P Ascough, N Bompard, M H Garnett, P Gulliver, C Murray, J-A Newton, C Taylor
The National Environmental Isotope Facility (NEIF) Radiocarbon Laboratory at the Scottish Universities Environmental Research Centre (SUERC) performs radiocarbon measurement of a wide range of sample matrices for applications in environmental research. Radiocarbon is applied to palaeoenvironmental, palaeoceanographic, and palaeoclimatic investigations, as well as work to understand the source, fate, turnover, and age of carbon in the modern carbon cycle. The NEIF Radiocarbon Laboratory supports users in the development and deployment of novel sampling techniques and laboratory approaches. Here, we give an overview of methods and procedures used by the laboratory to support the field collection, laboratory processing, and measurement of samples. This includes in-house development of novel and/or specialized methods and approaches, such as field collection of CO2 and CH4, hydropyrolysis, and ramped oxidation. The sample types covered include organic remains (e.g., plant material, peat, wood, charcoal, proteins), carbonates (e.g., speleothems, foraminifera, mollusc shell, travertine), waters (dissolved organic and inorganic carbon), gases (CO2 and CH4), soils and sediments (including sub-fractions).
{"title":"14C MEASUREMENT OF SAMPLES FOR ENVIRONMENTAL SCIENCE APPLICATIONS AT THE NATIONAL ENVIRONMENTAL ISOTOPE FACILITY (NEIF) RADIOCARBON LABORATORY, SUERC, UK","authors":"P Ascough, N Bompard, M H Garnett, P Gulliver, C Murray, J-A Newton, C Taylor","doi":"10.1017/rdc.2024.9","DOIUrl":"https://doi.org/10.1017/rdc.2024.9","url":null,"abstract":"The National Environmental Isotope Facility (NEIF) Radiocarbon Laboratory at the Scottish Universities Environmental Research Centre (SUERC) performs radiocarbon measurement of a wide range of sample matrices for applications in environmental research. Radiocarbon is applied to palaeoenvironmental, palaeoceanographic, and palaeoclimatic investigations, as well as work to understand the source, fate, turnover, and age of carbon in the modern carbon cycle. The NEIF Radiocarbon Laboratory supports users in the development and deployment of novel sampling techniques and laboratory approaches. Here, we give an overview of methods and procedures used by the laboratory to support the field collection, laboratory processing, and measurement of samples. This includes in-house development of novel and/or specialized methods and approaches, such as field collection of CO<jats:sub>2</jats:sub> and CH<jats:sub>4</jats:sub>, hydropyrolysis, and ramped oxidation. The sample types covered include organic remains (e.g., plant material, peat, wood, charcoal, proteins), carbonates (e.g., speleothems, foraminifera, mollusc shell, travertine), waters (dissolved organic and inorganic carbon), gases (CO<jats:sub>2</jats:sub> and CH<jats:sub>4</jats:sub>), soils and sediments (including sub-fractions).","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Radiocarbon (F14C) and stable carbon (δ13C) values were measured in single grains of spring barley (Hordeum vulgare L.) from the sample archive from two adjacent sites of the Long-term Experiments (LTEs) Hoosfield Spring Barley at Rothamsted Research (Harpenden, Hertfordshire, UK), covering the growing periods (March to September) of 1852 to 2020. F14C data of the barley grain confirm that recent values are approaching and will decline below the “nominal” F14C value of 1, tracking a similar decrease reported in other studies. Importantly, the measured δ13C values reveal a different temporal decline over the pre-bomb and post-bomb timescale. Detailed statistical analysis of δ13C data along with δ13C analysis of independent, archived barley mash samples, verifies and quantifies the extent and rate of this decline. Evidence presented from the barley grain and barley mash samples suggests a clear breakpoint in δ13C data occurring in 1995, where the rate of change alters, in that the slope in δ13C data for the pre-1995 period is declining at 1.4‰ per century, and the slope in δ13C for the post-1995 period is declining at 3.6‰ per century. Such a consistent shift in δ13C data could be used with F14C values to extend the use of the bomb peak for forensic, ecological, and environmental applications.
