Expanding Limits of Laser-Ablation U-Pb Calcite Geochronology

U-Pb geochronology of calcite by laser-ablation inductively-coupled mass spectrometry (LA-ICMPS) is an emerging field with potential to solve a vast array of geologic problems. Because of low levels of U and Pb, measurement by more sensitive instruments, such as those with multiple collectors (MC), is advantageous. However, whereas measurement of traditional geochronometers (e.g., zircon) by MC-ICPMS has been limited by detection of the daughter isotope, U-Pb dating of calcite can be limited by detection of the parent isotope, if measured on a Faraday detector. The Nu P3D MC-ICPMS employs a new detector array to measure all isotopes of interest on Daly detectors. A new method, described herein, utilizes the low detection limit and high dynamic range of the Nu P3D for calcite U-Pb geochronology, and compares it with traditional methods. A model is created to explore the limits of U, Pb, and U/Pb ratios that can be measured by LA-ICPMS and can serve as a guide to evaluate potential candidate materials for geochronology.