Laser ablation multi-collector mass spectrometry (LA-MC-ICP-MS) has emerged as the technique of c... more Laser ablation multi-collector mass spectrometry (LA-MC-ICP-MS) has emerged as the technique of choice for in situ measurements of Sr isotopes in geological minerals. However, the method poses analytical challenges and there is no widely adopted standardised approach to collecting these data or correcting the numerous potential isobaric inferences. Here, we outline practical analytical procedures and data reduction strategies to help establish a consistent framework for collecting and correcting Sr isotope measurements in geological materials by LA-MC-ICP-MS. We characterise a new set of plagioclase reference materials, which are available for distribution to the community, and present a new data reduction scheme for the Iolite software package to correct isobaric interferences for different materials and analytical conditions. Our tests show that a combination of Kr-baseline subtraction, Rb-peakstripping using βRb derived from a bracketing glass standard, and a CaCa/CaAr correction...
<p>The end-Triassic mass extinction (ETME; c. 201.6 Ma), one of the so-called &... more <p>The end-Triassic mass extinction (ETME; c. 201.6 Ma), one of the so-called “big-five” mass extinctions in the Phanerozoic era, is associated with widespread marine anoxia, ocean acidification, global warming, carbon cycle perturbations (δ<sup>13</sup>C) and an extinction of diverse marine and terrestrial groups. This extinction is frequently linked to the volcanic activity in the Central Atlantic Magmatic Province (CAMP) which is often cited to explain e.g., the correlative negative carbon excursions across many sections, mutagenesis of land plants by Hg-toxicity, and enrichment of Hg/TOC. Despite this, the exact identification of a volcanic signal in many of these sections is not well constrained. In this study we present high-precision platinum group element (PGE: Ir, Ru, Pt, Pd) and Re data for the Triassic-Jurassic boundary succession at the Kuhjoch section (Austria). These are the first results from our new analytical setup using high-pressure asher digestion, isotope dilution and multi-collector inductively-coupled plasma mass spectrometry for precise determination in low concentration (e.g. ppt) samples such as sediments. The PGE and Re concentrations and patterns vary significantly with stratigraphy. The c. 13 m of clayey sediments above the onset of the extinction (marked by the c. 16 cm thick T-bed) show pronounced enrichment in Pt, Pd and Ir concentrations relative to the under- and overlying carbonate dominated stratigraphy. Their PGE patterns are non-chondritic with Pd/Ir and Pt/Ir similar to CAMP basalts. Normalised for lithology (Al<sub>2</sub>O<sub>3</sub>), however, there are no significant variations in Pt, Pd and Ir values below, within and above the clayey sediments. Re and Ru are, however, depleted compared to the other PGEs in the clayey interval, something also observed in some CAMP basalts. One possibility is therefore to interpret the PGE-rich, clayey sediments, including the main extinction interval in the basal portion, as recording increased weathering of CAMP basalts. As the PGE enrichment increases up through the T-bed, this could show that the onset of CAMP weathering and mass extinction would have therefore coincided. However, further work is needed to identify the relative role of CAMP volatile emission during volcanic activity versus post-eruption weathering of basalts.</p>
ABSTRACT We describe the most magmatically evolved depleted shergottite yet discovered. It is the... more ABSTRACT We describe the most magmatically evolved depleted shergottite yet discovered. It is the first known specimen containing maskelynite phenocrysts but apparently lacks phosphates.
