Single-Pulse Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry U-Pb Dating Of Thin Zircon Rims: An Application To Metamorphic Rocks From Mount Everest, Eastern Nepal

This study describes an improved method for U-Pb dating of external zircon surfaces using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Single-pulse LA of zircons mounted in Teflon by Excimer and femtosecond lasers produced age-depth profiles with 0.1 mu m resolution. Application of this technique to samples from the Higher Himalayan Crystallines, Mount Everest region, eastern Nepal, revealed outer rims with ages of 15 +/- 1 Ma. Most of these rims were not visible on cathodoluminescence images of polished cross-sections of the grains.