Isotopic tools for uranium ores dating: application of uranium-lead and lead-lead dating systems
|Další prezentace na konferencích
|Fakulta / Pracoviště MU
|Isotopic tools used in geoanalysis are highly discussed topic nowadays. Many approaches for age determination of rocks and minerals are being developed relying on various isotope systems. Deposit Rožná appears to be a remarkable example including uranium minerals, e.g. uraninite, in which uranium has been stable and bound for more than 250 million years. Uraninite dating using U-Pb / Pb-Pb systems is possible, but with challenges remaining. Precise and accurate technique for isotope ratios measurements has been introduced already – Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). Other techniques, e.g. ICP-(Q)MS or ICP-(SF)MS, provide only acceptable results. Three approaches have been used. (I) Solution nebulization with specific sample preparation to eliminate matrix effects; (II) Laser Ablation MC-ICP-MS hyphenation, combined with standard solution nebulization; (III) Electron Probe Microanalysis (EPMA) to check the mineral phases analysed. Matrix effects elimination, instrumentation maintenance, tuning parameters and correction models need to be considered. All these parameters affect the ability to get the precise and accurate isotope ratios and ages, respectively. Our data which will be presented will be used to discuss the advantages and disadvantages of different analytical approaches.