Revisiting a type locality for Late Glacial aeolian sand deposition in NW Europe: Optical dating of the dune complex at Opgrimbie (NE Belgium)

All nine quartz samples showed satisfactory luminescence characteristics, and yielded an internally consistent set of optical ages. The dataset contains no clear outliers and the observed variation is not much larger than that expected from uncertainties. The sediments over- and underlying the lowermost bleached horizon are dated at 12.9 ± 0.9 ka (n = 6) and 13.0 ± 0.8 ka (n = 3), respectively. These ages do not confirm the Bølling age that was previously established for this horizon; the optical ages are, however, consistent with the chronostratigraphical position of the sediments below the Usselo soil of Allerød age. As such, the OSL ages question if the Lateglacial aeolian succession is fully developed at Opgrimbie, and they challenge its significance as a type locality.