Thick Crust at Earth's Slowest Spreading Ridge: 3D Gravity Insights From Eurasian Basin, Arctic Ocean

Abstract The Eurasian Basin of the Arctic Ocean opened by ultraslow spreading along the Gakkel Ridge, yet crustal thickness has remained poorly constrained due to sparse seismic data. We present a new basin‐wide 3‐D gravity model, updated by the most comprehensive sediment thickness and seismic observations, offering the first systematic view of crustal architecture. Since ∼45 Ma, the western Gakkel ridge (3°W–85°E), spreading at ∼10–14 mm/yr, has produced generally thin (2–4 km) crust. In contrast, the slower eastern Gakkel ridge (85–126°E; ∼6–10 mm/yr) generates basin‐wide robust volcanic crust 6–8 km thick. This “slower‐yet‐thicker” relationship challenges the classical spreading‐rate paradigm, showing that mantle fertility, elevated temperatures, and active upwelling—not spreading rate alone—govern crustal production at eastern part of Gakkel ridges.