Pub Date : 2019-01-01DOI: 10.1515/geochr-2015-0105
M. Duval, L. Martin
Abstract We used DosiVox to evaluate the impact of cement thickness on the dose effectively absorbed by the enamel layer. Until now, the thickness of the dental tissues adjacent to the enamel layer was not considered by any of the most widely used combined US-ESR dating programs (DATA and USESR). Instead, if adjacent tissues are present, their thickness is by default assumed to be sufficient to fulfill the infinite matrix conditions. Our result suggest that such an assumption may represent in first instance a fair approximation of the reality, as even with a thickness of only 1 mm, the cement contributes to at least 98% of the beta dose rate coming from the outer side of the enamel layer. However, when cement is < 1 mm thick, DATA or USESR would overestimate the external beta dose rate and the value should be corrected accordingly by considering the relative contribution of the sediment. The impact of this correction on the total dose rate may vary, as it is directly dependent on the radioactivity of the cement itself, as well as of the sediment or dentine. Our results show that a very thin cement layer (0.1 mm-thick) can significantly contribute to the beta dose rate and should therefore not be neglected. Consequently, based on these results, we recommend the systematic measurement of the thickness of the dental tissues adjacent to the enamel layer during sample preparation, in order to proceed to beta dose rate corrections if necessary. Although this work has been especially focused on the case of fossil teeth showing cement, the conclusions stand for any other geometry involving different dental tissues adjacent to the enamel layer dated by ESR.
{"title":"ESR dating of fossil teeth: In which extent the thickness of adjacent tissues should be taken into account in the external beta dose rate evaluation?","authors":"M. Duval, L. Martin","doi":"10.1515/geochr-2015-0105","DOIUrl":"https://doi.org/10.1515/geochr-2015-0105","url":null,"abstract":"Abstract We used DosiVox to evaluate the impact of cement thickness on the dose effectively absorbed by the enamel layer. Until now, the thickness of the dental tissues adjacent to the enamel layer was not considered by any of the most widely used combined US-ESR dating programs (DATA and USESR). Instead, if adjacent tissues are present, their thickness is by default assumed to be sufficient to fulfill the infinite matrix conditions. Our result suggest that such an assumption may represent in first instance a fair approximation of the reality, as even with a thickness of only 1 mm, the cement contributes to at least 98% of the beta dose rate coming from the outer side of the enamel layer. However, when cement is < 1 mm thick, DATA or USESR would overestimate the external beta dose rate and the value should be corrected accordingly by considering the relative contribution of the sediment. The impact of this correction on the total dose rate may vary, as it is directly dependent on the radioactivity of the cement itself, as well as of the sediment or dentine. Our results show that a very thin cement layer (0.1 mm-thick) can significantly contribute to the beta dose rate and should therefore not be neglected. Consequently, based on these results, we recommend the systematic measurement of the thickness of the dental tissues adjacent to the enamel layer during sample preparation, in order to proceed to beta dose rate corrections if necessary. Although this work has been especially focused on the case of fossil teeth showing cement, the conclusions stand for any other geometry involving different dental tissues adjacent to the enamel layer dated by ESR.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42049508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1515/geochr-2015-0111
D. Ciszewski, E. Łokas
Abstract The periodical nature of overbank sediment accumulation makes their detailed dating much more difficult than dating sediments in water reservoirs. To improve the commonly used dating with 137Cs, we combined this method with Pu isotopes and heavy metals in order to date sediments of the Chechło River (southern Poland), which was polluted by a lead-zinc mine. We analyzed 137Cs, Pu isotopes and heavy metal concentrations in three profiles of overbank sediments and in two profiles of subsidence basins in the lower river reach. The results indicate a lower accuracy and higher uncertainty of the overbank than the dating of reservoir sediments. The application of plutonium isotopes provided very important information validating caesium peaks or providing the principal information regarding horizons dated with heavy metals. The obtained dates give the earliest possible age of particular horizons with the actual sediment deposition delayed by several to a dozen years. This investigation shows that using plutonium radioisotopes can be a useful tool for dating, particularly of the youngest overbank sediments where numerous sedimentation gaps cause uncertainties in the application of other methods, e.g. radiocaesium and heavy metals.
