Towards U-Th/He dating of magnetite and spinel using LA-ICP-MS-MS (2022)

Project description

The application of the (U-Th)/He geo-thermo-chronological method to spinelgroup minerals faces the challenge of analyzing U and Th at the sub-ppm levelon µm-sized crystals. In order to avoid, when possible, tedious and time-consuming wet-chemical analyses, we propose here to analyze the U and Th content of natural spinel in situ using the new LA-ICP-MS-MS set-up at ISTerre (IMAP facility). One of the main challenges for this type of analysis is to prepare suitable spinel standards for calibration. The purpose of this project is therefore to synthesize and characterize U and Th doped synthetic spinel to be further used as standards for the U and Th analysis of natural spinel grains that have been studied, independently, in the frame of Marianna Corre’s PhD. The results of this methodological project, if successful, will be shared with the geo-thermo-chronology community, attract users to the IMAP platform (inconjunction with the He mass spectrometers that will also be installed at ISTerre) and strengthen the collaboration with Brest University (UBO) through inter-laboratory calibration using laser ablation.