Pub Date : 2021-01-01DOI: 10.2478/geochr-2020-0036
T. Tamura, J. Komatsubara, S. Sugisaki, Naohisa Nishida
Abstract We assessed the residual dose of K-feldspar grains from modern and Holocene beach–shoreface sands at Kujukuri, eastern Japan. Samples from the modern foreshore and shoreface (to 34 m depth) show residual doses <0.2 Gy for infrared-stimulated luminescence (IR)50 measured during post-IR infrared-stimulated luminescence (pIRIR)50/150, equivalent to potential burial age overestimation of only several decades for given dose rates. Residual doses of 1–3 Gy are retained by pIRIR50/150, equivalent to 400–1,300 years; pIRIR50/290 residual doses are up to 30 Gy, suggesting possible overestimation by >10,000 years. Residual doses of Holocene sands were also assessed by comparison with radiocarbon ages, revealing consistent results with modern sands. The pIRIR50/290 results show no pronounced correlation of residual dose with water depth, except for a few samples from <5 m depth with residual doses several tens of per cent lower than those of deeper sands, suggesting that most samples were not fully bleached and that sustained subaerial sunlight bleaching diminishes the difficult-to-bleach component. Compared to the uncertainties associated with other factors, such as the fading correction, the residual doses of IR50 and pIRIR50/150 are negligible for samples older than late and early Holocene, respectively. In contrast, the residual dose of pIRIR50/290 may lead to critical age overestimation of Late Pleistocene deposits if the residual dose is not properly corrected.
{"title":"Residual Dose of K-Feldspar post-IR Irsl of Beach-Shoreface Sands at Kujukuri, Eastern Japan","authors":"T. Tamura, J. Komatsubara, S. Sugisaki, Naohisa Nishida","doi":"10.2478/geochr-2020-0036","DOIUrl":"https://doi.org/10.2478/geochr-2020-0036","url":null,"abstract":"Abstract We assessed the residual dose of K-feldspar grains from modern and Holocene beach–shoreface sands at Kujukuri, eastern Japan. Samples from the modern foreshore and shoreface (to 34 m depth) show residual doses <0.2 Gy for infrared-stimulated luminescence (IR)50 measured during post-IR infrared-stimulated luminescence (pIRIR)50/150, equivalent to potential burial age overestimation of only several decades for given dose rates. Residual doses of 1–3 Gy are retained by pIRIR50/150, equivalent to 400–1,300 years; pIRIR50/290 residual doses are up to 30 Gy, suggesting possible overestimation by >10,000 years. Residual doses of Holocene sands were also assessed by comparison with radiocarbon ages, revealing consistent results with modern sands. The pIRIR50/290 results show no pronounced correlation of residual dose with water depth, except for a few samples from <5 m depth with residual doses several tens of per cent lower than those of deeper sands, suggesting that most samples were not fully bleached and that sustained subaerial sunlight bleaching diminishes the difficult-to-bleach component. Compared to the uncertainties associated with other factors, such as the fading correction, the residual doses of IR50 and pIRIR50/150 are negligible for samples older than late and early Holocene, respectively. In contrast, the residual dose of pIRIR50/290 may lead to critical age overestimation of Late Pleistocene deposits if the residual dose is not properly corrected.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43277596","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 : 2021-01-01DOI: 10.2478/geochr-2020-0031
J. Nawrocki, K. Standzikowski, M. Łanczont, T. Werner, J. Gancarski, Z. Gil
Abstract A set of brick samples from 26 historical buildings in SE Poland was taken for archeomagnetic study. As a result of this study, the secular variations of inclination of the geomagnetic field from 1200 to 1800 AD were defined for SE Poland. The course of them is approximately the same as obtained in other parts of Europe. The only remarkable difference is a more rapid and deeper drop of inclination noted in SE Poland at the end of the 18th century. The regional curve of secular variations of inclination for SE Poland differs substantially from the coeval curve defined earlier for N Poland (Gdańsk) in their segments dated at the first half of the 18th century, where a deep minimum of inclination was disclosed in the bricks from N Poland only. The reuse of medieval bricks for the construction of objects giving this minimum or later secondary heating of original bricks can be a reason for the difference observed. Further archeomagnetic studies of the bricks of the last millennium are necessary in SE Poland to eliminate the gaps and uncertainties in the regional curve of secular variations of inclination.
