Recent  

In situ ¹⁴C’s short half-life (5.7 ky) is unique among cosmogenic nuclides, making it sensitive to complex exposure/burial histories since 25 ka. Current extraction methods focus on quartz, but the ability to extract it from other minerals would expand applications. We developed MATLAB^® scripts to calculate in situ ¹⁴C production rates from a broad range of mineral compositions. Results confirm O, Si, Al, and Mg as key targets, but also find significant production from Na for the first time.

Deposits left behind by past glacial activity provide insight into the previous size and behavior of glaciers, and act as another line of evidence for past climate. Here we present new age control for glacial deposits in the mountains of Montana and Wyoming, United States. While some deposits indicate glacial activity within the last 2000 years, others are shown to be older than previously thought, thus redefining the extent of regional Holocene glaciation.

We constrained deposition phases of fluvial sediments (NE Belgium) over the last 1 Ma with analysis and modelling of rare isotopes accumulation within sediments, occuring in function of time and inverse function of depth. They allowed the determination of 3 superposed deposition phases and intercalated non-deposition periods of ~ 40 kyr each. These phases correspond to 20% of the sediment age, which highlights the importance to consider deposition phase when dating fluvial sediments.

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.