A new look at reflection seismic data from the Central Caledonian Transect across the Scandinavian Peninsula

Abstract. This study revisits seismic reflection data from the central Scandinavian Caledonides, initially acquired during campaigns in the late 1980s and early 1990s. Previous analyses faced challenges in merging and imaging due to varying trace spacing and data gaps, particularly in the western parts. To address these limitations, we spatially resampled the data to a consistent trace spacing, carefully merged segments, and migrated the entire merged section. This approach resulted in a revised seismic profile, with notable changes in the western section where the image reveals key differences compared to earlier interpretations. The updated profile indicates near-continuous reflections across merged segments, resolving issues of abrupt breaks present in some prior publications. Enhanced imaging in the western section unveils new structural details, including collapsed diffractions and shorter reflective segments, offset from one another. These reflecting segments in the Skardöra antiform are interpreted as representing dolerite sills that were once continuous over a larger area, but have been offset by normal faulting. This reinterpretation suggests a significantly thinner Upper Allochthon in the west than in previous interpretations. These results emphasize the importance of careful data integration and migration for seismic interpretation, shedding new light on the structural complexity of the western Scandinavian Caledonides. The study contributes to refining geological models and advancing understanding of the region's tectonic history.