Constraining the global variations in denudation rates associated with the last post-glacial transition

Abstract

The end of the last glaciation triggered major environmental changes with implications for geomorphological systems, ecosystems and societies. From the Last Glacial Maximum (LGM) to the start of the Holocene, landscapes have undergone profound changes, with increased temperature and modification of precipitation regimes affecting the way sediments are produced and transported at the Earth's surface. Records of past denudation rates are essential for understanding how landscapes responded to this transition and are required to assess the sensitivity of this response to local environmental, climatic and geomorphic contexts. Several methods, based on terrestrial cosmogenic nuclides (TCN) inventories, are available to constrain palaeo-denudation rates over millennial timescales, but few datasets exist that display strong signals regarding the dependency of this response to the setting, and the diversity of the approaches limits the possibilities for a global analysis. In this study, we propose a new method to constrain changes in erosion rates over the Pleistocene–Holocene transition, using the well-known concept that erosion rates derived from TCN concentrations are integrated over a timescale inversely proportional to the erosion rate. By combining TCN data with topographic information, we constrain the amplitude of erosion changes at 10 ka across neighbouring basins that are eroding at different rates. We highlight a complex pattern, with an overall several-fold increase in denudation rate when entering the Holocene. Intertropical high-relief areas appear to be more prone to displaying an increase in denudation rates, which might reflect a stronger sensitivity of these landscapes to periglacial processes, monsoon regime and/or threshold hillslope dynamics.