Omnain Kutos1, André Rochon1, Jean-Carlos Montero-Serrano1

Results

Acknowledgments

Multi-proxy reconstruction of Late Holocene paleoceanography and sediment dynamic over the Mackenzie slope (Beaufort Sea, Canadian Arctic)

1 Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski,310 allée des Ursulines, Rimouski, Québec, G5L 3A1, Canada & GEOTOP Research Center

The mineralogy and elemental geochemistry, as well as dinoflagellate cyst assemblages of two short sedimentary sequences

(box core and trigger weight core AMD0214-03) recovered on the Mackenzie slope, were analyzed to reconstruct and

document the hydrological variability over the last 2000 years in the Southeastern Beaufort Sea (Canadian Arctic), and its

influence on the sedimentary dynamics.

50

Banks Island

Victoria Island

Alaska (USA) CANADA

Beaufort sea

AmundsenGulf

50

100

500

3000

3000

1000

1000

500

1000

100

500

50

200

100

200

200

+ ++ + ++

++

+

+

+

+

+Mackenzie shelf

Point Barrow

500

50

50

Carbonates

Alaskan Coastal Current (CCA)

Current of the Beaufort Sea Maximum extent of the Mackenzie River PlumeBoundary of the sea ice in the Beaufort Sea (2013)

Intrusive andmetamorphic terrains

Clasticsrocks

+++ Intrusivesrocks

(kilometers)

AMD0214-03

BGCCA

MackenzieDelta

CapeBathurst

500

50

200100

Introduction

• How have the climatic and oceanographic conditions in the Beaufort Sea changed over the time period covered by the core?

• How have sedimentation conditions (sources and transport) evolved over the last 2000 years in the Canadian Beaufort Sea?

Figure 1. Bathymetric and topographic map of the western Arctic Ocean (Southeastern Beaufort Sea) and location of the coring site, derived from IBCAO data.

Photoplate of selected taxa

Methodology

This study allow to determine hydroclimatic changes with variying sedimentation rates, grain size, dinocyst assemblages and geochemistry, indicating relatively

stable conditions in the Mackenzie slope over the last 555 years (box core with occasionally cooler and warmer events. Cooling of surface temperatures occurs

at the end of the period corresponding to the Little Ice Age. Furthermore, around ~1925 AD, there has been an important variation in different proxy’s parameters

associated with relatively high discharge rates from the Mackenzie River. Hydroclimatic variations can be observed after the beginning of Industrial Era.

References

Operculodinium centrocarpum Cyst of

Pentapharsodinium dalei

Brigantedinium spp.

Echinidinium karaense

Deschamps C-E, St-Onge G, Montero-Serrano J-C, Polyak L. Chronostratigraphy and spatial distribution of the Chukchi and Beaufort Sea’s magnetic sediments since the last deglaciation. Boreas. 2017 (in preparation). Richerol T, Rochon A, Blasco S, Scott DB, Schell TM, Bennett RJ. Distribution of dinoflagellate cysts in surface sediments of the Mackenzie Shelf and Amundsen Gulf , Beaufort Sea ( Canada ). J Mar Syst. 2008;74(3-4):825-839. doi:10.1016/j.jmarsys.2007.11.003. Rochon A, de Vernal A, Turon J-L, Matthießen J, Head MJ. Distribution of recent dinoflagellate cysts in surface sediments from the North Atlantic Ocean and adjacent seas in relation to sea-surface parameters. Am Assoc Stratigr Palynol Contrib Ser. 1999;35:1-146. Macdonald RW, Gobeil C. Manganese sources and sinks in the Arctic Ocean with reference to periodic enrichments in basin sediments. Aquat Geochemistry. 2012;18(6):565-591. doi:10.1007/s10498-011-9149-9.

This research was partially funded by the ArcticNet Network of Centres of Excellence, the Natural Sciences and Engineering Research Council of Canada (NSERC) through Discovery Grants to A. Rochon and J-C Montero-Serrano, as well as through ship time support during the 2014 ArcticNet expedition (J-C Montero-Serrano, A. Rochon, and G. St-Onge). We wish to thank the officers and crew of the CCGS Amundsen for their help and support during sampling. We also thank Quentin Beauvais, Charles-Edouard Deschamps, Marie-Pier St-Onge and Pascal Rioux from ISMER for their technical support and advice.

Omnain.KutosYriza@uqar.ca

Islandinium minutum s.l.

0 20

kLF(x 10-5 SI)

-1 4clr.Mn

clr.Fe

-0.3 0.3Balance(Rb-Zn/Sr)

clr.Rb Dinocyst concentration(cysts/cm3)

50

40

30

20

10

0

4 5 -2 -1 0 2000

ImageDepth

(cm)

OXICANOXIC

AntigenManganese

CAT-Scan

5 35Fe/Ti

0 1Mn/Ti

0.2 0.4Rb/Ti

0 50

180

150

120

90

60

30

0

kLF(x 10-5 SI)

Depth (cm)

Years cal B

PTWC

BC

BC

Figure 2. Trigger weight core correlations with the boxcore and the piston core using a* (A1-A6). Box core and trigger weight core sedimentation rate and age model.

