
Sebastian KreutzerHeidelberg University · Institute of Geography
Sebastian Kreutzer
Dr. rer. nat.
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125
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Introduction
I am a geographer, geochronologist and data scientist. In a broader perspective, as a geographer, I am interested in recognition of rapid landscape changes during the last 2.3 million years, for example, on aeolian sediment sequences. To achieve this aim, I am working with a method called 'luminescence dating', which I am steadily trying to advance to obtain more accurate and precise ages. A crucial part of my daily work is data analysis and modelling. My language is R.
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Publications
Publications (125)
Measuring the infrared radiofluorescence (IR-RF) signal of K-feldspars, which is thought to be not affected by any anomalous fading potentially provides a promising alternative dating approach to the more studied IR and pIRIR signals. Here we report a series of experiments aimed at characterising the IR-RF signal, which led us to propose an improve...
Abstract Modelling (natural) quartz luminescence (TL/OSL) phenomena appears to be quite common nowadays. The corresponding simulations are capable of giving valuable insights into the charge transport system. By contrast, simulating radiofluorescence (RF) of quartz has rather been neglected in the past. Here we present and discuss (1) the RF signal...
A proper understanding of local palaeoenvironmental histories is an iterative process. Previously settled interpretations suddenly demand a reconsideration triggered by findings from sites not accessible before. The coastline of the Médoc area in South-West France faced considerable recent erosion, providing new valuable insights into the history o...
Luminescence dating methods on natural minerals such as quartz and feldspars are indispensable for establishing chronologies in Quaternary Science. Commonly applied sediment dating methods are optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). In 1999, Trautmann et al. (1999a, b) proposed a new related technique ca...
In nature, each mineral grain (quartz or feldspar) receives a dose rate (Dr) specific to its environment. The dose-rate distribution therefore reflects the micro-dosimetric context of grains of similar size. If all the grains were well bleached at deposition, this distribution is assumed to correspond, within uncertainties, with the distribution of...
Luminescence dating plays a pivotal role in Quaternary science, yet ongoing methodological challenges persist in refining the temporal range, accuracy, and precision of luminescence methods. Our contribution revisits zircons as potential alternative dosimeters to quartz, feldspar, or calcite for routine dating applications. The essential advantage...
The accurate and precise determination of the environmental dose rate is pivotal in every trapped-charge dating study. The environmental gamma-dose rate component can be determined from radionuclide concentrations using conversion factors or directly measured in situ with passive or active detectors. In-field measurements with an active detector ar...
Spectroscopic investigations provide important insights into the composition of luminescence emissions relevant to trapped-charge dating of sediments. Accurate wavelength calibration and a correction for the wavelength-dependent detection efficiency of the spectrometer system are crucial to ensure the correct spectrum interpretation and allow for i...
Luminescence dating plays a pivotal role in Quaternary science, yet ongoing methodological challenges persist in refining the temporal range, accuracy, and precision of luminescence methods. Our contribution revisits zircons as potential alternative dosimeters to quartz, feldspar, or calcite for routine dating applications. The essential advantage...
During ionizing irradiation, potassium (K)-rich feldspar grains emit infrared (IR) light, which is used for infrared radiofluorescence (IR-RF) dating. The late-saturating IR-RF emission centred at ∼880 nm represents a promising tool to date Quaternary sediments. In the present work, we report the presence of individual grains in the K-feldspar dens...
Loess–palaeosol sequences (LPSs) are important archives of landscape evolution, recording alternating periods of geomorphic activity (dust deposition and slope processes) and landscape stability (soil formation). LPSs of the Rhône Rift Valley are located along a spatial climatic gradient from the mid-latitudes to the Mediterranean region. This posi...
During the Last Glacial Period, the climate shift to cold conditions associated with changes in atmospheric circulation and vegetation cover resulted in the development of large aeolian systems in Europe. On a regional scale, many factors may have influenced dust dynamics, such as the latitudinal difference between the various aeolian systems and t...
BayLum' is an R-package that facilitates the application of Bayesian models to the field of OSL dating. Here we present two recent feature updates to 'BayLum', significantly reducing computation time and improving general use. The first feature allows users to parallelize the computations involved in the MCMC sampling of values, while the second in...
During ionising irradiation, potassium (K)-rich feldspar grains emit infrared (IR) light, which is used for infrared-radiofluorescence (IR-RF) dating. The late-saturating IR-RF emission centred at ~880 nm represents a promising tool to date Quaternary sediments. However, in the present work, we report the presence of individual grains of K-feldspar...
The concept of open data has become the modern science meme, and major funding bodies and publishers support open data. On a daily basis, however, the open data mandate frequently encounters technical obstacles, such as a lack of a suitable data format for data sharing and long-term data preservation. Such issues are often community-specific and be...
