Erosion rates in the source region of an ancient sediment routing system: comparison of depositional volumes with thermochronometric estimates
Datasets usually provide raw data for analysis. This raw data often comes in spreadsheet form, but can be any collection of data, on which analysis can be performed.
Calculation of the total depositional volume of an ancient source-to-sink system, combined with estimates of the area of catchments acting as source regions using provenance methods, is used to evaluate average catchment erosion rates on a million year time scale. These rates are compared with values derived from thermochronological methods. Using the mid- to late Eocene (33.9–41.6 Ma) Escanilla palaeo-sediment routing system from the south–central Pyrenean orogenic wedge-top zone as an example, c. 3500 ± 300 km3 of solid particulate sediment was derived from two catchments in the south–central Pyrenees over a 7.7 myr period, equivalent to a mean erosion rate of c. 0.15–0.18 mm a−1. Average exhumation rates in contributing catchments over the same time interval are estimated at 0.2–0.3 mm a−1 based on apatite fission-track analysis of pebbles in proximal conglomerates, and 0.23–0.34 mm a−1 from fission-track analysis of detrital apatites sampling a wider range of grain size. Sediment supply progressively increased during the mid- to late Eocene time period, at least in part driven by catchment expansion deep into the Pyrenean Axial Zone at c. 39 Ma. The consistency of the rates of catchment-averaged erosion calculated from different methods builds confidence that source areas have been connected to depositional sinks correctly.