The Littorina transgression in southeastern Sweden and its relation to

mid-Holocene climate variability

SHI-YONG YU

GeoBiosphere Science CentreDepartment of Geology/Quaternary

SciencesLund UniversitySölvegatan 12SE-223 62 LUND

Supervisors

P. Sandgren, B. E. Berglund and L. Barnekow

What are sea-level changes?

Sabadini, 2002

Sea level is the location where ocean water intercepts the land

Sea-level changes are the result of the complex feedback among the Earth’s different spheres at variable response time scales

Future sea-level rise: an enigma

Munk, 2002

Cabanes et al., 2001

Sea-level history over the last 100 years was well recorded by tide gauges (2 mm/yr). An acceleration was observed over the last decade (3 mm/yr). Other components involved in this complex pattern are unclear.

The best prophet of the future is the past

To give a credible scenario of future sea-level rise, go back to the past to look at sea level adaptations to climate changes under similar boundary conditions to the present.

The Littorina transgression: A best

analogue to the present sea-level rise

Warming climate (the mid-Holocene thermal maximum)

Soar of greenhouse gases (e.g. CO2, CH4) level

Absence of major continent ice sheets

The Littorina transgression (8500-3000 cal. BP) is a manifestation of Baltic Sea level rise in response to the pronounced drawdown of global ice volume

Littorina littorea Linné

The Littorina transgression - hypotheses and causes

Several minor transgression waves (the Danish-Swedish view)Caused by changing global ice volume and regional climate conditions

One main transgression (the Finnish view)Caused by the uniform eustatic rise of global sea level

R evised f rom H yvärinen, 1991

Climate changed, so did Baltic Sea level

Evidence from both ice cores and deep-sea sediments reveal that the North Atlantic area has experienced millennial-scale climate changes.

L L L L L L L

0 100 200 300 400

D istance (m )

E levation(m a.s.l.)

c lay tillL L L L L

10 410 10 190 cal. BP6570 6400 cal. BP

34 coring po in ts peat eo lian sand w ave w ashed pebb les

w ave w ashed sand

O LSÄNG (1978)

-4

-2

0

2

4

6

8

10

NW

SE

21 22 23

24

2526

27 28 2930

3132

3334

Beach ridge, Olsäng (Mikaelsson, 1978)

Beach ridges, Inlängan island (Photo: Berglund, 1964)

5

6

7

8

9

0 10 20 30 40 50 60 70 80 90 100 110

9.4 m

8.1 m

6.3 m

m

m abovesea leve l

N N E

0 10 20 30 40 50 60 70 80 905

6

7

8

9

m

9.5 m

m abovesea leve l

IN LÄ N G A N (1956)

A S P Ö (1956)

8 .2 m

6.8 m

N

S

S S W

Beach ridges on Inlängan and Aspö islands (Berglund, 1964)

Isolation lakes and lagoons: excellent benchmarks of past sea level

Dating the isolation/contact of the basins may provide a powerful constraint on relative sea-level changes

Smygen lagoon (Photo: Berglund, 2000)

BB

BA LT IC

S E A

Biskopsm åla

Sm y gen

56 10 '

56 0'

15 07 ' 15 08 '500 m0

-1.0

+0.5 +3.0

+0.9

+0.9

+2.2

+4.5

3.0BA LT IC

S E A

500 m0

56 10'

56 0' 14 53' 14 54 '

15 00 ' E

56 10 ' N

14 59 ' E 15 00 ' E

Lake

Färsks jön

B ruksviken

BALTIC

SEAE levation (m a .s .l.)

10 2515 205

0

15 05 'E

56 10 'N

+3.0 m

L a k e R y ss j ö n

+7.2 m

+4.5 m

BA LT IC S E A

a b

c d

Smygen: -1 m

Hunnemara: 3 m

Ryssjön: 4.5 m

Färsksjön: 7.2 m

(the highest lake containing brackish sediments in Blekinge)

Fieldwork (Photo: Berglund, 2000)

Co

rin

g Magnetic core scanning

Su

b-s

am

pli

ng

Pollen analysis

Diatom analysis

Macrofossilanalysis

Mineral magnetism

Carbon (LOI)