During the last glacial period, the climate shift to cold conditions associated with changes in atmospheric circulation and vegetation cover resulted in the development of large aeolian systems in Europe. On a regional scale, many factors may have influenced dust dynamics, such as the latitudinal difference between the various aeolian systems and t...
Colorimetric measurements are valuable in studying paleoenvironmental changes in sediment archives such as loess-paleosol sequences. These measurements allow for the identification of climate-sensitive minerals such as hematite, goethite, and secondary carbonates, as well as the observation of stratigraphic changes influenced by paleoclimate variat...
Open data has become the modern science meme, and major funding bodies and publishers support open data. On a daily basis, however, the open data mandate frequently encounters technical obstacles, such as a lack of a suitable data format for data sharing and long-term data preservation. Such issue is often community-specific and best addressed thro...
Spectroscopic investigations provide important insights into the composition of luminescence emissions relevant to trapped-charge dating of sediments. Accurate wavelength calibration and a correction for the wavelength-dependent detection efficiency of the spectrometer system are crucial to ensure the correct spectrum interpretation and allow for i...
Enhance and visualise stratigraphic colour profiles and decipher hidden features in loess-palaeosol records.
Infrared radiofluorescence (IR-RF) of K-feldspar is a luminescence dating method proposed for chronologies of older sediments in Quaternary science. Its key advantages are higher saturation doses than optically stimulated quartz luminescence and long-term stability (no fading). However, while successful dating applications using IR-RF seem to becom...
Further developments in luminescence dating, dosimetry and temperature-sensing require a deep understanding of luminescence processes and their driving parameters. Natural quartz is one of the most widely used minerals for these purposes, but poor reproducibility of results often hampers comparability and credibility from findings in the literature...
Past environmental information is typically inferred from proxy data contained in accretionary sediments. The validity of proxy data and analysis workflows are usually assumed implicitly, with systematic tests and uncertainty estimates restricted to modern analogue studies or reduced-complexity case studies. However, a more generic and consistent a...
Infrared Radiofluorescence (IR-RF) is a relatively new method for dosimetric dating of the depositional timing of sediments. This contribution presents an interlaboratory comparison of IR-RF measurements of sedimentary feldspar from eight laboratories. A comparison of the variability of instrumental background, bleaching, saturation, and initial ri...
The majority of palaeoenvironmental information is inferred from proxy data contained in accretionary sediments, called geo-archives. The validity of proxy data and analysis workflows are usually assumed implicitly, with systematic tests and uncertainty estimates restricted to modern analogue studies or reduced-complexity case studies. However, a m...
In nature, any mineral grain (quartz or feldspar) receives a dose-rate (Dr) specific to its environment. The dose-rate distributions, therefore, reflect the micro-dosimetric context of grains of similar size. If all the grains have been well bleached at deposition, this distribution corresponds, within uncertainties, to the distribution of equivale...
The dose rate of the 90Sr / 90Y beta source used in most luminescence readers is a laboratory key parameter. There is a well-established body of knowledge about parameters controlling accuracy and precision of the calibration value but some hard-to-explain inconsistencies still exist. Here, we have investigated the impact of grain size, aliquot siz...
Abstract Luminescence phenomena of insulators and semiconductors (e.g., natural minerals such as quartz) have various application domains. For instance, Earth Sciences and archaeology exploit luminescence as a dating method. Herein, we present the R package RLumCarlo implementing sets of luminescence models to be simulated with Monte Carlo (MC) met...
During the Last Interglacial-Early Glacial transition (MIS5-MIS4; ~73 ka), substantial hydroclimatic changes affected morphogenetic processes, landform dynamics, and ecosystem variability over the Mediterranean sub-alpine valleys. This transition is mainly preserved in the northern Mediterranean region in continuous marine, lacustrine, and peat bog...
The success of luminescence dating as a chronological tool in Quaternary science builds upon innovative methodological approaches, providing new insights into past landscapes. Infrared radiofluorescence (IR-RF) on K-feldspar is such an innovative method that was already introduced two decades ago. IR-RF promises considerable extended temporal range...
Statistical analysis has become increasingly important in optically stimulated luminescence (OSL) dating since it has become possible to measure signals at the single-grain scale. The accuracy of large chronological datasets can benefit from the inclusion, in chronological modelling, of stratigraphic constraints and shared systematic errors. Recent...
The La Combette rock-shelter, located in the Luberon mountains (Southern France), is an essential local archaeological discovery. The site comprises several Palaeolithic layers suggesting multiple phases of Mousterian occupation. The sediment sequence of c. 7 m thickness indicates rapid changes in the environmental conditions, which led to an aband...
