Effect of density uncertainties in cosmogenic 10Be depth-profiles: Dating a cemented Pleistocene alluvial fan (Carboneras Fault, SE Iberia)

Cosmonuclide depth-profiles can be used to calculate both the age of landforms and the rates at which erosion has affected them since their formation. Results are heavily dependent on the selection of the appropriate density of the material exposed to cosmic radiation. In materials where density has changed significantly through time, as in alluvial sediments affected by post-depositional calcrete cementation, the uncertainties in density must be accurately modelled to produce reliable results. We develop new equations for an accurate account of density uncertainties and to test the effect of density gain due to cementation processes. We apply them to two 10Be depth-profiles measured in an alluvial fan deformed by the Carboneras Fault (SE Iberia). When a linear increase of density through time is considered, model results yield an age ranging from 200 ka to 1 Ma within 1σ confidence level.