Investigating the Shallow to Mid-Depth (> 100-300 degrees C) Continental Crust Evolution with (U-Th)/He Thermochronology: A Review

Quantifying geological processes has greatly benefited from the development and use of thermochronometric methods over the last fifty years. Among them is the (U-Th)/He dating method, which is based on the production and retention, within a crystal structure, of radiogenic He-4 atoms associated with the alpha decay of U, Th and Sm nuclei. While apatite has been the main target of (U-Th)/He studies focusing on exhumation and burial processes in the upper levels of the continental crust (similar to 50-120 degrees C), the development of (U-Th)/He methods for typical phases of igneous and metamorphic rocks (e.g., zircon and titanite) or mafic and ultramafic rocks (e.g., magnetite) over the last two decades has opened up a myriad of geological applications at higher temperatures (>100-300 degrees C). Thanks to the understanding of the role of radiation damage in He diffusion and retention for U-Th-poor and rich mineral phases, the application of (U-Th)/He thermochronometry to exhumation processes and continental evolution through deep time is now mainstream. This contribution reviews the (U-Th)/He thermochronometer principle and the influence of radiation damage in modifying the diffusion behavior. It presents applications of (U-Th)/He dating to problems in tectonic and surface processes at shallow to middle crustal depths (>100-300 degrees C). New and promising applications using a combination of methods will stimulate a research avenue in the future.

Automated summary

The development and application of (U-Th)/He dating method has greatly improved the understanding of geological processes such as exhumation and burial in the continental crust, as well as continental evolution. Recent advancements in the method have expanded its range of applications to higher temperature geological problems.