High Resolution Elastic Thickness Variation Across Valles Marineris: New Insights on the Structure and Evolution of Martian Lithosphere
Abstract
Using convolution of response functions between topography and crust-mantle interface (CMI) derived from inversion of Bouguer gravity model based on the method of Braitenberg et al. (2002, EPSL), we derive elastic thickness (Te) across Valles Marineris and neighbouring Tharsis highlands and northern lowlands. The method can show spatial variation in Te and CMI at a resolution comparable to the Bouguer gravity anomaly (Genova et al., 2016, Icarus). The parameter space was investigated by varying CMI density contrast and convolution window size. We find that the region immediately surrounding Valles Marineris has a strong lithosphere with Te of ~65 km. This is consistent with the moderate regional estimates of Te of ~50 km by McKenzie et al. (2002, EPSL) and ~70 km by Audet (2014, PEPI). The zone of crustal thinning along the central segments of the Valles Marineris correlates with comparatively low Te (< 35 km). The Valles Marineris Te and CMI variation is analogous to rift-related low Te and thinned crust signatures along rifted conjugate continental margins. The thinned crust along the Valles Marineris possibly indicates an upwelled mantle along this structure and the low Te could be due to a crack in the elastic plate or from a thermally weakened lithosphere, or both. The inference is supported by interpretation of geological studies (McEwen et al., 1999, Nature; Williams et al., 2003, GRL) based on high-resolution morphology and compositional data suggests existence of layered intrusive rocks and flood basalts at Central Valles Marineris. In the adjacent northern lowlands, Te is predominantly low (<10 km) which reflects its significantly different strength regime and origin and evolution. The result is consistent with the low Te (10-25 km) by Hoogenboom and Smrekar (2006, EPSL). The neighboring southern highlands have high Te variations (from 10 km to 65 km) and they could be the remnants of an originally mechanically stronger lithosphere which is now weakened by the emplacement of Tharsis plume.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMDI51B0033R
- Keywords:
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- 6225 Mars;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 5430 Interiors;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 7299 General or miscellaneous;
- SEISMOLOGY