{"title":"CARBON ISOTOPE CHANGES THROUGH THE RECENT PAST: F14C AND δ13C VALUES IN SINGLE BARLEY GRAIN FROM 1852 TO 2020","authors":"E Dunbar, E M Scott, B G Tripney","doi":"10.1017/rdc.2024.8","DOIUrl":"https://doi.org/10.1017/rdc.2024.8","url":null,"abstract":"Radiocarbon (F<jats:sup>14</jats:sup>C) and stable carbon (δ<jats:sup>13</jats:sup>C) values were measured in single grains of spring barley <jats:italic>(Hordeum vulgare L.</jats:italic>) from the sample archive from two adjacent sites of the Long-term Experiments (LTEs) Hoosfield Spring Barley at Rothamsted Research (Harpenden, Hertfordshire, UK), covering the growing periods (March to September) of 1852 to 2020. F<jats:sup>14</jats:sup>C data of the barley grain confirm that recent values are approaching and will decline below the “nominal” F<jats:sup>14</jats:sup>C value of 1, tracking a similar decrease reported in other studies. Importantly, the measured δ<jats:sup>13</jats:sup>C values reveal a different temporal decline over the pre-bomb and post-bomb timescale. Detailed statistical analysis of δ<jats:sup>13</jats:sup>C data along with δ<jats:sup>13</jats:sup>C analysis of independent, archived barley mash samples, verifies and quantifies the extent and rate of this decline. Evidence presented from the barley grain and barley mash samples suggests a clear breakpoint in δ<jats:sup>13</jats:sup>C data occurring in 1995, where the rate of change alters, in that the slope in δ<jats:sup>13</jats:sup>C data for the pre-1995 period is declining at 1.4‰ per century, and the slope in δ<jats:sup>13</jats:sup>C for the post-1995 period is declining at 3.6‰ per century. Such a consistent shift in δ<jats:sup>13</jats:sup>C data could be used with F<jats:sup>14</jats:sup>C values to extend the use of the bomb peak for forensic, ecological, and environmental applications.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Magdalena Gómez-Puche, Javier Fernández-López de Pablo
The spread of trapeze industries (the creation of trapeze-shaped flint tips) during Late Mesolithic is one of the most disruptive phenomena of technological change documented in the European Prehistory. Understanding the chronological patterns of this process requires (i) a critical evaluation of stratigraphic relationship between trapeze assemblages and radiocarbon samples, and (ii) considering different levels of chronological uncertainty according to the inbuilt age of the samples and the calibration process. In this paper, we critically evaluate and analyze the radiocarbon record of the first trapeze industries in the Iberian Peninsula. A dataset of 181 radiocarbon dates from 67 sites dated to 8800–8200 cal BP was collected and evaluated following a strict data quality control protocol, from which 135 dates of 53 sites were retained and classified according to a reliability index. Then, three different phase Bayesian chronological models were created to estimate the duration of the first spread of trapezes across Iberia, considering different levels of chrono-stratigraphic resolution. We find that trapeze industries appeared in the eastern half of Iberia, over an area of 330,000 km2 between 8505–8390 and 8425–8338 cal BP, spanning 0–85 yr (95.4% CI). When the oldest evidence of trapezes from Portugal are considered, the probability distribution expands (8943–8457 and 8686–7688 cal BP), due to the chronological uncertainty of human samples with marine diet and regional ΔR values applied. For the eastern half of Iberia, the current evidence indicates a very rapid spread of trapeze industries initiated in the Central-Western Pyrenees, suggesting cultural diffusion within Mesolithic social networks as the main driving mechanism.
