1. By C. Haeger1,2, M. Kaban1, B. Chen3 & A. Petrunin1,4 June 15, 2017
Tectonic fragmentation of the Antarctic lithosphere as revealed by the analysis of effective elastic thickness variations
By C. Haeger1,2, M. Kaban1, B. Chen3 & A. Petrunin1,4
June 15, 2017
1GFZ German Research Centre for Geosciences, Potsdam, Germany. 2Free University Berlin, Germany.
3Central South University, Changsha, China.4Goethe University, Frankfurt am Main 60438, Germany.

2. The Project - MANTIS
Thermal, density and rheological model of the lithosphere of Antarctica based on the integration of satellite data and its application to the thermal regime of the ice shield

3. 1. Motivation
National Geographics
Derive the effective elastic thickness (Te) as a proxy for thermo-mechanical structure of the lithosphere
Controls initiation and evolution of deformation processes, e.g. glacial isostatic adjustment (GIA)
Klemann, pers. com.

4. 2. Geologic setting
Bedmap2
Fretwell et al., 2013

5. 3. Theory: Effective elastic thickness
Definition: Thickness of an idealized elastic beam that would bend similarly to the lithosphere under the same applied loads
 response of lithosphere to tectonic loading
 depends on thermal regime of lithosphere
Determination of Te by analysing both the relationship (admittance) and the correlation (coherence) between adjusted topography H and residual gravity anomaly B in the spectral domain
Admittance:
Coherence:
Morlet wavelet

6. Compilation of terrestrial (mainly airborne) data
4. Gravity Data
EIGEN-6c4
Combination of satellite (GRACE, GOCE, LAEGOS) and terrestrial data
Resolution: ~200km
AntGG
Compilation of terrestrial (mainly airborne) data
Resolution: up to 10km
Förste et al., 2014
Scheinert et al., 2016

7. 5. Gravity modeling Residual Gravity Disturbance B
Adjusted Topography H
5. Gravity modeling

8. 6.1 Results: Coherence ─ Predicted Coherence
● Observed Coherence
─ Predicted Coherence
-- Normalized Squared Imaginary Part

9. 6.1 Results: Coherence ─ Predicted CoherenceA A‘
● Observed Coherence
─ Predicted Coherence
-- Normalized Squared Imaginary Part
─ Te
─ Ice Surface
─ Bedrock Surface

10. 6.1 Results
Coherence
Admittance

11. 6.2 Results: Admittance
● Observed Coherence
─ Predicted Coherence

12. 6.2 Results: Admittance
● Observed Coherence
─ Predicted Coherence

13. 6.2 Results: Te bounds
Lower bound
Upper bound
Coherence
Admittance

14. 7. Thermal model
100 km
S-Velocity
Temperature
An et al., 2015

15. 8. Moho depth An et al., 2015 (AN-Moho) Janik et al., 2014
Lamarque et al., 2015

16. 9. Conclusions
We computed Te variations over Antarctica using two methods (coherence and admittance):
 The coherence method is found to provide more robust results compared to the admittance method.
 Te variation shows a general distinction between East and West Antarctica but also lithospheric fragmentation within these regions.
We estimated a 3D temperature model for the Antarctic mantle ( km) from seismic velocities using mineral physics equations
We created a new Moho depth map of Antarctica using a remove- compute-restore technique based on the AN-Moho compilation and the An1-Crust surface wave model in areas without other data [An et al., 2015]
Paper:
Bo Chen, Carina Haeger, Mikhail K. Kaban, Alexey G. Petrunin, Variations of the effective elastic thickness reveal tectonic fragmentation of the Antarctic
lithosphere, Tectonophysics (2017), doi: /j.tecto

17. Gravity calculations

18. Gravity modeling Residual Gravity Disturbance
Bedrock
Freeair
Residual
Water
Ice
Residual Gravity Disturbance
Freeair Gravity Disturbence
Gravity Effect - Topography
Gravity Effect - Water
Gravity Effect - Ice

19. The fan wavelet transform
Wavelet transform for signal g(x):
Morlet wavelet in wavenumber domain:
Kirby & Swain., 2011

20. Coherence
|k0|=2.668
|k0|=3.081
|k0|=3.773
|k0|=5.336

21. Admittance
|k0|=2.668
|k0|=3.081
|k0|=3.773
|k0|=5.336

22. Results - Coherence ─ Predicted Coherence
● Observed Coherence
─ Predicted Coherence
-- Normalized Squared Imaginary Part

23. Results – Admittance
● Observed Coherence
─ Predicted Coherence

24. Theory: Remove-Compute-Restore
Stolk et al., 2013