Pub Date : 2018-06-02DOI: 10.1515/geochr-2015-0091
Tongwen Zhang, Ruibo Zhang, Bo Lu, B. Mambetov, Nurzhan Kelgenbayev, D. Dosmanbetov, Bagila Maisupova, Feng Chen, Shulong Yu, Huaming Shang, Liping Huang
Abstract In this study, a total of 176 tree cores from Schrenk spruce (Picea schrenkiana) were used to establish a tree-ring chronology and a 167-year July–October normalized differential vegetation index (NDVI) for the Alatau Mountains in Central Asia was reconstructed using this newly developed chronology. The tree-ring based NDVI reconstruction tracks the observed data well (r=0.577, p<0.01, n=25) and precisely captures the drought events recorded in historical documents that occurred over a large area in 1917 and 1938. After applying a 21-year moving average, three dense (1860–1870, 1891–1907, and 1950–1974) and three sparse (1871–1890, 1908–1949, and 1975–2006) vegetation coverage periods were found in this reconstruction. Spatial correlation proves that the reconstructed NDVI series contains climatic signals representative for a large area including southern Kazakhstan. Although a comparison between this reconstruction and four climatic reconstructions for southeastern Kazakhstan, Nilka (in the Ili region), the Issyk Lake, and the Aksu region reveals similar variations, the coherence between these reconstructions become weak with the increase in spatial distance from north to south. In addition to the local representation, it was also demonstrated that the newly developed NDVI index can indicate the large-scale circulations over Eurasia, with the higher NDVI associated with stronger westerly winds from the Atlantic to the Alatau Mountains, and the lower NDVI associated with the weaker winds.
{"title":"Picea schrenkiana tree-ring chronologies development and vegetation index reconstruction for the Alatau Mountains, Central Asia","authors":"Tongwen Zhang, Ruibo Zhang, Bo Lu, B. Mambetov, Nurzhan Kelgenbayev, D. Dosmanbetov, Bagila Maisupova, Feng Chen, Shulong Yu, Huaming Shang, Liping Huang","doi":"10.1515/geochr-2015-0091","DOIUrl":"https://doi.org/10.1515/geochr-2015-0091","url":null,"abstract":"Abstract In this study, a total of 176 tree cores from Schrenk spruce (Picea schrenkiana) were used to establish a tree-ring chronology and a 167-year July–October normalized differential vegetation index (NDVI) for the Alatau Mountains in Central Asia was reconstructed using this newly developed chronology. The tree-ring based NDVI reconstruction tracks the observed data well (r=0.577, p<0.01, n=25) and precisely captures the drought events recorded in historical documents that occurred over a large area in 1917 and 1938. After applying a 21-year moving average, three dense (1860–1870, 1891–1907, and 1950–1974) and three sparse (1871–1890, 1908–1949, and 1975–2006) vegetation coverage periods were found in this reconstruction. Spatial correlation proves that the reconstructed NDVI series contains climatic signals representative for a large area including southern Kazakhstan. Although a comparison between this reconstruction and four climatic reconstructions for southeastern Kazakhstan, Nilka (in the Ili region), the Issyk Lake, and the Aksu region reveals similar variations, the coherence between these reconstructions become weak with the increase in spatial distance from north to south. In addition to the local representation, it was also demonstrated that the newly developed NDVI index can indicate the large-scale circulations over Eurasia, with the higher NDVI associated with stronger westerly winds from the Atlantic to the Alatau Mountains, and the lower NDVI associated with the weaker winds.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":"45 1","pages":"107 - 118"},"PeriodicalIF":1.2,"publicationDate":"2018-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46562915","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 : 2018-05-08DOI: 10.1515/geochr-2015-0090
R. Begy, S. Kelemen, H. Simon, C. Tănăselia
Abstract The aim of this study was to investigate the effects of the Iron Gates (IG) hydroelectric power station on the Danube Delta sediment dynamics, and to assess the heavy metal concentrations and pollution in a typical Central Danube Deltaic lake. Eight sediment cores were analysed. The total 210Pb content was measured with 210Po using alpha spectrometry, and the supported 210Pb (226Ra) and 137Cs were measured by gamma spectrometry. The age depth model was derived by applying the 210Pb dating method, and for the calculation of the ages and the sedimentation rates the CRS model was used. The sedimentation rates can be divided into four periods:1940–1972, 1972–1980, 1972–1989 and 1989–2013. In the case of Lake Iacob in the first period, the average sedimentation rate was 0.418 g/cm2y, while in the second it slowly decreased to 0.376 g/cm2y. In the third period, the sedimentation fell to 0.209 g/cm2y, which means the retention of 27.3% of the sediment by the IG dam. In the case of Lake Isac the changes were more visible: in the first period the average sedimentation rate was 0.446 g/cm2y, while in the second it decreased to 0.197 g/cm2y, which means a 42.35% retention of sediment. In the last period, in both cases, a high increase in the sedimentation rate is shown: 0.677 g/cm2y for Lake Iacob and 0.715 g/cm2y for Lake Isac. The heavy-metal concentrations for As, Co, Cr and Ni show decreasing and Hg increasing tendencies, while Cd and Pb show constant values of 310 ± 12 ppb and 9 ± 1 ppm respectively.
