Understanding geological processes over time through the thermal history of rocks

Mark Wildman and Kerry Gallagher from the Geosciences Rennes laboratory will use thermochronology, a method for reconstructing thermal history, to study the evolution of the first few kilometres of the Earth's crust in response to tectonic and erosive processes. This study was made possible by an individual grant funded under the European H2020 programme.
 Mark Wildman, à côté d'une ligne d'extraction de gaz pour l'analyse des concentrations de gaz dans les minéraux

The method

Thermochronology uses the temperature sensitivity of the retention of radiogenic decay products in different minerals to obtain information on the thermal history recorded over geological time. Dating methods based on apatite fission tracks and the ratio of (U-Th-Sm)/He are particularly powerful tools in geoscience because their temperature sensitivity (c. 40 -120°C) provides a way to explore geological history as a function of time-temperature. Their ability to constrain both time and thermal event rates comes from our ability to predict the annealing behaviour of fission tracks and helium diffusion over a temperature range equivalent to the upper 5 - 6 km of the Earth's crust.

Purpose of the project

This project will establish the state of the art of analytical procedures at the Université de Rennes 1, with the aim of obtaining :

  • fission track data (fission track analysis with Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS)
  • measurements of helium concentrations and the shape of the helium diffusion profile in apatite (4He/3He analysis).

In collaboration with scientists at Trinity College Dublin and the University of Paris-Sud, the project will investigate the role of apatite composition in controlling the rate of annealing of fission tracks and irradiation damage of faults, which may impede helium diffusion. Improving our knowledge of the kinetics involved in apatite thermochronology will allow us to resolve more complex geological histories on different time scales, ranging from 1 to 500 million years.

Identity card

European project AAT-NAA - HORIZON 2020 Programme - Marie S. Curie Action Curie Action

Institution: Université de Rennes 1

Beneficiary: Mark WILDMAN

Name of the Scientific Leader: Kerry GALLAGHER
Project duration: From 01/09/16 to 31/08/18 (2 years)