{"title":"Secular Variations of Inclination of the Geomagnetic Field in SE Poland Between 1200 and 1800 AD","authors":"J. Nawrocki, K. Standzikowski, M. Łanczont, T. Werner, J. Gancarski, Z. Gil","doi":"10.2478/geochr-2020-0031","DOIUrl":"https://doi.org/10.2478/geochr-2020-0031","url":null,"abstract":"Abstract A set of brick samples from 26 historical buildings in SE Poland was taken for archeomagnetic study. As a result of this study, the secular variations of inclination of the geomagnetic field from 1200 to 1800 AD were defined for SE Poland. The course of them is approximately the same as obtained in other parts of Europe. The only remarkable difference is a more rapid and deeper drop of inclination noted in SE Poland at the end of the 18th century. The regional curve of secular variations of inclination for SE Poland differs substantially from the coeval curve defined earlier for N Poland (Gdańsk) in their segments dated at the first half of the 18th century, where a deep minimum of inclination was disclosed in the bricks from N Poland only. The reuse of medieval bricks for the construction of objects giving this minimum or later secondary heating of original bricks can be a reason for the difference observed. Further archeomagnetic studies of the bricks of the last millennium are necessary in SE Poland to eliminate the gaps and uncertainties in the regional curve of secular variations of inclination.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41325959","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 : 2021-01-01DOI: 10.2478/geochr-2021-0007
M. K. Murari, S. Kreutzer, M. Frouin, Johannes Friedrich, T. Lauer, N. Klasen, Christoph Schmidt, S. Tsukamoto, D. Richter, N. Mercier, M. Fuchs
Abstract Infrared Radiofluorescence (IR-RF) is a relatively new method for dosimetric dating of the depositional timing of sediments. This contribution presents an interlaboratory comparison of IR-RF measurements of sedimentary feldspar from eight laboratories. A comparison of the variability of instrumental background, bleaching, saturation, and initial rise behaviour of the IR-RF signal was carried out. Two endmember samples, a naturally bleached modern dune sand sample with a zero dose and a naturally saturated sample from a Triassic sandstone (~250 Ma), were used for this interlaboratory comparison. The major findings of this study are that (1) the observed IR-RF signal keeps decreasing beyond 4000 Gy, (2) the saturated sample gives an apparent palaeodose of 1265 ± 329 Gy and (3) in most cases, the natural IR-RF signal of the modern analogue sample (resulting from natural bleaching) is higher than the signal from laboratory-induced bleaching of 6 h, using a solar simulator (SLS). In other words, the laboratory sample bleaching was unable to achieve the level of natural bleaching. The results of the investigations are discussed in detail, along with possible explanations.