{"title":"The history of the sedimentation processes and heavy metal pollution in the Central Danube Delta (Romania)","authors":"R. Begy, S. Kelemen, H. Simon, C. Tănăselia","doi":"10.1515/geochr-2015-0090","DOIUrl":"https://doi.org/10.1515/geochr-2015-0090","url":null,"abstract":"Abstract The aim of this study was to investigate the effects of the Iron Gates (IG) hydroelectric power station on the Danube Delta sediment dynamics, and to assess the heavy metal concentrations and pollution in a typical Central Danube Deltaic lake. Eight sediment cores were analysed. The total 210Pb content was measured with 210Po using alpha spectrometry, and the supported 210Pb (226Ra) and 137Cs were measured by gamma spectrometry. The age depth model was derived by applying the 210Pb dating method, and for the calculation of the ages and the sedimentation rates the CRS model was used. The sedimentation rates can be divided into four periods:1940–1972, 1972–1980, 1972–1989 and 1989–2013. In the case of Lake Iacob in the first period, the average sedimentation rate was 0.418 g/cm2y, while in the second it slowly decreased to 0.376 g/cm2y. In the third period, the sedimentation fell to 0.209 g/cm2y, which means the retention of 27.3% of the sediment by the IG dam. In the case of Lake Isac the changes were more visible: in the first period the average sedimentation rate was 0.446 g/cm2y, while in the second it decreased to 0.197 g/cm2y, which means a 42.35% retention of sediment. In the last period, in both cases, a high increase in the sedimentation rate is shown: 0.677 g/cm2y for Lake Iacob and 0.715 g/cm2y for Lake Isac. The heavy-metal concentrations for As, Co, Cr and Ni show decreasing and Hg increasing tendencies, while Cd and Pb show constant values of 310 ± 12 ppb and 9 ± 1 ppm respectively.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":"45 1","pages":"106 - 97"},"PeriodicalIF":1.2,"publicationDate":"2018-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43580653","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 : 2018-04-10DOI: 10.1515/geochr-2015-0087
Fuqiang Li, B. Pan, Z. Lai, Hongshan Gao, Xianjiao Ou
Abstract The partial bleaching of the luminescence signal prior to deposition results in age overestimation, and can be a problem in delineating fluvial evolution within an OSL chronological framework. The Inner Mongolian reaches of the Yellow River are characterised by a high sediment load and complex sources of sediments. To test the incomplete bleaching occurring in this type of environment, the residual doses and the luminescence signal characteristics of different particle size fractions from 14 modern fluvial sediment samples were investigated. Furthermore, 26 OSL ages derived from drilling cores were compared with 11 radiocarbon ages. Our results show that the residual equivalent doses principally range between 0.16 and 0.49 Gy for silt grains, and between 0.35 and 3.72 Gy for sand grains of modern samples. This suggests that medium-grained quartz has been well bleached prior to deposition, and is preferable to coarse-grained quartz when dating fluvial sediments in this region. The results also show that the De values of coarse-grained fractions display a stronger correlation with distance downstream. In addition, a comparison of OSL and radiocarbon ages from drilling cores establishes further confidence that any initial bleaching of these sediments was sufficient. As a result, we believe that the studied fluvial samples were well bleached prior to deposition.
