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A chironomid

A chironomid - - based temperature reconstruction for the Younger Dryas based temperature reconstruction for the Younger Dryas - - Holocene transition from a palaeo

Holocene transition from a palaeo - - channel of the Niers channel of the Niers - - Rhine, Germany Rhine, Germany

S. Kuiper 1,2 , E.I. Lammertsma 2 , O. Heiri 1 , W.Z. Hoek 2 , C. Kasse 3

1

Laboratory of Palaeobotany and Palynology, Institute of Environmental Biology, Utrecht University, The Netherlands;

2

Department of Physical Geography, Utrecht University, The Netherlands;

3

Department of Palaeoclimatology and Geomorphology, Vrije Universiteit Amsterdam, The Netherlands

Contact: saskiakuiper@gmail.com; emmylam@gmail.com

Research outline Conclusion

A multi-proxy analysis of a calcareous gyttja from a palaeo-channel resulted in a reconstruction of

temperature and local environmental conditions at the end of the last ice age (~12,000 to 10,500 cal yr BP).

Both aquatic and terrestrial proxies indicate a rapid ecosystem response to warming at the Younger

Dryas–Holocene transition in the Niers-Rhine valley.

Chironomids indicate a ~3˚C increase in mean July air temperature at this boundary.

1. Research area

Weeze Goch

Uedem

Kevelaer

Geldern

Kapellen

Issum Rhine Valley Kendel

Niers

Fleuth

NN

Palaeo

Palaeo channelschannels Floodplain

Floodplain Meander level Meander level

‘TransitionTransition’levellevel Braided

Braidedlevellevel Older

OlderRhineRhineterraceterrace Pushed

Pushedridgeridge/ Sandr/ Sandr

Legend Legend

City City

Village Village Niers Niers

DuneDune

ss Pollen and Pollen and 1414C siteC site This study

This study

27 26 25 24 23

50 m 22

0

Legend Legend

water water topsoil topsoil peat peat

calcareous gyttja calcareous gyttja fine sand

fine sand gravelly gravellysandsand older older terrace terrace detrital gyttja detrital gyttja

Sample core

m + NN

2. Methods 3. Local

developments

4. Regional framework

A sediment core (a) from one of the palaeo-

channels was analysed for chironomids (=non-biting midges) (b), pollen (c), stable isotopes (d) and

lithological parameters (e).

All proxies were measured on the same

sediment core to avoid problems previously encountered with correlating multiple,

independently dated records.

b. c. d. e. a.

60

80

100

120

140

160

180

200

Depth (cm)

0 30

Mite

0 90

Percentage (%) Statoblast Plumatella-type

0 10

Sialis mandible

0 50

Ephemeroptera mand.

0 10

Trichoptera mandible

0 10

Simuliidae hypostoma

60

80

100

120

140

160

180

200

Depth (cm)

0 20

Ablabesmyia

0 10

Dicrotendipes notatus-type

0 20

Cricotopus cylindraceus-type

0 20

Tanytarsus mendax-type

0 10

Paratanytarsus penicillatus-type

0 20

Percentage (%) Parakiefferiella

0 40

Zalutschia type B

0 40

Microtendipes

0 10

Phaenopsectra flavipes-type

0 10

Pagastiella

0 40

Tribelos-type

Invertebrates

Chironomids

Local vegetation

A clear shift in aquatic flora and fauna occurs at 137 cm sediment depth, indicating a sudden change in the local environment.

Early Holocene

Younger Dryas

˚

In comparison with regional pollen, the

transition in local flora and fauna reflects the Younger Dryas–Holocene boundary.

Channel infills of the Niers-Rhine fluvial system (abruptly abandoned in the Early Holocene) provide well-preserved records of Lateglacial/Early Holocene climate and environmental changes.

60

80

100

120

140

160

180

200

Depth (cm)

0 100

Characeae

0 40

Botryococcus

0 90

Percentage (%) Pediastrum

0 30

Potamogeton

0 20

Myriophyllum spic.

0 20

Myriophyllum vert.

0 10

Nuphar

0 80

Nymphaea

0 10

Sparganium -type

0 10

Typha latifolia

Chironomid-based temperatures show an increase of ~3˚C mean summer temperature at this

transition.

This climate amelioration

is reflected in the stable

isotope record.

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