Sedimentation rate:

BC: 0.073 cm.yr-1 (4 - 45 cm )

0.147 cm.yr-1 (0 - 4 cm)

• Medieval Warm Period (~1000 AD; ~75 cm): Detrital sediment input from the Mackenzie River

1st

2nd

clr.Zn

clr.Ticlr.Fe

clr.Rb

clr.Sr

Figure 3. High resolution image (MSCL: Multi-Sensor Core Logger) and X-ray (CAT-Scan) analyses of the box-core AMD0214-03BC.

Sediment chronology

A1

A2

A3

A4

A5-1 0 1 2 3

24

20

16

12

8

4

0

Dep

th (c

m)

R= 0.96SR = 0.147 cm.yr-1

R = 0.89SR = 0.073 cm.yr-1

Ln (210Pb excess)

2 4 6 8 10 12 14 16

20

16

12

8

4

0

Supp

orte

d 21

0 Pb

activ

ity =

2.9

dpm

/g

210Pb total activity (dpm/g)

0

50

100

150

0 1 2 3 4 5cal kyr BP

SR = 0.038 cm.yr-1

A6

TWCBC

BC

Dep

th (c

m)

Dep

th (c

m)

0 1 2 3a*

50

40

30

20

10

0

BCImage

CAT-Scan

Dep

th (c

m) A1

A2

A3

A4

A5

A6

-0.5 0 0.5 1 1.5 2

a*

2 00

160

120

80

40

0CAT-Scan

PC

5631 - 5946 cal a BP6000

5000

4000

3000

2000

1000

0

Age yr cal B

P

Calibrated age dating(Deschamps, et al. in press)

In particular, we aim at answering the following questions:

Extent of the spring ice-free zone

Figure 5. Dinocyst assemblage in box-core AMD0214-03BC. Autotrophic taxa (green). Heterotrophic taxa (red). Running average over 3 data points (thick curves)

• Zone I (1400 to 1650 AD): Dominated by Operculodinium centrocarpum and cyst of Pentapharsodinium dalei Relatively warm reconstructed sea surface temperature.

• Zone II (1650 to 1850 AD): Islandinium minutum and Echinidinium karaense. Cooling event associated with the

• Zone III (1850 to 1950 AD): Brigantedinium spp. Slight increase of sea surface temperature and primary productivity. Corresponds to the

• Zone IV (1950 to 2014 AD): Operculodinium centrocarpum and cyst of Pentapharsodinium dalei. Establishment of modern conditions with increased influx of all palynomorphs and

sediment particle size, possibly related to increased flow of the Mackenzie River.

Dinocyst assemblages and reconstructions of sea surface conditions

60.0

52.5

45.0

37.5

30.0

22.5

15.07.5

Hierarchical clustering2468

101214161820222426283032343638404244

0

I

0 2000

50

40

30

20

10

0

Dinocystconcentration

(cysts/cm3)20 100 0 50 0 20 0 30 0 50

III

IV

II

Years

AD

Depth

(cm) Dinocy

st

asse

mblages

zones

0 cal BP

100 cal BP

300 cal BP

200 cal BP

500 cal BP

400 cal BP

SR = 0.057 cm.yr-1

1400

1500

1600

1700

1800

1900

2000

Figure 6. Sea surface reconstruction of the box-core AMD0214-03BC using the modern analogue technique (MAT). The thick curves represent a running average over 3 data points.

-2 10

50

40

30

20

10

0Dep

th (cm

)Summer sea

surfacetemperature

(ºC)

10 20 30Summer sea

surfacesalinity

0 4 8 12

Sea ice cover(months/yr basedon the 1953-2003

mean)

0 100 200Primary

productivity(gC m-2 yr-1)

0

Freshwater palynomorphsinfluxes (cells/cm-2.yr-1)

40 140Dinocyst influxes(cysts/cm-2.yr-1)

50

40

30

20

10

0Dep

th (cm

)

10

III

IV

II

I

Little Ice Age

0 6Grain size (µm)

Years

AD

0 cal BP

100 cal BP

300 cal BP

200 cal BP

500 cal BP

400 cal BP

1400

1500

1600

1700

1800

1900

2000

40 80 120Reworked

palynomorphs(cells/cm-2.yr-1)

• Physical properties of the sediments were measured using a Multi-Sensor Core Logger (MSCL) and X-ray (CAT-Scan)

• Boxcore chronology was established based on 210Pb measurements for the box core

• Trigger weight core chronology was established with the boxcore and the piston core age model

• Standard palynological treatments followed by counts of all palynomorphs

• Grain size distribution measured from laser diffraction

Years

AD

0 cal BP

100 cal BP

300 cal BP

200 cal BP

500 cal BP

400 cal BP

100 AD

1000 AD

1400

1500

1600

1700

1800

1900

2000

600

1600

2600

3600

2000 AD

Years

AD

III

IV

II

I

Beginning of Industrial Era

Little Ice Age

BC

TWC: 0.038 cm.yr-1 (45 - 172 cm )

0.057 cm.yr-1 (0 - 45 cm)

Figure 4. High resolution image (MSCL: Multi-Sensor Core Logger) and X-ray (CAT-Scan) analyses of the gravity core AMD0214-03 TWC.

Conclusions

Multi-Sensor Core Logger (MSCL)

-0.5 0 0.5 1 1.5 2

160

120

80

40

0

TWC a*

ImageCAT-Scan

• Balance (Rb-Zn/Sr) : * Plagioclases (10 - 45 cm): higher precipitation in southern Mackenzie Delta basin. * Phyllosilicates (0 -10 cm): higher precipitation in northern Mackenzie Delta basin.