{"title":"Application of 239,240 Pu, 137Cs and heavy metals for dating of river sediments","authors":"D. Ciszewski, E. Łokas","doi":"10.1515/geochr-2015-0111","DOIUrl":"https://doi.org/10.1515/geochr-2015-0111","url":null,"abstract":"Abstract The periodical nature of overbank sediment accumulation makes their detailed dating much more difficult than dating sediments in water reservoirs. To improve the commonly used dating with 137Cs, we combined this method with Pu isotopes and heavy metals in order to date sediments of the Chechło River (southern Poland), which was polluted by a lead-zinc mine. We analyzed 137Cs, Pu isotopes and heavy metal concentrations in three profiles of overbank sediments and in two profiles of subsidence basins in the lower river reach. The results indicate a lower accuracy and higher uncertainty of the overbank than the dating of reservoir sediments. The application of plutonium isotopes provided very important information validating caesium peaks or providing the principal information regarding horizons dated with heavy metals. The obtained dates give the earliest possible age of particular horizons with the actual sediment deposition delayed by several to a dozen years. This investigation shows that using plutonium radioisotopes can be a useful tool for dating, particularly of the youngest overbank sediments where numerous sedimentation gaps cause uncertainties in the application of other methods, e.g. radiocaesium and heavy metals.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45836326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1515/geochr-2015-0119
P. Gębica, A. Michno, M. Sobucki, S. Czopek, K. Trybała-Zawiślak, A. Wacnik
Abstract This study presents the sedimentological and pollen analysis, and radiocarbon dating of the palaeochannel fill deposits situated on the wide alluvial ridge on which 131 archaeological sites were discovered. The analyzed territory covers the right bank of the San river valley (in the area of the Leszno profile) with an area of 72.5 km2. Increase of fine-grain sand sediments, and the presence of redeposited fragments of clayey silts (soil aggregates) correlates well with the increase man’s activity in the 2nd and the 1st half of the 1 st millennia BC (the decline of the Mierzanowice culture, the Trzciniec culture, the Tarnobrzeg Lusatian culture) as well as in the 1st millennium AD (the Przeworsk culture and the early Medieval settlement) and with transformation of plant communities recorded in the palynological sequence. The layer of sediments at the depth of 85–69 cm with the highest proportion of the finest clay fraction may indicate the reduction of cultivation or abandonment of arable land (the pre-Roman (La Tène) period).
{"title":"Temporal variation of prehistoric human settlement recorded in the oxbow lake deposits of San river (Sandomierz Basin, SE Poland)","authors":"P. Gębica, A. Michno, M. Sobucki, S. Czopek, K. Trybała-Zawiślak, A. Wacnik","doi":"10.1515/geochr-2015-0119","DOIUrl":"https://doi.org/10.1515/geochr-2015-0119","url":null,"abstract":"Abstract This study presents the sedimentological and pollen analysis, and radiocarbon dating of the palaeochannel fill deposits situated on the wide alluvial ridge on which 131 archaeological sites were discovered. The analyzed territory covers the right bank of the San river valley (in the area of the Leszno profile) with an area of 72.5 km2. Increase of fine-grain sand sediments, and the presence of redeposited fragments of clayey silts (soil aggregates) correlates well with the increase man’s activity in the 2nd and the 1st half of the 1 st millennia BC (the decline of the Mierzanowice culture, the Trzciniec culture, the Tarnobrzeg Lusatian culture) as well as in the 1st millennium AD (the Przeworsk culture and the early Medieval settlement) and with transformation of plant communities recorded in the palynological sequence. The layer of sediments at the depth of 85–69 cm with the highest proportion of the finest clay fraction may indicate the reduction of cultivation or abandonment of arable land (the pre-Roman (La Tène) period).","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42383111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1515/GEOCHR-2015-0101
J. Sikorski
Abstract The paper presents the results of measurements the specific concentration of lead-210 for six peat profiles representing four peat bogs from two regions of Poland and the problem of creating age-depth models. For the construction of age-depth models, it is proposed to use mathematical functions, the best fit to the measured activity. The F-statistics were used as a measure of the match quality. The obtained models are visualized in two ways – showing the age calculated on the basis of direct measurements of activity and indicating points that are the results of the used approximation. Such visualization is important to clearly distinguish the places of the age-depth model that result from the measurements of activity from those places that are the result of the approximation used. This paper proposes and tests the application of activity modelling for the cores shorter than the range of the lead method. The paper also outlines the limitations and potential dangers related to the interpretation of core dating results i) obtained by using the activity approximation resulting in the smoothing of the age-depth profile, and ii) for the cores of a length smaller than the depth of the presence of the unsupported lead. Additionally, the proposed models were compared with the models obtained by using SIT, Mod-Age, OxCal, Clam, and Bacon programs.
