDVIK AND HEIDI T. RYEN

BOREAS Alexanderson, H., Landvik, J. Y. & Ryen, H. T. 2010: Chronology and styles of glaciation in an inter-fjord setting,northwestern Svalbard. Boreas, 10.1111/j.1502-3885.2010.00175.x. ISSN 0300-9483.

A 30-m-thick sedimentary succession at Leinstranda on the southwestern coast of Brøggerhalvøya, northwesternSvalbard, spans the two last glacial–interglacial cycles and reveals information on glacial dynamics, sea-levelchanges and the timing of these events. We investigated the deposits using standard stratigraphical and sedi-mentological techniques, together with ground-penetrating radar, and established an absolute chronology basedmainly on optically stimulated luminescence dating. We identified facies associations that represent depositionalsettings related to advancing, overriding and retreating glaciers, marine and littoral conditions and periglacialsurfaces. The environmental changes show an approximate cyclicity and reflect glaciations followed by high sealevels and later regression. The luminescence chronology places sea-level highstands at 185�8 ka, 129�10 ka,99�8 ka and 36�3 ka. These ages constrain the timing of recorded glaciations at Leinstranda to prior to c. 190 ka,between c. 170 and c. 140 ka (Late Saalian) and between c. 120 ka and c. 110 ka (Early Weichselian). The glacia-tions include phases with glaciers from three different source areas. There is no positive evidence for either Middleor LateWeichselian glaciations covering the site, but there are hiatuses at those stratigraphic levels. A high bedrockridge separates Leinstranda from the palaeo-ice stream in Kongsfjorden, and the deposits at Leinstranda reflectice-dynamic conditions related to ice-sheet evolution in an inter-fjord area. The environmental information and theabsolute chronology derived from our data allow for an improved correlation with the marine record, and forinferences to be made about the interaction between land, ocean and ice during the last glacial–interglacial cycles.

Helena Alexanderson� (e-mail: [email protected]), Jon Y. Landvik (e-mail: [email protected]) andHeidi T. Ryen (e-mail: [email protected]), Department of Plant and Environmental Sciences, Norwegian Uni-versity of Life Sciences, PO Box 5003, NO-1432 As, Norway; �present address (e-mail: [email protected]), Department of Physical Geography and Quaternary Geology, Stockholm University, SE-106 91Stockholm, Sweden; received 21st January 2010, accepted 4th June 2010.

During the Quaternary, large climatic and environ-mental changes took place in the Arctic, and changeshere have affected and will continue to affect otherparts of the world (e.g. Darby et al. 2006; Sommerkorn& Hassol 2009). It is therefore of interest to improveour understanding of the dynamic Arctic system as awhole, and also to be able to place today’s much de-bated changes in a longer and larger perspective.

Terrestrial and marine stratigraphy on Svalbard re-cords the alternation of glacial (stadial) and interglacial(interstadial) events during the Middle and Late Pleis-tocene. Three major glaciations have been identifiedduring the Weichselian (Marine Isotope Stage, MIS,5d, 4, 2) and one during the Saalian (MIS 6; Mangerudet al. 1998; Svendsen et al. 2004). The Saalian glaciationis assumed to be the regionally most extensive of theseevents but all of them reached the continental shelf westof Svalbard and formed part of the Barents Sea IceSheet (Mangerud et al. 1998; Svendsen et al. 2004).

The glaciations were interrupted by interglacials andinterstadials from which shallow marine sediments arepreserved in raised sediment successions. The Eemianinterglacial (�MIS 5e) is characterized by a high re-lative sea level and waters as warm as or warmer thanpresent, while the Weichselian interstadials are coolerthan present but have high sea levels still (Miller et al.1989; Mangerud et al. 1998). The chronology for these

events has been derived from radiocarbon, lumines-cence and amino acid dating, and from correlation withoxygen isotope stratigraphy (Miller 1982; Mangerud &Svendsen 1992; Forman 1999).

Landvik et al. (2005) and Ottesen & Dowdeswell(2009) showed that the Late Weichselian ice sheet wasdynamically differentiated, with active ice streams de-positing tills in fjords, and largely inactive ice leavingno traces in inter-fjord (inter-ice-stream) areas. Thisresolved a discrepancy regarding the extent of the LateWeichselian ice advance that had existed for manyyears (review in Landvik et al. 1998). The present gla-ciation curve (Mangerud et al. 1998) is based largely ondata from fjord settings, and thus might not be re-presentative for the vast inter-fjord areas. Detailed in-vestigations of sites situated between the major fjordsof Svalbard, such as the west coast of Brøggerhalvøya,could thus contribute to an improved understanding ofthe entire glacial history of the archipelago (cf. Kaaki-nen et al. 2009; Ottesen & Dowdeswell 2009).

In this study we aim to enhance the absolute chron-ology and the palaeoenvironmental interpretations ofQuaternary terrestrial records on northwestern Sval-bard. Based on reinvestigations of Quaternary sedi-ments we reconstruct and discuss glaciation history andglacial dynamics as well as sea-level change in an inter-fjord area during the last two glacial–interglacial cycles.

DOI 10.1111/j.1502-3885.2010.00175.x r 2010 The Authors, Journal compilation r 2010 The Boreas Collegium

mailto:[email protected]





The improved absolute age control will aid future cor-relations with other geological records.

Setting and sites

Svalbard is situated in the North Atlantic between 741and 811N (Fig. 1A). It is at the boundary between coldArctic and warmer Atlantic air- and water-masses andis thus sensitive to any changes in the front systems. TheBrøggerhalvøya peninsula, between Kongsfjorden andForlandsundet on northwestern Svalbard, is dominatedby Palaeozoic bedrock with a thin Quaternary sedimentcover (Figs 1B, 2, 3) (Hjelle et al. 1999). On centraland southern Brøggerhalvøya there are mountains500–900m high with several cirque and small valleyglaciers, mainly on the northeastern slopes (Hagen et al.1993). The northwestern tip of the peninsula is char-acterized by the�4-km-wide Kvadehuksletta strandflatwith its raised beach sediments up to 80m a.s.l. The

present-day landscape is influenced mainly by glacial,periglacial and coastal processes.

The west coast of Brøggerhalvøya on northwesternSvalbard is situated south of the margin of the largeKongsfjorden palaeo-ice stream (Landvik et al. 2005;Ottesen et al. 2007). Bathymetric data from northernForlandsundet show that active ice has – at some stage– moved northwards in the sound towards Kongsfjor-den and deposited a large moraine at the northern end(Ottesen et al. 2007). However, the glacier drainagebasin for northern Forlandsundet is comparativelysmall (Hagen et al. 1993), suggesting a more limited iceflow during glacial times in this area. Furthermore,erratics of Spitsbergen origin have been found onnorthern Prins Karls Forland and have been dated tothe Late Weichselian (J. Y. Landvik, unpublisheddata), which indicates that phases of ice flow acrossForlandsundet occurred. The west coast of Brøgger-halvøya is therefore considered to be representative ofthe vast inter-fjord areas on western Svalbard. Weknow from previous studies (Troitsky et al. 1979; Miller

Kongsfjorden

Forlandsundet

Engelsk-bukta

Brøggerhalvøya

Prins Karls Forland

land

glacier

contour(100 m)

sea

0 5 10 km

N

B

A

warm current

cold current

LGM ice margin

Lein-stranda

NyÅle-sund

T

Å

U

0° 20°E 50°E20°W40°W

80°N

70°N

0° 20°E10°W

Gre

enla

nd

Scandi-navia

Svalbard

GreenlandSea

BarentsSea

ArcticOcean

Fig. 1. A. The location of Svalbard in the north Atlantic. Major ocean currents are indicated. The black square shows the location of (B).Limits for ice-sheet extent during the Last Glacial Maximum are from Svendsen et al. (2004; Barents Sea) and Funder et al. (2004; Greenland).B. The Kongsfjorden-Brøggerhalvøya area. The valleys behind Leinstranda are Traudalen (T), unnamed cirque (U) and Amdalen (A).

2 Helena Alexanderson et al. BOREAS

1982; Miller et al. 1989; Forman 1999) that there aresites with good records of Pleistocene events here, andone of these sites, Leinstranda (latitude 7815205400N,longitude 1113302400E; Fig. 1B), is the focus of thispaper.

The coastal cliffs at Leinstranda are at most �33mhigh, of which only the lowest �6m are bedrock (Fig.2). The main exposures (sites 204, 207; Fig. 2A) arewithin 100m of each other north of the large ravine,with supplementary exposures�180m further inland inthe ravine (205) and 40–60m south of the ravine (206,208). Two pairs of prominent marker beds (units 8/9and 14/15; Fig. 2B, C) were used for lateral correlations.

The sections at Leinstranda were previously in-vestigated by Troitsky et al. (1979; their site 1), Miller(1982; his site 3), Miller et al. (1989; their site 15) andForman (1999; his site 15). Troitsky et al. (1979) de-scribe one glacial event, younger than the Eemian (orTL-age 52.5 ka), and over- and underlying transgres-sional deposits. Miller (1982) and Miller et al. (1989)recognize four emergence cycles and correlate thesewith amino acid episodes D to A of Miller (1982).Major glaciations occurred in the early parts of epi-sodes C (Late Saalian) and B (Early Weichselian),and no evidence of Middle or Late Weichselian glacialactivity was found (Miller et al. 1989). Based on anumber of infrared stimulated luminescence (IRSL)dates, Forman (1999) revised the chronology of Milleret al. (1989) slightly and inferred ages of c. 140�20 ka

and c. 80�10 ka for the deglacial sequences thatcorrespond to Miller’s amino acid episodes C and B,respectively.

