70-1 From micron- to mountain-scales: Advances in (U-Th)/He and U/Pb chronology unlock geological problems

Abstract:

(U-Th)/He and U/Pb chronologic methods are under continuous development. Recent advances enable dating of previously undateable minerals, provide improved spatial resolution, and enhance data throughput and the affordability of the techniques. These improvements offer increasing opportunity to tightly couple (U-Th)/He and U/Pb analyses in new and novel ways and unlock the ability to address previously-inaccessible geological problems.

Here a suite of case studies will be showcased from collaborative research in the University of Colorado Boulder Thermochronology Research and Instrumentation Lab. Our recent technique-development work has included the design and construction of a custom 4He extraction and measurement system, development of laser-ablation (LA)-(U-Th)/He methods, implementation of LA-U/Pb analyses to complement our (U-Th)/He capabilities, and analysis of unconventional minerals via whole-crystal (U-Th)/He dating. Collaborative applications include paired (U-Th)/(He-Pb) dating of kimberlitic zircon megacrysts to determine when kimberlites erupted and links (or not) with megacryst genesis, pyrite (U-Th)/He analyses to date metallogenic deposits and sedimentary units, detrital magnetite (U-Th)/He dating as a sediment provenance tool for porphyry Cu systems, hematite U/Pb dating of iron ore formation and of sandstone injectites that record Snowball Earth meltwater events, in situ (U-Th)/He analysis of oxide phases (e.g., hematite, rutile) to avoid analytical issues and acquire robust data for texturally complex samples, and detrital zircon LA-(U-Th)/(He-Pb) analyses of the classic Sierra Nevada gold-bearing gravels to understand their sources. Leveraging geological data and the sample context are crucial for interpretation of geochronologic data and for developing geologically valid thermal history models of thermochronologic results. This approach – careful analytical work at the micron-scale collaboratively integrated with geological information and other datasets at macro-scales – can yield powerful new insights into Earth history and processes.

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.