MAGNUS--A Seismological Broadband Experiment to Resolve Crustal and Upper Mantle Structure beneath the Southern Scandes Mountains in Norway

Abstract

The 4-D evolution of topography is a complex scientific topic in geosciences that requires interdisciplinary efforts. In Europe, increased attention toward this research topic was originally coordinated by the TOPO-EUROPE initiative (Cloetingh et al. 2007), which has led to a continent-wide research program under the auspices of the European Science Foundation. One project within that framework is titled “TopoScandiaDeep— the Scandinavian Mountains: Deep Processes,” which aims at developing a self-consistent geophysical model for the lithosphere-asthenosphere system under southern Norway and at understanding the mechanisms that led to mountain-building far away from the plate boundary. A major component of the project is the analysis of recently acquired, passive seismological data from the MAGNUS ( MA ntle investi G ations of N orwegian U plift S tructures) experiment. The temporary network covered the high topography of southern Norway, which is, in the absence of compressional tectonics, a typical example of a particular geoscientific problem that is still not entirely understood—the origin of high topography along passive continental margins ( e.g. , Japsen and Chalmers 2000). Along the Northeast-Atlantic continental margin, at the western rim of the Fennoscandian shield, this topography is expressed through the Scandes mountain range, the second largest mountain range in Europe (Figure 1). It extends over a total length of more than 2,000 km along the entire Norwegian coast and has a peak topography of up to 2,500 m. With a few exceptions, such as the alpine formation in Sunnmore (central Norway), the topography is rather smooth, to a large extent dominated by subplanar (paleic) surfaces at elevations above 500 m. Contrary to the central European Alps, whose orogeny is in principle well understood as a classic collision belt, the evolution of the Scandes and its high topography remains an unsolved and highly debated issue. In particular the vicinity of …