A review and reinterpretation of the architecture of the South and South-Central Scandinavian Caledonides-A magma-poor to magma-rich transition and the significance of the reactivation of rift inherited structures

Interpretations of the pre-Caledonian rifted margin of Baltica commonly reconstruct it as a simple, tapering, wedge-shaped continental margin dissected by half graben, with progressively more rift-related magmas towards the ocean-continent transition zone. It is also interpreted to have had that simple architecture along-strike the whole length of the margin. However, present-day rifted margins show a more complex architecture, dominated by different and partly diachronous segments both along and across strike. Here, we show that the composition and the architecture of the Baltican-derived nappes of the South and South Central Scandinavian Caledonides are to a large extend rift-inherited. Compositional variations of nappes in similar tectonostratigraphic positions can be ascribed to variations along-strike the rifted margin, including a magma-rich, a magma-rich to magma-poor transition zone, and a magma-poor segment of the margin. The architecture of the nappe stack that includes the Baltican-derived nappes was formed as a result of the reactivation of rift-inherited structures and the stacking of rift domains during the Caledonian Orogeny.