NORTHWEST AFRICA 8679. K. T. Tait, A. J. Irving, R. I. Nicklin, J. M. D. Day, R. Andreasen, S. M.... more NORTHWEST AFRICA 8679. K. T. Tait, A. J. Irving, R. I. Nicklin, J. M. D. Day, R. Andreasen, S. M. Kuehner, K. Ziegler, T. J. Lapen and D. A. Gregory Royal Ontario Museum, Toronto, Canada (ktait@rom.on.ca), Dept. of Earth & Space Sciences, University of Washington, Seattle, WA, USA, Scripps Institution of Oceanography, La Jolla, CA 92093-0244, USA, Dept. of Earth & Atmospheric Sciences, University of Houston, Houston, TX, USA. Institute of Meteoritics, University of New Mexico, Albuquerque, NM, USA,
The defining characteristic of type B1 CAIs is a large (.5- 3mm) concentric melilite mantle [1]. ... more The defining characteristic of type B1 CAIs is a large (.5- 3mm) concentric melilite mantle [1]. In [2] we presented two isochrons from separate traverses across the melilite mantle of Allende EK 459-5-1. The primary petrographic differences between the traverses was the preservation of strong oscillatory zoning. The traverse that crossed the distinctive oscillatory zone produced a pristine internal isochron, while the other that did not have a strongly preserved oscillatory zone produced a disturbed isochron indicated by more scatter (higher MSWD) and a positive (delta)26Mg* intercept. The implication simply being that the oscillatory zone may represent varying conditions during the mantle formation event. We targeted a similar texture in Allende 5241 using the same methodology in an attempt to achieve similar results.
Agricultural liming severely affects the use of strontium isotopes in prehistoric provenance and ... more Agricultural liming severely affects the use of strontium isotopes in prehistoric provenance and migration studies.
The use of strontium isotopes in pre-historic mobility studies requires accurate isoscapes for ev... more The use of strontium isotopes in pre-historic mobility studies requires accurate isoscapes for evaluating whether pre-historic individuals are local to the areas in which they were buried or not. Isoscapes are often based on modern-day samples, commonly surface waters. There is, however, growing evidence that modern-day farming has a significant impact on the strontium isotopic composition of surface waters and farmed soils, mainly due to the use of agricultural lime for soil improvement. In this paper, we investigate the fate of strontium from agricultural lime in an experimentally-manipulated field in central Jutland, Denmark. Agricultural limestone was added to this field at very high rates in 2012 and 2013 to investigate CO2 storage in soils. Strontium was first measured from the site in 2014. In 2019 we reevaluated strontium concentrations and found that 80–100% of the strontium from the agricultural lime had leached out of the organic-rich topsoil, and likely seeped into the u...
Calcium-aluminum-rich inclusions (CAIs) are a type of coarse-grained clast composed of Ca-, Al-, ... more Calcium-aluminum-rich inclusions (CAIs) are a type of coarse-grained clast composed of Ca-, Al-, and Mg-rich silicates and oxides found in chondrite meteorites. Type B (CAIs) are exclusively found in the CV chondrite meteorites and are the most well studied type of inclusion found in chondritic meteorites. Type B1 CAIs are distinguished by a nearly monomineralic rim of melilite that surrounds an interior predominantly composed of melilite, fassaite (Ti and Al-rich clinopyroxene), anorthite, and spinel with varying amounts of other minor primary and secondary phases. The formation of Type B CAIs has received considerable attention in the course of CAI research and quantitative models, experimental results and observations from Type B inclusions remain largely in disagreement. Recent experimental results and quantitative models have shown that the formation of B1 mantles could have occurred by the evaporative loss of Si and Mg during the crystallization of these objects. However, comp...
Increasingly, strontium (Sr) isotopes are used to distinguish locals and migrants in prehistoric ... more Increasingly, strontium (Sr) isotopes are used to distinguish locals and migrants in prehistoric studies, by measuring87Sr/86Sr in human remains and comparing these values to the distribution of the bioavailable87Sr/86Sr in the study area, often in surface water. However, it has recently been shown that agricultural lime can have a substantial impact on the87Sr/86Sr ratio and strontium concentration in surface water in areas where soils are low- to non-calcareous. Agricultural lime is rich in strontium with low87Sr/86Sr ratios, such that interpretations of prehistoric migration based on surface waters affected by agricultural lime often overestimate the number of migrants in a given area. However, the impact of agricultural lime was questioned in a new study, which argues that strontium derived from agricultural lime is retained in the topsoil of the fields and therefore do not contaminate the surface water. In the present study and in a companion study in this volume, we show that ...
