Oceanic Core Complex

An oceanic core complex or magnalium is a seabed geological feature that forms a long ridge perpendicular to a mid-oceanic ridge. It contains smooth domes that are lined with transverse ridge like a corrugated roof.

They can vary in size from 10 to 150km in length, 5 to 15 km in width, and 500 to 1500m in height. Drilling of the feature shows that the footwall can be composed of both mafic plutonic and ultramafic rocks and a thin shear zone that includes hydrous phyllosilicates.

• Oceanic core complexes are often associated with active hydrothermal fields.
• They are formed at slow spreading oceanic plate boundaries which have a limited supply of upwelling magma.
• These zones have low upper mantle T and long transform faults develop