{"title":"Infrared Radiofluorescence (IR-RF) of K-Feldspar: An Interlaboratory Comparison","authors":"M. K. Murari, S. Kreutzer, M. Frouin, Johannes Friedrich, T. Lauer, N. Klasen, Christoph Schmidt, S. Tsukamoto, D. Richter, N. Mercier, M. Fuchs","doi":"10.2478/geochr-2021-0007","DOIUrl":"https://doi.org/10.2478/geochr-2021-0007","url":null,"abstract":"Abstract Infrared Radiofluorescence (IR-RF) is a relatively new method for dosimetric dating of the depositional timing of sediments. This contribution presents an interlaboratory comparison of IR-RF measurements of sedimentary feldspar from eight laboratories. A comparison of the variability of instrumental background, bleaching, saturation, and initial rise behaviour of the IR-RF signal was carried out. Two endmember samples, a naturally bleached modern dune sand sample with a zero dose and a naturally saturated sample from a Triassic sandstone (~250 Ma), were used for this interlaboratory comparison. The major findings of this study are that (1) the observed IR-RF signal keeps decreasing beyond 4000 Gy, (2) the saturated sample gives an apparent palaeodose of 1265 ± 329 Gy and (3) in most cases, the natural IR-RF signal of the modern analogue sample (resulting from natural bleaching) is higher than the signal from laboratory-induced bleaching of 6 h, using a solar simulator (SLS). In other words, the laboratory sample bleaching was unable to achieve the level of natural bleaching. The results of the investigations are discussed in detail, along with possible explanations.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45414441","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 : 2021-01-01DOI: 10.2478/geochr-2020-0040
Chuanyi Wei, Chun-ru Liu, G. Yin, Wenpeng Li
Abstract To assess if the heat-treated E1′ centre in quartz is suitable for fluvial sediment provenance tracing, eight granitic samples from sediments and their source rocks with distinct geological ages and origins were collected for electron spin resonance (ESR) measurements. The results show that the maximum heat-treated E1′ signal intensity of quartz in the fluvial sediments occurs upon heating at about 300°C, as previously observed in aeolian quartz. The heat-treated E1′ signal intensity of quartz in sediment samples also shows significant correspondence to those of their source rocks as well as their formation age. We propose that the heat-treated E1′ centre of sedimentary quartz, combined with other lithological discrimination parameters, could serve as an effective indicator for fluvial sediment provenance tracing.
{"title":"Electron Spin Resonance (ESR) Signal Intensity of Quartz E1′ Centre and Its Potential Use in Fluvial Sediments Provenance Tracing","authors":"Chuanyi Wei, Chun-ru Liu, G. Yin, Wenpeng Li","doi":"10.2478/geochr-2020-0040","DOIUrl":"https://doi.org/10.2478/geochr-2020-0040","url":null,"abstract":"Abstract To assess if the heat-treated E1′ centre in quartz is suitable for fluvial sediment provenance tracing, eight granitic samples from sediments and their source rocks with distinct geological ages and origins were collected for electron spin resonance (ESR) measurements. The results show that the maximum heat-treated E1′ signal intensity of quartz in the fluvial sediments occurs upon heating at about 300°C, as previously observed in aeolian quartz. The heat-treated E1′ signal intensity of quartz in sediment samples also shows significant correspondence to those of their source rocks as well as their formation age. We propose that the heat-treated E1′ centre of sedimentary quartz, combined with other lithological discrimination parameters, could serve as an effective indicator for fluvial sediment provenance tracing.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48430216","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 There are still controversies for the lakes evolution time during late Pleistocene in arid/semiarid north China. Badain Jaran Desert (BJD) features the coexisting of modern lakes in the lowland of megadunes. Also, lots of lacustrine relics could be found distributed widely in the desert, some of them just beside the modern lakes. These lacustrine relics indicated the paleo lakes evolution and the paleo environmental changes in the desert. In this study, one 3.9 m depth lacustrine deposits section was studied in the southeastern BJD which is close to a modern lake Zongzegedan (ZZGD). The deposit ages of the section were obtained by using optical dating with both of quartz and K-feldspar grains. Optically stimulated luminescence (OSL) dating of quartz grains shows that this paleolake was appeared during 65–34 ka, which is in the Marine Isotope Stage (MIS) 3 period, without the saturation of the OSL signals. On the other hand, the high temperature infrared stimulated luminescence (pIR IRSL) dating results from K-feldspar grains show that the paleolake was existed from late MIS 5 to late MIS 4 (86–60 ka) period with also good luminescence characteristics. The further study suggested that the OSL signals from quartz grains in this section show thermal instability, which may lead to the age underestimation. So the reliable age of the existed paleolake should be obtained by using pIRIR signals from K-feldspar, indicated that the relative humid environment in the desert happened at late MIS 5. The paleolake has same position with modern lake in the desert may contain geomorphological indications.