{"title":"SPATIOTEMPORAL PATTERNS ON THE APPEARANCE OF THE FIRST TRAPEZE INDUSTRIES IN THE LATE MESOLITHIC OF THE IBERIAN PENINSULA","authors":"Magdalena Gómez-Puche, Javier Fernández-López de Pablo","doi":"10.1017/rdc.2024.6","DOIUrl":"https://doi.org/10.1017/rdc.2024.6","url":null,"abstract":"The spread of trapeze industries (the creation of trapeze-shaped flint tips) during Late Mesolithic is one of the most disruptive phenomena of technological change documented in the European Prehistory. Understanding the chronological patterns of this process requires (i) a critical evaluation of stratigraphic relationship between trapeze assemblages and radiocarbon samples, and (ii) considering different levels of chronological uncertainty according to the inbuilt age of the samples and the calibration process. In this paper, we critically evaluate and analyze the radiocarbon record of the first trapeze industries in the Iberian Peninsula. A dataset of 181 radiocarbon dates from 67 sites dated to 8800–8200 cal BP was collected and evaluated following a strict data quality control protocol, from which 135 dates of 53 sites were retained and classified according to a reliability index. Then, three different phase Bayesian chronological models were created to estimate the duration of the first spread of trapezes across Iberia, considering different levels of chrono-stratigraphic resolution. We find that trapeze industries appeared in the eastern half of Iberia, over an area of 330,000 km<jats:sup>2</jats:sup> between 8505–8390 and 8425–8338 cal BP, spanning 0–85 yr (95.4% CI). When the oldest evidence of trapezes from Portugal are considered, the probability distribution expands (8943–8457 and 8686–7688 cal BP), due to the chronological uncertainty of human samples with marine diet and regional ΔR values applied. For the eastern half of Iberia, the current evidence indicates a very rapid spread of trapeze industries initiated in the Central-Western Pyrenees, suggesting cultural diffusion within Mesolithic social networks as the main driving mechanism.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Irka Hajdas, Giulia Guidobaldi, Negar Haghipour, Karin Wyss
Accurate radiocarbon (14C) analysis depends on a successful carbon separation relevant to the studied object. The process of 14C dating involves the following steps: characterization and sample choice, sample treatment, measurements, and evaluation of the results. Here, we provide an overview of conventional approaches to macromolecular samples and address specific issues such as detecting and removing contamination with roots, dolomite, and conservation products. We discuss the application of elemental analysis (%N, %C) in the preparation of bones and the infrared analysis in monitoring the contamination of samples. Our observations provide the basis for the discussions of the existing results and for planning the future sampling.
{"title":"SAMPLE SELECTION, CHARACTERIZATION AND CHOICE OF TREATMENT FOR ACCURATE RADIOCARBON ANALYSIS—INSIGHTS FROM THE ETH LABORATORY","authors":"Irka Hajdas, Giulia Guidobaldi, Negar Haghipour, Karin Wyss","doi":"10.1017/rdc.2024.12","DOIUrl":"https://doi.org/10.1017/rdc.2024.12","url":null,"abstract":"Accurate radiocarbon (<jats:sup>14</jats:sup>C) analysis depends on a successful carbon separation relevant to the studied object. The process of <jats:sup>14</jats:sup>C dating involves the following steps: characterization and sample choice, sample treatment, measurements, and evaluation of the results. Here, we provide an overview of conventional approaches to macromolecular samples and address specific issues such as detecting and removing contamination with roots, dolomite, and conservation products. We discuss the application of elemental analysis (%N, %C) in the preparation of bones and the infrared analysis in monitoring the contamination of samples. Our observations provide the basis for the discussions of the existing results and for planning the future sampling.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The radiocarbon (14C) dating method was applied to a survey of treasured items related to the ruins of the Imperial Residence in Anou, Nara Prefecture, which was one of the capitals of Japan during the 14th century. In this work, we dated two storage bags for Japanese musical instruments that are believed to be from the period of Emperor Go-Daigo who established the Southern Court. The 14C dating of these treasures proved that the musical instrument sacks are contemporaneous with the dating of the Imperial Residence ruins designated as an Important Cultural Property of Japan. In addition, there are limited surviving examples of silk fabrics from the Middle Ages compared to the Ancient and Early Modern periods, making this a valuable resource in the history of silk fabrics in Japan.
