Geochronology 

Apatite and zircon (U–Th) / He thermochronology is now a mainstream tool to reconstruct Earth's evolution through the history of cooling and exhumation over the first dozen kilometers. The geological implications of these data rely on the precision of measurements of He, U, Th, and Sm contents in crystals. This technical note documents the methods for He thermochronology developed at the GEOPS laboratory, Paris-Saclay University, that allow (U–Th) / He data to be obtained with precision.

Distinguishing between different dolomitization processes is challenging yet critical for resolving some of the issues and ambiguities related to the formation of dolomitic rocks. Accurate U–Pb absolute dating of dolomite by LA-ICP-MS could contribute to a better understanding of the dolomitization process by placing syngenetic, early diagenetic, and/or epigenetic events in the proper geological context.

We generated a synthetic dataset applying published kinetic models and distinct annealing kinetics for the apatite fission track and (U–Th)/He methods using a predetermined thermal history. We then tested how well the true thermal history could be recovered under different data interpretation schemes and geologic constraint assumptions using the Bayesian QTQt software. Our results demonstrate that multikinetic data increase time–temperature resolution and can constrain complex thermal histories.

Our contribution enhances the infrared radiofluorescence dating technique, used to determine the last sunlight exposure of potassium feldspars in a range of about 600 to 600 000 years backwards. We recorded radiofluorescence images of fine sands and processed them with tailored open-source software to obtain ages from single grains. Finally, we tested our new method successfully on two natural sediment samples. Studies in Earth science will benefit from improved age accuracy and new insights.

High-resolution geochronology is one of the key factors to predict volcanic eruptions. To build up a high-resolution geochronological framework, we reported 21 new high-precision eruption ages (⁴⁰Ar / ³⁹Ar) for a ~ 3.3 × 10⁶-year-old volcanic field: Milos (Greece). In combination with geochemical information and eruption volumes from the volcanoes of Milos, the long-lived volcanic history could provide important clues for the prediction of volcanic eruptions.

We carried out thermal annealing experiments between 500 and 1000 °C to determine the closure temperature of radiation-damage annealing in zircon (ZrSiO₄). Our results show that the different Raman bands of zircon respond differently to annealing. The repair is highest for the external rotation Raman band near 356.6 cm⁻¹. The closure temperature estimates range from 250 to 370 °C for different bands. The differences in closure temperatures offer the prospect of multi-T zircon Raman dating.

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.