The deep-water basin on the Lomonosov Ridge in Central Arctic was rapidly formed on a shallow water shelf in the early Miocene. The continuity of the main seismic reflectors in the sedimentary cover of the ridge indicates no significant crustal stretching during the subsidence. The absence of large free-air gravity anomalies above the ridge precludes the dynamic topography in the mantle from being a cause of the formation of the basin. In the Miocene, the ridge was very far from the convergent boundaries therefore lithospheric flexing is unlikely to produce the subsidence. Under these conditions, crustal subsidence on the ridge was most probably associated with the increase in the crustal density due to metamorphic reactions catalyzed by fluid infiltration from the mantle.