Abstract
In this paper we present and analyze spreading-parallel seismic transects that image the oceanic crust in the eastern Gulf of Aden, from the Oman to the Socotra margins, across the active Sheba mid-oceanic ridge and between the Socotra-Hadbeen and Eastern Gulf of Aden Fracture Zones. The correlation of potential field data sets and gravity modelling allow us to document the spreading history of this oceanic basin from the onset of seafloor spreading ∼16 Ma-ago to the present. Two main oceanic sub-domains display distinct structural characteristics associated with different magmatic budgets at this mid-ocean ridge. In addition, we document the occurrence of a magmatic pulse at the Sheba Ridge around 11 Ma leading to the construction of a magmatic plateau in the western part of the studied area. This event led to substantial deformation and additional magmatism in previously formed oceanic crust. It could be related to an off-axis magmatic event previously identified in the adjacent Sheba segment, itself possibly related to the Afar plume.
Highlights
Rifted margins, in particular the transition between continental and oceanic crusts, as well as midoceanic ridges, represent two foci of interest for the scientific community
We present previously unpublished, margin-to-margin seismic transects (ENCENS and MARGES-ADEN surveys) across the eastern Gulf of Aden, between the SocotraHadbeen Fracture Zone and the Eastern Gulf of Aden Fracture Zone
Result of this and previous studies (Leroy et al, 2012; Bellahsen et al, 2013; Pik et al, 2013; Ahmed et al, 2014) suggest that this elongated area could correspond to the location of a fracture zone, the Hadibo Fracture Zone (HFZ), which has been observed at the Oman and Socotra margins and on land
Summary
In particular the transition between continental and oceanic crusts, as well as midoceanic ridges, represent two foci of interest for the scientific community. These observations suggest that the smooth and regular basement subdomain represents a magmatic plateau which has been subsequently rifted by the ridge axis, similar to the interpretation proposed by Cannat et al (1999) for the Azores Platform in the Lucky Strike segment on the MAR This structure coincides with the transition between pre- and post-A5 oceanic domains, which is marked by an E-W lineation of basement highs, likely volcanic in origin. The smooth and regular basement subdomain, which is considered as a magmatic plateau, is bound to the east by a NE-SW elongated zone of thin oceanic crust (Figure 5) Result of this and previous studies (Leroy et al, 2012; Bellahsen et al, 2013; Pik et al, 2013; Ahmed et al, 2014) suggest that this elongated area could correspond to the location of a fracture zone, the Hadibo Fracture Zone (HFZ), which has been observed at the Oman and Socotra margins and on land. Would a young spreading center be less magmatic than at a more mature stage due to the close location of the margin? What is the effect of the proximity of a cold continental lithosphere for melt production below a young oceanic ridge? All these questions deserve to be indepth investigated in new studies
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