10:00 AM - 10:15 AM
[MTT37-05] Evaluation of acid leaching methods for high precision meteorite Pb-Pb chronology
Keywords:Pb-Pb chronology, Acid leaching method, Meteorites, Clinopyroxene, High-precision chronology, Isotopic fractionation
Our results revealed the following pictures as to elution of non-radiogenic Pb components; (i) weak acids (0.5 M HNO3) remove the most of non-radiogenic Pb components hosted by metal/sulfides, together with radiogenic Pb component hosted by phosphates, (ii) leaching with more intense acid (6 M HNO3 and HCl) results in removal of non-radiogenic Pb by dissolution of anorthitic plagioclase, whereas albitic plagioclase cannot dissolved by this step, (iii) leaching with diluted HF can dissolve albitic plagioclase enriched in non-ragiogenic Pb and pyroxenes enriched in radiogenic Pb. The detailed observation further revealed that exsolution lamellae in pyroxenes dissolved heterogeneously at HF attack: high-Ca lamellae were preferentially dissolved relative to low-Ca lamellae. Combining these observations with the results of modeling of Pb isotope evolution in each lamellae, we indicate that preferential dissolution of pyroxene lamellae gives an explanation for scattered Pb isotopic data found in previous work that was considered as evidence for Pb isotopic fractionation during acid leaching.