Abstract Norwegian eclogite-facies shear zones in the Lofoten islands served as major pathways for short-lived pulses of both 40 Ar-rich and 40 Ar-poor hot fluids during eclogitization and retrogression events related to the Caledonian orogeny. The open system for Ar affected most of the minerals leading to old 40 Ar/ 39 Ar ages, particularly in trioctahedral micas. 40 Ar concentration in the fluids appears to decrease during the amphibolite-facies retrogression and Ca-rich amphiboles yield 40 Ar/ 39 Ar ages of c. 415 Ma (Scandian event). Late- and post-Caledonian 40 Ar/ 39 Ar muscovite and K-feldspar ages and Rb/Sr biotite ages coincide with multiple extensional events, fluid infiltration and thermal activity during the final exhumation of the crustal rocks, potentially reflecting major tectonic episodes such as rifting of Pangaea and seafloor spreading between Europe and North America. Supplementary material: Sample coordinates from all the rocks, analytical methods, complete 40 Ar/ 39 Ar step-heating descriptions and electron microprobe results are available at http://www.geolsoc.org.uk/SUP18687 .

Abstract A heavy mineral, mineral chemical and detrital zircon study of Jurassic–Cretaceous (Bathonian–Valanginian) sandstones of the Andøya B borehole, Lofoten–Vesterålen, northern Norway, has revealed the existence of significant differences within the succession. These are related partly to changes in source and partly to variations in the extent of weathering during alluvial storage. Three mineralogical units have been identified. The main change takes place within the Bathonian, and is interpreted as marking a switch from eastern (West Troms) to western (Andøya–Lofoten High) sourcing, consistent with previously published sedimentological models. U–Pb age data indicate that most of the zircons were derived from Palaeoproterozoic rocks ( c. 1750–1860 Ma), with a subordinate Archaean group ( c. 2600–2800 Ma) and a small early Palaeozoic group (mostly in the 435–446 Ma range). These groups can all be tied back to lithological components of the Lofoten–Vesterålen and West Troms regions, including Palaeozoic rocks hosted in Caledonian allochthons. The provenance characteristics of the Andøya succession have no counterpart in Cretaceous and Paleocene sandstones of the Vøring Basin. This suggests that sediment fed into the basin from Lofoten–Vesterålen was of minor importance, and that prospective Cretaceous–Paleocene hydrocarbon reservoir sandstones in the Vøring Basin were mainly derived from either northern Nordland or northern East Greenland. Supplementary material: Zircon isotopic compositions and ages are available at http://www.geolsoc.org.uk/SUP18616 .