{"title":"A new method for constructing Pb-210 chronology of young peat profiles sampled with low frequency","authors":"J. Sikorski","doi":"10.1515/GEOCHR-2015-0101","DOIUrl":"https://doi.org/10.1515/GEOCHR-2015-0101","url":null,"abstract":"Abstract The paper presents the results of measurements the specific concentration of lead-210 for six peat profiles representing four peat bogs from two regions of Poland and the problem of creating age-depth models. For the construction of age-depth models, it is proposed to use mathematical functions, the best fit to the measured activity. The F-statistics were used as a measure of the match quality. The obtained models are visualized in two ways – showing the age calculated on the basis of direct measurements of activity and indicating points that are the results of the used approximation. Such visualization is important to clearly distinguish the places of the age-depth model that result from the measurements of activity from those places that are the result of the approximation used. This paper proposes and tests the application of activity modelling for the cores shorter than the range of the lead method. The paper also outlines the limitations and potential dangers related to the interpretation of core dating results i) obtained by using the activity approximation resulting in the smoothing of the age-depth profile, and ii) for the cores of a length smaller than the depth of the presence of the unsupported lead. Additionally, the proposed models were compared with the models obtained by using SIT, Mod-Age, OxCal, Clam, and Bacon programs.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42174231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1515/geochr-2015-0109
G. Poręba, Z. Śnieszko, P. Moska, P. Mroczek, I. Malik
Abstract Loess areas used for agriculture are susceptible to soil erosion. The intensive process of soil erosion in Polish loess areas began with the onset of the Neolithic and has continued intermittently until today. This work presents the results of soil erosion from simultaneous use of the 137Cs and 210Pbex methods on an agricultural field located on loess slope. Moreover, to establish the age of accumulated sediment connected with water slope erosion, OSL dating, selected physicochemical and micromorphological analyses were applied. The reference values of the 137Cs and 210Pbex fallout for the studied site (Biedrzykowice, the Proszowice Plateau, Małopolska Upland) equal 2627 (45% connected with Chernobyl) and 4835 Bq·m–2, respectively. The results of the 137Cs and 210Pbex inventories measured for the agricultural field range from 730 to 7911 and from 1615 to 11136 Bq·m–2, respectively. The mean soil erosion is about 2.1 kg·m–2·a–1 (about 1.4 mm·a–1). The accumulation of the colluvial sediments started in the Neolithic and drastically increased in the Middle Ages. The examined gully catchment in Biedrzykowice has probably developed quite rapidly as a result of increased erosion. This resulted in the abandonment of this area as farmland and, consequently, in the minimization of water erosion on the slope due to the entrance of woody vegetation in this area. Erosion processes were highly intensified during the last 70 years as a result of deforestation after World War II and intensive agricultural reuse of this area after a break, as indicated by isotope measurements and dendrochronology.
