(U–Th) / He dating relies on proper characterization of apatite crystal dimensions so that eU concentrations and dates can be calculated accurately and precisely, but there is systematic error and uncertainty in geometric measurements. By comparing 2D microscopy to true 3D measurements, we present a simple solution to correcting the error and quantifying the geometric uncertainty in eU and dates. Including this geometric correction and uncertainty matters for data evaluation and interpretation.

We apply quartz ³He paleothermometry along two deglaciation profiles in the European Alps to reconstruct temperature evolution since the Last Glacial Maximum. We observe a ³He thermal signal clearly colder than today in all bedrock surface samples exposed prior the Holocene. Current uncertainties in ³He diffusion kinetics do not permit distinguishing if this signal results from Late Pleistocene ambient temperature changes or from recent ground temperature variation due to permafrost degradation.

Apatite helium thermochronology is a method that dates the time at which a rock (and the apatite crystals contained within) cooled below a certain temperature by measuring radioactive parent isotopes (uranium and thorium) and daughter isotopes (helium). This paper proposes a revision to a commonly used calculation that corrects raw data to account for instances when the analyzed apatite crystals are fragmented. It demonstrates the improved accuracy and precision of the proposed revision.

Noble gases are largely excluded from minerals during rock formation, but they are produced by certain radioactive decay schemes and trapped in mineral lattices. However, they are present in the atmosphere, which means that they can be adsorbed or trapped by physical processes. We present details of a troublesome trapping mechanism for helium during sample crushing and show when it can be ignored and how it can be easily avoided during common laboratory procedures.

Multi-thermochronometry, in which methods such as (U-Th)/He dating of zircon and apatite and apatite fission track dating are combined, is used to reconstruct rock thermal histories. Our ability to reconstruct thermal histories and interpret the geological significance of measured ages requires modeling. Here we use forward models to explore effects of grain size and chemistry on cooling ages and closure temperatures for the (U-Th)/He decay systems in apatite and zircon.