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Introduction
Published in Jamie Bartram, Richard Ballance, Water Quality Monitoring, 1996
Jamie Bartram, Richard Ballance
Potassium is determined by precipitating it with sodium cobaltinitrite, oxidising the dipotassium sodium cobaltinitrite with standard potassium dichromate solution in the presence of sulphuric acid, and measuring the excess dichromate colorimetrically. A series of standards with known concentrations of potassium must be carried through the procedure with each set of samples because the temperature and the time of preparation can significantly affect the results.
Sediment provenance in the Murchison and Maruia basins, Aotearoa/New Zealand: a record of Neogene strike-slip displacement, convergence, and basement exhumation along the Australian–Pacific plate boundary
Published in New Zealand Journal of Geology and Geophysics, 2022
Matthew W. Sagar, Karen E. Higgs, Dominic P. Strogen, Kyle J. Bland, Greg H. Browne
Thin sections were prepared by PetroStrat Ltd, UK. The sections were stained for K-feldspar using sodium cobaltinitrite, and half-stained for carbonate using alizarin red and potassium ferricyanide. Twenty thin sections (samples P91818–29, P92157–70, P92380–89) were analysed for mineralogy/porosity based on 300 point-counts following the methods of Folk et al. (1970), for future comparability with the large dataset available for Taranaki Basin Cretaceous–Cenozoic sandstone (Higgs and King 2018 and references therein). All counting categories and their abbreviations are given in Table 3. Grain size was measured from 100 grain counts, recording the long axis of each grain. In addition, we have incorporated data for five samples (samples P79916–25 and P81113) previously analysed for mineralogy/porosity by Nick Mortimer (GNS Science), who used the Gazzi–Dickinson method (Dickinson 1970) and counted at least 300 points per thin section. Comparability of data acquired using these different methods is attested to by similar results for samples from the same outcrops (P91825 and P79916, P91818 and P79922). The primary quartz–feldspar–rock fragment (QFR) and secondary metamorphic rock fragment–igneous rock fragment–sedimentary rock fragment (Rm–Ri–Rs) of Folk et al. (1970), and the monocrystalline quartz–K-feldspar–plagioclase (QmKP) (Streckeisen 1976) ternary diagrams were used to classify and analyse sandstone compositions. Degraded rock fragments (Rd), those that have been altered to such a degree that they cannot be further classified, were included in the R component when normalising data for plotting on the QFR ternary diagram. However, due to their unknown affinity, Rd were not included when calculating proportions of Rm, Ri and Rs. The R packages GCDKit version 6.0 (Janoušek et al. 2006) and provenance (version 3.2) (Vermeesch et al. 2016) were used for calculating granitoid Mesonorms (Mielke and Winkler 1979) and plotting the ternary diagrams.