Kinetic models have been used extensively for modeling and numerical simulation of luminescence phenomena and dating techniques, for various dosimetric materials. Several comprehensive models have been implemented for quartz, which allow simulation of complex sequences of irradiation and thermal/optical events in nature and in the laboratory. In th...
The success of luminescence dating as a chronological tool in Quaternary science builds upon innovative methodological approaches, providing new insights into past landscapes. Infrared radiofluorescence (IR-RF) on K-feldspar is such an innovative method already introduced two decades ago. IR-RF promises considerable extended temporal range and a si...
Statistical analysis has become increasingly important in the field of OSL dating since it has become possible to measure signals at the single grain scale. The accuracy of large chronological datasets can benefit from the inclusion, in chronological modelling, of stratigraphic constraints and shared systematic errors. Recently, a number of Bayesia...
The purpose of this study is to better understand the system of Quaternary loess-palaeosol sequences (LPS) of the Matmata region in southern Tunisia. Results from a combination of predominantly classical methods (grain size and mineral analysis, CaCO3- content estimation, environmental magnetism) indicate strong soil formation phases during which t...
The dose rate of the 90Sr / 90Y beta source used in most luminescence readers is a laboratory key parameter. There is a well-established body of knowledge about parameters controlling accuracy and precision of the calibration value but some hard to explain inconsistencies still exist. Here we have investigated the impact of grain size, aliquot size...
A sedimentological and chronostratigraphical investigation was carried out on two loess sections located in the Mediterranean area in southeast France along the Rhône River (Lautagne) and the lower reach of a tributary of the Rho^ne River (Collias). High-resolution sampling (5–20 cm) for magnetic susceptibility, grain size distribution (including n...
We present additional experiments for alpha-Al2O3:C chips used to estimate in situ g-dose rates. Our contribution supplements the article by Kreutzer et al. (2018) and presents results from previously announced follow-up experiments. (1) We investigate the divergent g-dose rate results we obtained from cross-check experiments for one reference site...
Our multinational project enriches the reconstruction of paleoenvironmental conditions in central northern Africa with a further aspect. The number of artifacts found suggests the presence of humans in this region during the more humid soil formation phases. The next step will be to increase the sample size of archeological material during future fi...
Bayesian inference has been applied extensively to chronologies in archaeological science since it provides several advantages over the (classic) frequentist approach. One of the most important aspects of applying Bayesian methods is their capacity to consider the stratigraphic relationship in the final ages. More specifically, in luminescence dati...
Abstract. Feldspar, used for infrared stimulated luminescence (IRSL) dating, is known as a dosimeter which might not completely retain the environmental dose over time, therefore leading to age underestimation. The dose leakage is believed to be caused by non-thermal (anomalous) charge redistribution in the crystal and reflected in an IRSL signal w...
Phenomenological models are frequently used to analyze experimental signals in thermally and optically stimulated luminescence experiments. Typically, these models consist of systems of differential equations describing various electronic transitions. An alternative to the differential equation approach is the use of Monte Carlo (MC) methods, which...
Geochemical conditions (e.g., pH-value, temperature , availability of CO 2) in carbonate-rich sedimentary environments lead to cementation processes, i.e., air or water in the pore space are substituted by mineral phases. Consequently, in such environments the conventional formalism of estimating the environmental dose rate from U, Th and K concent...
The calibration of any artificial-source attached to a luminescence reader is fundamental for the accuracy of luminescence dating results. Here, we present calibration results obtained for a-source attached to a single grain Risø reader in Bordeaux using a series of quartz of different origins. The quartz was irradiated with three different-irradia...
Time-resolved optically stimulated luminescence (TR-OSL) is one of the few methods to characterise the type of recombination centre involved in luminescence production and its response to thermal, optical and irradiation treatments. TR-OSL experiments for natural quartz yielded lifetimes mainly in the range 30–45 μs, often supplemented by shorter o...
Pleistocene deposits exposed along the coast of the Médoc area, south‑west France, represent valuable palaeoenvironmental archives that have been the subject of extensive work in the past few decades. To further understand the palaeoenvironmental history and sedimentary dynamics of these deposits, a detailed lithostratigraphic study was performed o...
The Rhône Graben in south-eastern France stretches from 45°5’ N at the confluence of the Saône River southward to 43°2’ N at the Rhône delta on the Mediterranean coast. At present, the climatic conditions along this north-to-south transect represent a gradient from a humid-temperate to a Mediterranean climate. Mean annual temperature (MAT) increase...
Between 2012 and 2015, five successive archaeological campaigns were led by the Department of archaeology of Eure-et-Loir, on the Illiers-Combray plateau, 1 km to the east of the river Loir. Middle Palaeolithic remains were discovered in a Pleistocene loess-palaeosoils sequence, extending over an area of more than 10 km^2. This Early Weichselian si...