{"title":"14C DATING OF HISTORICAL JAPANESE MUSICAL INSTRUMENT SACKS","authors":"Misao Yokoyama, Minoru Sakamoto, Hikaru Takaya, Kazuyoshi Kanamori","doi":"10.1017/rdc.2023.114","DOIUrl":"https://doi.org/10.1017/rdc.2023.114","url":null,"abstract":"The radiocarbon (<jats:sup>14</jats:sup>C) dating method was applied to a survey of treasured items related to the ruins of the Imperial Residence in Anou, Nara Prefecture, which was one of the capitals of Japan during the 14th century. In this work, we dated two storage bags for Japanese musical instruments that are believed to be from the period of Emperor Go-Daigo who established the Southern Court. The <jats:sup>14</jats:sup>C dating of these treasures proved that the musical instrument sacks are contemporaneous with the dating of the Imperial Residence ruins designated as an Important Cultural Property of Japan. In addition, there are limited surviving examples of silk fabrics from the Middle Ages compared to the Ancient and Early Modern periods, making this a valuable resource in the history of silk fabrics in Japan.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Karis J McFarlane, Stefania Mambelli, Rachel C Porras, Daniel B Wiedemeier, Michael W I Schmidt, Todd E Dawson, Margaret S Torn
The long-standing assumption that aboveground plant litter inputs have a substantial influence on soil organic carbon storage (SOC) and dynamics has been challenged by a new paradigm for SOC formation and persistence. We tested the importance of plant litter chemistry on SOC storage, distribution, composition, and age by comparing two highly contrasting ecosystems: an old-growth coast redwood (Sequoia sempervirens) forest, with highly aromatic litter, and an adjacent coastal prairie, with more easily decomposed litter. We hypothesized that if plant litter chemistry was the primary driver, redwood would store more and older SOC that was less microbially processed than prairie. Total soil carbon stocks to 110 cm depth were higher in prairie (35 kg C m−2) than redwood (28 kg C m−2). Radiocarbon values indicated shorter SOC residence times in redwood than prairie throughout the profile. Higher amounts of pyrogenic carbon and a higher degree of microbial processing of SOC appear to be instrumental for soil carbon storage and persistence in prairie, while differences in fine-root carbon inputs likely contribute to younger SOC in redwood. We conclude that at these sites fire residues, root inputs, and soil properties influence soil carbon dynamics to a greater degree than the properties of aboveground litter.
{"title":"SOIL CARBON STOCKS NOT LINKED TO ABOVEGROUND LITTER INPUT AND CHEMISTRY OF OLD-GROWTH FOREST AND ADJACENT PRAIRIE","authors":"Karis J McFarlane, Stefania Mambelli, Rachel C Porras, Daniel B Wiedemeier, Michael W I Schmidt, Todd E Dawson, Margaret S Torn","doi":"10.1017/rdc.2024.5","DOIUrl":"https://doi.org/10.1017/rdc.2024.5","url":null,"abstract":"The long-standing assumption that aboveground plant litter inputs have a substantial influence on soil organic carbon storage (SOC) and dynamics has been challenged by a new paradigm for SOC formation and persistence. We tested the importance of plant litter chemistry on SOC storage, distribution, composition, and age by comparing two highly contrasting ecosystems: an old-growth coast redwood (<jats:italic>Sequoia sempervirens</jats:italic>) forest, with highly aromatic litter, and an adjacent coastal prairie, with more easily decomposed litter. We hypothesized that if plant litter chemistry was the primary driver, redwood would store more and older SOC that was less microbially processed than prairie. Total soil carbon stocks to 110 cm depth were higher in prairie (35 kg C m<jats:sup>−2</jats:sup>) than redwood (28 kg C m<jats:sup>−2</jats:sup>). Radiocarbon values indicated shorter SOC residence times in redwood than prairie throughout the profile. Higher amounts of pyrogenic carbon and a higher degree of microbial processing of SOC appear to be instrumental for soil carbon storage and persistence in prairie, while differences in fine-root carbon inputs likely contribute to younger SOC in redwood. We conclude that at these sites fire residues, root inputs, and soil properties influence soil carbon dynamics to a greater degree than the properties of aboveground litter.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the hyperarid eastern Sahara, west of the Nile River in Egypt, areas with vegetated eolian mounds have attracted people and animals because of shallow groundwater that at times of high water tables may be reached by hand digging shallow wells. An eolian phreatophytic mound with a living arak bush (Silvadora persica L.) on top, one of three known from this region of SW Egypt, provided a stratigraphic record of its growth. The geochronology of the mounds aggradation and that of a nearby tarfa mound (Tamarix nilatica Bunge) was determined by radiocarbon dating plant macrofossils within the stratigraphic succession. Eolian aggradation of the mound postdates deflation that eroded playa sediments of the Neolithic pluvial that ended ca. 5000 BP and appears to be due to a resurgence of the shallow aquifer. Subsequent deflation of the mounds is apparently due to post-1500 BP aridity. Regional vegetation is described in the Appendix I.
