Seminar Sébastien Ternois

Sébastien Ternois (Postdoc / IR, ISTO, Orléans) will give a seminar in room E001 entitled "Seeing is believing: what does zircon (U-Th)/He thermochronometry really tell us ?".

This webinar will also be accessible on Teams (link here).

Looking forward to seeing many of you!



To answer questions that involve tectonic movements and the thermal regime of the crust, an investigation tool sensitive to crustal processes should be used. Geo-thermochronometry is one of these tools, which can be applied to crystalline rocks as well as detritic rocks to reconstruct the thermal history of the minerals that compose them. Among the geo-thermochronometric methods developed, one of them is based on the measurement of the concentrations of parent elements (U, Th and Sm) and daughter products (He) in a mineral (apatite, zircon, titanite, rutile and sphene in particular) to calculate the a priori radiochronological age of the mineral: the (U-Th-Sm)/He dating method. Due to the ability of helium to diffuse within and outside minerals when they are subjected to crustal temperatures (<300°C), this method generally provides, however, a complex record resulting in non-uniqueness of (U-Th-Sm)/He ages for the same crystalline rock. Therefore considered imprecise, the (U-Th-Sm)/He method sometimes suffers from an awkward use if at all it is used. The objective of this seminar is to discuss advances in understanding the mechanisms of helium diffusion within a solid-state medium, as well as to present the multi-thermochronometric behaviour of the (U-Th-Sm)/He system with an example of application to zircon.