Crustal structure of the northern Main Ethiopian Rift from receiver function studies

GW Stuart, ID Bastow, CJ Ebinger

Research output: Chapter in Book/Report/Conference proceedingChapter in a book

68 Citations (Scopus)

Abstract

The northern Main Ethiopian Rift captures the crustal response to the transition from continental rifting in the East African rift to the south, to incipient seafloor spreading in the Afar depression to the north. The region has also undergone plume-related uplift and flood basalt volcanism. Receiver functions from the EAGLE broadband network have been used to determine crustal thickness and average Vp/Vs for the northern Main Ethiopian Rift and its flanking plateaus. On the flanks of the rift, the crust on the Somalian plate to the east is 38 to 40 km thick. On the western plateau, there is thicker crust to the NW (41–43 km) than to the SW ( 2.0, indicative of partial melt within the crust. Within the rift, the Vp/Vs ratio increases to greater than 2.0 (Poisson’s ratio, {sigma} > 0.33) northwards towards the Afar depression. Such high values are indicative of partial melt in the crust and corroborate other geophysical evidence for increased magmatic activity as continental rifting evolves to oceanic spreading in Afar. Along the axis of the rift, crustal thickness varies from around 38 km in the south to 30 km in the north, with most of the change in Moho depth occurring just south of the Boset magmatic segment where the rift changes orientation. Segmentation of crustal structure both between the continental and transitional part of the rift and on the western plateau may be controlled by previous structural inheritances. Both the amount of crustal thinning and the mafic composition of the crust as shown by the observed Vp/Vs ratio suggest that the magma-assisted rifting hypothesis is an appropriate model for this transitional rift.
Translated title of the contributionCrustal structure of the northern Main Ethiopian Rift from receiver function studies
Original languageEnglish
Title of host publicationThe Structure and Evolution of the East African Rift System in the Afar Volcanic Province
EditorsG Yirgu, CJ Ebinger, PKH Maguire
PublisherGeological Society of London
Pages253 - 267
Number of pages14
Volume259
ISBN (Print)1862391963
Publication statusPublished - 2006

Bibliographical note

Other identifier: 9781862391963
Other: doi:10.1144/GSL.SP.2006.259.01.20

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