In situ Rb-Sr and Lu-Hf dating techniques applied to petrochronology

Abstract

Petrochronology is the branch of Earth Sciences that relies on thermodynamic constraints of multicomponent and multiphase complex systems and accurate chronometers to successfully link time (ages or duration) with specific tectonic and/or rock-forming processes and their physical conditions. Therefore, the success application of the petrochronological approach is based on the development of thermodynamic datasets and computational techniques for thermodynamic modelling (forward, inverse and iterative models), and high-spatial resolution analytical techniques, including chemical and textural imaging and in-situ dating. Substantial advances on in-situ dating techniques have been achieved in the last decades using secondary ion mass spectrometry (SIMS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), allowing the measurement of chemical and isotopic composition of solid materials on a scale of a few microns. Furthermore, the recent development of a new equipment setup using a series of quadrupole spectrometers and reaction cells (LA-triple-quad-ICP-MS) enabled in-situ dating of minerals in Rb-Sr and Lu-Hf isotopic systems, opening a new dimension of possibilities to date rock-forming minerals, such as micas, feldspars, calcite and garnet, within the petrochronological philosophy. This revolutionary new equipment has been recently setup in the Cardiff Earth Laboratory for Trace Element and Isotope Chemistry (CELTIC), at Cardiff University (the CELTIC lab is headed by Dr. Andersen and Dr. Millet, partner investigators of this proposal). Hence, this mobility research proposal aims to support: (i) the analytical training and usage of this equipment by the principal investigator (visit to Cardiff University), (ii) a short course and field trip in Brazil by the partner investigators (visit to UNICAMP/Brazil) and (iii) the development of future joint research projects between the parties. (AU)