Notion de séquences loessiques :(successions loess / paléosols) et méthodologie générale

Ukraine / Dnieper Valley 2001

Pierre ANTOINE (1)Denis-Didier ROUSSEAU (2), C. HATTE (3), C. GAUTHIER (3)Olivier MOINE (1), Andreas LANG (4), Markus FUCHS (5), Ludwig ZöLLER (5) F. LAGROIX (6) & Adriana SIMA (2)

Enregistrement des

Evénements

Eoliens dansles séquences

Loessiques

Européennes

Aeolian dynamics and processes during the lastglacial in Europe :

data from loess-palaeosol sequences

(1) Laboratoire de Géographie Physique, UMR 8591 CNRS, Meudon FranceE-mail : Pierre.Antoine@cnrs-bellevue.fr

(2) Ecole Normale Supérieure, Laboratoire de MétéorologieDynamique, Paris France

(3) Laboratoire des Sciences du Climat et de l’environnement,CEA/CNRS Gif-sur-Yvette France

(4) Department of Geography, University of Liverpool,Liverpool L69 7ZT, UK.

(5) Lehrstuhl Geomorphologie, Universität Bayreuth,95440 Bayreuth, Germany.

(6) Université P.VI, Institut de Physique du Globe, Paris

Outline

1 - Loess in Europe: general considerations (loess map)

2 - Main characteristics of the pedosedimentary record from NorthernFrance, correlation with Central Europe

3 - High resolution records of the last glacial in Europe

Main conclusions

4 - Loess (dust) transport and sedimentation in Western Europe: somequestions first conceptual model

Main conclusions

According to K. van Gijssel, 2006, modified (base: International Quaternary Map of Europe, UN/BGR 1965-1995)

Deflation area

(outwash plain)

Danube

Rhin

e

Danube

Dniester

Dniper

Black Sea

North Sea

The Channel

Atlantic Ocean Vistula

1 - Loess in Europe: general considerationsmap of the European “Loess Belt”

2 - Main characteristics of the pedosedimentary record from NorthernFrance to Central Europe

2A - Location of the sequences in the global palaeogeography of Europe during the Last glacial

Dolni Vestonice (Cz)

Study area in N. France (± 80 profiles)

Main sequences used for comparison

Main wind direction

Simplified extension of the loess area (Upper Pleistocene)

Emerged continental shelf during the LGM (deflation area)

According to Antoine et al., 2002 (Q) & 2009 (QSR) modified.

2B-Renewal of field data in northern France

During the last 15 years: development of rescue archaeology in northern France has allowed to study numerous Upper Pleistocene loess-palaeosol records

A synthetic sequence for the whole areahas been produced on the basis of detailed study and correlation of about 80 individual

Test pit Archaeological excavation

2C - Pedosedimentary sequence in W. Europe: the importanceof periglacial features

Combined with palaeosols:Level marks for correlationProxies for the reconstructionof climatic condition(temperatures and moisture)

Platy structure (± 2-5mm) :Ice lensing in clayey silts / icerich permafrost

Former ice wedge cast(Ice rich permafrost)Preserved by loess deposition

Hiatus : ± 50 ka ….

Cryoturbation / gelifluxion(Ice rich permafrost)

2D - Weichselian Early-glacial soil complexes in northern France: a summary

Early

-gla

cial

A

SS-2

SS-3

SS-1

BSO

RS

ML

Ghz.

Ghz.

Ghz.

Grey forest Soil 2(Bth)

Luvisol(Bt)

Grey forest Soil 1(Bth)

Intermediate between

Bt and Bth

Early

-gla

cial

B

Pedogenesis

erosion

Colluvial

Aeolian

Frost events

Sedimentation

SteppeSoil 2 (Ah)

SteppeSoil 2 (Ah)

Reworking of SS-2

Deep seasonalfrostHyromorphy /

gelifluxion) /

Permafrost

SteppeAP < 15 % (Betula)Precipitations: ± 200mm2 short interstadials

Boreal forest(Pinus >>Betula)AP> 50%)Precipations: ± 600mm

2 long interstadials

Interglacial deciduous forest

EEMIAN(Intergl.)

