Preprints  

Goethite is one of the most common Fe- (oxy)hydroxide minerals which is formed during hydrolyzation of the rocks, implying it is a desired mineral for dating various surface and subsurface geological processes. Nowadays (U-Th)/He dating of goethite is widely used in geochronological studies. Here, on the example of goethite from the Chukchi Borderland, we introduce a new simple methodological approach for accurate (U-Th)/He dating of goethite.

This paper describes how krypton isotopes produced by nuclear fission can be used to determine the age of microscopic particles of used nuclear fuel. This is potentially useful for international safeguards applications aimed at tracking and identifying nuclear materials, as well as geoscience applications involving dating post-1950's sediments or understanding environmental transport of nuclear materials.

Cosmogenic nuclide geochronology requires accurately scaling production rates with altitude. The energy spectrum of cosmic radiation changes with altitude and reactions that are sensitive to different energies may have different scaling behavior. Here, we model the altitude scaling of ³⁶Cl production from Fe and evaluate this model against calibration data. The data are broadly consistent with the prediction of larger altitude scaling factors for ³⁶Cl from Fe than for other reactions.

We present an improved workflow for extracting and measuring chlorine isotopes in rocks and minerals. Experiments on seven geologic samples demonstrate that our workflow provides reliable results while offering several distinct advantages over traditional methods. Most notably, our workflow reduces the amount of isotopically enriched chlorine spike used per rock sample by up to 95 %, which will allow researchers to analyze more samples using their existing laboratory supplies.

Cosmogenic nuclides, such as ¹⁰Be, are rare isotopes produced in rocks when exposed at Earth’s surface and are valuable for understanding surface processes and landscape evolution. However, ¹⁰Be is usually measured in quartz minerals. Here we present advances in efficiently extracting and measuring ¹⁰Be in the pyroxene mineral. These measurements expand the use of ¹⁰Be as a dating tool for new rock types and provide opportunities to understand landscape processes in areas that lack quartz.

RA138 is a new reference material for U-Pb dating of carbonate samples via LA-ICP-MS. RA138 exhibits variable U/Pb ratios and consistent U content, resulting in a precise isochron with low uncertainty. ID-TIMS analyses fix a reference age of 321.99 ± 0.65 Ma. The observed systematic uncertainty challenges previous estimates. This research advances our ability to date carbonate samples accurately, providing deeper insights into geological processes and historical timelines.

We have discovered a new way of measuring the three-dimensional distribution of radioactive elements in individual crystals by shining a very bright light on apatite crystals at the Advanced Photon Source at Argonne National Laboratory. This allows us to learn about the rates and timing of geologic processes, and to help resolve problems that previously were unsolvable because we had no way to make this type of measurement.

Establishing an etching procedure for the monazite fission track (MFT) is essential for MFT dating. In this short communication, we have investigated the parameters governing the etching rate of MFT, in particular the effect of radiation damage. Our results show an inverse relationship between MFT etching time and the degree of radiation damage. We show that existing etching recipes may not sufficiently etch MFT of young monazite, advocating the importance of a revision of etching methods.

This study demonstrates the utility of the recently developed laser ablation-based Rb-Sr geochronology methodology to investigate the rates of exhumation and burial in active mountain building systems. It is further demonstrated that additional chemical data collected during spot analyses can be used to determine temperatures recorded in biotite. The method used has advantages over traditional methods in speed, ease of acquisition and the ability to collect additional chemical information.

We introduce a new statistical method for determining the time of "peak cooling" in thermochronological inversions. Specifically, we focus on the time-temperature paths that intersect the half-maximum cooling isotherm, signifying the zenith or most rapid cooling within a defined interval. The resultant interpolated time distribution provides a systematic metric, particularly applicable for evaluating model cooling characterized by relatively smooth histories featuring a single inflection point.

This note details a development of the (U-Th)/He method for dating apatite crystals in low-temperature thermochronology. Our innovation simplifies analysis protocols for gases (He) and crystals (U, Th, etc.), aiming to expedite data production and enhance study reliability.

The age of some geological materials can be estimated from the ratio of certain radiogenic 'daughter' isotopes to their radioactive 'parent'. However, in many cases, the age estimation process is complicated by the presence of an inherited component of nonradiogenic daughter isotopes. This paper presents an improved algorithm to estimate the radiogenic and non-radiogenic components, either separately or jointly.