{"title":"Luminescence Dating of Late Pleistocene Lacustrine Deposits in Badain Jaran Desert, North China","authors":"Hui Zhao, Xinfan Wang, Hongyu Yang, Keqi Wang, Jianwei Geng","doi":"10.2478/geochr-2020-0032","DOIUrl":"https://doi.org/10.2478/geochr-2020-0032","url":null,"abstract":"Abstract There are still controversies for the lakes evolution time during late Pleistocene in arid/semiarid north China. Badain Jaran Desert (BJD) features the coexisting of modern lakes in the lowland of megadunes. Also, lots of lacustrine relics could be found distributed widely in the desert, some of them just beside the modern lakes. These lacustrine relics indicated the paleo lakes evolution and the paleo environmental changes in the desert. In this study, one 3.9 m depth lacustrine deposits section was studied in the southeastern BJD which is close to a modern lake Zongzegedan (ZZGD). The deposit ages of the section were obtained by using optical dating with both of quartz and K-feldspar grains. Optically stimulated luminescence (OSL) dating of quartz grains shows that this paleolake was appeared during 65–34 ka, which is in the Marine Isotope Stage (MIS) 3 period, without the saturation of the OSL signals. On the other hand, the high temperature infrared stimulated luminescence (pIR IRSL) dating results from K-feldspar grains show that the paleolake was existed from late MIS 5 to late MIS 4 (86–60 ka) period with also good luminescence characteristics. The further study suggested that the OSL signals from quartz grains in this section show thermal instability, which may lead to the age underestimation. So the reliable age of the existed paleolake should be obtained by using pIRIR signals from K-feldspar, indicated that the relative humid environment in the desert happened at late MIS 5. The paleolake has same position with modern lake in the desert may contain geomorphological indications.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49084315","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 : 2021-01-01DOI: 10.2478/geochr-2021-0006
Laine Clark-Balzan, Venera R. May, F. Preusser
Abstract Olivine has so far attracted limited attention as a potential luminescence dosimeter. In particular, there is a dearth of information concerning the luminescence properties of geochemically characterised, pure olivine samples. Six well-characterised olivine samples from four intraplate settings are investigated in this study, including emission wavelengths and intensities, growth of signal with absorbed dose, signal stability and recovery of a given dose with a single aliquot regeneration (SAR) protocol. All tested olivines share a low-temperature (90–100°C) UV/blue thermoluminescence (TL) peak, and five of six samples also produce a low-temperature red/yellow emission. Higher temperature TL peaks, which would be thermally stable over geological timescales and could be used for dating, are rarely observed at low doses (c. 46 Gy), but detectable though dim at significantly higher doses (c. 460 Gy). Photostimulated luminescence (PSL) emissions are very dim, but reliably detected emissions are stimulated by blue, yellow and infrared (IR) light. PSL yielded generally successful dose recovery results; however, all tested signals are prone to significant anomalous fading and complex thermal transfer between unbleachable and bleachable traps. These characteristics must be addressed if olivine is to be used as a natural dosimeter for luminescence dating. Given the variety of luminescence responses, it appears that olivine samples in future dating work may need to be individually characterised prior to measurement.