{"title":"Identifying the degree of luminescence signal bleaching in fluvial sediments from the Inner Mongolian reaches of the Yellow River","authors":"Fuqiang Li, B. Pan, Z. Lai, Hongshan Gao, Xianjiao Ou","doi":"10.1515/geochr-2015-0087","DOIUrl":"https://doi.org/10.1515/geochr-2015-0087","url":null,"abstract":"Abstract The partial bleaching of the luminescence signal prior to deposition results in age overestimation, and can be a problem in delineating fluvial evolution within an OSL chronological framework. The Inner Mongolian reaches of the Yellow River are characterised by a high sediment load and complex sources of sediments. To test the incomplete bleaching occurring in this type of environment, the residual doses and the luminescence signal characteristics of different particle size fractions from 14 modern fluvial sediment samples were investigated. Furthermore, 26 OSL ages derived from drilling cores were compared with 11 radiocarbon ages. Our results show that the residual equivalent doses principally range between 0.16 and 0.49 Gy for silt grains, and between 0.35 and 3.72 Gy for sand grains of modern samples. This suggests that medium-grained quartz has been well bleached prior to deposition, and is preferable to coarse-grained quartz when dating fluvial sediments in this region. The results also show that the De values of coarse-grained fractions display a stronger correlation with distance downstream. In addition, a comparison of OSL and radiocarbon ages from drilling cores establishes further confidence that any initial bleaching of these sediments was sufficient. As a result, we believe that the studied fluvial samples were well bleached prior to deposition.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":"45 1","pages":"82 - 96"},"PeriodicalIF":1.2,"publicationDate":"2018-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49593829","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 : 2018-03-20DOI: 10.1515/geochr-2015-0088
P. Moska, W. Stankowski, G. Poręba
Abstract Geological materials used for luminescence dating and associated with the fall of meteorites on the Earth’s surface are extremely rare. The Morasko region has gained fame over the past 100 years because of a cosmic catastrophe which took place there. After thousands of years, the remains of a large metal meteorite which fell in this area have been found. In this article, we would like to state whether it is possible, using luminescence methods, to determine the moment when the iron meteorite fell on the surface of the Earth. The material which was analysed consisted of meteorite crust layers – melt/fusion and “semi melt/fusion”, including sintered ones, along with the sediments surrounding the meteorite. The final results are connected with four objects of different sizes (large ones and small shrapnel – 261 kg, 34 kg, 970 g and 690 g). The obtained results show a large discrepancy, which is most likely associated with the problem of resetting the luminescence signal of the tested materials.
{"title":"Optically stimulated luminescence techniques applied to the dating of the fall of meteorites in Morasko","authors":"P. Moska, W. Stankowski, G. Poręba","doi":"10.1515/geochr-2015-0088","DOIUrl":"https://doi.org/10.1515/geochr-2015-0088","url":null,"abstract":"Abstract Geological materials used for luminescence dating and associated with the fall of meteorites on the Earth’s surface are extremely rare. The Morasko region has gained fame over the past 100 years because of a cosmic catastrophe which took place there. After thousands of years, the remains of a large metal meteorite which fell in this area have been found. In this article, we would like to state whether it is possible, using luminescence methods, to determine the moment when the iron meteorite fell on the surface of the Earth. The material which was analysed consisted of meteorite crust layers – melt/fusion and “semi melt/fusion”, including sintered ones, along with the sediments surrounding the meteorite. The final results are connected with four objects of different sizes (large ones and small shrapnel – 261 kg, 34 kg, 970 g and 690 g). The obtained results show a large discrepancy, which is most likely associated with the problem of resetting the luminescence signal of the tested materials.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":"45 1","pages":"74 - 81"},"PeriodicalIF":1.2,"publicationDate":"2018-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44020510","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 : 2018-02-21DOI: 10.1515/geochr-2015-0080
R. Baydoun, O. Samad, B. Nsouli, G. Younes
Abstract The radiocarbon laboratory at the Lebanese Atomic Energy Commission is undertaking environmental studies, in order to determine the anthropogenic impact of technologies on the ecosystem through the determination of radiocarbon content in tree leaves and plants. Thus, it was important to validate the method used to demonstrate that the applied procedure gives reliable results. Method validation is universally applied in analytical laboratories as an essential part of quality assurance system and as a basic technical requirement of the ISO 17025 standard. The conventional method used for determination of Fraction Modern (F14C) is a standard method issued by the American Society for Testing and Materials in 2011 with a code ASTM-D 6866-11 Method C. According to Eurachem guide, internal validation was expressed in terms of accuracy that was evaluated by trueness and precision. Trueness was expressed in terms of relative bias, while for precision ten consecutive replicates were carried out to under repeatability conditions and five duplicates were analyzed under reproducibility conditions. The limit of detection and the minimum detectable activity (MDA) were calculated. Uncertainty sources were defined and their relative standard uncertainties were calculated in order to determine the combined standard uncertainty. Five reference samples of different matrices were analyzed; calculated z score values were acceptable as being between –2 and +2. The calculation and results are presented in this work.