Methods

The coastal cliff sections at Leinstranda were in-vestigated and documented by standard sedimentolo-gical procedures (logging, measurement of clastcharacteristics, documentation etc.). The cliffs weresurveyed along a 5-km stretch, and several exposureswere studied and combined into a composite strati-graphy (Fig. 4). The large-scale sediment geometry wassurveyed from the beach, from cliff tops and from aship offshore, as well as locally by ground-penetratingradar. Clast fabric measurements were carried out on atleast thirty 2–6 cm clasts with an a/b-axis ratio of43/2,and the results were plotted in a lower-hemisphereprojection in STEREONET for Windows 3.03 (GeologicalSoftware, Norway).

Petrographic analyses were based on approximatelyfifty 2–6 cm clasts per sample. Based on statistical clusteranalysis (WINSTAT 2009.1) and provenance, the sam-ples were grouped into four petrographical types (Fig. 3).We also documented other clast characteristics such asclast shape, presence of striations or carbonate pre-cipitation. X-ray diffraction (XRD; Philips PW1710 dif-fractometer) analysis was performed on bulk powder

204207

14/15

8/9

B

C

33 m

204

207

205

204

207

206208

A

Fig. 2. A. Leinstranda with sites (red dots)and ground-penetrating radar (GPR) profiles(white lines). Inset shows the location of GPRprofiles in Figs 2C, 8A and B. Excerpt fromaerial photo S90-6812, with permission from theNorwegian Polar Institute. B. View of thecentral part of the coastal cliffs. Studiedexposures are indicated with white squares. Themarker bed units 8/9 and 14/15 are indicated.C. 50-MHz GPR profile along the cliff shown in(B), not corrected for topography.

BOREAS Glaciation in an inter-fjord setting, NW Svalbard 3

samples (o180mm) from fine-grained units. The sampleswere measured untreated and after treatment with ethy-lene glycol and at 3001C and 5501C. Brown & Brindley(1980) was used as a reference for mineral identification.

We collected a total of 3381m of ground-penetratingradar (GPR) profiles parallel and at right angles to thecoastal cliffs using a Sensors & Software pulseEKKO100 radar (400V). The profiles were recorded with an-tenna frequencies of 50 and 200MHzwith 2-m and 0.5-mantenna spacing, respectively. Post-processing ofGPR-data was performed using EKKO_VIEW andEKKO_VIEW Deluxe software (Sensors & SoftwareInc.), and the data were classified according to GPRreflection patterns (Neal 2004; Table 1).

Positions and altitudes were determined with a Gar-min eTrex Vista C GPS-receiver complemented by aPaulin barometric altimeter. The altimeters were cali-brated at the local high-tide mark, which is our zero le-vel, before and after each measurement session.

Optically stimulated luminescence (OSL) ages arebased on sand-sized quartz and were measured at theNordic Laboratory for Luminescence Dating, AarhusUniversity, Denmark using standard SAR-protocols inRisø TL/OSL readers (Murray & Wintle 2000, 2003).Dose rates were determined by gamma spectrometry(Murray et al. 1987), and we included the cosmic raycontribution according to Prescott & Hutton (1994).Electron spin resonance (ESR) samples from marinemollusc shells (Hiatella arctica, Mya truncata, Astartesp.) were analysed at the Research Laboratory forQuaternary Geochronology at Tallinn University ofTechnology in Estonia following procedures in Mo-lodkov (1988, 1993). AMS-radiocarbon dating of bone,wood and shell samples was performed at the NationalLaboratory for Radiocarbon Dating in Trondheim,Norway. Details of samples and dating procedures aredescribed in Alexanderson et al. (submitted).

Stratigraphy and depositional environments

Facies and facies associations

We have identified 18 different facies in the Leinstrandasuccession and these have been classified into nine fa-cies associations (Table 1, Fig. 4). The classification isbased on the appearance and characteristics of sedi-mentary units, including architecture, boundaries, tex-ture and structure, major and minor lithofacies (cf.Table 2), fossil content, clast characteristics, colour andGPR reflection patterns. These attributes are found inTable 1, and the features of each unit are also shown inFigs 4 and 5.

The facies associations are interpreted to representdifferent depositional environments (Table 1) thatoccur in cycles throughout the sedimentarysuccession.

Absolute chronology

The absolute chronology is based on OSL, ESR andradiocarbon dates. OSL provided the most strati-graphically consistent chronology (Table 3). For mostof the ESR samples, unusually high internal uraniumcontents allowed only probable ESR age-ranges to becalculated (Alexanderson et al. submitted). Some ofthese age-ranges encompass very large time-spans(Table 4) and do not provide precise absolute ages. Theradiocarbon ages from unit 16 (Table 5) suggest thatthe lower end (o45 ka) of the ESR age-range is prob-ably too young. Compared with the OSL chronology,the upper part of the ESR age-ranges are also generallyyounger for the same units. Given the good agreementbetween OSL and 14C for younger sediments in the areaand the overall good characteristics of luminescencedates from Brøggerhalvøya, we use the OSL

limestone, dolomite red sandstone, conglomerate

sandstone, conglomerate phyllite, schist

quartzite, diamictite

marble

Kongsfjorden

Engelskbukta

Forlandsundet

Leinstrandasite

Till, unit 14

Type 3Type 1 Type 2

Till, unit 20

Type 4

Beach, unit 17

Fan, unit 3Ice-proximal,unit 12

Beach, unit 19

Till, unit 8 Ice-proximal,unit 7

5 km

Fig. 3. Map of the dominant lithologies on Brøggerhalvøya (adapted from Hjelle et al. 1999) and representative examples of the four petro-graphic types we identified in the sediments. Type 1 reflects a strong local source of material; type 2 has a mainly local to southeasterly prove-nance; type 3 has local to mainly northerly source areas; and type 4 contains all major lithologies in fairly large proportions and no distinctsource area can be determined.


chronology as our first choice for Leinstranda, andconsider the younger ESR chronology as a less likelyalternative (see full discussion in Alexanderson et al.submitted).

Leinstranda

Units 0–4: Subaqueous sedimentation during deglacia-tion. – The underlying bedrock (unit 0) consists of

Fig. 4. Leinstranda composite log. The log is based on site 204 (Fig. 2), complemented with information from the other sites. Unit 20 is strati-graphically overlying unit 19 but found, for example, at site 205, 4150 m inland from the coastal cliffs. The directional structures refer to dipdirections of beds and laminae (rose diagrams and wavy arrow), clast orientation (fabric plots) and the strike of striae or channel length axis(line). For petrographical types see Fig. 3, for details on the facies associations see Table 1, and for lithofacies codes see Table 2.


Table

1.Summary

descriptionandinterpretationoffacies

associationsforLeinstranda.Theground-penetratingradarreflectionpatternsare

described

accordingto

theterm

inologyofNeal(2004).

Facies

associations

Description

Interpretation

Facies

association

Facies

Occurs

inunit

Maxim

um

thickness

Lateral

extent

Bed/unit

geometry

Lower

boundary

Overall

texture

Overall

sedim

entary

structure

Major

lithofacies

1

Minor

lithofacies

1

Striated

clasts

MPS2

(cm)

Petrography

type3

C40;

RA

4

Macrofossils

Colour

GPR

reflection

pattern

Other

Depositional

process(es)

Depositional

environment

Sea

level

Diamicton

D1

Stratified

silty

diamicton

70.5m

80m

Tabular,

wedge

Sharp

Silty

diamicton

Stratified

D(Si)ms

D(SSi)mm

Yes

(70)

216%

12%

smallshell

fragments,shellgrey

(not

distinguished)

lateral

variationin

structure

and

texture;no

preferred

orientationof

clastlong-axes

density

flow

ice-proxim

al

glaciomarine

high

D2

Massive

sandy

diamicton

51m

�20m

Tabular

Sharp

Sandy

diamicton

Massive

D(S)m

m–

Yes

(26)

429%

0%

no

brown

(not

distinguished)

compact

debrisflow

orhyperconcen-

trateddensity

flow

ice-proxim

al

glaciomarinehigh

D3

Bouldery

gravel

12

2m

100sm

Tabular,

wedge

Interfinger-

ing

Cobbly

gravel

Cross-bedded,

stratified

B/C

oGcm

,Gcm

–Yes

29–32

(4300)

3,4

9%

7%

no

grey,

brown

I:discontinuous,

slightlywavy

reflectionswith

sub-horizontal

dip

andchaotic

relationship,

hyperboles

present

cohesionless

debrisflow;

waveorcurrent

reworking?

Poorlysorted

gravelly

sand

12

3m

100sm

Tabular,

wedge

Interfinger-

ing

Gravelly

sand

Cross-bedded,

stratified

D(S)m

mGSm,(ng)

No

13

317%

0%

no

grey,

brown

high-density

turbidity

currents,debris

flows

ice-proxim

al

glaciomarinehigh

Inversely

graded

gravel

60.8m

5m

Channel

Sharp,

erosive

Gravel

Stratified

CoGcm

(ig)

–Few

24(43)

423%

2%

wholeand

paired

shells

grey

(not

distinguished)

fillsa

half-pipeshaped

depression

cohesionless

debrisflow

D4

Massivesilty

diamicton

8,14,20

0.3m

1000m

Tabular

Sharp

Silty

diamicton

Massive

D(Si)mm

Di(SiS)m

mYes

�12(30)

1(2;unit20)31%

22%

no

red(unit

20brown)

II:strong

continuous,

planarreflections,

sub-horizontal

andparallelto

eachother

overconsolida-

ted;preferred

orientationof

clastlong-axes

deform

ation

anddeposition

belowglacier

sole

subglacial

n/a

Fines

FMud

9,15

1m

1000m

Tabular

Sharp

Clayey

silt

Massive

Cm,SiCm,

CSim

–No

n/a

n/a

n/a

wholeand

paired

shells,

shellfragments

grey

II,seeD4

fining

upward

deposition

from

suspen-

sion

Massivesand

9,15

1cm

o5m

Tabular

Sharp

Sand

Massive

Sm

–No

n/a

n/a

n/a

no

red,

yellow

(not

distinguished)

occuras

laminae

low-density

turbidity

currents

glaciomarinehigh

Clayey

diamicton

1,9,15

1m

1000m

(unit1:

5m)

Tabular

Sharp

Silty

clayey

diamicton

Massive

D(SiC)m

mD(C

)mm

No

n/a

n/a

n/a

shells(unit1

none)

grey

(unit1

black)

II,seeD4

scattered

fine

gravelclasts

from

suspension,

meltoutfrom

icebergs

Sand

SDiffusely

stratified

sand

2,10,16

30cm

�50m

Tabular,

wedge

Sharp

Sand

Stratified

Sl,Sr,

Sm,Slc

SiSm,(def),

(ng),(ig)

No

n/a

n/a

n/a

shells,whale

andbirdbones,

seaurchin,

kelp,wood

yellow

III:moderately

continuous,sub-

parallel,planar

towavy(vague)

reflectionswitha

sub-horizontal

dip,mainly

reflection-freein

50MHz

scattered

outsized

pebbles;diffuse

structures;

cross-lamination

angle2–61,

commonbed

thickness

10–15cm

waveand

nearshore

currentaction;

bioturbation

marine

shoreface

high

Massive

gravelly

sand

2,16

20cm

o�10m

Tabular,

lens

Sharp

Gravelly

sand

Massive,

vaguely

stratified

GSm

D(S)m

mNo

(20)

4(unit2

only)

11%

2%

shell

fragments

yellow

waveand

nearshore

currentaction,

gravitational

reworking


Gravel

G1

Tangentially

cross-bedded

gravel

31m

425m

Tabular,

wedge,lensSharp,

gradual

Gravel

Massive,

graded

Gcm

,SGcm

,(ig)

–Rare

9–10

3,4

9%o1%

no

yellow,

reddish

(not

distinguished)

unitcoarsening

upward;lateral

variationin

colour;cross-

bed

dip

14–201;

convex

lenses

andconvex

downwards

channels

commonly

�10m

wide

bedloadtraction,

cohesionless

debrisflows

subaqueous

fan

high

Tangentially

cross-bedded

gravelly

sand

325cm

425m

Tabular,

wedge,lens

Sharp,

gradual

Gravelly

sand

Massive,

graded

GSm,SGm

(ig)

Rare

n/a

47%

2%

no

yellow,

reddish

high-density

turbidity

currents,debris

flows

Diamictlenses3

25cm

o10m

Lens

Sharp

Silty

sandy

diamicton

Massive

D(S)m

mD(Si)mm

No

n/a

420%

6%

no

red

gravitational

reworkingoftill

Tangentially

cross-bedded

sand

340cm

425m

Tabular,

wedge,lensSharp,

gradual

Sand

Laminated

Spp,Sr

Sm

No

(6)

n/a

n/a

no

red

low-density

turbiditycurrents

G2

Cross-bedded

gravel

4,11,17

5m

30–400m

Wedge

Sharp,

interfinger-

ing

Stony

gravel

Massive,

graded

CoGcm

,

Gcm

,SGcm

,(ng)

GSm,(i)

No

10–21

3,4

14%

2%

shell

fragments

grey

IV:continuous

tomoderately

continuous

planarreflections,

dippingtowards

SW,sub-parallel

tooblique

divergent

unitslighly

coarsening

upward;cross-

bed

dip

3–121;

moderate

size-

andshape-

sorting

swash

and

backwash,

cusp

migration

andbeach

progradation

marine

beachface

high

G3

Stratified

gravelwithsilt

18,19

2m

1000m

Tabular

Sharp

Silty

gravel

Stratified

Gcm

(bi),

Gcm

(ng),

CoGcm

(ng)

SGm,GSm

No

17

414%

0%

verysm

all

shellfragments

grey

V:continuous

planarreflections,

horizontalor

sub-horizontal,

largelyparallel

tounderlying

boundary

containsclasts

w.carbonate

crustsandclasts

w.vertically

orientedlong-

axes;siltw.

vesicular

structure

fills

poresorontop

ofclasts;

morphologically

expressed

aslow

ridges

swash

and

backwash;soil

form

ation,

weathering,

aeolianinput,

cryoturbation

beach;

periglacial

subaerial

high;

low

Massivegravel

withsilt

13

0.6m

5m

Tabular

Sharp

Silty

gravel

Massive

Gcm

(bi)

–No

33

24%

5%

no

grey,

yellow

(not

distinguished)

siltorfinesand

onallsides

of

clasts;reddishat

thetop;loose

swash

and

backwash?

beach?

high

1See

Table2forlithofacies

codeexplanation.

2MPS=

maxim

um

particlesize

(averageofA-axes

of�10largestclasts);valuein

parenthesisissinglelargeclast.

3See

Fig.3.Type1reflectsastronglocalsourceofmaterial;type2hasamainly

localto

southeasterly

provenance;type3haslocalto

mainly

northerly

sourceareas;andtype4containsallmajor

lithologiesin

fairly

largeproportionsandnodistinct

sourceareacanbedetermined.

4C40=

%clastswithc/a�

0.4;RA=

%veryangularandangularclasts(K

rumbeinindex

112).

Table

1.Continued.

Facies

associations

Description

Interpretation

Facies

association

Facies

Occurs

inunit

Maxim

um

thickness

Lateral

extent

Bed/unit

geometry

Lower

boundary

Overall

texture

Overall

sedim

entary

structure

Major

lithofacies

1

Minor

lithofacies

1

Striated

clasts

MPS2

(cm)

Petrography

type3

C40;

RA

4

Macrofossils

Colour

GPR

reflection

pattern

Other

Depositional

process(es)

Depositional

environment

Sea

level


carbonate rocks and sandstones of the PalaeozoicScheteligfjellet Formation (Hjelle et al. 1999). It isheavily folded and later eroded to a flat level �6m a.s.l.Its surface is commonly cracked and shattered but inplaces it is glacially polished. Glacial striae striking851–2651 were found close to site 206.

Unit 1 is found near site 206, where a few-metres-long and �30-cm-thick patch of black-green clay withscattered coarse-grained sand or fine gravel clastsoverlies the bedrock and fills the cracks. Miner-alogically, unit 1 contains a large proportion of dolo-mite (Fig. 6).

Unit 2 directly overlies the bedrock or unit 1, but itcan only be mapped in a part of the section south of theravine. It consists of ripple-laminated or vaguely pla-nar-parallel laminated fine sand interbedded withpoorly sorted gravelly sand. The fine sand contains oc-casional and scattered outsized clasts. A few very small(�1mm) shell fragments were found. Current ripplesrecord palaeocurrents towards the SW-W.

Unit 2 grades into unit 3, which is volumetrically thelargest unit visible in the section, �8m thick and ex-tending more than 2 km laterally. It consists largely of acoarsening-upward succession of beds of inverselygraded massive gravel, massive gravelly sand and pla-nar-parallel laminated sand that form large-scale cross-beds, with shallow channels and lenses and somediscontinuous diamict beds (Fig. 5A, Table 1). Thesetangential cross-beds dip 141–201 towards the southwestand become increasingly red in colour and generallycoarser towards the south. Clasts belong to petro-graphical type 4 or 3 (Fig. 3). Individual beds becomethinner upwards, and there is also more frequent al-teration between lithofacies in the upper part. In thecentral part of the section, unit 3 is succeeded by threecoarser, normally graded gravelly beds that constituteunit 4 (Fig. 5C). The beds, which dip a few degreesseawards, are only discontinuously exposed within astretch of �30m.

The striae on the bedrock record a glacier comingout of Engelskbukta or from central Brøggerhalvøya(Fig. 1) some time prior to the deposition of the over-lying units 2 and 3 (4c. 190 ka).

The clay (unit 1) is classified as facies association F,interpreted as glaciomarine mud (Table 1). However,its mineralogical and fossil content is different fromunits 9 and 15 and a local weathered bedrock origincannot be ruled out.

Turbidity currents and debris flows, some of whicheroded chutes or shallow channels, dominated de-position on the unit 3 foresets (facies association G1,Table 1). The sorting of the sediments suggests thatthey experienced some fluvial or glacifluvial transportbefore reaching the sea. However, a few of the thindiamict beds resemble the local tills (cf. units 8 and 14below) and are probably reworked till material, in-dicating proximity to a glacier front. No other featurestypical of ice-contact environments were found (e.g.glaciotectonic deformation, ice-rafted debris, till clasts;cf. Lønne 1995), but neither did we find positiveevidence of a subaerial plain (although see unit 4).

We thus interpret the setting as one or more coales-cing submarine fans, or possibly fan deltas, that formeda slope apron (cf. Nemec 1990; Lønne 1995; Lønne &Nemec 2004), with unit 2 being the deeper, marinecontinuation at the toes of the gently sloping foresets(facies association S). Glaciers were nearby and the fansmay have been ice-contact submarine fans (Lønne1995). The few shell fragments that are found in unit 2are probably reworked (Miller et al. 1989).

The extensive sedimentation along the coast at thistime requires a laterally extensive sediment source, orseveral point sources, as well as river discharge largerthan today. We thus propose that glaciers existed in thethree valleys behind Leinstranda (Traudalen, Amdalen,unnamed cirque; Fig. 1B), providing meltwater trans-port to the sea along 4–5 km of the coastline. Thisis supported by petrographic composition and

Table 2. Lithofacies codes, modified from Eyles et al. (1983).