{"title":"Interpretation of soil erosion in a Polish loess area using OSL, 137Cs, 210Pbex, dendrochronology and micromorphology – case study: Biedrzykowice site (s Poland)","authors":"G. Poręba, Z. Śnieszko, P. Moska, P. Mroczek, I. Malik","doi":"10.1515/geochr-2015-0109","DOIUrl":"https://doi.org/10.1515/geochr-2015-0109","url":null,"abstract":"Abstract Loess areas used for agriculture are susceptible to soil erosion. The intensive process of soil erosion in Polish loess areas began with the onset of the Neolithic and has continued intermittently until today. This work presents the results of soil erosion from simultaneous use of the 137Cs and 210Pbex methods on an agricultural field located on loess slope. Moreover, to establish the age of accumulated sediment connected with water slope erosion, OSL dating, selected physicochemical and micromorphological analyses were applied. The reference values of the 137Cs and 210Pbex fallout for the studied site (Biedrzykowice, the Proszowice Plateau, Małopolska Upland) equal 2627 (45% connected with Chernobyl) and 4835 Bq·m–2, respectively. The results of the 137Cs and 210Pbex inventories measured for the agricultural field range from 730 to 7911 and from 1615 to 11136 Bq·m–2, respectively. The mean soil erosion is about 2.1 kg·m–2·a–1 (about 1.4 mm·a–1). The accumulation of the colluvial sediments started in the Neolithic and drastically increased in the Middle Ages. The examined gully catchment in Biedrzykowice has probably developed quite rapidly as a result of increased erosion. This resulted in the abandonment of this area as farmland and, consequently, in the minimization of water erosion on the slope due to the entrance of woody vegetation in this area. Erosion processes were highly intensified during the last 70 years as a result of deforestation after World War II and intensive agricultural reuse of this area after a break, as indicated by isotope measurements and dendrochronology.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49409573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1515/geochr-2015-0110
H. Hercman, M. Szczerba, P. Zawidzki, A. Trojan
Abstract A series of laboratory experiments was performed to determine the carbon stable isotopic composition of different combustion/pyrolysis (B/P) products. Variation in the δ13C values of the products was observed, up to 4‰. The differences in the carbon isotopic compositions of the B/P products were dependent on temperature, time and wood type. Comparison of the results for fresh and fossil oak wood suggested that the δ13C differences were the effect of selective decomposition of some wood components during the fossilization process. The temperature dependence of the carbon isotopic composition was linked to variation in the carbon isotopic composition of the main wood components, which each had different levels of thermal stability. Isotopes exchange reactions in between different products can be also considered as possible source of variation of δ13C on temperature. Both these hypotheses were supported by molecular simulations of cellulose and lignin B/P. The results confirm that B/P should be treated as a continuous process, where the results depend on the degree of process development. Natural burning processes are dynamic and burning conditions change rapidly and it is necessary to take care when using combustion products as a paleoenvironmental proxy or as an isotopic characteristic for the identification of source material.
{"title":"Carbon isotopes in wood combustion/pyrolysis products: experimental and molecular simulation approaches","authors":"H. Hercman, M. Szczerba, P. Zawidzki, A. Trojan","doi":"10.1515/geochr-2015-0110","DOIUrl":"https://doi.org/10.1515/geochr-2015-0110","url":null,"abstract":"Abstract A series of laboratory experiments was performed to determine the carbon stable isotopic composition of different combustion/pyrolysis (B/P) products. Variation in the δ13C values of the products was observed, up to 4‰. The differences in the carbon isotopic compositions of the B/P products were dependent on temperature, time and wood type. Comparison of the results for fresh and fossil oak wood suggested that the δ13C differences were the effect of selective decomposition of some wood components during the fossilization process. The temperature dependence of the carbon isotopic composition was linked to variation in the carbon isotopic composition of the main wood components, which each had different levels of thermal stability. Isotopes exchange reactions in between different products can be also considered as possible source of variation of δ13C on temperature. Both these hypotheses were supported by molecular simulations of cellulose and lignin B/P. The results confirm that B/P should be treated as a continuous process, where the results depend on the degree of process development. Natural burning processes are dynamic and burning conditions change rapidly and it is necessary to take care when using combustion products as a paleoenvironmental proxy or as an isotopic characteristic for the identification of source material.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44841932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1515/geochr-2015-0103
Jian-hui Jin, Yun-ming Huang, Zhi-zhong Li, Xue-chun Fan, Z. Ling, Zhi-xing Li, Xiao-ju Liu
Abstract The possible role of environmental change, especially sea level change, as a stimulus for the development of human residence and migration is poorly understood. We investigate this problem by showing a record of sea-level change and coastal transformation based on a sediment core (FN1 core) and a Neolithic site (Pingfengshan site) obtained from the Funing bay on the northeast coast of Fujian, China. The Funing bay coastal area represents a unique feature in China’s Neolithic cultures, comprising a silty beach dominated by quartz-rich sand and several important sites of Huangguashan cultural period. Samples from FN1 core and Pingfengshan site were taken for grain size ananlyses and for optically stimulated luminescence (OSL) dating. The blue-light stimulated OSL signals were measured by the single aliquot regenerative dose (SAR) protocol to determine the ages of of the samples. Samples from FN1 core yield OSL ages ranging from 49.9 ka to 0.8 ka, providing the systematic geochronological evidence for the sea level change of Funing bay. The comparison of sea level change and Neolithic cultural periods presents a good relationship in coastal area of Fujian, China since about 7 ka before present. In detail, the cultural types of Keqiutou culture and Huangguashan culture all belong to coastal mountainous culture, of which flourishing periods corresponds to the higher sea level periods of mid-late Holocene. Tanshishan culture belongs to estuarine coastal culture, and most sites of this period correspond to a lower sea level located at lower altitudes.