{"title":"Method validation for the determination of fraction of modern (F14C) in wood samples using conventional method","authors":"R. Baydoun, O. Samad, B. Nsouli, G. Younes","doi":"10.1515/geochr-2015-0080","DOIUrl":"https://doi.org/10.1515/geochr-2015-0080","url":null,"abstract":"Abstract The radiocarbon laboratory at the Lebanese Atomic Energy Commission is undertaking environmental studies, in order to determine the anthropogenic impact of technologies on the ecosystem through the determination of radiocarbon content in tree leaves and plants. Thus, it was important to validate the method used to demonstrate that the applied procedure gives reliable results. Method validation is universally applied in analytical laboratories as an essential part of quality assurance system and as a basic technical requirement of the ISO 17025 standard. The conventional method used for determination of Fraction Modern (F14C) is a standard method issued by the American Society for Testing and Materials in 2011 with a code ASTM-D 6866-11 Method C. According to Eurachem guide, internal validation was expressed in terms of accuracy that was evaluated by trueness and precision. Trueness was expressed in terms of relative bias, while for precision ten consecutive replicates were carried out to under repeatability conditions and five duplicates were analyzed under reproducibility conditions. The limit of detection and the minimum detectable activity (MDA) were calculated. Uncertainty sources were defined and their relative standard uncertainties were calculated in order to determine the combined standard uncertainty. Five reference samples of different matrices were analyzed; calculated z score values were acceptable as being between –2 and +2. The calculation and results are presented in this work.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":"45 1","pages":"68 - 73"},"PeriodicalIF":1.2,"publicationDate":"2018-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44006191","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 : 2018-02-21DOI: 10.1515/geochr-2015-0086
S. Kreutzer, Loïc A. Martin, G. Guérin, C. Tribolo, P. Selva, N. Mercier
Abstract In situ dosimetry (active, passive dosimeters) provides high accuracy by determining environmental dose rates directly in the field. Passive dosimeters, such as α-Al2O3:C, are of particular interest for sites with desired minimum disturbance (e.g., archaeological sites). Here, we present a comprehensive approach obtaining the environmental cosmic and γ-dose rate using α-Al2O3:C chips. Our procedure consists of (1) homemade field containers, (2) a homemade bleaching box, (3) a rapid measurement sequence and (4) software based on R to process the measurement results. Our validation steps include reproducibility, irradiation time correction, cross-talk evaluation and source calibration. We further simulate the effect of the container against the infinite matrix dose rate, resulting in attenuation of ca. 6%. Our measurement design uses a lexsyg SMART luminescence reader equipped with green LEDs. The irradiation is carried out under the closed β-source. The minimum dose that can be determined was estimated with ca. 10 μGy. However, we also show that for the equipment used, an irradiation time correction of ca. 2.6 s is needed and irradiation cross-talk should be taken into account. The suggested procedure is cross-checked with four reference sites at Clermont-Ferrand showing a good γ-dose rate for three out of the four sites. Finally, an application example, including needed analytical steps, is presented for dosimeters buried at the archaeological site of the Sierra de Atapuerca (Spain).
