Imperial College London
Alternate

Dr Ian Bastow

Faculty of Engineering, Department of Earth Science & Engineering

Senior Lecturer
 
 
 
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Contact

 

+44 (0)20 7594 2974i.bastow Website

 
 
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Location

 

4.45Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Boyce:2021:10.1029/2020gc009302,
author = {Boyce, A and Bastow, I and Cottaar, S and Kounoudis, R and Guilloud, De Courbeville J and Caunt, E and Desai, S},
doi = {10.1029/2020gc009302},
journal = {G3: Geochemistry, Geophysics, Geosystems: an electronic journal of the earth sciences},
title = {AFRP20: New P-wavespeed model for the African mantle reveals two whole-mantle plumes below East Africa and Neoproterozoic modification of the Tanzania craton},
url = {http://dx.doi.org/10.1029/2020gc009302},
volume = {22},
year = {2021}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Africa, but their morphology, number, location, and impact on the African lithosphere are debated. The broad slow wavespeed African Superplume, ubiquitous in largescale tomographic models, originates below South Africa, reaching the surface somewhere below East Africa. However, whether the diverse East African mantle geochemistry is best reconciled with one heterogeneous upwelling, or current tomographic models lack the resolution to image multiple distinct plumes, remains enigmatic. Swavespeed tomographic images of Africa are legion, but higher frequency Pwavespeed wholemantle models possessing complementary diagnostic capabilities are comparatively lacking. This hinders attempts to disentangle the effects of Cenozoic hotspot tectonism and Pan African (and older) tectonic events on the East African lithosphere. Here we develop a continentalscale Pwave tomographic model capable of resolving structure from uppertolower mantle depths using a recently developed technique to extract absolute arrivaltimes from noisy, temporary African seismograph deployments. Shallowmantle wavespeeds are δVP ≈ −4% below Ethiopia, but less anomalous (δVP ≥–2%) below other volcanic provinces. The heterogeneous African Superplume reaches the upper mantle below the Kenyan plateau. Below Ethiopia/Afar we image a second subvertical slow wavespeed anomaly rooted near the coremantle boundary outside the African LLVP, meaning multiple disparately sourced wholemantle plumes may influence East African magmatism. In contrast to other African cratons, wavespeeds below Tanzania are only fast to 90–135 km depth. When interpreted alongside Lower Eocene oncraton kimberlites, our results support pervasive metasomatic lithospheric modification caused by subduction during the Neoproterozoic PanAfrican orogeny.
AU  - Boyce,A
AU  - Bastow,I
AU  - Cottaar,S
AU  - Kounoudis,R
AU  - Guilloud,De Courbeville J
AU  - Caunt,E
AU  - Desai,S
DO  - 10.1029/2020gc009302
PY  - 2021///
SN  - 1525-2027
TI  - AFRP20: New P-wavespeed model for the African mantle reveals two whole-mantle plumes below East Africa and Neoproterozoic modification of the Tanzania craton
T2  - G3: Geochemistry, Geophysics, Geosystems: an electronic journal of the earth sciences
UR  - http://dx.doi.org/10.1029/2020gc009302
UR  - http://hdl.handle.net/10044/1/87528
VL  - 22
ER  -
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