{"title":"Optically stimulated luminescence dating of coastal sediments at Funing Bay, Southeastern China","authors":"Jian-hui Jin, Yun-ming Huang, Zhi-zhong Li, Xue-chun Fan, Z. Ling, Zhi-xing Li, Xiao-ju Liu","doi":"10.1515/geochr-2015-0103","DOIUrl":"https://doi.org/10.1515/geochr-2015-0103","url":null,"abstract":"Abstract The possible role of environmental change, especially sea level change, as a stimulus for the development of human residence and migration is poorly understood. We investigate this problem by showing a record of sea-level change and coastal transformation based on a sediment core (FN1 core) and a Neolithic site (Pingfengshan site) obtained from the Funing bay on the northeast coast of Fujian, China. The Funing bay coastal area represents a unique feature in China’s Neolithic cultures, comprising a silty beach dominated by quartz-rich sand and several important sites of Huangguashan cultural period. Samples from FN1 core and Pingfengshan site were taken for grain size ananlyses and for optically stimulated luminescence (OSL) dating. The blue-light stimulated OSL signals were measured by the single aliquot regenerative dose (SAR) protocol to determine the ages of of the samples. Samples from FN1 core yield OSL ages ranging from 49.9 ka to 0.8 ka, providing the systematic geochronological evidence for the sea level change of Funing bay. The comparison of sea level change and Neolithic cultural periods presents a good relationship in coastal area of Fujian, China since about 7 ka before present. In detail, the cultural types of Keqiutou culture and Huangguashan culture all belong to coastal mountainous culture, of which flourishing periods corresponds to the higher sea level periods of mid-late Holocene. Tanshishan culture belongs to estuarine coastal culture, and most sites of this period correspond to a lower sea level located at lower altitudes.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43175743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1515/geochr-2015-0104
L. Jiao, Sheng-jie Wang, Yuan Jiang, Xuerui Liu
Abstract In this paper, a fragile ecological area in the Western Tianshan National Nature Reserve of China was selected as the research region, and Picea schrenkiana, which is sensitive to climate change, was selected as the research object. The mean minimum temperature in the growing season of the previous year (May to September) was the main limiting factor for tree radial growth based on an analysis of the relationship between chronological series and climatic factors during 1959–2012 (r = –0.792, p < 0.05). Moreover, the relationship was stable, which showed that tree rings can be used as alternative materials for climate reconstruction. Therefore, the mean minimum temperature of the previous year in 1680–2012 was reconstructed, and the explained variance of the reconstruction equation was 62.7% (R2adj = 62.0%, F = 85.8). The 31 dramatically altered years were found via characteristic year analyses, and extreme changes occurred most often under relatively warm conditions. The mean minimum temperature in the reconstruction shows a clear warming trend by the 11-year moving average of the reconstructive series since the 1950s (the temperature increase: 0.341°C/decade). The driving factors of the mean minimum temperature were influenced mainly by the interaction of solar activity and large-scale atmospheric–oceanic variability, especially the westerly circulations.