{"title":"GEOCHRONOLOGY OF PHREATOPHYTIC MOUNDS ON THE ATMUR EL KIBIESH, EGYPT: WITH DESCRIPTIONS OF PLANTS COLLECTED DURING THE EXPEDITION TO THE EASTERN SAHARA, EGYPT, AND SUDAN (APPENDIX I)","authors":"C Vance Haynes, Loutfy Boulos, Anthony B Muller","doi":"10.1017/rdc.2024.1","DOIUrl":"https://doi.org/10.1017/rdc.2024.1","url":null,"abstract":"In the hyperarid eastern Sahara, west of the Nile River in Egypt, areas with vegetated eolian mounds have attracted people and animals because of shallow groundwater that at times of high water tables may be reached by hand digging shallow wells. An eolian phreatophytic mound with a living arak bush (<jats:italic>Silvadora persica</jats:italic> L.) on top, one of three known from this region of SW Egypt, provided a stratigraphic record of its growth. The geochronology of the mounds aggradation and that of a nearby tarfa mound (<jats:italic>Tamarix nilatica</jats:italic> Bunge) was determined by radiocarbon dating plant macrofossils within the stratigraphic succession. Eolian aggradation of the mound postdates deflation that eroded playa sediments of the Neolithic pluvial that ended ca. 5000 BP and appears to be due to a resurgence of the shallow aquifer. Subsequent deflation of the mounds is apparently due to post-1500 BP aridity. Regional vegetation is described in the Appendix I.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G Artioli, S Barone, M Fedi, A Galli, L Liccioli, M Martini, F Marzaioli, F Maspero, L Panzeri, I Passariello, G Ricci, M Secco, F Terrasi
For several decades, many efforts have been dedicated to enhancing the accuracy of mortar radiocarbon dating and evaluating the reliability of the results concerning the typology of the examined specimens. Several assumptions that are fundamental for the application of the method may be in many cases not fulfilled, such as (a) complete primary limestone dissociation during calcination, (b) efficient separation of geogenic carbon contained in calcareous aggregates, (c) short carbonation time, and (d) absence of secondary calcite. Many laboratories all over the world have proposed different methods to select suitable fractions of mortar. The first intercomparison attempt, involving eight international laboratories, was organized in 2016 aiming at comparing and statistically treating the results obtained on the same materials by different laboratories with their own characterization and pre-treatment methods (Hajdas et al. 2017; Hayen et al. 2017). Following this first step, a new intercomparison experiment was proposed and set up in 2018 during the Mortar Dating International Meeting (Bordeaux, FR). A new set of three mortar samples was chosen, taking care of the selection of standardized materials (homogeneity, known mineralogical composition, absence of exogenous inclusions, known expected age). This work describes the results of two research teams involved in the intercomparison. The samples were characterized, selected, and dated depending on each laboratory strategy. The results stress the importance of the characterization of the raw material is to better understand the mineralogical and petrographical composition of the samples. Such information can support the choice of the most appropriate strategy for the extraction of CO2 and then for data interpretation.
