{"id":891,"date":"2021-10-18T21:25:59","date_gmt":"2021-10-19T04:25:59","guid":{"rendered":"https:\/\/labs.wsu.edu\/rigl\/?page_id=891"},"modified":"2026-04-13T12:45:41","modified_gmt":"2026-04-13T19:45:41","slug":"analytical-capabilities","status":"publish","type":"page","link":"https:\/\/labs.wsu.edu\/rigl\/analytical-capabilities\/","title":{"rendered":"Analytical Capabilities"},"content":{"rendered":"
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Analytical Capabilities<\/span><\/h1>\n\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t<\/div>\n<\/div>\n\n\n\n
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Lu-Hf, Sm-Nd geochronology (by ID-MC-ICPMS)<\/em><\/h2>\n\n\n\n

The Radiogenic Isotope & Geochronology Laboratory (RIGL) at WSU specializes in garnet Lu-Hf and Sm-Nd geochronology. Garnet geochronology takes advantage of garnet\u2019s high compatibility for Lu and Sm relative to Hf and Nd, which results in the elevated Lu\/Hf and Sm\/Nd ratios in the garnets, and thus can be utilized for use in the isochron technique. We determine an isochron age for each sample from the analyses of several garnet fractions and their co-genetic low Lu\/Hf and Sm\/Nd phases (typically a whole rock powder).<\/p>\n\n\n\n

All garnet fractions are dissolved using a nonaggressive HF-HNO3<\/sup> dissolution protocol designed to avoid the digestion of low Lu\/Hf zircon. For some garnet fractions containing substantial phosphate inclusions with low Sm\/Nd ratios (e.g., apatite, monazite), we apply the sulfuric acid (98% H2<\/sub>SO4<\/sub>) leaching method before dissolving the garnets. In terms of the whole rock fractions for Lu-Hf chemistry, it is noteworthy that powders should not be ground in a tungsten-carbide mortar in order to prevent 180<\/sup>W contamination; otherwise, the procedure is similar to garnet digestion. After HF-HNO3<\/sub> dissolution, the sample solution is spiked with mixed 176<\/sup>Lu-180<\/sup>Hf and 149<\/sup>Sm-150<\/sup>Nd tracers. Our 176<\/sup>Lu-180<\/sup>Hf spikes cover a range of low Lu\/Hf ratio for zircon, intermediate Lu\/Hf ratio for felsic and mafic rocks, to high Lu\/Hf ratio for garnet (Vervoort et al., 2004). After isotopic equilibrium of the sample and spike mixture, the elements of interest (Lu, Hf, Sm, and Nd) are isolated from the solution by ion-exchange chromatography.<\/p>\n\n\n\n

All isolated elements are analyzed using a Thermo Scientific Neptune Plus MC-ICPMS at RIGL. The measured values are corrected for interference and mass bias; here, the exponential law is employed for mass bias correction (see Vervoort et al., 2004 for the detailed description of Lu-Yb correction protocol). The widely accepted values of the JMC475 Hf standard and the JNdi Nd standard are 176<\/sup>Hf\/177<\/sup>Hf = 0.282160 (Vervoort & Blichert-Toft, 1999) and 143<\/sup>Nd\/144<\/sup>Nd = 0.512115 (Tanaka et al., 2000). Our average determinations of these standards over hundreds of analyses at RIGL are 0.282147\u00b112 (2SD) and 0.512096\u00b120 (2SD), respectively.<\/p>\n\n\n\n

References<\/h3>\n\n\n\n