High-precision ID-TIMS U Pb geochronology of perovskite (CaTiO3) from the Ice River Complex, Southeastern British Columbia

Uranium‑lead perovskite in situ geochronology has become a cornerstone technique for determining the emplacement timing of alkaline, ultrapotassic, and silica-undersaturated igneous rocks, kimberlites, and carbonatites. Accurate in situ dates are dependent on the availability of matrix matched mineral reference materials which themselves are chemically well characterized and dated accurately to the highest possible precision. When dating perovskite to high precision, such as by isotope dilution thermal ionization mass spectrometry (ID-TIMS), appropriately accounting and correcting for the quantity and isotopic composition of Pb incorporated into the crystal upon crystallization (Pbi) is a large source of uncertainty and potential inaccuracy. Unfortunately, although ultra-high precision perovskite dates are attainable with modern mass spectrometry techniques, the accuracy of applied Pbi compositions, which can be a considerable percentage of total Pb in a crystal, has not kept pace, resulting in percent level inaccuracy on precisely measured isotopic ratios.