Shear wave velocity structure beneath the Tanzania Craton and adjacent areas from a Bayesian Monte-Carlo joint inversion of surface wave dispersion and receiver functions
Abstract
A joint inversion of receiver functions and Rayleigh wave phase velocity dispersion derived from ambient seismic noise and teleseismic data is conducted to investigate lithospheric structure beneath the Archean Tanzania Craton, the surrounding Proterozoic-early Paleozoic orogenic belts, and segments of the East African Rift System (EARS). The resulting 3-D shear velocities for the depth range of 0 - 120 km and the crustal thickness and Vp/Vs measurements show a clear spatial correspondence with major geological features observed on the surface. The new results confirm the existence of a high velocity layer in the lowermost crust previously identified beneath the southern Tanzania Craton and adjacent areas, but also reveal that the layer exists beneath the entire craton, which is found to be underlain by a low velocity layer in the uppermost mantle. Most part of the Kenya Rift and the Rungwe Volcanic Province are characterized by high crustal Vp/Vs measurements, which cannot be attributed solely to magmatic intrusion in the crust and indicate that crustal partial melting may also play an important role. Localized low Vs and low Vp/Vs observations are obtained in the vicinity of the Virunga Volcanic Province and part of the Kenya Rift, and can be explained by CO2-filled fractures or conduits. Low crustal velocities observed beneath the two branches of the EARS are attributable to higher-than-normal crustal temperature and partial melting, and the high elevation of the Tanzania Craton is mostly caused by the thicker-than-normal crust and a mantle-derived low density layer beneath the Moho.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMT041.0001W
- Keywords:
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- 8105 Continental margins: divergent;
- TECTONOPHYSICS;
- 8109 Continental tectonics: extensional;
- TECTONOPHYSICS;
- 8178 Tectonics and magmatism;
- TECTONOPHYSICS