The isostatic gravity anomaly: key to the evolution of the ocean-continent boundary at passive continental margins

Isostatic gravity highs bordering the passive continental margins are interpreted as resulting from oceanic basement highs. These basement elevations are relics of the transient phenomenon of a higher ridge axis elevation during early rifting. The steep landward gradient in the isostatic gravity field, generally associated with a magnetic edge effect anomaly, delineates the boundary between oceanic and continental basement.