Stone-line formation processes documented by in situ-produced Be distribution, Jardim River basin, DF, Brazil

Concentrations of in situ-produced cosmogenic ¹⁰Be (T_1/2=1.5 Myr) were measured in quartz samples from a quartz vein and its connected stone line from the Jardim River basin, Distrito Federal, Brazil, in order to quantify the processes involved in the landscape evolution of that region. The exponential decrease of the ¹⁰Be concentrations along the quartz vein, as well as their systematic increase along the stone-line away from the quartz vein, suggests an autochthonous development. Two models allow to estimate the lateral displacement rate. A plugs model assuming that the sample depth, and hence the production rate, is constant, and a burial model assuming that the sample depth, and hence the production rate, varies through time, yield lateral displacement rate of 37±5 and 68±6 m Myr⁻¹, respectively.