L. Audin et al., Fault propagation and climatic control of sedimentation on the Ghoubbet Rift Floor: insights from the Tadjouraden cruise in the western Gulf of Aden, GEOPHYS J I, 144(2), 2001, pp. 391-413
A detailed geophysical survey of the Ghoubbet Al Kharab (Djibouti) clarifie
s the small-scale morphology of the last submerged rift segment of the prop
agating Aden ridge before it enters the Afar depression. The bathymetry rev
eals a system of antithetic normal faults striking N130 degreesE, roughly a
ligned with those active along the Asal rift. The 3.5 kHz sub-bottom profil
er shows how the faults cut distinct layers within the recent, up to 60 m t
hick, sediment cover on the floor of the basin. A large volcanic structure,
in the centre of the basin, the 'Ghoubbet' volcano, separates two sediment
ary flats. The organization of volcanism and the planform of faulting, with
en echelon subrifts along the entire Asal-Ghoubbet rift, appear to confirm
the westward propagation of this segment of the plate boundary. Faults thr
oughout the rift have been active continuously for the last 8400 yr, but ce
rtain sediment layers show different offsets. The Varying offsets of these
layers, dated from cores previously retrieved in the southern basin, imply
Holocene vertical slip rates of 0.3-1.4 mm yr(-1) and indicate a major decr
ease in sedimentation rate after about 6000 yr BP. The two central sub-basi
ns E and W of the volcano have distinct depositional histories and the Ghou
bbet may have been isolated from the sea between 10 and 72 kyr BP.