CENOZOIC UPLIFT OF FENNOSCANDIA INFERRED FROM A STUDY OF THE MID-NORWEGIAN MARGIN

Studies of the mid-Norwegian margin reveal that the Fennoscandian cont inental uplift represents a flexural intraplate deformation event sepa rated in time and space from the regional syn-rift uplift associated w ith crustal breakup at the Paleocene-Eocene transition. In the area 64 -68 degrees N, the uplift occurred from late Oligocene through Pliocen e. During Late Pliocene and Pleistocene times the tectonic uplift was amplified by isostatic rebound in response to the Northern Hemisphere glaciation. The tectonic uplift component reaches similar to 1 lan in the northern part of the study area decreasing to the south. The shelf stratigraphy and sediment composition record the combined effects of tectonic uplift, eustatic sea level changes and Neogene climatic deter ioration. The coeval uplift and climatic change may suggest causal rel ations. The resulting depositional model has three stages: (1) late Mi ocene (similar to 10.5-5.5 m.y.) increased continental erosion and dep osition of prograding wedges most of which were later removed; (2) ear ly-middle Pliocene (5.5-2.6 m.y.) development of extensive local ice-s heets reaching the coastline and deposition of the prominent, oldest P liocene wedges; (3) Northern Hemisphere glaciation (2.6-0.01 m.y.) res ulting in the younger wedges farther west covered by Quaternary deposi ts. The model is consistent with the development of landforms on the a djacent mainland. Both the tectonic and isostatic components of the Fe nnoscandian uplift appear to vary in magnitude along the uplift axis, however separation of the syn-rift plate boundary related uplift and t he intraplate event support the Neogene age of the main Fennoscandian uplift. We document a correspondence between structural and physiograp hic margin segmentation and uplift magnitude and suggest that the intr aplate deformation has a thermal origin. A hot-cold asthenosphere boun dary beneath the Caledonide-Baltic Shield transition combined with pre -Tertiary relief at the base of the lithosphere might induce small-sca le convection and preferential volume expansion beneath the observed e longate uplift.