Texture Structure

D(S, Si, . . .) Diamicton, sandy, silty, . . . m MassiveB Boulder ms Matrix-supported, stratifiedCoG Cobbly gravel mm Matrix-supported, massiveG Gravel cm Clast-supported, massiveGS Gravelly sand lc Low-angle cross-laminatedSG Sandy gravel r Ripple-laminatedS Sand pp Planar-parallel laminatedSiS Silty sand l LaminatedSSi Sandy silt (ng) Normally gradedSi Silt (ig) Inversely gradedSiC Silty clay (def) DeformedCSi Clayey silt (i) ImbricatedC Clay(bi) Bimodal


A B

1 m

25 cm25 cm

C D

E F

G H I

3

5

6

9

8

7

15

14 13

12

16

17

17

16

19

18

19

17

Fig. 5. Photographs of units and facies associations (cf. Table 1 and Fig. 4). Unit numbers are in white circles. The blue handle of the trowelused for scale is 10 cm in length. A. The gravelly foresets of unit 3 (facies association G1) also contain some sandy and diamict beds. The visiblepart of the ruler is�20 cm. B. Coarsening-upward gravel of unit 6 (D3) fills a channel cut into unit 5 (D2). C. Sharp lower and upper boundariesseparate the red unit 8 (subglacial diamicton, D4) from the underlying thin unit 7 (D1) and the overlying unit 9 (F). D. Overview of units 12–15at site 204, including the deformation structure shown in Fig. 9. The red unit 14 (D4) and the compact unit 15 (F) are useful marker beds. E.Stratified sand with thin kelp laminae and scattered dropstones (S) in unit 16. F. The stony gravelly G2 facies association in unit 17. The visiblepart of the ruler is 50 cm. G. A whale rib bone in the upper part of unit 16 (S), overlain by unit 17 (G2). H. A discontinuous cobble horizonforms the boundary between units 19 and 18, which is in turn underlain by unit 17 gravel (G2). The visible part of the ruler is 80 cm. I. Clast-supported stratified gravel with secondary silt infilling (facies association G3) in the upper part of unit 19.


palaeocurrent directions, which suggest that much ofthe material is derived from the hinterland, includingthe red-coloured Brøggertinden Formation at theBrøggerfjellet Mountain (Hjelle et al. 1999). The highrelative sea level (Z15m), as well as the underlying gla-ciomarine clay and striae, also suggests an isostaticloading and is in agreement with the presence of largerglaciers than today.

The overlying unit 4 (facies association G2) is inter-preted as a beachface deposit based on its seaward-dipping low-angle cross-beds (Massari & Parea 1988),its texture and its fossil content. It is most probablyunit 3 sediments reworked by waves and reflects achange from a fan- to a wave-dominated regime(cf. Lønne & Nemec 2004; Blair & McPherson 2008)during a regression caused by fan aggradation and/or

Table 3. Optically stimulated luminescence (OSL) data from Leinstranda. The samples are presented in stratigraphic order (cf. Fig. 4). Formore details on the OSL ages see Alexanderson et al. (submitted).

Sample no. Site Unit Depth (m) Age (ka) Dose (Gy) n Dose rate (Gy/ka) w.c. (%)

081341 Beach – 0 – 0.24�0.05 15 – –081323 204 18 1.5 36�3 29�2 26 0.80�0.04 31081333 207 17 2.8 89�5 113�3 25 1.27�0.05 33081324 204 16 7.0 98�6 87�2 25 0.89�0.05 26081325 204 16 7.3 97�6 108�5 25 1.11�0.05 33081326 204 16 8.0 94�6 131�5 28 1.40�0.06 33081327 204 16 9.5 111�7 132�5 23 1.18�0.05 33081334 207 16 9.0 106�6 120�4 24 1.13�0.05 28081328 204 11 14.0 129�10 98�4 23 0.76�0.05 32081329 204 10 14.5 122�8 116�4 23 0.94�0.05 22081330 204 10 14.5 122�10 121�7 23 0.99�0.05 30081335 207 10 14.5 143�9 134�5 24 0.94�0.04 30081331 204 3 20.5 173�11 133�3 22 0.77�0.04 28081336 207 3 22.5 184�12 141�5 18 0.77�0.04 30081332 204 3 25.0 239�17 156�5 17 0.65�0.04 30081337 206 3 26.0 187�14 151�6 24 0.81�0.05 29081338 206 3 26.5 183�15 109�5 24 0.60�0.04 28081339 206 3 26.8 151�11 119�3 24 0.79�0.05 30081340 206 2 27.0 196�15 128�4 27 0.65�0.04 32

w.c., water content.

Table 4. Electron spin resonance (ESR) data from Leinstranda (cf. Fig. 4). Owing to unusually high internal uranium contents (Uin), onlyprobable age ranges could be calculated for all but three samples (375-039, 371-039, 383-039-OS); see Alexanderson et al. (submitted) for furtherdiscussion.

Sample no.1 Site Unit Depth (m) Age2 (ka) Dose (Gy) Uin (ppm) Used (ppm) Thsed (ppm) Ksed (%)

376-088 204 16 8.0 50–29 68 6.44 1.22 5.84 1.23381-039 207 16 9.5 111–46 106 7.40 1.29 2.45 0.77382-039 207 16 9.5 127–41 121 10.97 1.29 2.45 0.77372-039 204 15 10.0 64–36 123 9.00 1.88 8.45 2.25373-039 204 15 10.0 58–35 107 7.40 1.88 8.45 2.25374-039 204 15 10.0 65–36 113 8.00 1.88 8.45 2.25375-039 204 15 10.0 59�5 126 0.73 2.12 12.59 3.15377-088 204 10 14.5 96–58 93 3.87 1.03 2.33 0.73369-039 204 9 15.0 46–35 80 3.75 1.90 7.99 2.07370-039 204 9 15.0 52–38 100 4.40 1.90 7.99 2.07371-039 204 9 16.0 79�6 159 0.80 2.28 9.88 2.58383-039 204 6 17.0 365–72 380 19.10 1.90 1.05 0.53383-039-OS3 204 6 17.0 405�31 94 0.41 1.90 1.05 0.53384-039 204 6 17.0 335–95 356 11.40 1.90 1.05 0.53379-039 204 6 17.0 232–85 273 9.10 2.61 1.61 0.61380-039 204 6 17.0 184–78 208 7.30 2.61 1.61 0.61

1The laboratory code RLQG is omitted in the table.2The upper age limit is for early uptake of uranium assuming a typical average of internal uranium content in the shells Uin=0.80 ppm derived

from measurements of more than 300 Pleistocene shells (A. Molodkov, unpublished). The lower limit is for early uptake using the measured

value of Uin. 59�5 and 79�6 are ages of shells with measured Uin values close to typical ones and can be considered as reliable.3The sample is dated by the ESR open systemmethod (Molodkov 1988). The dose is the internal dose (total dose is equal to that of 383-039) and

Uin the time-average internal uranium content.


glacioisostatic rebound. However, owing to limited ex-posures the interpretation is not very certain.

OSL ages from units 2 and 3 average 188�27 ka(n=7); if two outliers are excluded, the mean is185�8 ka (Table 3, Fig. 4). The OSL ages place theseevents in late MIS 7 or early MIS 6.

Units 5–7: Advancing glacier. – Unit 5 is a 1-m-thickbrown, massive sandy diamicton mapped laterally for

�20m near site 204 (Fig. 5B) and as a 20-cm-thickpatch �80m further north (site 207). It is compact, hasa sharp lower boundary and contains striated clasts. Itis erosionally cut by unit 6, which comprises coarse in-versely graded beds that fill in a channel striking �1651(Fig. 5B). The channel appears roughly V-shaped, is atleast 1m wide (only half could be excavated) and�60 cm deep, and the channel walls are up to 401 steep.This unit contains clasts 440 cm in diameter, some of

Unit 1 clay

0

5000

10000

15000

CP

S

2 30 35°2 Theta

Unit 14 till

2500

5000

7500

10000

CP

S

02 30 35

°2 Theta60

2500

5000

7500

10000

CP

S

02 30 35

°2 Theta60

Unit 15glaciomarinemud

2500

5000

7500

10000

CP

S

02 30 355 10 15 20 25 40 45 50 55 60

5 10 15 20 25 40 45 50 55 5 10 15 20 25 40 45 50 55

5 10 15 20 25 40 45 50 55°2 Theta

60

Unit 19 siltingravel

C

A B

D

Fig. 6. X-ray diffraction (XRD) plots of untreated powdered bulk samples (o180 mm). d-values (in A) and interpretations for the most significantpeaks are shown. Unit 1 clay (A) is mineralogically different from the other glaciomarine muds, here represented by unit 15 (B), and its composi-tion is more similar to that of the underlying carbonate bedrock. The grey glaciomarinemud (B) and the red till (unit 14, C) have on the other handa largely similar mineralogical composition, although the till has relatively more K-feldspars, quartz and biotite and lower amounts of clay mi-nerals such as illite and chlorite. The silt in the beach gravel (unit 19, D) has high contents of both quartz and dolomite, which may reflect its dualorigin from weathering of carbonate clasts and aeolian input. Note the different scale of the Y-axis in (C) compared to (A), (B) and (D).

Table 5. AMS-14C ages from Leinstranda (cf. Fig. 4). All samples are from unit 16 at site 204. Infinite ages are stated with 1s. The finite age iscalibrated according to Fairbanks et al. (2005).

Sample no. Material 14C age (a BP)1s

Calibrated age (cal. a BP) d13C

TUa-7529 Bird bone (Uria lomvia) 454 220 �17.8TUa-7530 Shell (Mya truncata) 42 045�615 46 515�569 2.4TUa-7531 Wood (prob. Larix) 445 850 �22.5TUa-7532 Whale rib bone1 449 975 �16.7

1Possibly Balaena mysticetus (according to a find of bones at the same site/level by Miller et al. 1989).


which are striated. AbundantHiatella arcticawere foundin the upper part of the unit, some in living position.

The overlying thin unit 7 varies laterally over �80mfrom a stratified sandy silty diamicton in the south to alargely massive silty diamicton in the north (Fig. 5C). Itcontains a few boulders up to 70 cm in size and alsosome millimetre-sized shell fragments. Fabric analysisshows a moderate isotropy and no preferred particleorientation (Figs 4, 7). Clast petrography is of type 2(Fig. 3).

