Journal of Quaternary Science vol:26 issue:1 pages:44-58
Floodplain deposition is an essential part of the Holocene sediment dynamics of many catchments and a thorough
dating control of these floodplain deposits is therefore essential to understand the driving forces of these sediment dynamics. In this
paper we date floodplain and colluvial deposition in the Belgian Dijle catchment using accelerator mass spectrometric radiocarbon
and optical stimulated luminescence dating. Relative mass accumulation curves for the Holocene were constructed for three colluvial
sites and 12 alluvial sites. A database was constructed of all available radiocarbon ages of the catchment and this database was
analysed using relative sediment mass accumulation rates and cumulative probability functions of ages and site-specific sedimentation
curves. Cumulative probability functions of ages were split into different depositional environments representing stable phases
and phases of accelerated clastic deposition. The results indicate that there is an important variation between the different dated sites.
After an initial stable early and middle Holocene phase with mainly peat growth in the floodplains, clastic sedimentation rates
increased from 4000 BC on. This first phase was more pronounced and started somewhat earlier for colluvial deposits then for alluvial
deposits. The main part of the Holocene deposits, both in colluvial and alluvial valleys, was deposited during the last 1 ka. The
sedimentation pattern of the individual dated sites and the catchment-wide pattern indicate that land use changes are responsible for
the main variations in the Holocene sediment dynamics of this catchment, while the field data do not provide indications for a
climatological influence on the sediment dynamics.