No abstract

Although sulfur is a relatively abundant element, measurement results with small uncertainties remain challenging to achieve, especially at S mass fractions below 100 μg g -1 . We report > 1700 measurement results of S for thirty-seven geological reference materials including igneous, metamorphic and sedimentary rocks, and one soil. Measurement results were obtained in two laboratories (Macquarie GeoAnalytical and Géosciences Montpellier) over a long period of time ≈ 25 years (1997-2022), using several measurement procedures: X-ray fluorescence, high temperature iodo titration and elemental analysers equipped with thermal conductivity and/or infra-red detectors. Sulfur mass fractions for these diverse geological reference materials range between 5.5 and 11,395 μg g -1 . While the comprehensive data set reported here should contribute significantly to a better characterisation of the S mass fractions of widely used geological reference materials, computed uncertainties, data distribution and comparison to published values still indicate heterogeneous distribution of S carrier(s) and analytical bias.

The terms "wet" or "hydrous" mantle are commonly used in the literature and refer to modally metasomatised mantle bearing amphibole, phlogopite. In recent years, the community has focussed on the nominally anhydrous minerals (NAMs) and not so much on the nominally hydrous phases (NHMs). Only few studies have investigated the effect of NHMs on the content and bulk distribution of H2O in metasomatised mantle assemblages. Here, three xenolith suites (alkali-basalt hosted) containing varying modes of amphibole (up to 30%) have been investigated; two from the French Massif Central (MCF), and one from the Newer Volcanic Province (Australia; BM-GN suite). We used a range of analytical methods to quantify the concentration and distribution of water and water-derived species both at wholerock and at the mineral scales, including: elemental analyser (EA), fourier transform infra-red spectrocopy (FTIR) and thermal gravitation analysis (TGA). The relationship between bulk water content (EA) and amphibole is not straightforward. MCF suites show a rough positive correlation. This is not observed for the BM-GN suite, which shows a positive correlation with CO2. Recomputed bulk Hydrogen concentrations from FTIR are independent from amphibole abundances and are typical of a "dry" lithospheric mantle. In contrast, well-defined negative and positive correlations are found between hydrogen in NAMs and olivine, opx and cpx abundances, respectively. The partitioning of H2O between co-existing NAMs does not seems to be affected either. BM-GN and MCF amphiboles show different geochemical characteristics: contrasted REE fractionations ((Sm/Yb)