{"title":"Luminescence Characteristics of Intraplate-Derived Olivines","authors":"Laine Clark-Balzan, Venera R. May, F. Preusser","doi":"10.2478/geochr-2021-0006","DOIUrl":"https://doi.org/10.2478/geochr-2021-0006","url":null,"abstract":"Abstract Olivine has so far attracted limited attention as a potential luminescence dosimeter. In particular, there is a dearth of information concerning the luminescence properties of geochemically characterised, pure olivine samples. Six well-characterised olivine samples from four intraplate settings are investigated in this study, including emission wavelengths and intensities, growth of signal with absorbed dose, signal stability and recovery of a given dose with a single aliquot regeneration (SAR) protocol. All tested olivines share a low-temperature (90–100°C) UV/blue thermoluminescence (TL) peak, and five of six samples also produce a low-temperature red/yellow emission. Higher temperature TL peaks, which would be thermally stable over geological timescales and could be used for dating, are rarely observed at low doses (c. 46 Gy), but detectable though dim at significantly higher doses (c. 460 Gy). Photostimulated luminescence (PSL) emissions are very dim, but reliably detected emissions are stimulated by blue, yellow and infrared (IR) light. PSL yielded generally successful dose recovery results; however, all tested signals are prone to significant anomalous fading and complex thermal transfer between unbleachable and bleachable traps. These characteristics must be addressed if olivine is to be used as a natural dosimeter for luminescence dating. Given the variety of luminescence responses, it appears that olivine samples in future dating work may need to be individually characterised prior to measurement.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44842180","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 : 2021-01-01DOI: 10.2478/geochr-2021-0003
G. Sipos, Christoph Schmidt, Tamás Bartyik, Dávid Filyó, Gergő Magyar, V. Havasi, Á. Kukovecz
Abstract In terms of fine-grain luminescence dating applications, the efficiency of α-radiation in producing luminescence is an important issue when determining environmental dose rates. Efficiency is usually assessed by measuring the ratio of luminescence intensities induced by known α and β laboratory doses. Consequently, most thermoluminescence (TL)/optically stimulated luminescence (OSL) readers besides the standard 90Sr/90Y β-source can also be equipped with a 241Am α-source. A crucial point is, however, the calibration of these sources. The calibration of β-sources is routinely performed using standard quartz samples previously irradiated by a known γ-dose, though, in the case of α-sources, the procedure is less standardised, partly because there are no calibration materials with a known α-efficiency value. In this study, we aimed to cross-calibrate the built-in α-source of a RISØ TL/OSL DA-20 luminescence reader by testing and comparing five procedures, applying different samples (quartz and polymineral), different protocols multiple aliquot regeneration (MAR) and single aliquot regeneration (SAR) and different calibration sources. Throughout the tests, the performance of the fine-grain RISØ calibration quartz was also assessed. Regardless of the applied procedure, the calculated α-dose rates with one exception gave similar results. On the one hand, the applied polymineral sample due to potential fading, fairly high residuals after bleaching and relatively low infrared stimulated luminescence (IRSL) sensitivity proved to be the least optimal choice for cross-calibration. On the other hand, the tested natural fine grain quartz gave almost identical results when using different types of bleaching and different calibration α-sources. The mean dose rate determined for the source was 0.080 ± 0.004 Gy/s. The cross-calibration by using the RISØ fine grain quartz yielded somewhat higher but at the apparent uncertainty of luminescence dating still not significantly different dose rate for the source under calibration. Tests showed that the calibration quartz saturates at a relatively low α-dose, and the shape of α- and β-dose-response curves also depart from each other quite early, suggesting that cross-calibration with this material seems to be reliable only at low doses. For the first time, the a-value of the fine-grain calibration quartz was also determined using the freshly calibrated α-source, and the measurement yielded a 0.054 ± 0.003 value. We propose that after further validation of this result, the RISØ calibration quartz can ease the dose rate assessment of uncalibrated α-sources in the future.