ABSTRACT With the introduction of new generation multi-collector thermal ionization mass spectrom... more ABSTRACT With the introduction of new generation multi-collector thermal ionization mass spectrometer (TRITON) a number of studies have investigated the 142Nd isotope excesses/deficits in terrestrial and extra- terrestrial materials. A key issue is the extent to which the fractionation behavior of Nd in the ion-source affects the accuracy and the ultimate experimental precision to which the Nd isotopes can be measured using thermal ionization mass spectrometry. We investigated if there is a systematic fine structure to the observed mass dependent isotope fractionation of Nd isotopes during thermal ionization, which violates the exponential law and requires its further refinement for high precision Nd isotope data. We find that: 1. The exponential fractionation law is fully adequate in correcting for mass dependent fractionation introduced in the TIMS source at the level of precision presently obtainable. This is not the case for other fractionation laws, including the Rayleigh law. 2. Seemingly mass dependent correlations between fractionation corrected isotope ratios are correlated errors caused by counting statistics uncertainty. These correlations are not related to the fractionation behavior of the sample. 3. In the case of Nd where variations in the light isotopes 142Nd and 143Nd are of primary interest, more precise data are obtained when the isotope pairs with greater mass range (i.e., 150Nd/144Nd or 150Nd/142Nd) are used to assess fractionation factor. However, this only increases the precision with ~20%. The downside of using this normalization is an increase in the demand of the chemical purification of Nd to reduce/eliminate Sm (and Ce) interference. 4. Rreservoir mixing can introduce variations in isotope ratios as large as 50% of the external reproducibility. However, the fractionation behavior of a sample is not necessarily a good measure of the amount of mixing between reservoirs on the filament. For samples showing reverse fractionation, there appear to be mixing at the same extent before, during, and after the period of reverse fractionation. There is likely significant mixing taking place in samples showing only normal fractionation. 5. It is imperative to measure all the isotopes of Nd with the best possible precision to assess whether measured anomalies (positive or negative) in 142Nd are real or could be the product of reservoir mixing on the filament.
Introduction: The ongoing discovery of diverse Martian meteorites (now totaling about 80 unpaired... more Introduction: The ongoing discovery of diverse Martian meteorites (now totaling about 80 unpaired specimens), predominantly (>60 %) from Morocco and elsewhere in northwestern Africa, has considerably expanded our knowledge of Martian magmatic rocks. Until (and even after) an eventual sample return mission to Mars, the rocks found as meteorites on Earth will provide invaluable insights into Martian lithologic diversity. Here we describe a large ~3.7 kg shergottite find from Jrifiya, southwestern Morocco plus others found in 2014. Nd and Hf isotopic analyses for these and Northwest Africa 6963 (from Fej Arrih, Morocco) establish key characteristics of their mantle sources.
The Pb-Tl and Cd isotope systematics of ordinary chondrites RASMUS ANDREASEN*, MARIA SCHÖNBÄCHLER... more The Pb-Tl and Cd isotope systematics of ordinary chondrites RASMUS ANDREASEN*, MARIA SCHÖNBÄCHLER AND MARK REHKÄMPER IARC, Department of Earth Science and Engineering, Imperial College London, South Kensington SW7 2AZ, UK (*correspondence: r.andreasen@imperial.ac.uk) (markrehk@imperial.ac.uk) School of Earth, Atmospheric, and Environmental Science, University of Manchester, Manchester M13 9PL, UK (m.schonbachler@manchester.ac.uk)
Introduction: Northwest Africa (NWA) 4480 is a small (13 gram) unpaired shergottite recovered in ... more Introduction: Northwest Africa (NWA) 4480 is a small (13 gram) unpaired shergottite recovered in Algeria in 2006 [1]. Our earlier isotopic work revealed that NWA 4480 has Nd and Hf isotope compositions between depleted and intermediate shergottites (Figure 1)[2], despite the apparent intermediate signature of REE abundances. This is a unique composition for a shergottite. There are a few other features make this meteorite unique. First, the CRE age of ~16 Myr [2] is much older than all except for Dhofar 019 (18.15 Myr) [3]. Second, NWA 4480 has hirefringent plagioclase instead of maskelynite [2]. Together, these signatures make NWA 4480 unique among the shergottites. It will be important to investigate detailed mineralogy, mineral chemistry, and precise crystallization age in order to constrain its petrogenesis, composition of source reservoir(s), and timing of shergottite magmatic activity. Sample and Analytical Procedures: A polished section of NWA 4480 was examined by a SEM and E...