Geochemistry

AMS dating

Palaeoecologicalinterpretation

Flowchart of lab analyses

First order sea-level changes: Eustasy vs. isostasy

A big thaw of the Antarctic Ice Sheet

1st story

Coastal basins: Precise sea-level “index points”

L L L L LL L LL L L L L

Smygen-1.0 m

L L L L L

12.5

11.5

10.5

9.5

8.5

7.5

6.5

5.5

4.5

3.5

2.5

1.5

Dep

th b

elow

wat

er le

vel (

m)

2820 110

2920 95

3950 85

5645 85

4555 105

3090 105

6020 95

7310 100 7220 90

8475 95

8225 95 9650 95

L L L L LL L L L LL L LL L L L L

2935 80

4575 95

4850 90

4800 95

4875 90

5455 90

6415 90 7860 95

8220 110

9890 100

Hunnemara3.0 m

L L L

L L LL L L L L L L L L L L L L

2100 100

3200 90

4610 105 5575 105 6575 100 5805 95 6705 95 7245 90

9005 95

9565 120

Facies Facies Facies

SB

OB

SF

OF

SB

OB

SF

OF

SB

OB

SF

OF

L L LL L L

L L L L L

SB

OB

SF

OF

FaciesKalvöviken-2.0 m

4580 115

5315 100 6440 100 7445 90 7700 95 8005 100 8440 100 9650 100

Facies

6470 110

L L L L LL L L L L L L L L L

SB

OB

SF

OF

6570 110 7200 100 6810 100 7240 140 7480 150 7660 120 8230 150 8630 140 8810 160 8530 110

Sörevik-2.0 m

Ryssjön4.5 m

6.5

5.5

4.5

3.5

2.5

1.5

Dep

th b

elow

wat

er le

vel (

m)

L L L

L L LL L LS

BO

B

SF

OF

Färsksjön7.2 m

4830 100 5250 90 5705 80 6150 95 6695 105

L L LL L LL L L

L L L

SB

OB

SF

OF

3820 65

6640 70 6220 70

3950 60

6090 70

5040 65

Siretorp5.0 m

L L L L L L L L L L L L LL L L

SB

OB

SF

OF

Hallarums mosse4.7 m

4585 70 5040 855665 85 5945 75 6220 85 6395 125 6950 90 7105 90

L L L L L L L L L L 3145 65 3545 65 4170 75

SB

OB

SF

OF

Inlängans mosse5.0 m

4270 60 4470 80

5290 65 5430 65 5700 70 5930 70

Lithology key

Grey clay

Sand

Gyttja clay

Clayey gyttja

GyttjaFine-detritus gyttja Coarse-detritus gyttja

Peat

L L L L L

L L L L L

L L L L L

B

FaciesFaciesFaciesFacies

Sedimentary faciesOpen freshwater (OF)

Shallow freshwater (SF)

Shallow brackish-water (SB)

Open brackish-water (OB)

The Littorina transgression is caused by a continuous ice-volume-equivalent sea-level rise, interspersed with variable rates

2500 3500 4500 5500 6500 7500 8500

Age (cal. yr BP)

- 2

0

2

4

6

8

Bal

tic r

elat

ive

sea

leve

l (m

)

-30

-25

-20

-15

-10

-5

0

Far

-fie

ld r

elat

ive

sea

leve

l (m

)

Southeastern Sw eden

Barbados

N ew G uinea

Tahiti

1 m m yr -1

15 m m yr -1

3 m m yr -1

A changing ice volume?

6500 7000 7500 8000 8500

Age (ca l. yr BP)

-38

-37

-36

-35

-34

-33

18O

(‰

SM

OW

)

-40

-39

-38

-37

-36

18O

(‰

SM

OW

)

0

5

10

15

Rat

e (m

m y

r-1)

-1 .4

-1 .2

-1

-0 .8

18O

(‰

PD

B)

A

B

C

D

• Storegga tsunami (Andrén, 2001)?

• Slow down of crustal rebound?

• Laurentide floods (Tooley, 1989)?