{"title":"CHARACTERIZATION AND SELECTION OF MORTAR SAMPLES FOR RADIOCARBON DATING IN THE FRAMEWORK OF THE MODIS2 INTERCOMPARISON: TWO COMPARED PROCEDURES","authors":"G Artioli, S Barone, M Fedi, A Galli, L Liccioli, M Martini, F Marzaioli, F Maspero, L Panzeri, I Passariello, G Ricci, M Secco, F Terrasi","doi":"10.1017/rdc.2024.3","DOIUrl":"https://doi.org/10.1017/rdc.2024.3","url":null,"abstract":"For several decades, many efforts have been dedicated to enhancing the accuracy of mortar radiocarbon dating and evaluating the reliability of the results concerning the typology of the examined specimens. Several assumptions that are fundamental for the application of the method may be in many cases not fulfilled, such as (a) complete primary limestone dissociation during calcination, (b) efficient separation of geogenic carbon contained in calcareous aggregates, (c) short carbonation time, and (d) absence of secondary calcite. Many laboratories all over the world have proposed different methods to select suitable fractions of mortar. The first intercomparison attempt, involving eight international laboratories, was organized in 2016 aiming at comparing and statistically treating the results obtained on the same materials by different laboratories with their own characterization and pre-treatment methods (Hajdas et al. 2017; Hayen et al. 2017). Following this first step, a new intercomparison experiment was proposed and set up in 2018 during the Mortar Dating International Meeting (Bordeaux, FR). A new set of three mortar samples was chosen, taking care of the selection of standardized materials (homogeneity, known mineralogical composition, absence of exogenous inclusions, known expected age). This work describes the results of two research teams involved in the intercomparison. The samples were characterized, selected, and dated depending on each laboratory strategy. The results stress the importance of the characterization of the raw material is to better understand the mineralogical and petrographical composition of the samples. Such information can support the choice of the most appropriate strategy for the extraction of CO<jats:sub>2</jats:sub> and then for data interpretation.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fluvial and colluvial deposits of Late Holocene age in South-Central Ontario catchments have provided few 14C dates, most by conventional methods registering century-old ages. Other young deposits, dated by conventional and accelerator mass spectrometry radiocarbon (AMS 14C), have yielded bomb-affected post-1950 ages over variable time limits. Attempts to date the base of Ah and lower-in-section soil horizons, in Early to Late Holocene stream terrace deposits, have yielded atomic bomb effects. Comparing bomb contamination in Late Holocene fluvial deposits, using both conventional and AMS methods, identifies a mix of bomb-affected beds juxtaposed with dated beds, the latter yielding ages with narrow standard deviations. Colluvial deposits overlying key glacial sections in the Rouge Catchment, while rare, yield bracketed AMS ages for an Ahbk horizon that refines weathering times relative to previously obtained conventional 14C dates. Bomb-affected sediment appears variably distributed within floodplain soils and in the ground soil of a colluvial section. Mass wasted deposits, with AMS 14C ages spread over the last few centuries, appear related to Little Ice Age (LIA) changes in climate, corroborated by pollen records. Further, these AMS-14C dated beds calibrate weathering of secondary Fe-Al oxihydroxides over the first half a millennium of weathering time.
{"title":"A SUMMARY OF RADIOCARBON MEASUREMENTS OF FLUVIAL AND COLLUVIAL DEPOSITS IN CATCHMENTS OF SOUTH-CENTRAL ONTARIO, CANADA","authors":"William C Mahaney, Andrew M Stewart","doi":"10.1017/rdc.2024.2","DOIUrl":"https://doi.org/10.1017/rdc.2024.2","url":null,"abstract":"Fluvial and colluvial deposits of Late Holocene age in South-Central Ontario catchments have provided few <jats:sup>14</jats:sup>C dates, most by conventional methods registering century-old ages. Other young deposits, dated by conventional and accelerator mass spectrometry radiocarbon (AMS <jats:sup>14</jats:sup>C), have yielded bomb-affected post-1950 ages over variable time limits. Attempts to date the base of Ah and lower-in-section soil horizons, in Early to Late Holocene stream terrace deposits, have yielded atomic bomb effects. Comparing bomb contamination in Late Holocene fluvial deposits, using both conventional and AMS methods, identifies a mix of bomb-affected beds juxtaposed with dated beds, the latter yielding ages with narrow standard