Neogene uplift and tectonics around the North Atlantic: overview

Abstract

There appear to have been at least two significant episodes of uplift around the North Atlantic during the Cenozoic, and in many places it is not easy to separate the two. Effects related to emplacement of the Iceland plume probably caused one episode, mostly in the Palaeogene. The second episode took place in the late Cenozoic, and comprised uplift of basin margins as well as accelerated subsidence of basin centres adjacent to the uplifted landmasses. Cenozoic uplift of Scandinavia and of the British Isles has been suggested since at least the beginning of the 20th century. However, it is only recently being recognised in the literature that a major Neogene tectonic event has affected nearly every continental margin in the area (including western and eastern Greenland) and far into the European craton. Pre-Cenozoic rocks are generally exposed onshore and the pre-Quaternary sediments offshore are generally of Neogene age. Between the two, inclined Palaeogene and older beds are truncated by erosional unconformities along many coastlines. This structural configuration is in accordance with a Neogene uplift of the continents. A variety of methods have been used to investigate uplift, erosion and redeposition: studies of maximum burial, fission tracks, geomorphology, sediment supply and structural relations. These methods each investigates only one aspect of the phenomenon, and a thorough understanding of the processes of uplift and erosion can only be achieved if results from these methods are integrated. The main mechanisms suggested in the literature for the large-scale, late Cenozoic events are: emplacement of magma in and at the base of the crust leading to isostatic uplift, flow of asthenospheric material into active diapirs, isostacy associated with glacial erosion, phase changes in the lithosphere due to pressure relief and regional compression of the lithosphere. It is premature to judge between these mechanisms because of the insufficient regional analyses carried out so far. A general model must be constrained by observations from all affected areas, it must separate the effects of Palaeogene uplift from those of Neogene uplift that reach beyond the passive margins, and also include the subsidence patterns observed adjacent to the landmasses.