ESTIMATING RATES OF DENUDATION USING COSMOGENIC ISOTOPE ABUNDANCES INSEDIMENT

We propose, as a testable hypothesis, a basin-scale approach for inter preting the abundance of in situ produced cosmogenic isotopes, an appr oach which considers explicitly both the isotope and sediment flux thr ough a drainage basin. Unlike most existing models, which are appropri ate for evaluating in situ produced cosmogenic isotope abundance at di screte points on Earth's surface, our model is designed for interpreti ng isotope abundance in sediment. Because sediment is a mixture of mat erials, in favourable cases derived from throughout a drainage basin, we suggest that measured isotope abundances may reflect spatially aver aged rates of erosion. We investigate the assumptions and behaviour of our model and conclude that it could provide geomorphologists with a relatively simple means by which to constrain the rate of landscape ev olution if a basin is in isotopic steady state and if sampled sediment s are well mixed.