[SMP38-13] Single-shot laser ablation ICP-MS U-Pb dating of invisible outer-rim of zircon
Keywords:LA-ICPMS, U-Pb age, zircon, outer-rim
U-Pb dating using the above techniques was performed on the natural external surfaces of zircon crystals. Because the laser pit depth from a single shot is approximately 0.2 μm, depth profiles with five ages can be obtained over a thickness of 1 μm. Results are presented for zircons from mylonitic granite and metamorphic rocks in the Mount Everest region. The U-Pb age profiles of most of the zircons allow to distinguish a ~ 0.5 μm outer rim of 15 Ma and an inner rim of 19 Ma. The outer rims are not distinguishable in CL images of an internal cross section of the crystal. The single-shot LA technique is a major improvement for dating the metamorphic rims of zircon.
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Obayashi et al. (2017) JAAS 32, 686-691.