"(U-Th)/He thermochronology applied to active orogenesis and landscape evolution in the Amazonian Andes

Abstract

Low-temperature thermochronology has become one of the most widely employed techniques to address the spatial and temporal pattern of orogenesis (e.g., Reiners and Brandon, 2006), as it allows to extract the thermal history that a rock has experienced in the uppermost few kilometers of the crust. In orogenic settings, and less so in cratons, (U-Th)/He has the potential to resolve these histories from the lowest temperatures and hence shallow exhumation depths, due to the relatively higher diffusivity of Helium from U-rich minerals (Ault et al., 2019, Gautheron et al., 2022). The JPII Project to which this research is ascribed aims to document the shortening rates and the topographic history of the Amazonian Andes using a multi-method approach that includes (U-Th)/He dating of apatites and zircons. So far, this task has been conducted in collaboration with partner researchers in Germany and France. The main contribution of this PD project is implementing (U-Th)/He chronology at the Center of Geochronological Research (CPGeo) at the Institute of Geosciences, University of Sao Paulo (IGc-USP). We intend to update and use existing analytical equipment of CPGeo that is under-utilized and has made available to the project Principal Inverstigator (PI) M. Parra. This post-doctoral fellowship seeks to (1) establish the analytical protocols for (U-Th)/He dating in various minerals, (2) perform the (U-Th)/He analyses foreseen for the project using this new facility, and (3) make this laboratory available for the academic and industrial community as a part of the Multi-User facility USPMulti CPGeo-LTC.