Early glaciations in the surrounding continents of the polar Arctic Ocean have been revealed
through the occurrence of ice rafted detritus (IRD) in the marine sediments. The glacigenic origin of the
deposited sediment is generally recognised either by the grain size, but also by distinctive grain
morphology, grain surface textural features and clay mineral compositions. In this study the mineralogy
of the submarine Lomonosov Ridge sediments are analysed using X-ray diffraction (XRD) and scanning
electron microscope (SEM) methods. The study combines both the quartz sand grain surface
microtextural and clay mineralogical data from drill cores obtained during the IODP Arctic Coring
Expedition (ACEX) 302. The studied interval (141–197 m below sea floor) of the coring Site M0002
represents a time slice of 6 million years critical for the onset of glaciation, between ca. 12–18 Ma at the
Middle Miocene. The sediments consist mainly of homogenous siliciclastic detritus characterised by low
organic carbon concentrations. The specific glacial crushing and transport features – high angularity,
conchoidal fractures, steps and subparallel linear fractures – were observed from quartz sand grain
surfaces, coinciding with significant drops in the smectite contents. The reduced smectite and
corresponding increase in the chlorite and illite contents refer to cooler climate conditions, continental
ice generation and increased physical erosion on land.