Decay of U to Pb in the mineral baddeleyite is used for precisely dating mafic rocks, but some daughter Pb atoms can be ejected out of the crystal, resulting in an age that appears too young. Atom Probe Tomography was used to map the distribution of U and Pb atoms in 3 dimensions within a baddeleyite crystal and estimate the average distance that Pb atoms are displaced by decay of U. This allows us to correct the measured age on a baddeleyite crystal knowing its size and shape.

We date Laurentide Ice Sheet retreat after the Last Glacial Maximum in western New York, USA. We apply radiocarbon and optically stimulated luminesce dating to glacial features. We find that ice began retreating shortly after 20 ka, but hummocky moraine stabilization is delayed until climate warming at ~15–14 ka.

We present a new data analysis workflow for thermochronological data based on plots of radiogenic daughter vs. radioactive parent concentration. The daughter-parent relationship helps to identify the sources of age variation. Our workflow classifies the daughter-parent relationship and provides further suggestions, e.g., if a dataset can be described by a sample age and which type of sample age to report.

In this study, we use cosmogenic-sourced ³He to determine the eruption ages of 23 lava flows at Mt. Ruapehu, New Zealand, and we show how this method can help overcome challenges associated with traditional dating methods in young lavas. Comparison with other methods demonstrates the accuracy of our data, and the method's reliability. The new eruption ages allowed us to identify periods of quasi-simultaneous activity from different volcanic vents during the last 20,000 years.

(U-Th)/He chronology relies on accurate measurements of zircon grain dimensions, but the systematic error and uncertainty associated with those measurements have been unquantified, until now. We build on the work of Zeigler et al. (2023) and present the zircon Geometric Correction Method, 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 present a new ¹⁰Be production rate for the mid-elevation mountain ranges of central Europe. Beryllium-10 surface exposure dating of moraines and radiocarbon dating of presumably younger lake sediments allowed for determining the accumulation rate of ¹⁰Be in the surfaces of large boulders on moraines. The accumulation of ¹⁰Be was slower at most European reference sites. The estimated rate will not only be useful for future age determinations but also for revising existing age estimates.

Radiocarbon serves as powerful dating tool, but there remain significant challenges in the calibration of marine radiocarbon dates. This is because the whole surface ocean cannot be represented by a single calibration curve. Here we use climate model outputs to assess a novel method for developing regional marine calibration curves. Our results are encouraging, particularly for the high latitude regions, and point a way forward for solving the marine radiocarbon age calibration problem.

Marine sediments are excellent archives for reconstructing past changes in climate and ocean circulation. Yet, dating uncertainties, particularly during the 20^th century, pose major challenges. Here we propose a novel chronostratigraphic approach that uses anthropogenic signals, such as the oceanic ¹³C Suess effect and spheroidal carbonaceous fly ash particles, to reduce age model uncertainties in high-resolution marine archives over the 20^th century. 

Zircon is a mineral where uranium decays to lead. Some radiation damage lets lead escape. A method called chemical abrasion (CA) dissolves out the damaged portions of zircon, so that remaining zircon retains lead. We compare ion beam analyses of untreated and chemically abraded zircons. The ion beam ages for untreated zircons match the reference values for untreated zircon. The ion beam ages for CA zircon match CA reference ages. Other elements are unaffected by the chemical abrasion process.

Carbon-14 produced in quartz provides a new tool to date exposure of bedrock surfaces. Samples from ten exposed bedrock surfaces in east central Sweden give dates consistent both with the timing of landscape emergence above sea level through postglacial rebound and retreat of the last ice sheet shown in previous reconstructions. Carbon-14 in quartz (half-life 5700 ± 30 years) can therefore be used for dating in landscapes where isotopes with longer half-lives give complex exposure results.

The `Likhall´ zircon bed helps to constrain the timing of increased meteorite bombardment of the Earth, during the Ordovician period. It is important to understand the timing of this meteorite bombardment when attempting to correlate it with biodiversity changes during the Ordovician period. Calibrating a good age for the ´Likhall´ bed is however challenging and benefited in this study from advances in sample preparation.

The mollusc Arctica islandica can survive for hundreds of years and its annual growth captures environmental conditions, so each shell provides a detailed climatic record. Dating is essential for sample selection, but radiocarbon and crossdating are time-consuming and costly. As an alternative, amino acid geochronology was investigated in the three aragonitic layers forming the shells. This study confirms the value of AAG as a method for rangefinder dating Quaternary A. islandica shells.