Weichs.Lower

Pgl.

Pedosedimentary record (up to 3.5m)

Environment

Based on: Antoine et al., 2003b(Q), 2003c(JQS), Locht et al., 2003 (GP), & Loess Fest 09 Abstract Book

± 75

± 80

± 112

2E - Chronostratigraphy and correlation with global records

First dust peaks

105 ± 12 ka (V. Adam)106 ± 7.5 ka (Fresnoy)

77.6 ± 7.2 ka (Mauquenchy)

83.7 ± 7.2 ka (Mauquenchy)

TL dates from heated Palaeolithic flint artefacts(N. Debenham)

Climatic signal extracted from the sequence / subdivision of the various soils units: two highly contrasted pedosedimentary budgets:Upper part (B) short story (± 6 ka) aeolian origin of the material Lower part: long story (± 30 ka ), low sedimentation rates colluvialprocesses / locally recorded in sediment traps as lower asymmetric valleys, dissolutions features …

According to Antoine et al., 2003a (GP) & 2003b (JQS) modified

2F - Synthetic sequence for northern France

Homogeneous loess

Laminated colluvial deposits

According to Antoine et al., 2003b (JQS), & 2003c (BSPF)modified

2G - Correlation between northern France and other European records

Correlation:1 - Main level-marks: soil horizons / Periglacial horizons / Tephra layer (Eltviller tephra ET)2 - Logic and hierarchy of the various units composing record

According to Antoine et al., 2001 (QI) modified

3 - High-resolution recordsin Europe3A - Location of the sequences

3B -Methodology

3C - Nussloch (Germany)

3D - Stayky (Ukraine)

3E - Surduk (Serbia)

3A - Location of the sequences in the global palaeogeography of Europeduring the Last glacial

Dolni Vestonice (Cz)

Study area in N. France (± 80 profiles)

Main sequences used for comparison

Main wind direction

Simplified extension of the loess area (Upper Pleistocene)

Emerged continental shelf during the LGM (deflation area)

According to Antoine et al., 2002 (Q) & 2009 (QSR) modified.

Antoine et al., QSR, submitted

3B1 - Methodology : ex. active Quarry Nussloch (Germany)

Sampling methodology developed within the EOLE project :- Based on continuous samplings from sliced loess columns (CCS):- 5cm : grain size, organic carbon and δ13C analysis (±300grs)- 10 cm for molluscs (15kgrs)- Magnetic susceptibility 10 measurements averaged each 5cm (Bartington)

Objective : provide from the same vertical panel detailed description of the profile accurate correlation between all the proxies

19m

cleaning of the « loess wall »

3B2 - Methodology (2) ex. 2: Surduk (Serbia): ± 20m vertical loess cliffalong the Danube River

5cm continuoussamplingcolumn(height: 19m)

5cm

3C - Nussloch (Germany Right bank of the Rhine river)

According to: Antoine et al., 2009 (QSR)

3C2 - Nussloch P4: grain size data

Cyclic variations / Rapid events (max. 13m ± 10 ka) / grain size trends / Main change G7

Antoine et al., Quaternary Science Reviews, 2009

Loess-TG doublets

Antoine et al., QSR, 2009

3C3 - Nussloch: comparison with Greenland dust records (GRIP NGRIP)

According to: Antoine et al.,, 2009 (QSR)

3C4 -Nussloch: comparison with other Late Pleniglacial grain size records inEurope

According to: Antoine et al.,, 2009 (QSR)

3C5 - Nussloch: Location of thermokarst features (TK) within thestratigraphy

Field observation:

Sharp & irregularerosion gulliescarving features

Heterogeneous infill: stratified sands &frozen blocks

Strongly deformed Ice Wedge at the base:

Locally Preservation of organicmaterial (wood) (14C dating)

31.8 ka radiocarbon (± 37.5 corr. Ka)

According to:Antoine et al., 2001 (QI),2002 (Q), 2009 (QSR)

± 55 ka(TK 2)

P1/P5

37.5 corr. ka BP

Infered processes:

Rapid meltingof the Ice of thepermafrost

Response to rapidwarming events(begining of themain D-OInterstadials as GIS8 / 12 or 14)

3D1 - Stayky (Ukraine / Dnieper valley) : location and context

According to: Antoine et al.,, 2009 (QSR)Map: according to: Chlebowski, 2003 (GQ)

3D2 - Stayky: stratigraphy, grain size, organic carbon, total iron and OSLdating

3E1 - Surduk: location andcontextSurduk : South of the Carpathian Basin around

45°N, SW of Novi Sad

Left bank of the Danube River Natural exposure : cliff

3E2 - Stratigraphy and dating

1 - Pedosedimentary record of thewhole Last Interglacial-Glacial cycle

2 - One of the first complete recordof the Last climatic cycle in thesouthern part of the loess area

(Antoine et al., 2009, QI)

Bth Hz (Luvic Chernozen)

Ah Hz Chernozen

Condensed budget of the Last IG and EGl

Antoine et al., 2009 (QI), Fuchs et al., 2007 (Bor.)

3E3 - Results Grain size

Laser Coulter LS 230

(Grain size index)

UPLG 1 - As in W. Europe: Upper Plenigl., loesssedimentation starts before MIS3/2 boundary (±30)

2 - Short events of coarse loess deposition (millennial)

Coarse loess events

15.75±1.6

19.69±2

31.79±3.87

39.77±4.48

53.07±5.54

66.00±6.96

According to:Antoine et al., 2009(QI)

Main conclusions (part 2 and 3): Stratigraphy and high resolution records:

1 - Great homogeneity in the response of European continental environments to climate changes duringthe last climatic cycle (from Western to Central Europe / ± 3000 km)

2 - Evidence of rapid and cyclic loess depositionbetween about 30 and 18 ka BP in Europe

Shown by:occurrence of millennial events during loess deposition, Alternation of aeolian pulses (Loess events) andof periodof low dust input (climatic improvement /tundra gley development) in Western Europe

4 - Strong link between the loess sequences and the dust record from Greenland Ice cores

- Link between North Atlantic climate dynamics and Europeanenvironments during the Last glacial

5 - During the Middle Pleniglacial (± MIS 3): thermokarst: evidence for very abrupt climatic warming eventsconnected with the main D-O Interstadials

4 - Loess (dust) transport and sedimentation in WesternEurope: some data and first conceptual model

Questions:

1- Location of sources areas ?

2 - Main wind directions (leading to loess deposition) in Europe ?

3 - Relations between topography, dust transport and loess deposition ?

Data:Extension of loess area,morphology of the deposits,Palaeogeography,Grain size gradients,Loess mineralogy

4A - Example of relation between loess deposition and morphology:the case of the little asymmetric valleys in N. France …

Plateau

Leeward slope

Well preserved Loess-palaeosols sequenceslower leeward slope (thickness: 4-6m)

According to: Antoine et al., 2003 (BSPF) modified

4B1 - Conceptual model (phase 1)

Relation between the location of sources, the wind directions and the climatic conditions

EWA: Parts of the deflations area located upwind of the loess area (mobile with the displacement of the storm)

Antoine et al., 2009 (QSR)

Antoine et al., 2009 (QSR)

4B2 - Conceptual model (phase 2)

Data from field (morphology and palaeogeography) analytic approaches(Grain size gradients / Loess mineralogy) produce important information about:

1- Location of sources areasThe importance of the Channel & North Sea basins as deflation areas for NW Europe

2 - Main wind directionsReconstructions show systematically main wind directions from W to NNW in WesternEurope and the main part of Central and Eastern EuropeLocally W-E or N-S directions are reported from the southern part of the Loess belt

In the whole area the loess outcrops are “lowland deposits” located below 500 m asl andeven below 200m in NW France & Belgium and are delimited by relief barrier.

Thus high altitude transported dust likely represents an insignificant part of loesssediments in Europe

European loess are mainly composed by dust produced by local sources as periglacialbraided river plains or emerged continental shelf and transported by dust storms(suspension clouds) mixed with a weak amount of dust transported at high altitude (jetstreams)

Main conclusions (part 4)