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What lies beneath: A detailed bathymetry of the sea-floor below Ekström Ice Shelf, East Antarctica

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What lies beneath: A detailed bathymetry of the sea-floor below Ekström Ice Shelf, East Antarctica

Emma C. SMITH ¹

Reinhard DREWS

2

, Todd EHLERS

2

, Dieter FRANKE

3

, Christoph GAEDICKE

3

, Coen HOFSTEDE

1

, Gerhard KUHN

1

, Astrid LAMBRECHT

4

, Christoph MAYER

4

, Ralf TIEDEMANN

1,5

, and Olaf EISEN

1,5

1Alfred-Wegener-InsLtut (AWI), Germany, 2Department of Geosciences, University of Tübingen, Germany

3BGR, Germany,4 Geodesy and Glaciology, Bavarian Academy of Sciences and HumaniLes, Germany,

5Department of Geosciences, University of Bremen, Germany

OV E R V IE W

Method Comparison to BedMap2

Bathymetry

Features

(2)

TWO M IN U TE M A D N E S S

Antarctic Peninsula

Ronne- Filchner Ice Shelf

Ekström Ice Shelf

What lies beneath: A detailed bathymetry of the sea-floor below Ekström Ice Shelf, East Antarctica

Emma C. SMITH ¹

Reinhard DREWS

2

, Todd EHLERS

2

, Dieter FRANKE

3

, Christoph GAEDICKE

3

, Coen HOFSTEDE

1

, Gerhard KUHN

1

, Astrid LAMBRECHT

4

, Christoph

MAYER

4

, Ralf TIEDEMANN

1,5

, and Olaf EISEN

1,5

(3)

TWO M IN U TE M A D N E S S What lies beneath: A detailed bathymetry of the sea-floor below Ekström Ice Shelf, East Antarctica

Emma C. SMITH ¹

Reinhard DREWS

2

, Todd EHLERS

2

, Dieter FRANKE

3

, Christoph GAEDICKE

3

, Coen HOFSTEDE

1

, Gerhard KUHN

1

, Astrid LAMBRECHT

4

, Christoph

MAYER

4

, Ralf TIEDEMANN

1,5

, and Olaf EISEN

1,5

• Sea floor topography à past ice dynamics

• Cavity à ocean circulaQon and ice melt

• Be.er SLR Predic6ons!

(4)

TWO M IN U TE M A D N E S S What lies beneath: A detailed bathymetry of the sea-floor below Ekström Ice Shelf, East Antarctica

Emma C. SMITH ¹

Reinhard DREWS

2

, Todd EHLERS

2

, Dieter FRANKE

3

, Christoph GAEDICKE

3

, Coen HOFSTEDE

1

, Gerhard KUHN

1

, Astrid LAMBRECHT

4

, Christoph

MAYER

4

, Ralf TIEDEMANN

1,5

, and Olaf EISEN

1,5

Key Findings:

• Sea-floor trough

• Glacial debris deposits 10-60 m thick

• Deviates from BedMap2 by up to 700 m

Elevation from SL (m)

-240

-1100

~700 km of high

quality (up to 10

fold) seismic data

(5)

ME T H O D : V ib ro se is

Vibroseis on Ice!

Eisen et al., Polar Sci., 2015

1500 m, 60 channels

Sweep: 10 – 220 Hz

Time: 10 seconds

SPs 75 – 750 m

(6)

Comparison to Bedmap2

Elevation from SL (m) -240

-1100

CO M P A RI S O N Bedmap2

Seismic Bathymetry

Difference Comparison

Method Comparison to BedMap2 Bathymetry Features

(7)

Comparison to Bedmap2

Elevation from SL (m) -240

-1100

CO M P A RI S O N Bedmap2

Seismic Bathymetry

Difference

Comparison

(8)

Comparison to Bedmap2

Bedmap –Seismic (m)

CO M P A RI S O N Bedmap2

Seismic Bathymetry

Difference Comparison

Method Comparison to BedMap2 Bathymetry Features

(9)

Comparison to Bedmap2

Elevation from SL (m) -240 -1100

Bedmap – Seismic (m)

-700 0 700

CO M P A RI S O N

Bedmap2 Seismic

Bathymetry Difference

(10)

Elevation from SL (m)

-240

-1100

Bathymetry Features

FE A TU R E S

Method Comparison to BedMap2 Bathymetry Features

Click on the map to see some of the key features!

bedrock high

drumlin

trough

changing roughness

trough profile

sediment wedge

With annotation

Without

annotation

(11)

Bathymetry Features

FE A TU R E S

Elevation from SL (m)

-240

-1100

With annotation

Without

annotation

(12)

Elevation from SL (m)

-240

-1100

Sea-floor Trough

FE A TU R E S

Method Comparison to BedMap2 Bathymetry Features

x

Two-way travel time (ms)

600

800

1000

Seismic multiple Lineation/channels

Volcanic Explora wedge

x x’

x’

y y’

Two-way travel time (ms)

600

800

1000

y’

Possible GZW

y’

~50 m

2000 m

~50 m

2000 m Trough

line y line x

Back to Map

(13)

Elevation from SL (m)

-240

-1100

Drumlin and glacial

FE A TU R E S

Back to Map

x’

x

Two-way travel time (ms)

400

600

800

Seismic multiple

x x’

Glacial debris

~50 m

2500 m

Sediment wedge

Drumlin

Underlying dipping sediments

(14)

Elevation from SL (m)

-240

-1100

Bedrock high and overdeepend basin

FE A TU R E S

Method Comparison to BedMap2 Bathymetry Features

x

x’

Two-way travel time (ms)

600

800

1000

Seismic multiple

x x’

3500 m

~50 m 1200

1400

1600

bedrock high

over-deepend basin

Back to Map

(15)

Elevation from SL (m)

-240

-1100

Bedrock high and overdeepend basin

FE A TU R E S

x

x’

Two-way travel time (ms)

400

600

800

1000 200

3000 m

~50 m

x x’

Glacial debris

Shallow rough areas Smooth plateau

Smooth trough-flanks Rough

trough?

Back to Map

(16)

Elevation from SL (m)

-240

-1100

Bedrock high and overdeepend basin

FE A TU R E S

Method Comparison to BedMap2 Bathymetry Features

x

x’

x x’

= constrained by data

Retrograde slope Possible GL retreat positions

Back to Map

(17)

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Antarctic Peninsula

Ronne- Filchner Ice Shelf

Ekström Ice Shelf

Referenzen

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