{"title":"A 333-year record of the mean minimum temperature reconstruction in the Western Tianshan Mountains, China","authors":"L. Jiao, Sheng-jie Wang, Yuan Jiang, Xuerui Liu","doi":"10.1515/geochr-2015-0104","DOIUrl":"https://doi.org/10.1515/geochr-2015-0104","url":null,"abstract":"Abstract In this paper, a fragile ecological area in the Western Tianshan National Nature Reserve of China was selected as the research region, and Picea schrenkiana, which is sensitive to climate change, was selected as the research object. The mean minimum temperature in the growing season of the previous year (May to September) was the main limiting factor for tree radial growth based on an analysis of the relationship between chronological series and climatic factors during 1959–2012 (r = –0.792, p < 0.05). Moreover, the relationship was stable, which showed that tree rings can be used as alternative materials for climate reconstruction. Therefore, the mean minimum temperature of the previous year in 1680–2012 was reconstructed, and the explained variance of the reconstruction equation was 62.7% (R2adj = 62.0%, F = 85.8). The 31 dramatically altered years were found via characteristic year analyses, and extreme changes occurred most often under relatively warm conditions. The mean minimum temperature in the reconstruction shows a clear warming trend by the 11-year moving average of the reconstructive series since the 1950s (the temperature increase: 0.341°C/decade). The driving factors of the mean minimum temperature were influenced mainly by the interaction of solar activity and large-scale atmospheric–oceanic variability, especially the westerly circulations.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43003154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Three quartz samples extracted from different origins were collected for ESR evaluation to appreciate the optical bleaching characteristics of the E1’ centre in a long time scale. After exposure of about 400 hours to artificial sunlight, the E1’ centre were bleached to a steady increasing level, about 2.5 times of its natural level, and the increase level also exhibit a small variability among different sample origins. The constant increasing level provide a significantly evidence for the potential use of the natural signal intensities of quartz E1’ centre in tracing sediment provenance. The results show that the signal intensity of E1’ centre increased within beginning 84 h and decreased after 202 h as previous researches have partly predicted. After long time exposed to sunlight, there is no correlation between irradiated samples’ dose rate and its E1’ centre ESR signal intensity. Thus, no new convenient indication shed light on the possible use of the E1’ centre for ESR sediment dating.
{"title":"Application of long time artificial optical bleaching of the E1’ centre to sediment ESR dating","authors":"Chuanyi Wei, Chun-ru Liu, Chang‐An Li, G. Yin, Yufen Zhang, Wenpeng Li, Lu-Peng Yu","doi":"10.1515/geochr-2015-0106","DOIUrl":"https://doi.org/10.1515/geochr-2015-0106","url":null,"abstract":"Abstract Three quartz samples extracted from different origins were collected for ESR evaluation to appreciate the optical bleaching characteristics of the E1’ centre in a long time scale. After exposure of about 400 hours to artificial sunlight, the E1’ centre were bleached to a steady increasing level, about 2.5 times of its natural level, and the increase level also exhibit a small variability among different sample origins. The constant increasing level provide a significantly evidence for the potential use of the natural signal intensities of quartz E1’ centre in tracing sediment provenance. The results show that the signal intensity of E1’ centre increased within beginning 84 h and decreased after 202 h as previous researches have partly predicted. After long time exposed to sunlight, there is no correlation between irradiated samples’ dose rate and its E1’ centre ESR signal intensity. Thus, no new convenient indication shed light on the possible use of the E1’ centre for ESR sediment dating.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48790740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1515/GEOCHR-2015-0108
Y. Shitaoka, T. Saito, J. Yamamoto, M. Miyoshi, H. Ishibashi, Tsutomu Soda
Abstract We estimated the eruption age of Kannabe volcano, located in southwestern Japan. Although the eruption age had been estimated using tephrochronology and K-Ar dating, the precision of its age determination left some room for improvement. The latest eruption age of Kannabe volcano is well constrained by wide spread tephras to ca. 7.2–30 ka. We applied paleomagnetic dating to a basaltic lava and optically stimulated luminescence (OSL) dating to a soil layer, which are associated with the Kannabe volcano. The soil layer above the Kannabe scoria was newly dated to be 21 ± 6 ka, as inferred from OSL dating. We also made paleomagnetic investigation to estimate the eruption age of the Kannabe basaltic lava. Paleomagnetic data of 23 rock samples from six locations in the Kannabe basaltic lava showed good mutual agreement. The average of remanent magnetizations yields declination of 0.3° and inclination of 65.9° with 95% confidence limit of 2.7°. This paleomagnetic direction with a relatively steep inclination is thought to be correlated with the paleomagnetic secular variation data of sediments in Lake Biwa at ca. 21.5 ka. Based on that information from multi-dating, we inferred that the Kannabe volcano erupted at ca. 22 ka. This result presents profound scientific implications for the precise age determination of young basaltic lava flow, for which few dating methods exist.
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