4 results found
Brett A, Prytulak J, Hammond SJ, et al., 2018, Thallium mass fraction and stable isotope ratios of sixteen geological reference materials, Geostandards and Geoanalytical Research, Vol: 42, Pages: 339-360, ISSN: 1639-4488
Thallium stable isotope ratio and mass fraction measurements were performed on sixteen geological reference materials spanning three orders of magnitude in thallium mass fraction, including both whole-rock and partially-separated mineral powders. For stable isotope ratio measurements, a minimum of three independent digestions of each reference material were obtained. High-precision trace element measurements (including Tl) were also performed for the majority of these RMs. The range of Tl mass fractions represented is 10 ng g-1 to 16 μg g-1, and Tl stable isotope ratios (reported for historical reasons as ε205Tl relative to NIST SRM 997) span the range -4 to +2. With the exception – attributed to between-bottle heterogeneity – of G-2, the majority of data are in good agreement with published or certified values, where available. The precision of mean of independent measurement results between independent dissolutions suggests that, for the majority of materials analysed, a minimum digested mass of 100 mg is recommended tomitigate the impact of small-scale powder heterogeneity. Of the sixteen materials analysed, we therefore recommend for use as Tl reference materials the USGS materials BCR-2, COQ-1, GSP-2, and STM-1; CRPG materials AL-I, AN-G, FK-N, ISH-G, MDO-G, Mica-Fe, Mica-Mg, and UB-N; NIST SRM 607; and OREAS14P.
Prytulak J, Brett A, Webb M, et al., 2016, Thallium elemental behavior and stable isotope fractionation during magmatic processes, Chemical Geology, Vol: 448, Pages: 71-83, ISSN: 1872-6836
Stable thallium (Tl) isotopes are an extremely sensitive tracer for the addition of small amounts of sediments or materials altered at low temperatures to the source(s) of mantle-derived melts. The ability of Tl to trace such materials is due to the largeconcentration contrast between the mantle (Tl < 2ng/g) and possible exotic inputs (Tl$+" ~100ng/g to >g/g), which also often display fractionated Tl isotope compositions.However, the magnitude of Tl isotope fractionation induced by igneous processesalone has not been systematically assessed. Here, two suites of co-genetic magmas, spanning a large range of differentiation, from Hekla, Iceland, and Anatahan, in the Mariana arc, are used to assess the behavior of thallium and its stable isotope variations during magmatic processes. Thallium behaves as a near-perfectly incompatible lithophile element throughout magmatic evolution, mirroring elements such as Rb, Cs, and K. Lavas from Hekla have restricted Cs/Tl ratios and stable Tl isotope compositions, which overlap with mantle estimates. Lavas from subduction-related Anatahan volcano also have a restricted range in Tl isotope composition, which overlaps with Hekla and MORB, demonstrating that fractional crystallisation and partial melting does not fractionate stable Tl isotopes. Subduction environments display variable Cs/Tl, indicating that the subduction process commonly fractionates these two elements. The immunity of thallium stable isotopes to fractionation by magmatic processes coupled with its extreme sensitivity for tracing pelagic sediments, FeMn crusts and low temperature altered oceanic crust highlight its value in elucidating the nature of mantle sources of both oceanic basalts and arc lavas. Critically, meaningful interpretation of thallium isotope compositions need not be restricted to primitive lavas.
Kersten M, Xiao T, Kreissig K, et al., 2014, Tracing Anthropogenic Thallium in Soil Using Stable Isotope Compositions, ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol: 48, Pages: 9030-9036, ISSN: 0013-936X
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