Frei’s comment Frei (2021) argues that we selected an inappropriate mass balancing method in our ... more Frei’s comment Frei (2021) argues that we selected an inappropriate mass balancing method in our paper (Andreasen and Thomsen, 2021), and that our conclusions therefore are unsupported. We maintain that our mass balance and our conclusions are sound. Our mass balance is based on well-constrained time series measurements of soil strontium content in 2014, measured just after the liming experiment in 2012–2013 and 5 years later in 2019. The field was fallow in the interim, with no anthropogenic addition of strontium and no removal through crop yield, providing an excellent opportunity to see how much of the strontium was left after 5 years. The results show that a significant amount of strontium (>3.9 g/m2) was lost from the soil, compared with the amount of strontium added during the liming experiment (3.6-4.8 g/m2) (Jessen et al., 2014), such that 80–100% of the strontium added during the liming experiment was leached from the soil over the next 5 years. By contrast, Frei’s comme...
Laser ablation multi-collector mass spectrometry (LA-MC-ICP-MS) has emerged as the technique of c... more Laser ablation multi-collector mass spectrometry (LA-MC-ICP-MS) has emerged as the technique of choice for in situ measurements of Sr isotopes in geological minerals. However, the method poses analytical challenges and there is no widely adopted standardised approach to collecting these data or correcting the numerous potential isobaric inferences. Here, we outline practical analytical procedures and data reduction strategies to help establish a consistent framework for collecting and correcting Sr isotope measurements in geological materials by LA-MC-ICP-MS. We characterise a new set of plagioclase reference materials, which are available for distribution to the community, and present a new data reduction scheme for the Iolite software package to correct isobaric interferences for different materials and analytical conditions. Our tests show that a combination of Kr-baseline subtraction, Rb-peakstripping using βRb derived from a bracketing glass standard, and a CaCa/CaAr correction...
<p>The end-Triassic mass extinction (ETME; c. 201.6 Ma), one of the so-called &... more <p>The end-Triassic mass extinction (ETME; c. 201.6 Ma), one of the so-called “big-five” mass extinctions in the Phanerozoic era, is associated with widespread marine anoxia, ocean acidification, global warming, carbon cycle perturbations (δ<sup>13</sup>C) and an extinction of diverse marine and terrestrial groups. This extinction is frequently linked to the volcanic activity in the Central Atlantic Magmatic Province (CAMP) which is often cited to explain e.g., the correlative negative carbon excursions across many sections, mutagenesis of land plants by Hg-toxicity, and enrichment of Hg/TOC. Despite this, the exact identification of a volcanic signal in many of these sections is not well constrained. In this study we present high-precision platinum group element (PGE: Ir, Ru, Pt, Pd) and Re data for the Triassic-Jurassic boundary succession at the Kuhjoch section (Austria). These are the first results from our new analytical setup using high-pressure asher digestion, isotope dilution and multi-collector inductively-coupled plasma mass spectrometry for precise determination in low concentration (e.g. ppt) samples such as sediments. The PGE and Re concentrations and patterns vary significantly with stratigraphy. The c. 13 m of clayey sediments above the onset of the extinction (marked by the c. 16 cm thick T-bed) show pronounced enrichment in Pt, Pd and Ir concentrations relative to the under- and overlying carbonate dominated stratigraphy. Their PGE patterns are non-chondritic with Pd/Ir and Pt/Ir similar to CAMP basalts. Normalised for lithology (Al<sub>2</sub>O<sub>3</sub>), however, there are no significant variations in Pt, Pd and Ir values below, within and above the clayey sediments. Re and Ru are, however, depleted compared to the other PGEs in the clayey interval, something also observed in some CAMP basalts. One possibility is therefore to interpret the PGE-rich, clayey sediments, including the main extinction interval in the basal portion, as recording increased weathering of CAMP basalts. As the PGE enrichment increases up through the T-bed, this could show that the onset of CAMP weathering and mass extinction would have therefore coincided. However, further work is needed to identify the relative role of CAMP volatile emission during volcanic activity versus post-eruption weathering of basalts.</p>
ABSTRACT We describe the most magmatically evolved depleted shergottite yet discovered. It is the... more ABSTRACT We describe the most magmatically evolved depleted shergottite yet discovered. It is the first known specimen containing maskelynite phenocrysts but apparently lacks phosphates.
