Calcium Isotope Ratios (δ^44/40Ca) of Thirty‐Four Geological Chinese Reference Materials Measured by Thermal Ionisation Mass Spectrometry

Abstract

High-precision calcium isotopic ratios of thirty-four Chinese geological reference materials, including igneous, metamorphic and sedimentary rocks, river/marine sediments and soils, are reported. Measurements were conducted by thermal ionisation mass spectrometry (Triton TIMS) using a 42 Ca-43 Ca double spike. These reference materials cover a wide range of chemical compositions with CaO ranging from 0.10 to 51.1% m/m. The δ 44/40 Ca variation of igneous rocks was up to 0.75‰, ranging from 0.61 AE 0.06‰ to 1.35 AE 0.04‰. Two metamorphic rocks yielded δ 44/40 Ca of 0.39 AE 0.02‰ and 0.86 AE 0.02‰, respectively. δ 44/40 Ca values of sedimentary rocks varied from -0.14 AE 0.09‰ to 0.98 AE 0.12‰, suggesting significant isotopic fractionation during low-temperature processes. Like sedimentary rocks, river/marine sediments and soil displayed large Ca isotopic variations, with δ 44/40 Ca spanning from 0.12 AE 0.06‰ to 0.77 AE 0.03‰ and -0.09 AE 0.11‰ to 0.74 AE 0.08‰, respectively. The comprehensive data set reported in this study serves as a reference for quality assurance and inter-laboratory comparison for high-precision Ca isotopic studies.

High-Precision Measurements of 44Ca/40Ca Using Multiple-Collector Inductively Coupled Plasma Mass Spectrometry without Collision-Cell Technology

“…Comparison between previously reported Ca isotopic data and values measured in this study. Previously reported values are from the literature. ,,− ,,− Gray, red, and blue spots represent data from the literature, this study, and average values of literature values. All the compiled data are listed in Table S9.…”

“…1 As a major element, Ca is involved in various geological and biological processes. 2,3 It has six isotopes, which are 40 Ca (96.941%), 42 Ca (0.647%), 43 Ca (0.135%), 44 Ca (2.086%), 46 Ca (0.004%), and 48 Ca (0.187%). Among these isotopes, 40 Ca is a major product of the decay of 40 K (T 1/2 = 1.25 Gyrs).…”

Geostandards and Geoanalytical Research Bibliographic Review 2022

“…Liu et al . (2022) report high‐precision Ca isotopic ratios of thirty‐four Chinese geological RMs, including igneous, metamorphic and sedimentary rocks, river and marine sediments as well as soils. Liu and Han (2022) not only produced δ‐Mg isotopic data for fourteen geological RMs including soils, riverine sediments and plants but also characterised a new pure Mg solution (Alfa‐Mg) which could potentially be used as a δ‐zero RM.…”