deviations. Colluvial deposits overlying key glacial sections in the Rouge Catchment, while rare, yield bracketed AMS ages for an Ahbk horizon that refines weathering times relative to previously obtained conventional <jats:sup>14</jats:sup>C dates. Bomb-affected sediment appears variably distributed within floodplain soils and in the ground soil of a colluvial section. Mass wasted deposits, with AMS <jats:sup>14</jats:sup>C ages spread over the last few centuries, appear related to Little Ice Age (LIA) changes in climate, corroborated by pollen records. Further, these AMS-<jats:sup>14</jats:sup>C dated beds calibrate weathering of secondary Fe-Al oxihydroxides over the first half a millennium of weathering time.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Catherine E Ginnane, Jocelyn C Turnbull, Sebastian Naeher, Brad E Rosenheim, Ryan A Venturelli, Andy M Phillips, Simon Reeve, Jeremy Parry-Thompson, Albert Zondervan, Richard H Levy, Kyu-Cheul Yoo, Gavin Dunbar, Theo Calkin, Carlota Escutia, Julia Gutierrez Pastor
Radiocarbon (14C) dating of sediment deposition around Antarctica is often challenging due to heterogeneity in sources and ages of organic carbon in the sediment. Chemical and thermochemical techniques have been used to separate organic carbon when microfossils are not present. These techniques generally improve on bulk sediment dates, but they necessitate assumptions about the age spectra of specific molecules or compound classes and about the chemical heterogeneity of thermochemical separations. To address this, the Rafter Radiocarbon Laboratory has established parallel ramped pyrolysis oxidation (RPO) and ramped pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) systems to thermochemically separate distinct carbon fractions, diagnose the chemical composition of each fraction, and target suitable RPO fractions for radiocarbon dating. Three case studies of sediment taken from locations around Antarctica are presented to demonstrate the implementation of combined RPO-AMS and Py-GC-MS to provide more robust age determination in detrital sediment stratigraphy. These three depositional environments are good examples of analytical and interpretive challenges related to oceanographic conditions, carbon sources, and other factors. Using parallel RPO-AMS and Py-GC-MS analyses, we reduce the number of radiocarbon measurements required, minimize run times, provide context for unexpected 14C ages, and better support interpretations of radiocarbon measurements in the context of environmental reconstruction.
{"title":"ADVANCING ANTARCTIC SEDIMENT CHRONOLOGY THROUGH COMBINED RAMPED PYROLYSIS OXIDATION AND PYROLYSIS-GC-MS","authors":"Catherine E Ginnane, Jocelyn C Turnbull, Sebastian Naeher, Brad E Rosenheim, Ryan A Venturelli, Andy M Phillips, Simon Reeve, Jeremy Parry-Thompson, Albert Zondervan, Richard H Levy, Kyu-Cheul Yoo, Gavin Dunbar, Theo Calkin, Carlota Escutia, Julia Gutierrez Pastor","doi":"10.1017/rdc.2023.116","DOIUrl":"https://doi.org/10.1017/rdc.2023.116","url":null,"abstract":"Radiocarbon (<jats:sup>14</jats:sup>C) dating of sediment deposition around Antarctica is often challenging due to heterogeneity in sources and ages of organic carbon in the sediment. Chemical and thermochemical techniques have been used to separate organic carbon when microfossils are not present. These techniques generally improve on bulk sediment dates, but they necessitate assumptions about the age spectra of specific molecules or compound classes and about the chemical heterogeneity of thermochemical separations. To address this, the Rafter Radiocarbon Laboratory has established parallel ramped pyrolysis oxidation (RPO) and ramped pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) systems to thermochemically separate distinct carbon fractions, diagnose the chemical composition of each fraction, and target suitable RPO fractions for radiocarbon dating. Three case studies of sediment taken from locations around Antarctica are presented to demonstrate the implementation of combined RPO-AMS and Py-GC-MS to provide more robust age determination in detrital sediment stratigraphy. These three depositional environments are good examples of analytical and interpretive challenges related to oceanographic conditions, carbon sources, and other factors. Using parallel RPO-AMS and Py-GC-MS analyses, we reduce the number of radiocarbon measurements required, minimize run times, provide context for unexpected <jats:sup>14</jats:sup>C ages, and better support interpretations of radiocarbon measurements in the context of environmental reconstruction.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：