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.

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

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.

2. Geologic setting Bedmap2 Fretwell et al., 2013

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

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

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

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

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

6.1 Results Coherence Admittance

6.2 Results: Admittance ● Observed Coherence ─ Predicted Coherence

6.2 Results: Admittance ● Observed Coherence ─ Predicted Coherence

6.2 Results: Te bounds Lower bound Upper bound Coherence Admittance

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

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

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 (50- 300km) 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: 10.1016/j.tecto.2017.06.012

Gravity calculations

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

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

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

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

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

Results – Admittance ● Observed Coherence ─ Predicted Coherence

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