The upper-mantle low-velocity anomaly beneath Ethiopia, Kenya, and Tanzania: Constraints on the origin of the African superswell in eastern Africa and plate versus plume models of mantle dynamics

Research output: Chapter in Book/Report/Conference proceedingChapter

23 Citations (Scopus)

Abstract

To further advance our understanding of the way in which a portion of the African superswell in eastern Africa formed, and also to draw attention to the importance of eastern Africa for the plume versus plate debate about mantle dynamics, uppermantle structure beneath eastern Africa is reviewed by synthesizing published results from three types of analyses applied to broadband seismic data recorded in Tanzania, Kenya, and Ethiopia. (1) Joint inversions of receiver functions and surface wave dispersion measurements show that the lithospheric mantle of the Ethiopian Plateau has been signifi cantly perturbed, much more so than the lithospheric mantle of the East African Plateau. (2) Body wave tomography reveals a broad (≥300 km wide)and deep (≥400 km) low-velocity anomaly beneath the Ethiopian Plateau and the eastern branch of the rift system in Kenya and Tanzania. (3) Receiver function stacks showing Ps conversions from the 410 km discontinuity beneath the eastern branch in Kenya and Tanzania reveal that this discontinuity is depressed by 20-40 km in the same location as the low-velocity anomaly. The coincidence of the depressed 410 km discontinuity and the low-velocity anomaly indicates that the low-velocity anomaly is caused primarily by temperatures several hundred degrees higher than ambient mantle temperatures. These findings cannot be explained easily by models invoking a plume head and tail, unless there are a sufficient number of plume tails presently under eastern Africa side-by-side to create a broad and deep thermal structure. These fi ndings also cannot be easily explained by the plate model. In contrast, the breadth and depth of the upper-mantle thermal structure can be explained by the African superplume, which in some tomographic models extends into the upper mantle beneath eastern Africa. Consequently, a superplume origin for the anomalous topography of the African supers well in eastern Africa, in addition to the Cenozoic rifting and volcanism found there, is favored.

Original languageEnglish (US)
Title of host publicationVolcanism and Evolution of the African Lithosphere
PublisherGeological Society of America
Pages37-50
Number of pages14
ISBN (Print)9780813724782
DOIs
StatePublished - Jan 1 2011

Publication series

NameSpecial Paper of the Geological Society of America
Volume478
ISSN (Print)0072-1077

Fingerprint

upper mantle
plume
mantle
anomaly
discontinuity
plateau
thermal structure
wave dispersion
body wave
surface wave
tomography
rifting
Africa
volcanism
seismic data
temperature
topography

All Science Journal Classification (ASJC) codes

  • Geology

Cite this

Nyblade, A. A. (2011). The upper-mantle low-velocity anomaly beneath Ethiopia, Kenya, and Tanzania: Constraints on the origin of the African superswell in eastern Africa and plate versus plume models of mantle dynamics. In Volcanism and Evolution of the African Lithosphere (pp. 37-50). (Special Paper of the Geological Society of America; Vol. 478). Geological Society of America. https://doi.org/10.1130/2011.2478(03)
Nyblade, Andrew Arnold. / The upper-mantle low-velocity anomaly beneath Ethiopia, Kenya, and Tanzania : Constraints on the origin of the African superswell in eastern Africa and plate versus plume models of mantle dynamics. Volcanism and Evolution of the African Lithosphere. Geological Society of America, 2011. pp. 37-50 (Special Paper of the Geological Society of America).
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Nyblade, AA 2011, The upper-mantle low-velocity anomaly beneath Ethiopia, Kenya, and Tanzania: Constraints on the origin of the African superswell in eastern Africa and plate versus plume models of mantle dynamics. in Volcanism and Evolution of the African Lithosphere. Special Paper of the Geological Society of America, vol. 478, Geological Society of America, pp. 37-50. https://doi.org/10.1130/2011.2478(03)

The upper-mantle low-velocity anomaly beneath Ethiopia, Kenya, and Tanzania : Constraints on the origin of the African superswell in eastern Africa and plate versus plume models of mantle dynamics. / Nyblade, Andrew Arnold.

Volcanism and Evolution of the African Lithosphere. Geological Society of America, 2011. p. 37-50 (Special Paper of the Geological Society of America; Vol. 478).

Research output: Chapter in Book/Report/Conference proceedingChapter

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