Mercury isotopic composition of various ocean island basalts

The mercury isotopic composition of the basalts was measured in 2021 by MC-ICPMS, using a Nu Plasma Instrument. We report both mass-dependent ( δ202Hg) and mass-independent (Δ199Hg, Δ201Hg) isotopic composition of mercury. The mantle composition least affected by crustal recycling is estimated from high-3He/4He lavas from Samoa and Iceland, providing an average of Δ199Hg=0.000.10, Δ201Hg=-0.020.0.09, δ202Hg=-1.71.2; 2SD, N=11.
HIMU-type lava shows positive Δ199Hg, consistent with the incorporation of altered oceanic crust in its mantle source, while a Samoan (EM2) lava has negative Δ199Hg reflecting incorporation of continental crust materials into its source.

2021年，研究团队采用多接收电感耦合等离子体质谱（MC-ICPMS），搭配Nu Plasma型质谱仪，对玄武岩的汞同位素组成开展了测定。本研究同时报道了汞的质量分馏同位素组成（δ²⁰²Hg）与无质量分馏同位素组成（Δ¹⁹⁹Hg、Δ²⁰¹Hg）。通过萨摩亚与冰岛地区的高³He/⁴He比值熔岩，估算得到受地壳循环影响最弱的地幔端元同位素组成，其平均数值为Δ¹⁹⁹Hg=0.00±0.10，Δ²⁰¹Hg=-0.02±0.09，δ²⁰²Hg=-1.7±1.2；误差为两倍标准偏差（2SD），样本数（N）=11。
HIMU（高U/Pb比值）型熔岩呈现正Δ¹⁹⁹Hg值，这与其地幔源区掺入蚀变洋壳的特征一致；而萨摩亚地区的富集地幔2（EM2）型熔岩则具有负Δ¹⁹⁹Hg值，反映其源区混入了大陆地壳物质。