Molybdenum Mass Fractions and Isotopic Compositions of International Geological Reference Materials

Abstract

The double-spike method with multi-collector inductively coupled plasma-mass spectrometry was used to measure the Mo mass fractions and isotopic compositions of a set of geological reference materials including the mineral molybdenite, seawater, coral, as well as igneous and sedimentary rocks. The long-term reproducibility of the Mo isotopic measurements, based on two-year analyses of NIST SRM 3134 reference solutions and seawater samples, was ≤ 0.07‰ (two standard deviations, 2s, n = 167) for d Molybdenum (Mo) is one of the most abundant transition metals in the oceans and is important for a range of biological and geochemical processes (Manheim and Landergren 1974, Colodner et al. 1995, Morford and Emerson 1999. It has seven stable isotopes with relative abundances ranging from 9% to 25%, covering a mass range of about 8% (Anbar 2004). Molybdenum isotopes are increasingly being used in Earth sciences. Of particular interest is the highly redox-sensitive behaviour of Mo, which is primarily used to investigate the oxygenation of Earth's ocean and atmosphere (Barling et al.

The Molybdenum Isotope System as a Tracer of Slab Input in Subduction Zones: An Example From Martinique, Lesser Antilles Arc

“…All δ 98 Mo values are reported per mil relative to the NIST 3134 standard (Goldberg et al, ), which is set to 0—following recent studies of igneous applications of the Mo isotope system (e.g., Bezard et al, ; Freymuth et al, ; König et al, ). Four analyses of three separately digested aliquots of the USGS reference material BHVO‐2 yield a mean δ 98 Mo value of −0.08 ± 0.03‰ (2σ) (Table ), which is within range of the values reported by Burkhardt et al (), Hin et al (), Li et al (), König et al (), Bezard et al (), Freymuth et al (), Zhao et al (), and Liang et al (). One analysis of the USGS reference material W‐2 yielded a δ 98 Mo value of −0.04 ± 0.08‰ (2σ), which overlaps with the values given by Burkhardt et al (), Zhao et al (), and Bezard et al ().…”

Precise determination of the molybdenum isotopic composition of urine by multiple collector inductively coupled plasma mass spectrometry

“…Molybdenum concentrations and isotopic ratios are uniform in open seawater because of the long residence time of Mo relative to ocean mixing . After spiking and Mo separation via the BPHA column procedure, the average δ 98/95 Mo value and the mean Mo concentration of the IAPSO seawater standard were found to be 2.05 ± 0.06‰ and 10.5 ± 0.5 ng g −1 (2SD, n = 16), respectively (Table and Figure ) – values that are in excellent agreement with those previously reported . In addition to the seawater standard, replicate analyses of an in‐house urine standard were performed.…”

“…The precision of the individual measurements, referred to as internal precision, was typically ±0.04‰ ( After spiking and Mo separation via the BPHA column procedure, the average δ 98/95 Mo value and the mean Mo concentration of the IAPSO seawater standard were found to be 2.05 ± 0.06‰ and 10.5 ± 0.5 ng g −1 (2SD, n = 16), respectively ( Table 2 and Figure 3)values that are in excellent agreement with those previously reported. 32,37,38 In addition to the seawater standard, replicate analyses of an in-house urine standard were performed. This in-house urine standard sample yielded a mean δ 98/95 Mo value of 1.68 ± 0.07‰ with a mean concentration of 54.8 ± 0.3 ng g −1 (Ave ± 2SD, n = 15, Table 2).…”

Controlling Mechanisms for Molybdenum Isotope Fractionation in Porphyry Deposits: The Qulong Example

“…The reproducibility of δ 98/95 Mo values in the molybdenite samples was further evaluated using three international Re-Os molybdenite age reference materials: JDC, HLP-5, and NIST RM8599 (Table 1; Du et al, 2004;Markey et al, 2007). The obtained δ 98/95 Mo values of the NIST RM8599 (Henderson), JDC, and HLP-5 were −0.11 ± 0.01‰ (n = 9, 2 SD), −0.02 ± 0.04‰ (n = 9, 2 SD), and −0.61 ± 0.02‰ (n = 9, 2 SD), respectively, which are the same within uncertainties as previous studies (Siebert et al, 2001;Malinovsky et al, 2005;Breillat et al, 2016;Zhao et al, 2016b). An additional in-house molybdenite Re-Os age control sample, 2706.…”