{"title":"Cross-Calibration of an α-Source Used for Luminescence Dating by Applying Different Samples and Procedures","authors":"G. Sipos, Christoph Schmidt, Tamás Bartyik, Dávid Filyó, Gergő Magyar, V. Havasi, Á. Kukovecz","doi":"10.2478/geochr-2021-0003","DOIUrl":"https://doi.org/10.2478/geochr-2021-0003","url":null,"abstract":"Abstract In terms of fine-grain luminescence dating applications, the efficiency of α-radiation in producing luminescence is an important issue when determining environmental dose rates. Efficiency is usually assessed by measuring the ratio of luminescence intensities induced by known α and β laboratory doses. Consequently, most thermoluminescence (TL)/optically stimulated luminescence (OSL) readers besides the standard 90Sr/90Y β-source can also be equipped with a 241Am α-source. A crucial point is, however, the calibration of these sources. The calibration of β-sources is routinely performed using standard quartz samples previously irradiated by a known γ-dose, though, in the case of α-sources, the procedure is less standardised, partly because there are no calibration materials with a known α-efficiency value. In this study, we aimed to cross-calibrate the built-in α-source of a RISØ TL/OSL DA-20 luminescence reader by testing and comparing five procedures, applying different samples (quartz and polymineral), different protocols multiple aliquot regeneration (MAR) and single aliquot regeneration (SAR) and different calibration sources. Throughout the tests, the performance of the fine-grain RISØ calibration quartz was also assessed. Regardless of the applied procedure, the calculated α-dose rates with one exception gave similar results. On the one hand, the applied polymineral sample due to potential fading, fairly high residuals after bleaching and relatively low infrared stimulated luminescence (IRSL) sensitivity proved to be the least optimal choice for cross-calibration. On the other hand, the tested natural fine grain quartz gave almost identical results when using different types of bleaching and different calibration α-sources. The mean dose rate determined for the source was 0.080 ± 0.004 Gy/s. The cross-calibration by using the RISØ fine grain quartz yielded somewhat higher but at the apparent uncertainty of luminescence dating still not significantly different dose rate for the source under calibration. Tests showed that the calibration quartz saturates at a relatively low α-dose, and the shape of α- and β-dose-response curves also depart from each other quite early, suggesting that cross-calibration with this material seems to be reliable only at low doses. For the first time, the a-value of the fine-grain calibration quartz was also determined using the freshly calibrated α-source, and the measurement yielded a 0.054 ± 0.003 value. We propose that after further validation of this result, the RISØ calibration quartz can ease the dose rate assessment of uncalibrated α-sources in the future.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43944214","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 : 2021-01-01DOI: 10.2478/geochr-2020-0038
J. Qin, Jie Chen, Ke-chang Li
Abstract The post-infrared (post-IR) pulsed blue light stimulated luminescence (PBLSL) signal has been employed to determine the equivalent dose (De) of feldspar contaminated quartz grains, but it sometimes suffers from the interference of feldspars. Since the green light stimulated luminescence (GLSL) signal of feldspars might be more reduced by a prior IR stimulation, we compared the characteristics of post-IR PBLSL and post-IR pulsed GLSL (post-IR PGLSL) signals of quartz and feldspars in this study to evaluate the feasibility of employing the green light for pulsed stimulation. We investigated the effect of the signal integration period, pulsed stimulation temperature, and prior IR stimulation temperature on the intensities of post-IR PBLSL and post-IR PGLSL of quartz and feldspars, and evaluated the potential feldspar interference on these two signals for the hypothetical and artificial quartz-feldspar mixture. The results demonstrate a lower feldspars contribution for the post-IR PGLSL signal. The feldspar interference only slightly increases with the increase of integration period for the post-IR PGLSL signal measured at low stimulation temperature, which permits a long integration period to be employed to enhance the signal to noise ratio. This study shows that the green light is a promising alternative for pulsed stimulation to suppress the feldspar contribution.
