Seafloor spreading of the third arm of the Afar triple junction: A review

Abstract

The only place within the East African Rift System where seafloor spreading is being manifested along with new crust being formed is at the Afar triple junction, a seismically active area defined by latitude 9°N to 14°N and longitude 43E° to 49E°. Previous seafloor spreading studies have primarily concentrated on the Aden-Owen Carlsberg Ridge (AOCR). The AOCR defines the boundary between the Eastern Gulf of Aden and the Western Gulf of Aden. Although the previous studies have provided insight into seafloor spreading rates, the timing of seafloor spreading, particularly in the Western Gulf of Aden (encompassing the study area) remains unclear. This study seeks to estimate the rates of seafloor spreading by reviewing data from previous studies and integrating geophysical (paleomagnetic anomalies), geological data and systematically estimating seafloor spreading rates and determining the timing of the initial seafloor spreading in the Afar region using advanced geo-software (Gplates). The results from our modeling show that the initial seafloor spreading began approximately 16 million years ago, with spreading rates varying from 12.29 to 20.12 mm/yr (average = 15.75 mm/yr). The average seafloor spreading rates in the study area are nearly 1.5-fold lower than the average seafloor spreading in the Eastern Gulf of Aden (23 mm/yr). The predominant seafloor spreading in the study area is East-West. Further, the angular rotation of the Somalian plate against the Arabian plate has been estimated to be 0.5353°/Ma. The study enhances understanding of plate tectonics, seismic hazards, volcanism and hydrocarbon systems in the Afar region.

Keywords

• Seafloor spreading
• Afar triple junction
• Gulf of Aden
• Aden-Owen Carlsberg ridge
• Arabia plate
• Somalia plate