Developing a method for extraction of the in-situ cosmogenic ¹⁰Be radionuclide from Pyroxene mineral along the Mooi River

MSc(Applied Radiation Science and Technology), North-West University, Mafikeng CampusThe quantification of the concentrations of cosmogenic nuclides in terrestrial rocks plays an important role in quantifying landscape evolution. In geomorphology, factors that influence landscape change also affect the accumulation of cosmogenic nuclides in rocks. Generally, in the quartz mineral from which ¹⁰Be and ²⁶Al are commonly extracted, this is a ubiquitous mineral on the earth's surface. Quartz is, therefore, used in the analysis of cosmogenic nuclides. South Africa has landscapes with all sorts of lithologies, dykes, sills and intrusions, which do not necessarily have quartz-containing rocks such as granite. In those cases, it then becomes necessary that the cosmogenic radionuclide extraction methods are extended to include other lithologies. In this study, pyroxene, was utilised to with the intention of extracting ⁰Be to further extend the range of mineral in South African landscapes in which it can be extracted. However, this study could reach that conclusion, nonetheless we were able to concentrate Be. In other similar studies, a modified decontamination method was used to completely remove the meteoritic ¹⁰Be in pyroxene, leaving in-situ ¹⁰Be in mineral crystal lattice. The intrusive rock Karoo dolerite was the lithology from which the pyroxene was extracted. Pyroxene as a chronometer using ¹⁰Be as a proxy, is to be used to study the South African landscapes that lack quartz in the extension of this study. This could play a pivotal role in land evolution studies. The original intention of this study was the extraction of the in-situ ¹⁰Be from pyroxene without any impurities, hence the adaptation of various cleaning methods during the chemical preparation of the samples. The two methods of quartz and pyroxene were used to elute ¹⁰Be using by addition of 1.2N HCl and 0.5M HNO₃ acids. Be was successfully eluted with 0.5M HNO₃ on the pyroxene method at concentration ranging 0 to 11 mg/l, while in quartz method it was eluted in 0.65M H₂SO₄, 1.2N HCl and 4N HCl respectively. Apprehension of this new extraction method prospect extensively widen the range of applications of the cosmogenic method in geomorphology. The ICP-OES analysis of isotopic cation species within the aliquots yielded uncounted cations within samples. Improving sample preparation for the isotopic measurement of ¹⁰Be extracted from minerals other than quartz had a direct positive effect on the accuracy and precision of the isotopic analysis. The optimization of strategies increased the amount of ¹⁰Be during analysis and when using the ICP-OES.Master