NORTHWEST AFRICA 8679. K. T. Tait, A. J. Irving, R. I. Nicklin, J. M. D. Day, R. Andreasen, S. M.... more NORTHWEST AFRICA 8679. K. T. Tait, A. J. Irving, R. I. Nicklin, J. M. D. Day, R. Andreasen, S. M. Kuehner, K. Ziegler, T. J. Lapen and D. A. Gregory Royal Ontario Museum, Toronto, Canada (ktait@rom.on.ca), Dept. of Earth & Space Sciences, University of Washington, Seattle, WA, USA, Scripps Institution of Oceanography, La Jolla, CA 92093-0244, USA, Dept. of Earth & Atmospheric Sciences, University of Houston, Houston, TX, USA. Institute of Meteoritics, University of New Mexico, Albuquerque, NM, USA,
The defining characteristic of type B1 CAIs is a large (.5- 3mm) concentric melilite mantle [1]. ... more The defining characteristic of type B1 CAIs is a large (.5- 3mm) concentric melilite mantle [1]. In [2] we presented two isochrons from separate traverses across the melilite mantle of Allende EK 459-5-1. The primary petrographic differences between the traverses was the preservation of strong oscillatory zoning. The traverse that crossed the distinctive oscillatory zone produced a pristine internal isochron, while the other that did not have a strongly preserved oscillatory zone produced a disturbed isochron indicated by more scatter (higher MSWD) and a positive (delta)26Mg* intercept. The implication simply being that the oscillatory zone may represent varying conditions during the mantle formation event. We targeted a similar texture in Allende 5241 using the same methodology in an attempt to achieve similar results.
Agricultural liming severely affects the use of strontium isotopes in prehistoric provenance and ... more Agricultural liming severely affects the use of strontium isotopes in prehistoric provenance and migration studies.
The use of strontium isotopes in pre-historic mobility studies requires accurate isoscapes for ev... more The use of strontium isotopes in pre-historic mobility studies requires accurate isoscapes for evaluating whether pre-historic individuals are local to the areas in which they were buried or not. Isoscapes are often based on modern-day samples, commonly surface waters. There is, however, growing evidence that modern-day farming has a significant impact on the strontium isotopic composition of surface waters and farmed soils, mainly due to the use of agricultural lime for soil improvement. In this paper, we investigate the fate of strontium from agricultural lime in an experimentally-manipulated field in central Jutland, Denmark. Agricultural limestone was added to this field at very high rates in 2012 and 2013 to investigate CO2 storage in soils. Strontium was first measured from the site in 2014. In 2019 we reevaluated strontium concentrations and found that 80–100% of the strontium from the agricultural lime had leached out of the organic-rich topsoil, and likely seeped into the u...
Calcium-aluminum-rich inclusions (CAIs) are a type of coarse-grained clast composed of Ca-, Al-, ... more Calcium-aluminum-rich inclusions (CAIs) are a type of coarse-grained clast composed of Ca-, Al-, and Mg-rich silicates and oxides found in chondrite meteorites. Type B (CAIs) are exclusively found in the CV chondrite meteorites and are the most well studied type of inclusion found in chondritic meteorites. Type B1 CAIs are distinguished by a nearly monomineralic rim of melilite that surrounds an interior predominantly composed of melilite, fassaite (Ti and Al-rich clinopyroxene), anorthite, and spinel with varying amounts of other minor primary and secondary phases. The formation of Type B CAIs has received considerable attention in the course of CAI research and quantitative models, experimental results and observations from Type B inclusions remain largely in disagreement. Recent experimental results and quantitative models have shown that the formation of B1 mantles could have occurred by the evaporative loss of Si and Mg during the crystallization of these objects. However, comp...