{"title":"Characteristics of Pulsed Blue and Green Light Stimulated Luminescence Signals of Quartz and Feldspars","authors":"J. Qin, Jie Chen, Ke-chang Li","doi":"10.2478/geochr-2020-0038","DOIUrl":"https://doi.org/10.2478/geochr-2020-0038","url":null,"abstract":"Abstract The post-infrared (post-IR) pulsed blue light stimulated luminescence (PBLSL) signal has been employed to determine the equivalent dose (De) of feldspar contaminated quartz grains, but it sometimes suffers from the interference of feldspars. Since the green light stimulated luminescence (GLSL) signal of feldspars might be more reduced by a prior IR stimulation, we compared the characteristics of post-IR PBLSL and post-IR pulsed GLSL (post-IR PGLSL) signals of quartz and feldspars in this study to evaluate the feasibility of employing the green light for pulsed stimulation. We investigated the effect of the signal integration period, pulsed stimulation temperature, and prior IR stimulation temperature on the intensities of post-IR PBLSL and post-IR PGLSL of quartz and feldspars, and evaluated the potential feldspar interference on these two signals for the hypothetical and artificial quartz-feldspar mixture. The results demonstrate a lower feldspars contribution for the post-IR PGLSL signal. The feldspar interference only slightly increases with the increase of integration period for the post-IR PGLSL signal measured at low stimulation temperature, which permits a long integration period to be employed to enhance the signal to noise ratio. This study shows that the green light is a promising alternative for pulsed stimulation to suppress the feldspar contribution.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47624401","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 : 2020-07-31DOI: 10.2478/geochr-2020-0008
Yand Yan, Jia-Fu Zhang, G. Hu, Liping Zhou
Abstract The precise chronology of the fluvial terraces of the Yellow River in China is essential to understand its geomorphological evolution history. More terrace ages are needed for the correlation of the terraces along the river and the construction of the longitudinal profile. In this study, seven terraces (T1–T7) in the Heiyukou area of the Jinshaan Canyon of the river were identified and were sampled for optical dating. The reliability of the ages was evaluated on the bases of bleachability, comparison of optical ages on fine and coarse grains, stratigraphic consistency of OSL ages, age distribution and geomorphological setting. The results show that the paired T2 terrace was formed at 72 ± 3 ka, and the T4, T5 strath terraces were dated to 108 ± 4 and >141 ± 4 ka, respectively. The ages for the samples from T6 and T7 were significantly underestimated, and the ‘infinitely old’ pre-Quaternary Red-Clay sample on the T7 terrace was dated to 134 ± 6 ka. The long-term river incision rates were calculated to be <0.36, 0.34 and 0.18 mm/a for at least the past 141, 108 and 72 ka, respectively, which also reflect the uplift rates of the Ordos plateau. The implication for dating terrace deposits is that terraces should be systemically sampled and dated using both fine and coarse grain fractions. The reliability of the ages obtained for high terraces should be evaluated using a relative chronology of dated samples on a case-by-case basis, if no independent numerical age controls are available.
黄河河流阶地的精确年代学对了解其地貌演化历史至关重要。沿河阶地的对比和纵剖面的构建需要更多的阶地年代。本文对金山河峡谷黑峪口地区的7个阶地(t1 ~ t7)进行了鉴定，并进行了光学测年。根据可漂白性、细粒和粗粒光学年龄对比、OSL年龄的地层一致性、年龄分布和地貌背景对年龄的可靠性进行了评价。结果表明，配对的T2阶地形成于72±3 ka, T4、T5阶地形成于108±4 ka和>141±4 ka。T6和T7阶地样品的年龄被明显低估，T7阶地的“无限老”前第四纪红粘土样品的年龄为134±6 ka。至少在过去141、108和72 ka，河流切割速率分别<0.36、0.34和0.18 mm/a，这也反映了鄂尔多斯高原的隆升速率。对阶地沉积物定年的启示是，阶地应该用细粒和粗粒组分系统地取样和定年。如果没有独立的数字年龄控制，高阶地年龄的可靠性应该在个案的基础上，使用年代样本的相对年表来评估。