Unit 5 is interpreted as an ice-proximal glaciomarinesediment gravity flow deposit (facies association D2)owing to characteristics such as diamict texture,striated clasts and limited lateral extent (Table 1). AN–S-striking channel is eroded and filled by a series ofcohesionless debris flows (unit 6, facies association D3;O Cofaigh et al. 1999). The change from massive tostratified lithofacies within unit 7 (facies association D1)may record some reworking. The fabric characteristicsare similar to those of other glaciomarine diamictons(Fig. 7; Bennett et al. 1999) and show that clasts wererelatively free to rotate in a dilatant medium.

Taken together, these units indicate a nearby glacialsource reaching the marine environment, perhaps anoutlet glacier coming out of Engelskbukta in the southas suggested by the mainly southerly clast provenanceof unit 7 and the direction of the channel. The sedi-ments were deposited in an ice-proximal or ice-margin-

al setting, such as a grounding-line fan or morainalbank (Powell 2005). The geometry of the deposit can-not be determined from the point data we have. Thisimplies that the glacier was warm-based and had a de-veloped subglacial drainage system (O Cofaigh et al.1999).

ESR ages from unit 6 range from c. 405 to c. 70 ka(Table 4, Fig. 4), with the most likely age 4200 ka(Alexanderson et al. submitted). Strictly speaking thesewide age ranges do not contradict the under- and over-lying OSL ages that provide a more constrained agerange (between c. 190 ka and c. 140 ka), and accordingto both chronologies the deposition of these units canprobably be placed in MIS 7.

Units 8–11: Glacial overriding, deglaciation and re-gression. – Unit 8 is a 0.3-m-thick, massive compactsilty diamicton with a distinct reddish colour (Fig. 5C).It is laterally extensive, and the lower and upperboundaries are sharp. Clasts up to �20 cm are present,but most are 1–3 cm and include well-rounded discs androds. A few clasts have carbonate crusts. Striated clastsare common (20–30%), with striae being short andshallow and mainly, but not only, oriented parallel toclast long axes and occurring on opposite sides of aclast. Petrographic composition is type 1 (Fig. 3). Clastfabric analyses indicate moderately preferred particleorientations in a N–S direction (Figs 4, 7).

Fig. 7. Ternary plot of fabric data from diamictunits 7, 8 and 14. For stereoplots of the samedata, see Fig. 4. There is a clear differencebetween fabric characteristics from faciesassociation D1 (ice-proximal glaciomarinedeposits, fabric 1) and from D4 (subglacial till,fabrics 2–5). Clasts in the latter have a preferredorientation, while clasts in the former were ableto rotate more freely.


The subhorizontal unit 9 is up to 2m thick and iscomposed of massive silty clay and clayey silt withscattered coarse sand and fine gravel grains, mainly inthe lower part (Fig. 5C). Some thin sand laminae arefound. Shell fragments are frequent and some pairedmollusc shells (Hiatella arctica, Astarte borealis) arefound.

Both beds are clearly distinguishable on the GPRprofiles (GPR reflection pattern II, Table 1, Fig. 2C)and can be mapped over long distances (�1 km).The actual thickness varies owing to truncation by anoverlying erosional unconformity. The limited thick-ness also prevents GPR resolution of the unit 8/9 com-plex, and they show up as one prominent reflectiononly.

The thin, wedge-shaped sandy unit 10 erosivelyoverlies unit 9. It increases in thickness to an observedmaximum of 0.4m towards the east, and low-anglecross-stratifications dip gently (2–61) towards thesouthwest. Whole and fragmented mollusc shells (Myatruncata, Astarte borealis, Macoma calcarea) are com-mon at the base. The sand interfingers with the gravellysand of unit 11. The gravelly sand is normally graded,dips towards the southwest and contains a few shellfragments. Both units have only been observed locally,but can be mapped in GPR profiles for a distance of50–60m both along and perpendicular to the section(GPR reflection pattern III; Table 1, Fig. 4).

Unit 8 (facies association D4) is interpreted as asubglacial till based on the sharp lower boundary, largelateral extent, compaction and common striated clasts(Table 1; Kruger & Kjær 1999). The fabric character-istics (Fig. 7), which are similar to those of other basaltills (Bennett et al. 1999), and the striae pattern indicatethat clast rotation was constrained, and particles’ longaxes were preferably aligned in one direction. This sug-gests a rather stiff matrix and probably brittle or brittle-ductile deformation below the glacier sole (Benn 1995).The directions of the primary vectors from the twofabric analyses are, however, almost opposite to eachother, but we consider this an effect of the very low dip,and treat them as indicating the same south-to-northice-movement direction.

The sediment texture and content of foraminifera(Miller et al. 1989) suggest that the glacier has over-ridden and picked up older marine sediments (mud)and beach deposits (rod- and disc-shaped clasts). Thered colour indicates a local source of reddish Carboni-ferous sandstones for the original marine deposits (i.e.the Brøggerfjellet Mountain), as also suggested byMiller et al. (1989). For the glacier to have picked themup, these muds must have been deposited between thepresent-day coast and the Brøggerfjellet Mountain, andare thus indications of a previous period of higher sealevel and probably significant local erosion in themountains. This is different from other glaciomarinephases, which are dominated by greyish sediments (e.g.

unit 9, 15). Additional local input to unit 8 may havecome from direct glacial erosion.

The unit 8 till represents an ice sheet that must havebeen warm-based and had a significant local impact,but the ice-movement direction at the site appears tohave been controlled by regional flow along For-landsundet. The till was succeeded by glaciomarinesediments (unit 9) deposited when sea level wasZ20m higher than today, requiring significant isostaticloading.

The fine-grained sediments of unit 9 were depositedfrom suspension in a glaciomarine environment (faciesassociation F) as the ice margin retreated. Ice-raftingsupplied outsized clasts, and occasional turbidity cur-rents deposited isolated sandy laminae. The fining-up-ward trend of the silt/clay and the decreasing frequencyof gravel-sized ice-rafted debris reflect an increasingdistance to the glacier margin. As the sedimentationrate decreased, a pioneer mollusc community (cf. Gor-dillo & Aitken 2001) was established, and the for-aminifera became more abundant (Miller et al. 1989).

After erosion, sand (unit 10) and gravel (unit 11)were deposited (facies association S, G2). This reflects asuccessively shallower environment, owing to a fallingrelative sea level (cf. Miller et al. 1989).

Units 10 and 11 are OSL-dated to 129�10 ka(n=4), whereas ESR ages from units 9 and 10 rangefrom 96 to 35 ka, with one more precise age of 79�6 ka(Table 3). We believe that these ESR ages under-estimate the real age (see above and in Alexandersonet al. submitted), whereas the OSL ages indicate de-position of units 9–11 during MIS 5e or late MIS 6.Faunal analysis of marine macrobenthos also supportsan interglacial age of the deposit (S. Funder, pers.comm. 2010; Alexanderson et al. submitted). This cor-roborates the conclusion by Miller et al. (1989), whoinferred an Eemian interglacial age based on the for-aminiferal assemblage of the sediments.

Units 12–13: Glacier in northern Forlandsundet. – Themost prominent characteristics of unit 12 are its contentof boulders 43m in diameter (Figs 2B, 5D) and the in-land dip of the beds (towards the SE-NE sector) asconfirmed by the GPR profiles (GPR reflection patternI; Table 1, Fig. 8). The unit is slightly wedge-shaped,thinning towards the south, with a laterally varying in-terfingering or sharp lower boundary. It is 3–4m thickand can be mapped laterally for more than 100m northof the ravine. A few small shell fragments have beenobserved and striated clasts are present.

Unit 13 consists of two 25–30 cm thick beds, bothwith clast-supported well-rounded gravel but the lowerone with a fine sand matrix and the upper one with asilty matrix. The matrix is massive (no vesicular struc-ture seen), evenly distributed between particles, andreddish in the upper few centimetres. The unit has avery limited lateral extent and is, at the studied section,


slightly deformed as a result of the depression in unit14/15 (see below and Fig. 5D); this prevents us fromgaining reliable information on its geometry.

The content of large boulders and the occurrence ofstriated clasts suggest a glacial origin of the sedimentsand deposition in an ice-proximal environment (faciesassociation D3; Table 1). The lack of fines could be theresult of previous (subglacial) glacifluvial transport orof post-depositional reworking by currents or waves(cf. Miller et al. 1989). Similar deposits, interpreted ascohesionless debris flows, have been described from ice-contact subaqueous fans (e.g. Cheel & Rust 1982; Ait-ken 1995). In this case, we believe unit 12 represents alateral-frontal deposit at or near the apex of a ground-ing-line fan.

Compared with the preceding glacial unit (the unit 8till), unit 12 contains less local material and is insteaddominated by limestone from the northern part ofBrøggerhalvøya. Together with the dip of the beds, to-wards land (Fig. 8A), the petrography indicates a dif-ferent glacial pathway compared with ice movementfrom the Brøggerhalvøya/Engelskbukta area, as withunit 8. Thus the glacier must have been occupying thenorthern part of Forlandsundet, fed either by an outletglacier in Kongsfjorden, or possibly by an accumula-tion area over northern Prins Karls Forland, althoughthe latter is considered less likely given the petrography.Although there are carbonate rocks on northern PrinsKarls Forland, the potential glacial source area isdominated by phyllite, quartzite and conglomerate(Hjelle et al. 1999).

The well-sorted, rounded sediments of unit 13 sug-gest a littoral environment, possibly a beach. Its ap-pearance is slightly different from the other unitsbelonging to facies association G3 at Leinstranda, butsimilar lithofacies have been seen at other sites in thearea, usually related to shallow-water deposits. The ex-posure is too small and disturbed to give enough in-formation for a definitive interpretation. If it representsa beach, it is an indication of shallowing conditions,owing to a forced or normal regression.

