Heavy mineral provenance of the mesozoic succession in Andøya, northern Norway: Implications for sand transport in the Vøring Basin

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-Vestera°len 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-Vestera°len 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.