Increasingly, strontium (Sr) isotopes are used to distinguish locals and migrants in prehistoric ... more Increasingly, strontium (Sr) isotopes are used to distinguish locals and migrants in prehistoric studies, by measuring87Sr/86Sr in human remains and comparing these values to the distribution of the bioavailable87Sr/86Sr in the study area, often in surface water. However, it has recently been shown that agricultural lime can have a substantial impact on the87Sr/86Sr ratio and strontium concentration in surface water in areas where soils are low- to non-calcareous. Agricultural lime is rich in strontium with low87Sr/86Sr ratios, such that interpretations of prehistoric migration based on surface waters affected by agricultural lime often overestimate the number of migrants in a given area. However, the impact of agricultural lime was questioned in a new study, which argues that strontium derived from agricultural lime is retained in the topsoil of the fields and therefore do not contaminate the surface water. In the present study and in a companion study in this volume, we show that ...
ABSTRACT With the introduction of new generation multi-collector thermal ionization mass spectrom... more ABSTRACT With the introduction of new generation multi-collector thermal ionization mass spectrometer (TRITON) a number of studies have investigated the 142Nd isotope excesses/deficits in terrestrial and extra- terrestrial materials. A key issue is the extent to which the fractionation behavior of Nd in the ion-source affects the accuracy and the ultimate experimental precision to which the Nd isotopes can be measured using thermal ionization mass spectrometry. We investigated if there is a systematic fine structure to the observed mass dependent isotope fractionation of Nd isotopes during thermal ionization, which violates the exponential law and requires its further refinement for high precision Nd isotope data. We find that: 1. The exponential fractionation law is fully adequate in correcting for mass dependent fractionation introduced in the TIMS source at the level of precision presently obtainable. This is not the case for other fractionation laws, including the Rayleigh law. 2. Seemingly mass dependent correlations between fractionation corrected isotope ratios are correlated errors caused by counting statistics uncertainty. These correlations are not related to the fractionation behavior of the sample. 3. In the case of Nd where variations in the light isotopes 142Nd and 143Nd are of primary interest, more precise data are obtained when the isotope pairs with greater mass range (i.e., 150Nd/144Nd or 150Nd/142Nd) are used to assess fractionation factor. However, this only increases the precision with ~20%. The downside of using this normalization is an increase in the demand of the chemical purification of Nd to reduce/eliminate Sm (and Ce) interference. 4. Rreservoir mixing can introduce variations in isotope ratios as large as 50% of the external reproducibility. However, the fractionation behavior of a sample is not necessarily a good measure of the amount of mixing between reservoirs on the filament. For samples showing reverse fractionation, there appear to be mixing at the same extent before, during, and after the period of reverse fractionation. There is likely significant mixing taking place in samples showing only normal fractionation. 5. It is imperative to measure all the isotopes of Nd with the best possible precision to assess whether measured anomalies (positive or negative) in 142Nd are real or could be the product of reservoir mixing on the filament.
Introduction: The ongoing discovery of diverse Martian meteorites (now totaling about 80 unpaired... more Introduction: The ongoing discovery of diverse Martian meteorites (now totaling about 80 unpaired specimens), predominantly (>60 %) from Morocco and elsewhere in northwestern Africa, has considerably expanded our knowledge of Martian magmatic rocks. Until (and even after) an eventual sample return mission to Mars, the rocks found as meteorites on Earth will provide invaluable insights into Martian lithologic diversity. Here we describe a large ~3.7 kg shergottite find from Jrifiya, southwestern Morocco plus others found in 2014. Nd and Hf isotopic analyses for these and Northwest Africa 6963 (from Fej Arrih, Morocco) establish key characteristics of their mantle sources.
