Raman Spectroscopy of Carbonaceous Materials geothermometry: a reliable method to investigate thermal history of foreland basins.
Résumé
To investigate the thermal evolu-tion of foreland basins, many classical methods includ-ing clay mineralogy, vitrinite reflectance, fluid inclu-sions and illite cristalinity are used. These methods are probably not perfectly reliable taken individually, but provides a robust estimate when they give a coherent results. Raman Spectroscopy of Carbonaceous Materials (RSCM) could be an alternative method to constrain paleotempeartures of rocks. This method has been calibrated firstly in the range 330-640°C [1] then in the range 200-350° [2]. The aim of this study is to extend the applicability of this method towards palotemperatures lower than 200°C. For this purpose, we discuss a new fitting pro-cedure which would allow us to define a new Raman parameter R3. This parameter is different of RA1 [1] and R2 [2] used previously to characterize the thermal evolution of the Carbonaceous Materials. Raman spectra measured and treated are obtained by analysing samples from turbiditic deposits of differ-ent basins located in the western part of the South Pyrenean Zone. The thermal history of these samples, that underwent diagenesis, is well known using a vari-ous techniques. These methods are vitrinite reflec-tance, fluid inclusion thermometry, low-T thermochro-nology, index mineralogy and illite cristallinity. Although our results are preliminary, they suggest that the RSCM geothermometer could be a reliable method to constrain the thermal history of foreland basins. We are currently working on the acquisition of more data to determine temperatures of the basin that underwent diagenesis conditions during the Pyrenean activity. Reference
Domaines
Minéralogie
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