Hidden mantle on full display: oceanic core complexes rewrite the ocean floor story
Geologists once thought the ocean floor formed from steady upwelling magma that cools into basalt, but a 2009 high-resolution sonar survey revealed low-angle detachment faults that pull mantle rock up to the seafloor, creating oceanic core complexes. With more than 170 identified along slow-spreading ridges, these structures show mantle rock, not just crust, is exposed to seawater, triggering serpentinization and powering hydrothermal vents. The findings reframe crust formation, illuminate global geochemical cycles, and offer models for extraterrestrial oceans.