Natural Allanite Reference Materials forIn SituU‐Th‐Pb and Sm‐Nd Isotopic Measurements by LA‐(MC)‐ICP‐MS

Allanite is a common accessory mineral that generally incorporates considerable amounts of Th, U and light rare Earth elements in its structure, making it a useful mineral for in situ U‐Th‐Pb geochronology and Sm‐Nd isotope measurements. Here, we present in situ U‐Th‐Pb ages and Sm‐Nd isotopic compositions for nine allanite samples considered as potential reference materials (CAP b , Tara, Daibosatsu, LE40010, LE2808, A007, A011, A012 and SQ‐51), with ages ranging from ~ 2650 Ma to ~ 12 Ma. Our study indicates that Daibosatsu and LE40010 have relatively homogeneous 147 Sm/ 144 Nd and 143 Nd/ 144 Nd isotopic compositions ( 147 Sm/ 144 Nd ratio variation is less than 2%) and, thus, can serve as primary reference materials for Sm‐Nd microanalysis. In contrast, CAP b , Tara, LE2808, A007, A011 and A012 all show homogeneous calculated initial 143 Nd/ 144 Nd isotopic compositions, but with variable 147 Sm/ 144 Nd compositions, and thus can be used only as secondary reference materials for Sm‐Nd microanalysis. Of these materials, LE40010 allanite can serve as a suitable primary reference material for in situ U‐Pb dating, CAP b allanite can serve as a suitable primary reference material for in situ Th‐Pb dating, and LE2808, LE40010, A007, A011 and A012 can serve as suitable secondary reference materials for in situ U‐Pb geochronology. In addition, Daibosatsu is suitable as a secondary reference material for Cenozoic Th‐Pb dating to monitor data reproducibility.