Arabia‐Somalia plate kinematics, evolution of the Aden‐Owen‐Carlsberg triple junction, and opening of the Gulf of Aden

Abstract

[1] New geophysical data collected at the Aden-Owen-Carlsberg (AOC) triple junction between the Arabia, India, and Somalia plates are combined with all available magnetic data across the Gulf of Aden to determine the detailed Arabia-Somalia plate kinematics over the past 20 Myr. We reconstruct the history of opening of the Gulf of Aden, including the penetration of the Sheba Ridge into the African continent and the evolution of the triple junction since its formation. Magnetic data evidence three stages of ridge propagation from east to west. Seafloor spreading initiated ∼20 Myr ago along a 200 kmlong ridge portion located immediately west of the Owen fracture zone. A second 500 kmlong ridge portion developed westward up to the Alula-Fartak transform fault before Chron 5D (17.5 Ma). Before Chron 5C (16.0 Ma), a third 700 km-long ridge portion was emplaced between the Alula-Fartak transform fault and the western end of the Gulf of Aden (45°E). Between 20 and 16 Ma, the Sheba Ridge propagated over a distance of 1400 km at an extremely fast average rate of 35 cm yr −1. The ridge propagation resulted from the Arabia-Somalia rigid plate rotation about a stationary pole. Since Chron 5C (16.0 Ma), the spreading rate of the Sheba Ridge decreased first rapidly until 10 Ma and then more slowly. The evolution of the AOC triple junction is marked by a change of configuration around 10 Ma, with the formation of a new Arabia-India plate boundary. Part of the Arabian plate was then transferred to the Indian plate.

Large-scale phylogeny of chameleons suggests African origins and Eocene diversification

“…Of these peripherally distributed species, Chamaeleo monachus from Socotra Island is the oldest (ca 20 +5 Myr). Although sea floor spreading in the Western portion of the Gulf of Aden is recent, Socotra is located substantially eastward, where rifting was complete ca 20 Ma [56][57][58][59]. The timing of divergence for C. monachus overlaps with the timing of separation between Socotra and Africa, and therefore, neither the isolation owing to vicariance nor oceanic dispersal [60] can be ruled out.…”

Architecture of rifted continental margins and break-up evolution: insights from the South Atlantic, North Atlantic and Red Sea–Gulf of Aden conjugate margins

“…5), where the breakup between Somalia and Yemen occurred around 18 Ma, at least 5-10 Ma before the salt deposition in the Red Sea (Bosworth et al 2005). Based on identification of oceanic crust magnetic anomalies, the continental breakup between Somalia and Arabia is estimated around 20 Ma between Oman and Socotra, and around 16 Ma towards the western Gulf of Aden, where the present-day Aden propagator is advancing towards Afar (Fournier et al 2010). This suggests diachronous drifting between the Gulf of Aden and the Red Sea, similar to the differences in chronology observed for the rifting and continental breakup of the North Atlantic.…”

Kinematics of Post-obduction Deformation of the Tertiary Ridge at Al-Khod Village (Muscat, Oman)

“…[20] and white arrow from Oman [21]. a - [22]; b - [19]; c - [17]; d - [18]; e - [13]; f - [14]; g - [8]; h - [15]; i - [16]. Map modified from [23].…”

“…The age of the southern Red Sea is 30 to 24 Ma and the amount of extension measures about 300 km [13, 14 their Figure 3]. Although the age of the Gulf of Aden is younger (20 Ma) the amount of extension is 100 km larger [8,15].…”