Echinoid skeletal carbonate as archive of past seawater magnesium isotope signatures – Potential and limitations

Early diagenetic constraints on Permian seawater chemistry from the Capitan Reef

“…The effect of [Mg] on δ 26 Mg was established using a 5-point calibration between 135 and 165 ppb, and corrected for using the ratio of the intensity of mass 24 for each sample to that of the prior analysis of the bracketing standard, whose [Mg] was known and constant throughout the run. Long-term external reproducibility was ±0.10‰ (2σ, n=34) for IHD, ±0.11‰ (2σ, n=44) for seawater, and ±0.11‰ (2σ, n=30) for RUB, which had average δ 26 Mg values of −1.77‰, −0.78‰, and −3.69‰, respectively, the latter two in line with published values (Riechelmann et al, 2018).…”

“…For Ca isotopes, these were: seawater (collected at Woods Hole Oceanographic Institution), EN-1 from the USGS (modern Tridacna shell, Enewetak lagoon, Marshall Islands), NIST SRM 915b calcium carbonate, the 'PUA' in-house aragonite standard from Princeton University, and an in-house aragonite standard (San Salvador Sand; 'SSS'). For Mg isotopes, these were: seawater, the 'RUB' in-house calcite standard from Ruhr University Bochum (Riechelmann et al, 2018), a high purity Mg ICP standard obtained from Princeton University, and an in-house dolomite standard from the University of Chicago collection ('IHD').…”

Magnesium and carbon isotope fractionation during hydrated Mg-carbonate mineral phase transformations

“…Samples were loaded onto 10 mL Bio-Rad poly-prep columns containing AG-50W-X12 (Mavromatis et al, 2012(Mavromatis et al, , 2013(Mavromatis et al, , 2014a(Mavromatis et al, , 2014bPearce et al, 2012;Beinlich et al, 2014Beinlich et al, , 2018, as well as from other laboratories (Bolou-Bi et al, 2009;Wombacher et al, 2009;Geske et al, 2015;Riechelmann et al, 2016Riechelmann et al, , 2018Mavromatis et al, 2017a;2017c). The reproducibility of chromatographic separation was assessed by repeated analyses of selected samples and the JDo-1 (dolomite) and IAPSO seawater as shown in Table 2, and was better than 0.08‰.…”

Time series of δ26Mg variability in precipitation of north‐west Germany

“…These values agree with previously published values (Immenhauser et al, 2010; Teng, 2017; Teng et al, 2015). For further details regarding the Mg isotope analysis, the reader is referred to Immenhauser et al (2010) and Riechelmann et al (2018).…”

“…Moreover, Mg is important in biological and hydrological systems given that it is a common element in plant material, seawater, groundwater, as well as dust and aerosols (Appelo & Postma, 2005; Black et al, 2008; Bolou‐Bi et al, 2010; Négrel & Roy, 1998; Sigg & Stumm, 2011). As a consequence, the number of studies focussing on the magnesium isotope composition (δ 26 Mg) of carbonate and silicate rocks, plants, river water, groundwater, seawater and biogenic shell material has rapidly increased over the last decades (Black et al, 2008; Geske et al, 2015; Hu et al, 2021; Kimmig et al, 2018; Li et al, 2019; Murray et al, 2021; Novak et al, 2020; Pogge von Strandmann et al, 2008; Riechelmann et al, 2012, 2016, 2018; Rollion‐Bard et al, 2016; Teng et al, 2010; Teng, 2017 and references therein; Tipper et al, 2006a; Wombacher et al, 2011).…”