The Pb-Tl and Cd isotope systematics of ordinary chondrites RASMUS ANDREASEN*, MARIA SCHÖNBÄCHLER... more The Pb-Tl and Cd isotope systematics of ordinary chondrites RASMUS ANDREASEN*, MARIA SCHÖNBÄCHLER AND MARK REHKÄMPER IARC, Department of Earth Science and Engineering, Imperial College London, South Kensington SW7 2AZ, UK (*correspondence: r.andreasen@imperial.ac.uk) (markrehk@imperial.ac.uk) School of Earth, Atmospheric, and Environmental Science, University of Manchester, Manchester M13 9PL, UK (m.schonbachler@manchester.ac.uk)
Introduction: Northwest Africa (NWA) 4480 is a small (13 gram) unpaired shergottite recovered in ... more Introduction: Northwest Africa (NWA) 4480 is a small (13 gram) unpaired shergottite recovered in Algeria in 2006 [1]. Our earlier isotopic work revealed that NWA 4480 has Nd and Hf isotope compositions between depleted and intermediate shergottites (Figure 1)[2], despite the apparent intermediate signature of REE abundances. This is a unique composition for a shergottite. There are a few other features make this meteorite unique. First, the CRE age of ~16 Myr [2] is much older than all except for Dhofar 019 (18.15 Myr) [3]. Second, NWA 4480 has hirefringent plagioclase instead of maskelynite [2]. Together, these signatures make NWA 4480 unique among the shergottites. It will be important to investigate detailed mineralogy, mineral chemistry, and precise crystallization age in order to constrain its petrogenesis, composition of source reservoir(s), and timing of shergottite magmatic activity. Sample and Analytical Procedures: A polished section of NWA 4480 was examined by a SEM and E...
Frei’s comment Frei (2021) argues that we selected an inappropriate mass balancing method in our ... more Frei’s comment Frei (2021) argues that we selected an inappropriate mass balancing method in our paper (Andreasen and Thomsen, 2021), and that our conclusions therefore are unsupported. We maintain that our mass balance and our conclusions are sound. Our mass balance is based on well-constrained time series measurements of soil strontium content in 2014, measured just after the liming experiment in 2012–2013 and 5 years later in 2019. The field was fallow in the interim, with no anthropogenic addition of strontium and no removal through crop yield, providing an excellent opportunity to see how much of the strontium was left after 5 years. The results show that a significant amount of strontium (>3.9 g/m2) was lost from the soil, compared with the amount of strontium added during the liming experiment (3.6-4.8 g/m2) (Jessen et al., 2014), such that 80–100% of the strontium added during the liming experiment was leached from the soil over the next 5 years. By contrast, Frei’s comme...
In the time of the emperors Augustus and Tiberius, present-day Denmark is marked by the sudden de... more In the time of the emperors Augustus and Tiberius, present-day Denmark is marked by the sudden deposition of contemporary Roman vessels in graves. They attest to the first close encounter with the Roman world, an important transition and moment in Danish prehistory into the Roman Iron Age, which would last the next four centuries. We do not know how these objects arrived. Some could have found their way indirectly via various exchange routes. However, there are strong indications that the very first influx of Roman metal vessels occurred because of direct interactions with the Romans, possibly in the form of the naval expedition of Tiberius in 5 CE.
The project focuses on the metal vessels found in ten graves in Denmark dated to the first forty years CE, in particular a bronze basin of type Eggers 92. This vessel is present in seven out of the ten graves. Through detailed metallurgical investigations, we will study the Roman vessels as a catalyst for the initial contact. Through chemical and isotope analyses of the vessels, we will examine, whether the vessels can be materially connected. If these Roman vessels are shown to be identical in their manufacture and origin, then their distribution across Denmark would be a material form of Tiberius’s expeditionary fleet, materialising Rome’s diplomatic efforts with the North.
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The project focuses on the metal vessels found in ten graves in Denmark dated to the first forty years CE, in particular a bronze basin of type Eggers 92. This vessel is present in seven out of the ten graves. Through detailed metallurgical investigations, we will study the Roman vessels as a catalyst for the initial contact. Through chemical and isotope analyses of the vessels, we will examine, whether the vessels can be materially connected. If these Roman vessels are shown to be identical in their manufacture and origin, then their distribution across Denmark would be a material form of Tiberius’s expeditionary fleet, materialising Rome’s diplomatic efforts with the North.