A global meltwater pulse 8000 years ago

• Rapid depletion of seawater 18O

• A IRD spike in the South Atlantic (Hodell et al., 2001)

• Flooding in Chesapeake Bay/8000 cal. BP (Bratton et al., 2003)

• A break of coral growth in the Caribbean area (Blanchon and Shaw, 1995)

• Black Sea transgression

Global climate during the “Noah’s Flood”

Linking Baltic Sea-level fluctuations to North Atlantic storminess at millennial time scale

Coastal dune, W Denmark (Photo: Yu, 2003)

2nd story

Dating sea-level-sensitive floras (e.g. dinoflagellates, diatoms, seagrasses, stoneworts) provides evidence for millennial-scale sea-level changes

9000 8000 7000 6000 5000 4000 3000 2000 1000 0

Age (ca l. BP )

-2 .0

0 .0

2 .0

4 .0

6 .0

8 .0

Rel

ativ

e se

a le

vel (

m)

-35 .4

-35 .2

-35

-34.8

-34 .6

-34 .4

18O

(‰

SM

OW

)

S örev ikK a lvöviken

S m ygen

H unnem ara

R yss jönS ire to rp

Färsks jönO lsäng

1. N W England2. W N etherlands

S torm surges

B each ridges3. N E Ire land4. Svalbard5. W M ed ite rranean

S and dunes

6. N S co tland7. W S cotland8. SW France9. W Ire land

10 . W D enm ark11 . N W E ngland12 . S W France13 . N W France14 . N W D enm ark15 . W D enm ark16 . N Fennoscandia

Ö ppenskär

U tlängan

17 . G reen land ice coreS ea-sa lt ions

Ble

king

ese

a-le

vel h

ighs

tan

dsN

ort

hG

RIP

ice

core

a

b

c

L1

L2L3

L4 L5

Centennial-scale sea-level changes: A window to the NAO past?

3rd story

0 1 2 3 4 5

O. centrocarpum( 103 cysts cm -2 yr-1)

2 4 6 8

GISP2 sea salt Na+

(p.p.b.)

6 8 10 12 14 16

Organic carbon(%)

10 100ARM

( 10-5 m3 kg-1)

2500

3500

4500

5500

6500

7500

8500

Age

(cal

. BP

)

0 0.1 0.2 0.3

Spinif er ites. spp.( 103 cysts cm -2 yr-1)

Regional transgression

A B C D E

L2

L3

L4

L5

Sea-level changes: Cycle, cycle all the time?

Per

iod

(yr)

128

256

512

1024

0 0.04 0.08 0.12

Pow er

180 yr

220 yr

480 yr

940 yr

1470 yr

95% c. l.A B0 0 .5 1 .0 2 .0 3 .0

Pow er (re la tive to g lobal)

3500 4500 5500 6500 7500

Age (cal. yr B .P .)

Wavelet and power spectral transforms of a macrofossil series from Lake Ryssjön

The 480-yr cycle:

tidal origin?

480*2=960 yr

480*3=1440 yr

the enigmatic 1500 yr cycle was solved!

Conclusions

•Within the Littorina Sea phase, five minor transgressions are recorded: L1 8500–8200, L2 7800–6900, L3 6400–5600, L4 5300–4700, and L5 4500–4100 cal. BP. These minor transgressions, lasting 500–1000 years in the study sites, occurred almost synchronously across the southern Baltic Sea.

•The Littorina transgression in southeastern Sweden covers the time span 8500–3000 cal. BP. It can be ascribed to the accelerated rise of global sea level, overprinting the slow isostatic uplift in southern Scandinavia during the middle Holocene.

•The first transgression (L1) can be linked to the flood of the proglacial lakes in North America. The most pronounced transgression (L2) is marked by a Baltic Sea level rise by ca. 8 m in 500 years, at an accelerated rate of ~15 mm yr-1. It suggests a global meltwater pulse probably triggered by the partial

collapse of the Antarctic Ice Sheet.

•The younger minor transgressions were possibly caused by ice-volume changes in combination with submillennial-scale variations in regional storminess.

•Centennial-scale sea-level fluctuations show good coherence with ice-core sea-salt ions and cosmogenic nuclides in some time windows, suggesting solar forcing probably through a system similar to the dipole oscillation of the North Atlantic atmosphere (i.e. NAO). In addition, tidal actions related to lunar cycles may exert another important influence on Baltic Sea level during the middle Holocene.