THE EROSIONAL AND UPLIFT HISTORY OF NE ATLANTIC PASSIVE MARGINS - CONSTRAINTS ON A PASSING PLUME

New apatite fission-track analyses from NW Britain indicate that a max imum of 2.5 km of erosion has occurred there during the Cenozoic, simi lar to values for SE Greenland and the east Greenland coast north of S coresby Sund. The erosion may have been facilitated by magmatic underp lating during break-up. However, at Kangerdlugssuaq, East Greenland, 4 -6 km of erosion is measured since 45 Ma. Lower-mid-Eocene marine sedi mentary rocks overlying the lavas on the Blosseville Coast indicate th at magmatic underplating on the central Greenland coast substantially post-dated flood volcanism and break-up, behaviour not predicted by si mple plume-rift models. Subsidence reconstructions of the Hebrides She lf, and the east and west Greenland coasts, show that rapid, dynamic u plift was effectively synchronous at 63 Ma and preceded volcanism by < 1.6 million years. The magnitude of uplift on the Hebrides Shelf (c. 4 00 m) is compatible with a mantle temperature anomaly of c. 100 degree s C. These data suggest very rapid lateral Bow of the impacting Icelan d plume head. The predicted crossing of the plume by the east Greenlan d coast in the mid-late Eocene would account for post-rift magmatic un derplating and dynamic support on the Greenland but not the European s ide of the North Atlantic basin.