Mabahiss Deep in the Northern Red Sea: New insights from high-resolution bathymetric mapping and analysis

The northern Red Sea is largely floored by evaporites, covering its basement structure and associated lithology of the lithosphere. The basement is exposed at only a few locations, called “Deeps”. Mabahiss Deep is the largest deep in the northern Red Sea. It hosts a large submarine volcano, Mabahiss Mons, and lies north of the Zabargad Fracture Zone. We use new high-resolution bathymetric data, ROV images, and basalt sample analysis to map the morphology of the Mabahiss Deep to understand the volcano-tectonic setting of this area and study its geologic evolution, providing insights into a young ocean basin that is potentially representative of other ultra-slow spreading ridges worldwide. Our results show that Mabahiss Deep is a 2360 m deep axial valley bordered by NW-SE Red Sea axis-parallel normal faults. The Mabahiss Mons has a ∼2 km summit caldera containing columnar basalts at its footwall, volcanic cones with pillow lavas, and extensive lava flows indicating Holocene activity. The basaltic submarine caldera is rare in such settings but is consistent with considerable lava flows and high melt supply due to magma focusing and elevated heat flux in the Red Sea, in spite of the slow spreading rates. The rock samples analysis shows MORB-type composition without any interaction of continental crust. Together our results show that Mabahiss Deep is a typical mid-oceanic ridge segment, confirming that oceanic spreading processes are occurring in this part of the northern Red Sea.