Lateglacial to Middle Holocene landscape development in a small-sized river valley near Antwerp (Belgium)

At the transition between the Scheldt valley and the Campine microcuesta near Antwerp, two separate organic deposits are present in the subsoil. Sedimentological, macrobotanical and palynological analyses from two cores are used to reconstruct the evolutions of the local depositional and ecological environment, as well as the regional vegetation. An age-depth model based on radiocarbon dates allows to frame those evolutions chronologically. During the Weichselian lateglacial, a mesotrophic lake was filled with peat during GI-1. The sand input indicates continued aeolian activity, also during forested phases. This peat was covered by wind deposits during GS-1. From the start of the Holocene onwards, a river channel in the Opstal Valley started to fill with peat in a mesotrophic fen. Pollen records show a temporary opening of the regional forest, that can be linked to the 11.4 ka event. The peat dried out around 11,000 cal BP and wetter conditions returned by the beginning of the Middle Holocene, with the development of an alder/birch carr. Unlike the Scheldt valley, the Opstal valley was not under tidal influence in the Middle Holocene. After ca. 6000 cal BP, the valley was part of the coastal peatlands that evolved from mesotrophic fen into oligotrophic bog.