Between 2012 and 2015, five successive archaeological campaigns were led by the Department of archaeology of Eure-et-Loir, on the Illiers-Combray plateau, 1 km to the east of the river Loir. Middle Palaeolithic remains were discovered in a Pleistocene loess-palaeosoils sequence, extending over an area of more than 10 km ² . This Early Weichselian s...
This paper presents Monte Carlo simulations of tunneling recombination in random distributions of defects. Simulations are carried out for four common luminescence phenomena in solids exhibiting tunneling recombination, namely continuous wave infrared stimulated luminescence (CW-IRSL), thermoluminescence (TL), isothermal thermoluminescence (iso-TL)...
The pre-dose effect is one of the most well-known phenomena in quartz luminescence. It refers to an increase in dose sensitivity subsequent to radiation pre-exposure and annealing. A theoretical description of this phenomenon exists since the 1970s and is widely used in recent luminescence models. However, also the opposite effect has been describe...
In the Rhône Valley, a north-south oriented Cenozoic rift in southeast France, thick Pleistocene loess deposits have been recognized since the beginning of the last century. These loess records, which are disconnected from the North European Loess Belt (NELB), are of significant interest to document the evolution of perimediterranean landscapes and...
We introduce a new R package ‘BayLum’ devoted to the analysis of OSL data and to construct chronological models in a Bayesian framework. Our contribution presents a summary of the statistical models, and introduces the main functions implemented in the package.
Infrared radiofluorescence (IR-RF) of K-feldspar is an alternative luminescence dating approach to infrared luminescence (IRSL). The application of IR-RF on coarse grain K-feldspar untreated with HF requires knowledge of the IR-RF α-efficiency. We present IR-RF α-efficiency measurements performed on four natural fine grain (4–11 μm) K-feldspar samp...
We discuss the dose recovery behaviour IR-RF from K-rich feldspar extracts from modern-analogue sediment samples. The zero-dose of these samples was previously confirmed by quartz OSL and feldspar IRSL measurements. In our experiments, the IR-RF curve (RFnat) from the naturally bleached sample was taken as a regenerated curve within dose recovery e...
Kinetic models of quartz luminescence have gained an important role for predicting experimental results and for better understanding charge transfers in (natural) quartz. Mathematically, the models comprise a set of several ordinary coupled first-order differential equations (ODEs), which describe the evolution of electron and hole populations on t...
Thermal quenching is a well-known phenomenon in quartz, which describes the decrease in luminescence efficiency (light output) with sample temperature. In the present work, the UV radiofluorescence (RF) signals of three different quartz samples during cooling from 500 °C to room temperature were monitored and analysed. Resulting thermal quenching p...
The general behaviour of the main UV emission during radiofluorescence (RF) in natural quartz with dose rates ranging from 10 to 500 mGy s⁻¹ is analysed. RF emission spectra were recorded and deconvolved to extract information on the C band, which is often the main emission of quartz annealed at a temperature close to 500 °C. Our results confirmed...
In situ dosimetry (active, passive dosimeters) provides high accuracy by determining environmental dose rates directly in the field. Passive dosimeters, such as α-Al2O3:C, are of particular interest for sites with desired minimum disturbance (e.g., archaeological sites). Here, we present a comprehensive approach obtaining the environmental cosmic a...
Knowledge of the kinetic parameters E (thermal activation energy) and s (frequency factor) of charge-trapping defects in the quartz crystal lattice is of paramount importance to assessing the thermal stability of associated luminescence signals used for dosimetry and dating. Since methods proposed for constraining thermoluminescence (TL) kinetics u...
Age-depth-relationships are essential to understand expressions of Earth history. Age-depth-relationships reveal the environmental significance of (terrestrial) sediment deposits and relate them to other paleoenvironmental archives. Although luminescence-based ages are of paramount importance, their incorporation in age-depth- models is limited due...
Fundamental studies on luminescence production in natural quartz require samples which can be studied by groups of laboratories using complementary methods. In the framework of a European collaboration studying quartz luminescence, a sample originating from the Fontainebleau Sandstone Formation in France was selected for characterisation and distri...
The relevance of luminescence dating is re- flected by the steadily growing quantity of published data. At the same time, the amount of data available for analysis has increased due to technological and methodological advances. Routinely, luminescence data are analysed using a mixture of commercially available soft- ware, self-written tools and spe...
Luminescence ages were obtained from six sediment samples at the archaeological site ‘Le Rozel’. These samples are associated with hundreds of footprints left by humans (probably Neanderthals) in the archaeological layers. The single-grain technique was applied to 200–250 μm quartz grains, whereas K-feldspar grains were measured using the multi-gra...