Units 14–17: Glaciation, deglaciation and re-gression. – Units 14 and 15 (Fig. 5D) are assigned tothe same facies associations as units 8 and 9, respec-tively, and only a few differing characteristics are men-tioned here. The clast fabric in unit 14 indicates amoderately preferred particle orientation (�SW–NE;Figs 4, 7). Unit 15 is thinner than unit 9 and containsmore frequent sand laminae, some of which are red.

At exposure 204, a linear steeply trough-shapedstructure �0.5m deep was found at the boundary be-tween units 14 and 15, also affecting unit 13 (Figs 5D,9). The structure strikes 140–3201 and has a concentra-tion of clasts o25 cm at the base.

Unit 16 is a predominantly sandy unit that is at most�3m thick and wedges out towards the northwest andinland. It can be followed in GPR profiles for about50m along the section north of the ravine and �40minland from the present cliff face (GPR reflection pat-tern III; Table 1). The lower boundary is horizontal,

signal lost

GPR : unit 17IV

direct waves

0

10

5

Depth (m)

0

10

5

0 5 10 15 20 25 30Distance (m)

NW SE

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0 10 20 30 40 50 60Distance (m)

70

W E

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GPR IV: unit 17

direct waves

GPR III: unit 16GPR :unit 12

I

GPR II:unit 15

GPR : u.18/19V

Depth (m)

GPR :unit 15

II

50 MHz 200 MHz

A B

GPR : u.18/19V

Fig. 8. Ground-penetrating radar (GPR) profiles from Leinstranda; see Fig. 2A for location. A. A 50-MHz profile at right angles to the coastline reveals that the beds of unit 12 dip inland. B. A strong reflector at about 2.5 m depth indicates a silt-rich horizon within unit 17. It does notseparate different GPR reflection patterns and is cut by continuous reflectors representing the dipping beds, suggesting that it is a secondaryfeature (see text for further explanation). This reflector is visible both in 200-MHz (shown here) and in 50-MHz profiles run parallel and at rightangles to the coast. Note the different scales of (A) and (B). This figure is available in colour at http://www.boreas.dk.


sharp and erosive. The upper boundary is interfingeringwith the gravel of unit 17 (Fig. 5G).

Low-angle cross-beds are built up of vaguely lami-nated or ripple-laminated sand, with a few gravellysandy or sandy diamict beds in between (Fig. 5E). Thegeneral dip is 21–61 (max 131) towards the SSE, andripples indicate palaeocurrents ranging from towardsthe NNE to towards the south (Fig. 4). Scattered out-sized clasts (o10 cm) have deformed the underlyingbeds, largely with bended bottom contacts (cf. Thomas& Connell 1985). Remains of kelp (coarse seaweed)were found attached to one of these clasts.

The sand contains remnants of a varied fauna, in-cluding mollusc shells in living position, a sea urchinand bones from a large whale (rib, unknown species;Fig. 5G) and bird (jaw, Uria lomvia). The sand is espe-cially rich in shells close to the lower boundary, butshells are found scattered throughout the unit. Themost common species are Mya truncata (in the upperpart) and Hiatella arctica (in the lower part), but Ma-coma calcarea, Astarte sp. and Buccinum undatum havealso been observed. M. truncata, H. arctica and M.calcarea have been found as paired shells and in livingposition. Within the sand are laminae consisting of thinmats of seaweed. Close to the whale bone we also founda piece of wood (probably Larix).

According to the GPR data, the coarse gravel over-lying unit 16 consists of two subunits, both of GPR re-flection pattern IV. The boundary between these twosubunits was poorly visible in section but is prominent

in the GPR profiles (Fig. 8B). It appears to correlatewith a silt-rich horizon at �2.5m depth, where the siltmainly caps the particles. However, the horizon doesnot follow bed boundaries (Fig. 8B). Both subunitscontain clast-supported, normally graded gravelly bedsdipping 31–121 towards the southwest (Figs 5F, H),some of which exhibit imbrication. Compared with thelower part, the upper subunit has slightly more gentlydipping beds, a slightly larger maximum particle sizeand slightly more angular clasts, but otherwise nodifferences. The whole package is 4–5m thick, wedge-shaped, slightly coarsening-upwards and with an inter-fingering or sharp lower boundary. The lateral extent ofthe unit exceeds 200m. A few small shell fragmentshave been observed.

Similarly to units 8 and 9, units 14 and 15 are inter-preted as subglacial till (facies association D4) and gla-ciomarine sediments (facies association F), respectively.

The linear depression is interpreted as an icebergscour (e.g. Woodworth-Lynas & Guigne 1990), formedright after the deglaciation during the deposition of unit15, as units 13, 14 and 15 all seem to be involved in thedeformation. The iceberg keel pushed down the pre-viously deposited sediments and caused some advectivemixing. An iceberg source would also account for thenumerous large clasts, which otherwise are uncommonboth in the subglacial till (facies association D4) and inthe glaciomarine mud (facies association F). The strikeof the depression shows that the iceberg movedSE–NW out of Forlandsundet. Other possible causes

0

0.5

1.0

1.5 m0 0.5 1.0 1.5 2.0 2.5 m

0

0.5

1.0 m

0 0.5 1.0 1.5 mNE SW

ENE WSW

strike 140 - 320°

1.5 m

covered

covered

14

15

13

14

15

13

SGcm(bi)

D(SiS)mm

CSim

D(CSi)mm

SGm

SiGcm(bi)D(Si)mm

Fig. 9. A linear deformation structure thataffects units 13, 14 and 15 is interpreted as aniceberg scour (unit numbers in circles). The twoexposures are on opposite sides of a protruding‘knee’ at site 204. Note the odd contact in themiddle of the lower figure (just slightly to theright of the SGm label), which may indicate thatthe contact is more deformational than purelyerosional. See also Fig. 5D for a photographand Table 2 for lithofacies codes.


for the linear depression could be deformation by asubglacial protrusion (ice, boulder) or by sea ice, butfor the reasons stated above we consider these less likely.

The glaciomarine mud implies a high relative sea le-vel (highstand) as a result of glacioisostatic loadingduring the preceding glaciation. The iceberg scour wasrapidly buried by glaciomarine mud, which suggeststhat it was formed below the wave base and was notaffected by waves or strong bottom currents (cf. Eyleset al. 2005). Presently, iceberg scouring is not found atdepths 440m in Kongsfjorden (Dowdeswell & Fors-berg 1992), which may be considered a probable max-imum depth for unit 15. This is also in line with thedepth range indicated by the general sand–mudboundary in the area (cf. Boulton 1990). However,most published records of iceberg scours describe largerstructures than this one (e.g. Eden & Eyles 2001), al-though scours of similar size have been identified(Winsemann et al. 2003).

The low-angle cross-lamination in unit 16 that hasbeen partly disturbed by bioturbation (facies associa-tion S; Table 1) is typical for sedimentation in theshoreface, or offshore–shoreface, zone (Massari &Parea 1988; Reading & Collinson 1996). The drop-stones were mostly kelp-rafted, as indicated by kelpremnants attached to one clast and supported by thescattered occurrence of clasts (no dumps of severalparticles) and the general pebble size (Gilbert 1990).However, some dropstones may also derive from sea-ice or icebergs. The limited extent of unit 16 suggeststhat the sand was deposited in a small bay, perhaps re-lated to a drowned, wider version of the present-dayravine.

The cross-beds of unit 17 represent a progradingbeach-face system, either on, for example, a spit, or ona fluvially dominated deposit building out into a bay orlagoon, as indicated by the underlying sand (cf. Massari& Parea 1988). The general dip of the beds shows pro-gression towards the southwest; variation in dip direc-tion and irregular reflectors in the GPR profile (Fig. 8B)result from lateral and temporal variation, includingerosional events and, for example, cusp formation. Themoderate size- and shape-sorting is typical of texturallyrelatively immature beaches (Bluck 1999) and reflectslarge sediment input and rapid sedimentation. The fewand fragmented shells that we found also testify to adynamic environment.

The silt-rich horizon is interpreted as a secondaryfeature formed by silt infiltration into the gravellybeach material. Commonly, such processes are asso-ciated with soil formation (Forman & Miller 1984;Locke 1986), and are most likely to have occurred afterthe sea level was lowered below �30m a.s.l. However,the horizon is situated more than 1m below the top ofthe unit, cutting bed boundaries, and we find no posi-tive evidence of its being formed at a ground surface (cf.unit 19). Instead, we believe it may be related to the

position of a groundwater or permafrost table or otherform of barrier at some depth below a former surface.

OSL ages from units 16 and 18 range from 111�7 kaat the base to 89�5 at the top (mean 99�8 ka, n=6;Table 3, Fig. 4), whereas ESR ages from units 15 and 16range between 127 and 29 ka, with an emphasis on ages65–35 ka (n=7; Table 4). AMS-radiocarbon ages ofmacrofossils in unit 16 give one finite (46�0.6 cal. kaBP) and three infinite (Table 5, Fig. 4) ages. The lumi-nescence chronology is preferred also here, and OSLages centre on MIS 5c.

Units 18–19: Beach, hiatus and soil formation. – Normallygraded beds of clast-supported gravel make up both unit18 and the tabular unit 19 (Fig. 5I). Unit 18 is only a fewdecimetres thick, while unit 19 is 1–2m thick. The bound-ary between the units can discontinuously be followed at�1.5m depth from site 204 to 207 as a hiatus representedby a concentration of subangular cobbles or small bould-ers (o60 cm), some of which are polished or striated (Fig.5H). In addition, some rounded soft-sediment clasts occur.In unit 19, beds with silt infill in pores alternate with bedswhere clast undersides are commonly almost completelycovered with a thin (o1mm) carbonate crust. Most clastswith carbonate precipitation are found at 30–40 cm depth,but occur down to 2m. The silt mainly caps the particlesand exhibits a vesicular structure. According to the classi-fication of Forman & Miller (1984), silt accumulation hasreached stage 6 in the upper part and stage 3–5 in the lowerpart, whereas most carbonate precipitation on clasts hasreached stage Ic–IIa.

