Abstract The core of the Rodinia supercontinent has long been considered to have consisted of three cratons – Baltica, Laurentia and Amazonia – amalgamated along the late Mesoproterozoic Sveconorwegian, Grenville and Sunsas orogens. In recent years, however, it has become increasingly clear that the metamorphic and magmatic evolution of the Sveconorwegian orogen is inconsistent with a collisional model. Although geological data alone do not rule out proximity to Rodinia, palaeomagnetic data indicate significant latitudinal separation of Baltica and Laurentia during supercontinent assembly. In this contribution, we briefly review two recently proposed and mutually exclusive tectonic models for the Sveconorwegian orogeny and present a compilation of previously published and new chemical and isotopic data. A lack of crustal thickening throughout much of the orogen and few if any changes in lower-crustal sources and melting conditions between 1.3 and 0.9 Ga suggest that the western part of the Sveconorwegian orogeny represents a change from a dominantly extensional to a compressional back-arc regime, but without a significant change in overall tectonic setting. This orogenic evolution is incompatible with amalgamation into Rodinia and suggests that Baltica may have been isolated until the Silurian Caledonian orogeny.

Abstract Since the term was coined in 1873, palaeogeography has provided a powerful map-based tool for synthesizing, visualizing, and testing diverse regional data and hypotheses, but there are problems in deducing the palaeogeography of areas with few data points. As an example, the Scottish Highlands are better mapped and more studied than almost any other ancient orogen, yet questions remain on the persistence of topography since the Caledonian orogeny and the possibility of Cretaceous marine inundation. This paper reviews the data available on Scottish Cretaceous outcrops using published geological maps and memoirs to extract data: outcrop length, stratigraphic thickness and component units, elevation range of the outcrop and subcrop formations. All Cretaceous rocks in western Scotland were deposited in shallow marine and shoreline environments; deposits thin northwards and appear to be close to a feather edge. Elevation data are used to construct a Cretaceous surface which intersects present-day topography at low to intermediate altitudes. It is concluded that the Scottish Highlands were largely emergent during the Late Cretaceous, confirming previous palaeogeographic studies.