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Zircon U–Pb dating by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) is a widely used analytical method in the field of geology. However, the U–Pb dating of zircons with complex interior structures has always been a challenge in laser in situ analysis. To address this issue, we introduce a novel method, termed reverse depth profiling, for LA-ICPMS U–Pb dating of such zircons. This method combines the traditional LA-ICPMS method with depth profiling, analyzing the over-polished zircon from core to rim. We applied this method to zircons from the Himalayan leucogranites in Dinggye and garnet-bearing granitic gneiss in Yadong. The method allows the successful dating of zircon rims as narrow as only 0.6 μm. Characterized by high sample analysis efficiency, superior vertical spatial resolution, and optimal data utilization, this method enhances the success rate of U–Pb dating of structurally complex zircons. Valid geochronological information on the inherited cores and magmatic/metamorphic rims of zircons can be obtained by this method, which has great potential for unraveling complex magmatic and metamorphic events in tectonically active regions in geological history. [ABSTRACT FROM AUTHOR]

Assisted by laser ablation (LA) inductively coupled plasma mass spectrometry (ICPMS) analytical techniques, calcite is now accepted as an important U–Pb dating mineral for application to various issues in geology. However, appropriate calcite reference materials with homogeneous composition and structure remain lacking due to limited research work on such reference materials. This study successfully identifies a new natural megacryst calcite reference material, TARIM, for in situ U–Pb isotope measurement by LA-ICPMS analysis. Electronic probe microanalysis (EPMA) shows TARIM to be a homogenous low-Mg calcite. LA-ICPMS trace elemental analyses and mapping results suggest that TARIM is relatively homogenous with U content (mean value = 0.48 μg g−1) appropriate for U–Pb isotopic dating. U–Pb analysis using isotope dilution-thermal ionization mass spectrometry methods (ID-TIMS) yielded a lower intercept age of 208.5 ± 0.6 Ma (2S, mean squared weighted deviation (MSWD) = 1.04). A total of 515 LA-ICPMS U–Pb isotope analyses on random calcite pieces show consistent ages with a lower intercept age of 208.0 ± 0.4/3.2 Ma (2S, MSWD = 3.0), overlapping with the ID-TIMS age. We propose that TARIM calcite can be applied as a reference material for matrix-matched calibration or as a monitoring standard for calcite LA-ICPMS U–Pb dating. [ABSTRACT FROM AUTHOR]

New zircon reference materials for in situ zircon radiogenic Hf isotope and stable Zr isotopic determinations made by laser ablation multi‐collector inductively coupled plasma‐mass spectrometry (LA‐MC‐ICP‐MS) are required due to high data productivity and consequently high reference material consumption rate. This study examines a new natural zircon for Zr isotope ratios by double spike thermal ionisation mass spectrometry (TIMS), and for Hf isotopes by bulk solution nebuliser (SN)‐MC‐ICP‐MS with both Zr and Hf determined by LA‐MC‐ICP‐MS. A total of five zirconium isotope measurements from drilled zircons, determined by TIMS, yield a mean δ94/90ZrIPGP‐Zr value of ‐0.09 ± 0.06‰ (2s). Five and eight hafnium isotope measurements for powders from the drilled zircons and Ban‐1‐4 by SN‐MC‐ICP‐MS, yield mean 176Hf/177Hf ratios of 0.282985 ± 0.000011 (2s) and 0.282982 ± 0.000007 (2s), respectively. The mean δ94/90ZrIPGP‐Zr value and 176Hf/177Hf ratio determined by LA‐MC‐ICP‐MS analyses are ‐0.06 ± 0.09‰ (2s, n = 504) and 0.282985 ± 0.000035 (2s, n = 327), respectively. The isotopic homogeneities suggest that the Ban‐1 zircon is a suitable reference material for microbeam Zr and Hf isotopic measurements. [ABSTRACT FROM AUTHOR]