In the upper �40 cm of unit 19, the long axes ofmany clasts are vertically oriented. Very small (milli-metre-sized) shell fragments, most of them abraded,have been found throughout the unit. Unit 19 caps thecoastal section, and the surface morphology shows low,parallel ridges that can be mapped for42 km (Fig. 2A).

Both units are classified as facies association G3 andinterpreted as beach gravel, deposited at or above themean sea level (cf. Massari & Parea 1988), at leastpartly as beach ridges, as indicated by the geomor-phology (Fig. 2A). Thus, they indicate sea levels of30–32m above present. The sediment is more mature(size- and shape-sorted) than in facies association G2(Table 1), a sign of more energy or time spent on thismaterial (Bluck 1999).

The upper part of unit 19 has been altered as a resultof surface processes and soil formation. The silt matrixis mainly the result of different weathering mechanismsacting on the parent beach gravel, and the carbonatehas precipitated from the soil solution (Swett 1974;Forman & Miller 1984; French 1996; Van Vliet-Lanoeet al. 2004). There could be some aeolian input to thesoil as well (e.g. Locke 1986), as indicated by thequartz–dolomite mineralogical composition (Fig. 6D).The upturned structures and vertical alignment of


elongate clasts is the result of cryoturbation in the ac-tive layer (Pissart 1969; French 1996).

The characteristics of the clasts at the boundary be-tween units 18 and 19 (size, shape, surficial features)suggest an input of material that is different from thesurrounding beach material. The clasts are probablyreworked, at least partly from frozen sediment, and arean erosional remnant of a glacial deposit. The hiatusthus represents a glacial advance across the site.

An OSL age from unit 18 gives 36�3 ka. We did notfind anything to date in unit 19 as the sediment was toocoarse-grained for OSL and the shell fragments toosmall for radiocarbon dating, as well as probably beingreworked.

Unit 20: Local glaciation. – The uppermost beach se-diment (unit 19) can be traced �200m inland, where itis sharply overlain by a brown silty diamicton (unit 20).The diamicton is associated with large (o3m) bouldersand is affected by post-depositional soil processes.

The spatial position of unit 20 and its associationwith large boulders suggest a different origin from theother silty diamictons (facies association D4). It is in-terpreted as a till, and probably – judging from its lo-cation – derived from local glaciers on Brøggerhalvøyaand not from a glacier or ice-sheet tongue in For-landsundet. However, the extent and characteristics ofthe unit need to be mapped in more detail before defi-nitive conclusions can be drawn.

Glacial signatures and depositionalenvironments – discussion

Factors controlling the deposition

The sediments at Leinstranda show a cyclic repetitionof events, with the main factors controlling depositionbeing the sea level and proximity to glaciers. Most unitswere deposited during periods when relative sea levelwas higher than present, and were influenced by differ-

ent degrees of glacial sediment input (cf. Fig. 10). Incontrast to non-glacial or low-latitude settings, the lo-cal sea level in the area is controlled largely by glacialisostasy. High local sea levels at Svalbard during timeswhen the global sea level was low, as it has been formost of the last 200 000 years (Waelbroeck et al. 2002),must imply glacial isostatic loading and thus extensiveglaciation in the region. In addition to being influencedby local isostatic loading, the isostatic depression ofwestern Svalbard is strongly influenced by glacial load-ing further east, that is, by the Barents Sea Ice Sheet(Mangerud et al. 1998).

A rough reconstruction of local relative sea levelduring deposition has been derived from the lithofaciesinterpretations (Fig. 11). The present elevation of thetop of each (subaqueously deposited) unit is taken as aminimum sea-level estimate, while a maximum level isassumed from inferred depths of deposition (see unitinterpretations above). For unit 9, we have used theelevation of the episode C beach deposits at Kvade-huksletta (�80m a.s.l.; Forman & Miller 1984) as amaximum limit; these sediments are interpreted to re-present the marine limit during the Eemian or an EarlyWeichselian interstadial (110–70 ka, H. T. Ryen, un-published OSL ages).

Based on the identified facies associations of theLeinstranda succession, we illustrate deposition duringa glacial cycle with a facies model (Fig. 10). At Lein-stranda, none of the cycles is complete, but an idealizedrecord of such a cycle (glacial advance – glaciation –deglaciation – regression during glacial minimum) isshown in Fig. 10B.

Glacial advance (facies associations D1–D3)

The coarse-grained glaciomarine sediments (facies as-sociations D1–D3; Table 1) are ice-proximal, part ofthem may actually be subglacial, and they formgrounding-line fans or morainal banks. Such depositsare characteristic of slowly moving glaciers with a large

Glacial influence

Time

Facies association and interpretation

F: glaciomarine mudS: shoreface sandG2: beachface gravelG3: beach gravel

G1: subaqueous fan gravel

D1-3: ice-proximalglaciomarine diamictonD4: subglacial till

A

B

Fig. 10. A. Schematic model of depositionalenvironments found in the Leinstrandasuccession. B. Idealized depositional record of acomplete cycle through glacial advance,glaciation, deglaciation and regression. Neitherfigure is to scale.


sediment input in relatively shallow water (cf. faciesassociation II of Powell 1981) and can form duringboth glacial advance and retreat. These facies associa-tions thus record glaciers that actively erode, transportand deposit sediments.

At Leinstranda, we find these deposits at two strati-graphic levels (units 5–7 and 12), and clast petrographyand directional structures point to different glacialsources for the two events. For units 5–7, the strati-graphic context suggests that these beds represent an

185±8

129±10

99±8

36±3

Fig. 11. Interpretation of depositional environments, and reconstruction of local relative sea level, simplified palaeoegography and ice-move-ment directions. The ages for the marine units are based on our OSL chronology, and the uncertainty attached to each age is the standarddeviation of the population of ages for each event. Previous age determinations from the site are also presented (Miller et al. 1989; Forman1999).


initial stage of a glaciation, as they were later over-ridden by a glacier (unit 8). This is probably also thecase for unit 12, but the possibly littoral sediments ofunit 13 may indicate that there was some non-glacialdeposition in between. However, these glacial advancesmay not be directly related to the subsequent overridingby a glacier, as, for example, ice-movement directionsare (quite) different from that indicated by the over-lying till, and so the ice-proximal glaciomarinesediments represent a different (regional) glacial sig-nature.

Based on the available data, at least two local sce-narios for the advance of tidewater glaciers over theLeinstranda site can be suggested (cf. Fig. 11). (i) TheComfortlessbreen and Uversbreen glaciers at the headof Engelskbukta advanced into the Forlandsundetsound and inundated Leinstranda. This scenario is re-presented by units 5–7. (ii) A tidewater glacier filling theKongsfjorden basin drained into the northern parts ofForlandsundet. This could explain the landward de-position of unit 12. Both scenarios require an increasedgrowth of glacier ice over Spitsbergen, feeding the tide-water glaciers. Such a growth is compatible with thehigh relative sea level during deposition. Another po-tential scenario, for unit 12, is a large expansion of gla-ciers on Prins Karls Forland to reach acrossForlandsundet.

Glacial overriding (facies association D4)

At Leinstranda, the strongest glacial signal – glacialoverriding – is represented by silty subglacial tills over-lying sharp, probably erosional, boundaries (facies as-sociation D4, Table 1). The incorporation of redmarine mud into the tills indicates that these glacialphases were, at some time, preceded by intensified ero-sion and locally high relative sea levels on centralBrøggerhalvøya. Clast petrography also shows a largelocal (�easterly) component, and clast fabric of theupper till (unit 14) displays a preferred orientation�E–W. For the lower till (unit 8), on the other hand,fabric data suggest ice movement largely parallel to thedirection of Forlandsundet (�SE–NW).

We interpret these tills to represent glaciation phaseswith at least locally warm-based conditions over Brøg-gerhalvøya, and during which glaciers moved west-wards into Forlandsundet and/or were steered along it.They must be related to a large, regional glaciation,giving rise to enough isostatic loading to explain thehigh sea level evidenced by the overlying glaciomarinemuds (see below).

Although the tills are the strongest glacial signals atLeinstranda, as they signify glacial overriding, theymay not represent the actual (ice-sheet volumetrical)glacial maxima on western Svalbard. Landvik et al.(2005) propose that during the Last Glacial Maximum,

glacial ice in inter-fjord settings was inactive, largelycold-based and with an ice-movement direction that, atLeinstranda, was dominated by a regional flow west-wards across Forlandsundet. This is supported by theoccurrence of Late Weichselian erratics from Spitsber-gen on northern Prins Karls Forland (J. Y. Landvik,unpublished data). At Leinstranda, this event is re-corded only by a hiatus, and, similarly, hiatuses else-where in the stratigraphic record could also representsuch advances. The tills could then possibly be relatedto a late glacial phase during which a northward-mov-ing tributary glacier was active, for example in thenorthern part of the Forlandsundet (Landvik 2009).

Such a dynamic situation is compatible with our ob-servations from two glacial–interglacial cycles at Lein-stranda. The unconformity below the tills (units 8, 14)and the mismatch of ice-movement directions betweenglacial advance and glacial overriding facies allows fora cold-based ice sheet to have existed after the advanceof tidewater glaciers and prior to the deposition of thetills during a post-maximum phase dominated by morelocal glaciation. The high sea levels during deglaciation(units 9, 15) are also in line with a late phase of ex-tensive glaciation.

Glacial retreat (facies association F)

The deposition of subglacial tills is directly replaced byglaciomarine muds containing some ice-rafted debris(cf. facies association I of Powell 1981). This suggeststhat deglaciation took place fairly rapidly, as no coarse-grained ice-marginal deposits indicative of a still-standare left, and in relatively deep water, probably owing torapid break-up and calving. The greyish mud in units 9and 15 is very similar to the modern sediments in En-gelskbukta, off the Comfortlessbreen glacier (Alex-anderson, unpublished), and we assume that itrepresents the prevailing glaciomarine sedimentation inForlandsundet. A few reddish laminae within facies as-sociation F do, however, point to input from othersources, notably from the Brøggertinden Formation oncentral Brøggerhalvøya (similar to facies associationD4). Glaciers probably remained in the mountains be-hind Leinstranda, and occasionally red sediments wereprovided to the site, either directly or as a result of re-working, for example through the slumping of olderdeposits.

