Recent  

There is currently no standardized method of performing uncertainty propagation in the (U-Th)/He system, causing difficulties in data interpretation. We present two methods of uncertainty propagation and describe a free, open-source software (HeCalc) to apply these methods. A compilation of real data using only analytical uncertainty, and 2 % and 5 % uncertainties in F_T yields respective median relative date uncertainties of 2.9 %, 3.3 % and 5.0 % for apatites and 1.7 %, 3.3 % and 5.0 % for zircons.

We developed code to automatically and semi-automatically measure dimensions of detrital mineral grains in reflected light images saved at LA-ICP-MS facilities that use Chromium targeting software. Our code uses trained deep learning models to segment grain-images with greater accuracy than is possible using other image segmentation techniques. We implement our code in user-accessible, ready-to-run Google Colab notebooks, links to which can be found at https://github.com/MCSitar/colab_zirc_dims.

Apatite helium thermochronology is a method used for dating 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.

We proposed a new non-destructive mineralogical methodology on inframilimetric grains that allows to quantify the hematite and goethite content and hematite/goethite ratio of grains prior to (U-Th)/He geochronological analysis. (U-Th)/He data performed on different aliquots with different acquisition time shows no remarkable differences in age, opening a new way to investigate the (U-Th)/He data evolution in supergene lateritic duricrusts.

The U-Pb dating by in situ laser ablation mass spectrometry (LA-ICPMS) technique requires reference materials of the same nature as the samples to be analysed. Here, we have explored the suitability of using carbonate materials as reference for sulfates, since there is no sulfate reference material. The results we obtained are satisfactory and thus, from now on, the sulfates can also be analysed.

Cryogenic cave carbonates (CCCs) provide a marker for past permafrost conditions. Their formation age is determined by ²³⁰Th/U dating. However, samples can be contaminated with small amounts of ²³⁰Th at formation, which can cause inaccurate ages and requires correction. We analysed multiple CCCs and found that varying degrees of contamination can cause an apparent spread of ages, when really all samples formed within a single freezing event. A statistical correction method is presented.

Advancements in technology allow for new techniques to date rocks quicker, cheaper, and with little sample preparation. A unique use of this method is to date carbon-rich siltstones and constrain when these rocks were first deposited. This approach can also time when these sequences are subsequently affected by heat or fluids after they were deposited. This is useful, as the formation of metal-bearing fluids or petroleum source rocks is commonly associated with such processes.

Apatite and zircon are the most widely used minerals for dating rocks, but they can be difficult to identify in crushed rock samples. Incorrect mineral identification results in wasted analytical resources and inaccurate data. We show how X-ray computed tomography can be used to rapidly and accurately distinguish apatite from zircon based on density variations, and provide non-destructive 3D grain-specific size, shape, and inclusion information for improved data quality.

Cosmogenic nuclides are a tool to quantify denudation – the total removal of mass from near the Earth's surface. Chemical weathering can introduce biases to cosmogenic nuclide based denudation rates measurements. Here, we investigate the effects of weathering on cosmogenic nuclides and develop tools to correct for this influence. Our results highlight which additional measurements are required to determine accurate denudation rates in regions where weathering is not negligable.

Secondary Ion Mass Spectrometer (SIMS) is the oldest and most sensitive analytical technique for in-situ U-Pb geochronology. This paper introduces a new algorithm for SIMS data reduction that treats the data as 'compositional data', which means that the relative abundances of ²⁰⁴Pb, ²⁰⁶Pb, ²⁰⁷Pb and ²³⁸Pb are processed within a tetrahedral data space or 'simplex'. The new method is implemented in an eponymous computer program that is compatible with the two dominant types of SIMS instruments.

Chemical weathering alters the chemical composition of mineral grains, and it follows that luminescence dating signals may also be progressively modified. We artificially weathered feldspar samples under different chemical conditions to understand the effect of feldspar partial dissolution on their luminescence properties. Only minor changes were observed on luminescence dating properties, implying that chemical alteration of feldspar surfaces may not affect luminescence dating signals.