Uplift, deflation and marine onlap of a Jurassic rift dome, illustrated by a backstepping Middle–Upper Jurassic shelf-to-slope succession, Geographical Society Ø, East Greenland

“Doming–rifting–spreading” constitute the main phases of classical plate tectonics. The Middle–Upper Jurassic succession of East Greenland is interpreted as reflecting formation, deflation and onlap of a rift dome, similar to contemporaneous rift domes in the North Sea, Denmark and southern Sweden. The succession forms a northwards backstepping and onlapping early rift succession in the N–S oriented basin. Deposition ranged from coastal over shallow marine and slope sands, through offshore siltstones to deep basinal mudstones. An outlier on the island Geographical Society Ø fills an important gap in the documentation of the doming, deflation and progressive onlap. Bajocian deposition took place in a shallow marine shelf. This was followed in the late Oxfordian by slope and base-of-slope deposition. The backstepping succession onlaps progressively older rocks towards the north, illustrating the gradual deflation, erosion and onlap of the dome, constituting the early part of the doming–rifting–spreading phases of classical plate tectonics.