{"title":"Luminescence Chronology of the Yellow River Terraces in the Heiyukou Area, China, and Its Implication for the Uplift Rate of the Ordos Plateau","authors":"Yand Yan, Jia-Fu Zhang, G. Hu, Liping Zhou","doi":"10.2478/geochr-2020-0008","DOIUrl":"https://doi.org/10.2478/geochr-2020-0008","url":null,"abstract":"Abstract The precise chronology of the fluvial terraces of the Yellow River in China is essential to understand its geomorphological evolution history. More terrace ages are needed for the correlation of the terraces along the river and the construction of the longitudinal profile. In this study, seven terraces (T1–T7) in the Heiyukou area of the Jinshaan Canyon of the river were identified and were sampled for optical dating. The reliability of the ages was evaluated on the bases of bleachability, comparison of optical ages on fine and coarse grains, stratigraphic consistency of OSL ages, age distribution and geomorphological setting. The results show that the paired T2 terrace was formed at 72 ± 3 ka, and the T4, T5 strath terraces were dated to 108 ± 4 and >141 ± 4 ka, respectively. The ages for the samples from T6 and T7 were significantly underestimated, and the ‘infinitely old’ pre-Quaternary Red-Clay sample on the T7 terrace was dated to 134 ± 6 ka. The long-term river incision rates were calculated to be <0.36, 0.34 and 0.18 mm/a for at least the past 141, 108 and 72 ka, respectively, which also reflect the uplift rates of the Ordos plateau. The implication for dating terrace deposits is that terraces should be systemically sampled and dated using both fine and coarse grain fractions. The reliability of the ages obtained for high terraces should be evaluated using a relative chronology of dated samples on a case-by-case basis, if no independent numerical age controls are available.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2020-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44621992","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 : 2020-07-22DOI: 10.1515/geochr-2015-0117
S. Tengis, S. Solongo, Rinchinkhorol Munkhtulga
Abstract This study presents single-grain optically stimulated luminescence (OSL) results from pottery and sediments from the archaeological site “The burials in Khutag Uul Mountains (Mongolia)”. A global fitting procedure was used on a selection of single grains from pottery, D0 values obtained were between 16 to 40 Gy and 25 to 82 Gy and the equivalent doses De ranged from ∼8 to 12 Gy and from 4.2 ± 0.4 Gy to 37.3 ± 2.5 Gy for pottery and sedimentary quartz, correspondingly. For pottery, the relative spread in CAM De values increases as higher precision constraints are applied and lead to significant increases in the relative standard error from 2.7% to ∼7.5%. The number of accepted grains which passed acceptance criteria reduced from 180 to 65. For sedimentary quartz, there is a trend observed that both MAM De and FMM De values increase as higher precision in De is applied, and the number of accepted grains reduces from 146 to 53. The detailed study of the OSL decay curves identified an ultrafast OSL component with the decay rates of 53 ± 1 s−1 in addition to the fast and medium components and its effect on De was examined.
{"title":"Ultrafast Component Effects on Quartz Single Grains Dose Estimation from Khutagt Uul Mountains, Mongolia","authors":"S. Tengis, S. Solongo, Rinchinkhorol Munkhtulga","doi":"10.1515/geochr-2015-0117","DOIUrl":"https://doi.org/10.1515/geochr-2015-0117","url":null,"abstract":"Abstract This study presents single-grain optically stimulated luminescence (OSL) results from pottery and sediments from the archaeological site “The burials in Khutag Uul Mountains (Mongolia)”. A global fitting procedure was used on a selection of single grains from pottery, D0 values obtained were between 16 to 40 Gy and 25 to 82 Gy and the equivalent doses De ranged from ∼8 to 12 Gy and from 4.2 ± 0.4 Gy to 37.3 ± 2.5 Gy for pottery and sedimentary quartz, correspondingly. For pottery, the relative spread in CAM De values increases as higher precision constraints are applied and lead to significant increases in the relative standard error from 2.7% to ∼7.5%. The number of accepted grains which passed acceptance criteria reduced from 180 to 65. For sedimentary quartz, there is a trend observed that both MAM De and FMM De values increase as higher precision in De is applied, and the number of accepted grains reduces from 146 to 53. The detailed study of the OSL decay curves identified an ultrafast OSL component with the decay rates of 53 ± 1 s−1 in addition to the fast and medium components and its effect on De was examined.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2020-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45920686","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}
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：