Palaeomagnetism and K-Ar and <SUP>40</SUP>Ar/<SUP>39</SUP>Ar ages in the Ali Sabieh area (Republic of Djibouti and Ethiopia): constraints on the mechanism of Aden ridge propagation into southeastern Afar during the last 10 Myr - Archive ouverte HAL Access content directly
Journal Articles Geophysical Journal International Year : 2004

Palaeomagnetism and K-Ar and 40Ar/39Ar ages in the Ali Sabieh area (Republic of Djibouti and Ethiopia): constraints on the mechanism of Aden ridge propagation into southeastern Afar during the last 10 Myr

(1) , (1) , (1) , (1) , (1) , (1) , (1) , (1) ,
1

Abstract

A new detailed palaeomagnetic study of Tertiary volcanics, including extensive K-Ar and 40Ar/39Ar dating, helps constrain the deformation mechanisms related to the opening processes of the Afar depression (Ethiopia and Djibouti). Much of the Afar depression is bounded by 30 Myr old flood basalts and floored by the ca 2 Myr old Stratoid basalts, and evidence for pre-2 Ma deformation processes is accessible only on its borders. K-Ar and 40Ar/39Ar dating of several mineral phases from rhyolitic samples from the Ali Sabieh block shows indistinguishable ages around 20 Myr. These ages can be linked to separation of this block in relation to continental breakup. Different amounts of rotation are found to the north and south of the Holhol fault zone, which cuts across the northern part of the Ali Sabieh block. The southern domain did not record any rotation for the last 8 Myr, whereas the northern domain experienced approximately 12 +/- 9° of clockwise rotation. We propose to link this rotation to the counter-clockwise rotation observed in the Danakil block since 7 Ma. This provides new constraints on the early phases of rifting and opening of the southern Afar depression in connection with the propagation of the Aden ridge. A kinematic model of propagation and transfer of extension within southern Afar is proposed, with particular emphasis on the previously poorly-known period from 10 to 4 Ma.
Fichier principal
Vignette du fichier
158-1-327.pdf (1.25 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

insu-03600280 , version 1 (07-03-2022)

Licence

Attribution - CC BY 4.0

Identifiers

Cite

L. Audin, X. Quidelleur, E. Coulié, V. Courtillot, S. Gilder, et al.. Palaeomagnetism and K-Ar and 40Ar/39Ar ages in the Ali Sabieh area (Republic of Djibouti and Ethiopia): constraints on the mechanism of Aden ridge propagation into southeastern Afar during the last 10 Myr. Geophysical Journal International, 2004, 158, pp.327-345. ⟨10.1111/j.1365-246X.2004.02286.x⟩. ⟨insu-03600280⟩
6 View
4 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More