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The distribution of trace elements among constituent minerals in H chondrites: focusing on rare earth elements and some other lithophile elements.

Thursday 8 April, 4 PM CET

Ryoga Maeda

Radioactive isotope systematics, such as Rb-Sr, Sm-Nd, Lu-Hf, Hf-W, and Re-Os, are known to be important chronometers and tracers for chemical differentiation processes. Trace elements including the elements relating to these isotope systematics are distributed in the respective constituent minerals in meteorites depending on their condensation temperature, diffusion and partition coefficients. Various elements are known to re-distribute and diffuse in the constituent minerals during parent body processes, affecting their isotope systematics. Terrestrial weathering while meteorites reside at the Earth’s surface can also disturb their original elemental and isotopic compositions. For example, our previous study analyzed Sm-Nd and Lu-Hf isotope ratios in Antarctic H chondrites demonstrates that thermal metamorphism on the parent bodies generally enlarges the heterogeneities of Sm-Nd and Lu-Hf isotope data in bulk chondrites based on the (re-)distributions of rare earth elements. Moreover, the study indicates the disturbance of their isotope systematics by terrestrial weathering in Antarctica if the sample is severely weathered. As such, the understanding of the distribution of trace elements in meteorites plays a pivotal role and is useful for understanding planetary processes. Nevertheless, the relative mobility of these elements during parent body processes, as well as during the terrestrial weathering remains poorly understood. Therefore, this study aims to better understand the (re-)distribution of trace elements, especially focusing on rare earth elements, as well as to constrain any weathering effects quantitatively, by studying H chondrites in a methodical manner. This talk will provide preliminary results from LA-ICP-TOF/MS.