EGU21-10129, updated on 04 Mar 2021
https://doi.org/10.5194/egusphere-egu21-10129
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Nano-sized particles and semimetal-rich melts in PGE-rich magmatic mineral systems 

José María González-Jiménez1, Joaquín A. Proenza2, Fernando Gervilla1,3, and Rubén Piña4
José María González-Jiménez et al.
  • 1Universidad de Granada, Departamento de Mineralogía y Petrología, Granada, Spain (jmgonzj@ugr.es)
  • 2Universidad de Barcelona, Departamento de Mineralogia, Petrologia i Geologia Aplicada, Barcelona, Spain
  • 3Consejo Superior de Investigaciones Científicas (CSIC), Instituto Andaluz de Ciencias de la Tierra, Armilla, Spain
  • 4Universidad Complutense de Madrid, Departamento de Mineralogía y Petrología, Madrid, Spain

The results of several high temperature experiments predict that nanoparticles and nanomelts enriched in noble metals indeed exist in magmatic systems. Nanoparticles of Ru-Os-Ir or P-bearing sulfides alloys have been synthetized from S-free or S-undersaturated basaltic silicate melts at > 1000 °C at > 1000 °C. Pt-rich arsenide nanoparticles have also been synthesized in high-temperature sulfide melts well before the melt had reached a Pt–As concentration at which discrete Pt arsenide minerals become stable phases. More recently, the immiscibility of PGE-rich bismuthide melts within Ni-Fe-Cu sulfide liquids have also observed in high-temperature experiments, evidencing the key role played by nanomelts in controlling the PGE partitioning in magmatic mineral systems and their necessary existence for the formation of PGE-rich nanoparticles. However, many researches still remain convinced that these nanoparticles represent artifacts produced during quenching of experimental runs. The combination of focused ion beam micro-sampling techniques with high-resolution transmission electron microscopy (HRTEM) observations allowed the identification of PGE nanoparticles and nanominerals in magmatic base-metal sulfides from the PGE-Cr deposits from the Bushveld Complex in South Africa  and the eastern Cuban ophiolites. Moreover, nanometer sized of all six PGEs (Os, Ir, Rh, Ru, Pt, Pd) are relatively frequent natural quenched silicate melts preserved in mantle xenoliths. Collectively, all these observations made on natural rocks confirm the predictions of previous experiments on the possible formation of PGE mineral nanoparticles in magmatic systems rather to be result of low-temperature subsolidus re-equilibrium of magmatic minerals.

 

 

How to cite: González-Jiménez, J. M., Proenza, J. A., Gervilla, F., and Piña, R.: Nano-sized particles and semimetal-rich melts in PGE-rich magmatic mineral systems , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10129, https://doi.org/10.5194/egusphere-egu21-10129, 2021.

Corresponding presentation materials formerly uploaded have been withdrawn.