The presence of ice-rafted debris throughout the gla-ciomarine muds shows that tidewater glaciers werepresent in Forlandsundet during all the time re-presented by these sediments at Leinstranda. The ice-rafted debris is, however, less frequent upwards, whichreflects an increasing distance to these glaciers and/or asmaller number of them.

We find that the Late Weichselian deglaciation isprobably a good analogue for this phase. During the


Late Weichselian deglaciation, ice flow was topo-graphically controlled in Forlandsundet (Forman 1989;Ottesen et al. 2007), and rapid ice break-up of the lowice in the sound probably took place as a result of eu-static sea-level rise (Landvik 2009).

Glacial minimum (facies associations S, G1, G2, G3)

The minimum glacial influence (interstadial or inter-glacial conditions) is at Leinstranda represented by si-liciclastic coastal deposits strongly influenced by forcedregression. A successive shallowing is evidenced by thechange from shoreface sand to gravelly subaqueous fanor from beach-face into beach (ridge) gravel (facies as-sociations S ! G1 ! G2 ! G3). Sedimentation alongsuch regressional coastlines volumetrically dominatesthe successions both at Leinstranda and for other lateQuaternary stratigraphies in the region (Mangerudet al. 1998; Andersson et al. 1999, 2000). These beachsystems commonly form near tributary valleys, whichare the main sediment source (Powell 2005), a situationthat is true for the Leinstranda succession.

Input from land-based glaciers dominates facies as-sociation G1 (cf. facies association IV of Powell 1981),and local glaciers larger than today’s must have existedalong the south coast of Brøggerhalvøya. The extensivesediment supply led to shallowing of the basin, and theregression was probably not related to any change insea level. Facies associations G2 and G3, on the otherhand, are influenced mainly by littoral processes, andwe interpret the shallowing evidenced by them to havebeen caused by a forced regression attributable to gla-cioisostatic adjustment.

Based on the fossil content of unit 16, we believe thatthese facies associations were formed under ice-free andseasonally open conditions, as shown by the bones ofwhale and of Brunnich’s guillemot (Uria lomvia). TheLarix wood, however, requires seasonal sea ice fortransportation from the source areas to the Svalbardcoasts (Haggblom 1982). There is no positive evidenceof tidewater glaciers in Forlandsundet from any ofthese facies associations.

As the relative sea level eventually dropped, the landsurface was exposed to periglacial processes, includingsoil formation and aeolian activity.

Timing and correlation

At Leinstranda four glacial sequences have been iden-tified, five if the hiatus between units 18 and 19 is inter-preted as a glacial erosion surface. The sequenceslargely match the four emergence cycles of Miller et al.(1989) and we are able to correlate our stratigraphywith theirs very well. The sequences have variousdegrees of preservation, the older ones being morecomplete than the younger. It is nonetheless important

to note that, as with many land-based records, al-though the sediment pile is thick, it still represents onlyshort periods of total time and is not a continuousrecord.

Our chronology provides absolute age control for themarine events, and we find that stages with high sea le-vel (interstadials or interglacials) occurred c. 185�8 ka,129�10 ka, 99�8 ka and 36�3 ka (Fig. 11). These agesare also maximum and/or minimum ages for the glacialphases and indicate that major glaciations took placeprior to c. 190 ka, between c. 170 and c. 140 ka, betweenc. 120 ka and c. 110 ka, and after c. 30 ka. The chronol-ogy is based mainly on OSL ages, and is largely inagreement with the chronologies of Miller et al. (1989)and Forman (1999) from this site. Results from ESRdating are partly in accordance with the OSL data,partly indicating a younger age range for some of theunits (Fig. 4). However, as discussed in Alexandersonet al. (submitted), in this case we prefer the OSLchronology to the ESR, mainly because the latter hasless precise ages, some stratigraphic inconsistencies andproblems with high internal uranium content in theshells.

The Leinstranda succession consequently recordsglaciations over northwestern Svalbard sometime priorto the Saalian, during the Late Saalian and during theEarly Weichselian. A Late Weichselian glaciation ishinted at, but not positively proved locally. The highsea levels during the intervening interstadials/inter-glacials demonstrate that all these events were part ofextensive glaciations over Svalbard and/or the BarentsSea. Middle and Late Weichselian glaciations in thearea are also indicated by the (isostatically) raisedmarine units 18 and 19. This pattern corresponds wellto the glacial history of Svalbard presented by Man-gerud et al. (1998) and Svendsen et al. (2004), andwhich is based both on terrestrial and on marine re-cords. We would, however, like to revise one of thecorrelations between the Leinstranda (Site 15) recordand the Kapp Ekholm stratigraphy, which forms thebasis for the glaciation curve of Svalbard (Mangerudet al. 1998). Based on the lithostratigraphy and our new(OSL) chronology we prefer a correlation between ourunits 15–17 (cycle B ofMiller et al. 1989) at Leinstrandaand the Early Weichselian Phantomodden interstadialat Kapp Ekholm (Mangerud & Svendsen 1992), insteadof with the Middle Weichselian Kapp Ekholm inter-stadial as preferred by Mangerud et al. (1998).

From the inter-ice-stream areas, Ottesen & Dow-deswell (2009) described a glacial landform assemblagedistinctly different from that found within former ice-stream pathways. It is characterized by mainly trans-verse landforms and hummocky terrain, reflecting thedynamic differences within various parts of the Sval-bard ice sheet, with ice streams draining the main fjordsystems and less active ice covering the inter-fjord areas(Landvik et al. 2005).


The ice dynamic record found in the Leinstrandastratigraphy demonstrates active glaciers with a sig-nificant component controlled by the local topographyand with periodically stable ice-front positions in theForlandsundet sound. This is not diagnostic for eitherof the dynamic assemblages (cf. Ottesen & Dowdeswell2009). Lithostratigraphically, however, the sedimentsat Leinstranda show large similarities to those at siteswithin the major fjords (ice-stream areas) such asKongsfjorden (Houmark-Nielsen & Funder 1999;Alexanderson & Ryen, unpublished data), Isfjorden(Mangerud & Svendsen 1992) and Bellsund (Landviket al. 1992). At the present stage, we thus conclude thatpalaeo-ice-stream and inter-ice-stream conditions can-not be easily differentiated from the stratigraphic re-cord.

Conclusions

� Four more or less preserved glaciation–deglaciationcycles have been identified at Leinstranda; theseconform with the conclusions of Miller et al. (1989).A complete cycle includes ice-proximal glaciomar-ine diamictons deposited during the advance of ti-dewater glaciers, subglacial tills related to theoverriding of locally active glaciers, and, as glaciersretreated, glaciomarine mud followed by shorefacesand, gravelly subaqueous fans fed by valley gla-ciers, and eventually beach-face and beach gravel asland was uplifted owing to isostatic rebound. Peri-glacial soil processes then acted on the exposed sur-face sediments.

� The chronology of these events is based mainly onOSL dating of raised marine sediments that provideabsolute ages of interstadial/interglacial events.Sea-level highstands are dated to 185�8 ka,129�10 ka, 99�8 ka and 36�3 ka. These ages pro-vide maximum and/or minimum ages for interjacentglaciations.

� Positive evidence of glaciation within the Lein-stranda succession includes tills and striae. Majorglaciations are recorded prior to the Late Saalian,during the Late Saalian and during the EarlyWeichselian. In addition, indirect evidence (raisedmarine sediments) indicates Middle and LateWeichselian glaciations on Svalbard. At the LastGlacial Maximum stratigraphic level there is a hia-tus. A local glacial advance took place probablyduring the Holocene.

� Three distinct glacial pathways have been identifiedin the Leinstranda succession. Tidewater glaciersadvanced from the Engelskbukta area in the south-east and from a westerly-northerly sector (possiblyKongsfjorden), while at least locally warm-basedglaciers from central Brøggerhalvøya overrode the

site. Cold-based ice-sheet maxima may be re-presented by hiatuses.

� On the scale of major glacial advances and inter-stadials, the Leinstranda record corresponds wellwith the glaciation curve on Svalbard proposed byMangerud et al. (1998). However, within each gla-cial event we recognize phases of different ice dy-namics that may be related to the site’s location inan inter-fjord area and to the successive evolution ofindividual ice sheets.

Acknowledgements. –We wish to thank: Mikael Lindqvist and GustafPeterson (Stockholm University) for excellent field assistance; theNorwegian Polar Institute, especially Wojciech Moskal, in Ny Ale-sund for logistic support; Leif V. Jakobsen and Lars Martin Færseth(Norwegian University of Life Sciences) for XRD and clast analyses,respectively; and Rodney Stevens (University of Gothenburg) fordiscussions about XRD interpretation. Olafur Ingolfsson (Universityof Iceland) and the students of the UNIS course AG332 in 2009 sup-plied valuable additional field data and discussions on interpretations.Help with species identification of fossils was provided by SvendFunder, Geological Museum, Copenhagen (molluscs), Anne KarinHufthammer, Bergen Museum (bird bones) and Helge I. Høeg, Lar-vik (wood). The chronological work was much improved by the inputfromAndrewMurray, Aarhus University (OSL), AnatolyMolodkov,Tallinn University of Technology (ESR) and Steinar Gulliksen, Nor-wegianUniversity of Science and Technology (C14).MonaHenriksen(Norwegian University of Life Sciences) and the two reviewers M.Johnson and J. Winsemann provided valuable and constructive com-ments on the manuscript. This study was undertaken as part of theNorwegian Research Council-funded project SciencePub, which is acontribution to the International Polar Year 2007–2008.

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