USING INHERITED OSL SIGNALS TO QUANTIFY LANDSCAPE DYNAMICS: EXAMPLES FROM THE JALISCO BLOCK TO THE FAULTS OF SIERRA DE JUáREZ (MEXICO)
For the first approach we extracted and analyzed two cores from Sayula and San Marcos lakes located in the triple junction of the Jalisco Block (west-central Mexico). Even though OSL signals exhibit the expected pattern of increasing luminescence age with depth, our analysis of cores using a Pulsed Photon Stimulated Luminescence unit indicate that there has been different rates of deposition and changes in the precedence of sediment. These results are also supported with geochemical analysis of major elements. For the second approach we analyzed the faults of Oaxaca and Donají which form the front of Sierra de Juarez (southern Mexico). From the active channels incising across thefaults we extracted sediment samples to determine the 10Be catchment-averaged erosion rates and to measure the OSL signals. At Donají fault, OSL signals closely scale with 10Be catchment-averaged denudation rates (R2 = 0.78 for IRSL and R2 = 0.71 for BLSL) and the last correlates with the mean basin rainfall (R2 = 0.86). At Oaxaca fault, OSL signals are negatively correlated with 10Be catchment-averaged denudation rates. Based on our OSL and 10Be data, as well as on topographic analyses we propose that the landscape along the Oaxaca fault is in disequilibrium due to the fault offset, whereas in Donají, which is known to be a transfer fault, the landscape seems to have reach a state close to equilibrium. Here we demonstrate that OSL signals, supported with 10Be-derived denudation rates, can yield information on the rates that prevail in the landscape.