Geochronology 

We developed code to automatically and semi-automatically measure dimensions of detrital mineral grains in reflected-light images saved at laser ablation–inductively coupled plasma–mass spectrometry facilities that use Chromium targeting software. Our code uses trained deep learning models to segment grain images with greater accuracy than is achievable using other segmentation techniques. We implement our code in Jupyter notebooks which can also be run online via Google Colab.

There is currently no standardized method of performing uncertainty propagation in the (U–Th) / He system, causing data interpretation difficulties. We present two methods of uncertainty propagation and describe free, open-source software (HeCalc) to apply them. Compilation of real data using only analytical uncertainty as well as 2 % and 5 % uncertainties in FT 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.

Sediment cores from the volcanic lake Holzmaar provide a very precise chronology based on tree-ring-like annual laminations or varves. We statistically combine this varve chronology with radiometric dating and tested three different methods to upgrade the age–depth model. However, only one of the three methods tested improved the dating accuracy considerably. With this work, an overview of different age integration methods is discussed and made available for increased future demands.

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.

Thermochronometric data can provide unique insights into the patterns of rock exhumation and the driving mechanisms of landscape evolution. Several well-established thermal models allow for a detailed exploration of how cooling rates evolved in a limited area or along a transect, but more regional analyses have been challenging. We present age2exhume, a thermal model that can be used to rapidly provide a synoptic overview of exhumation rates from large regional thermochronologic datasets.

This paper describes geoChronR, an R package that streamlines the process of quantifying age uncertainties, propagating uncertainties through several common analyses, and visualizing the results. In addition to describing the structure and underlying theory of the package, we present five real-world use cases that illustrate common workflows in geoChronR. geoChronR is built on the Linked PaleoData framework, is open and extensible, and we welcome feedback and contributions from the community.

Using a relatively new dating technique, in situ Rb–Sr geochronology, we constrain the ages of two generations of mineral assemblages from the Tropicana Zone, Western Australia. The first, dated at ca. 2535 Ma, is associated with exhumation of an Archean craton margin and gold mineralization. The second, dated at ca. 1210 Ma, has not been previously documented in the Tropicana Zone. It is probably associated with Stage II of the Albany–Fraser Orogeny and additional gold mineralization.

Rates of landscape evolution over the past million years are difficult to quantify. This study develops a technique which is able to measure changes in rock cooling rates (related to landscape evolution) over this timescale. The technique is based on the electron spin resonance dating of quartz minerals. Measurement protocols and new numerical models are proposed that describe these data, allowing for their translation into rock cooling rates.

The oldest known minerals on Earth are Hadean (> 4.0 Ga) zircons from the Jack Hills, Australia. We present the first application to such Hadean zircons of stepwise chemical abrasion–isotope dilution–thermal ionization mass spectrometry with trace element analysis (stepwise CA-ID-TIMS-TEA). We examine the evolution in the U–Pb age and trace element chemistry of zircon domains accessed by successive chemical abrasion steps in the context of the geologic history of the Jack Hills zircons.