We demonstrate a machine learning method to estimate the temperature changes of the earth's crust over time. The method respects physical laws and conditions imposed by users. By using observed rock cooling ages as constraints, the method can be used to estimate the tectonic and landscape evolution of the earth. We show the applications of the method using a synthetic rock uplift model in 1D and an evolution model of a real mountain range in 3D.

Decay of U to Pb in the mineral baddeleyite is used for precisely dating mafic rocks, but some daughter Pb atoms can be ejected out of the crystal, resulting in an age that appears too young. Atom Probe Tomography was used to map the distribution of U and Pb atoms in 3 dimensions within a baddeleyite crystal and estimate the average distance that Pb atoms are displaced by decay of U. This allows us to correct the measured age on a baddeleyite crystal knowing its size and shape.

Sedimentary provenance utilizes the composition of sedimentary rocks to investigate the sources of sediment and the geologic processes controlling it. Common techniques struggle to track mafic igneous and metamorphic rock sources, yet rutile forms in these rock types. We use rutile from ancient sedimentary rocks in Türkiye to present a new workflow for integrating rutile U-Pb ages and chemical composition into an accurate sedimentary provenance reconstruction.

We investigate the relationship between damage trails from uranium fission in apatite and the etched tracks measured with an optical microscope. We aim to understand sampling biases and to improve etching, selection and measurement protocols. The track orientation and length, apatite and track etch rate, and effective etch time co-determine whether a track is suitable for measurement. Reliable data are attainable because the specific sample properties have but a limited effect on these factors.

As a result of increasing precision and accuracy in geochronology, interpreting complicated age spectra has become increasingly important, since individual mineral ages often do not directly date the actual geologic process of interest. Here we propose a method for estimating the age of eruption or deposition of a set of minerals dated by the U-Pb system which, in contrast to previous approaches, remains accurate even when the dated minerals have experienced loss of the daughter product Pb.

The carbonate wall deposits of the Trou du Renard Cave (France) were dated using a multimethod approach: U-Th dating by bulk dissolution of samples and ICPMS, U-Th dating by laser ablation ICPMS imaging and radiocarbon dating. The sample compositions were studied to ensure that they can give reliable ages. Ages ranging from 187.9 ± 5.3 ka and 1.4 ± 0.1 ka were found. This approach should make it possible to establish more robust chronologies of archaeological caves.

Volcanic ash layers are a common tool to synchronize records of past climate, and their estimated age relies on external dating methods. Here, we show that the chemical composition of the well-known, 12000 year-old Vedde Ash is indistinguishable with several other ash layers in Iceland that are ~1000 years younger. Therefore, chemical composition alone cannot be used to identify the Vedde Ash in sedimentary records.

The Great Unconformity represents an enormous amount of time lost from the sedimentary record. Its origin is debated, in part, due to different approaches used to interpret zircon (U–Th)/He ages. This thermochronometric system is ideal for this problem because the temperature sensitivity varies according to radiation damage. Here we explore the uncertainty associated with the radiation damage model and show how this limits our ability to resolve the origin of the Great Unconformity.

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.

Paleomagnetic data from Cascade Lake (Brooks Range, Alaska) extend the radiometric-based age model of the sedimentary sequence extending back 21 kyr. Correlated ages based on prominent features in paleomagnetic secular variations (PSV) diverge from the radiometric ages in the upper 1.6 m, by up to about 2000 years at around 4 ka. Four late Holocene cryptotephra in this section support the PSV chronology and suggest the influence of hard water or aged organic material.

Prehistoric volcanic eruptions are often dated by wiggle matching series of radiocarbon ages on tree rings to standard calibration curves, ignoring potential contamination by 'old' carbon given off by the volcano. We modeled the effects of low amounts of contamination on wiggle match dates for the 10th century Changbaishan eruption and found evidence of contamination in all. We propose a new protocol to identify the presence of contamination, and provide more secure dates for major eruptions.

The timing and duration of fluid activity within a gold deposit enables a greater understanding of how the deposit evolved and thus help future mineral exploration. This research uses high resolution dating methods to unravel the overprinting fluid activity at the Martabe gold field in Sumatra. Methods outline in this report can be applied to deposits globally.

Potassium-based geochronology, including the ⁴⁰Ar/³⁹Ar and K-Ar methods, provides critical constraints on the timing and duration of many events and processes in earth history. These methods assume that a key parameter, the fraction of potassium with a mass of 40, does not vary in some relevant materials. Some recent work has identified some variability in these materials. This work examines the effects of this variability on calculated K-Ar and ⁴⁰Ar/³⁹Ar ages.