Provenance and geochronology of Lomonosov Ridge: a contribution to the geology and tectonic history of the Arctic Ocean from dredged rock samples

Abstract

This thesis analyzes the OD2016-D2 dredge rock samples collected from a flank of Lomonosov Ridge, a major topographic feature in the Arctic Ocean. U-Pb- and Hf-isotopes were analyzed for 719 detrital zircon grains from ten sandstone samples using the Sensitive High-Resolution Ion Microprobe. The dredge rocks have similar detrital zircon U-Pb age distributions, a Neoproterozoic maximum depositional age, and Scandinavian provenance. Ten lithologies were defined from 176 samples and ten lithofacies from a selection of 96 samples to categorize the rocks and use as a basis for comparison. Two lithofacies associations are present: one indicates a tidal-influenced delta setting with fluvial input and the other indicates a tidal flat setting. The lithologies have similar heavy mineral assemblages, whole-rock geochemistry, and have a largely granitic component to their provenance. Overall, the results suggest that there are two Neoproterozoic units unconformably overlain by a possible Lower Paleozoic unit.