摘要原位剂量测定法（主动、被动剂量计）通过直接在现场测定环境剂量率来提供高精度。被动剂量计，如α-Al2O3:C，对于具有所需最小干扰的遗址（例如考古遗址）特别感兴趣。在这里，我们提出了一种使用α-Al2O3：C芯片获得环境宇宙和γ剂量率的综合方法。我们的程序包括（1）自制的现场容器，（2）自制的漂白箱，（3）快速测量序列和（4）基于R的软件来处理测量结果。我们的验证步骤包括再现性、辐照时间校正、串扰评估和源校准。我们进一步模拟了容器对无限基质剂量率的影响，导致约6%的衰减。我们的测量设计使用配备绿色LED的lexsyg SMART发光读取器。辐照是在封闭的β源下进行的。可以确定的最小剂量估计为ca.10μGy。然而，我们也表明，对于所使用的设备，需要大约2.6秒的辐照时间校正，并且应该考虑辐照串扰。建议的程序与克莱蒙费朗的四个参考站点进行了交叉检查，四个站点中有三个站点的γ剂量率良好。最后，介绍了埋在Sierra de Atapuerca（西班牙）考古遗址的剂量计的应用实例，包括所需的分析步骤。
{"title":"Environmental dose rate determination using a passive dosimeter: Techniques and workflow for α-Al2O3:C chips","authors":"S. Kreutzer, Loïc A. Martin, G. Guérin, C. Tribolo, P. Selva, N. Mercier","doi":"10.1515/geochr-2015-0086","DOIUrl":"https://doi.org/10.1515/geochr-2015-0086","url":null,"abstract":"Abstract In situ dosimetry (active, passive dosimeters) provides high accuracy by determining environmental dose rates directly in the field. Passive dosimeters, such as α-Al2O3:C, are of particular interest for sites with desired minimum disturbance (e.g., archaeological sites). Here, we present a comprehensive approach obtaining the environmental cosmic and γ-dose rate using α-Al2O3:C chips. Our procedure consists of (1) homemade field containers, (2) a homemade bleaching box, (3) a rapid measurement sequence and (4) software based on R to process the measurement results. Our validation steps include reproducibility, irradiation time correction, cross-talk evaluation and source calibration. We further simulate the effect of the container against the infinite matrix dose rate, resulting in attenuation of ca. 6%. Our measurement design uses a lexsyg SMART luminescence reader equipped with green LEDs. The irradiation is carried out under the closed β-source. The minimum dose that can be determined was estimated with ca. 10 μGy. However, we also show that for the equipment used, an irradiation time correction of ca. 2.6 s is needed and irradiation cross-talk should be taken into account. The suggested procedure is cross-checked with four reference sites at Clermont-Ferrand showing a good γ-dose rate for three out of the four sites. Finally, an application example, including needed analytical steps, is presented for dosimeters buried at the archaeological site of the Sierra de Atapuerca (Spain).","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":"45 1","pages":"56 - 67"},"PeriodicalIF":1.2,"publicationDate":"2018-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46943374","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 : 2018-01-24DOI: 10.1515/geochr-2015-0083
R. Nepop, A. Agatova
Abstract This paper presents the results of paleoseismogeological investigations including tree-ring analysis and radiocarbon dating in pleistoseist zone of the 2003 Chuya earthquake, SE Altai, Russia. Twenty-five radiocarbon dates of previously unknown evidences of prehistoric earthquakes along the fault bounders of the Chagan-Uzun massif, North Chuya and South Chuya ranges are reported. Perspectives of applying dendroseismological approach within the high mountainous seismically active southeastern part of Russian Altai are demonstrated. In addition to estimating the germination ages of trees growing on the bare surfaces of seismically triggered landslides, analysis of wood penetrating injuries in the individual tree ring series was applied for dating paleorock-falls. Analysis of distribution patterns of tree-ring anomalies and injured trees suggests a criterion of recognizing seismic origin of past rock-falls. Dendrochronologically obtained dates of abrupt intensifications of rock-falls can be considered as supposed dates of past earthquakes, which should be verified by alternative proxy data. Obtained results argue for the high regional seismicity in the second half of the Holocene. Strong earthquakes occurred here AD 1532, and 600–700, 1300–1500, 2400–2700, 3400–3700, 3800–4200 cal BP. This data clarifies the chronology of seismic events within the SE Altai. The specified recurrence interval of strong earthquakes is about 400 years during the last 4000 years.
摘要本文介绍了2003年俄罗斯阿尔泰东南部楚亚地震更新世带的古地震地质调查结果，包括树木年轮分析和放射性碳定年。报道了查干-乌宗断层边界、北楚亚山脉和南楚亚山脉的25次史前地震的放射性碳定年。论述了在俄罗斯阿尔泰东南部高山地地震活跃区应用树木地震学方法的前景。除了估计地震引发的滑坡裸露表面上生长的树木的发芽年龄外，还应用了对单个树木年轮系列中木材穿透伤的分析来确定古岩石瀑布的年代。通过对树木年轮异常和损伤树木分布规律的分析，提出了识别过去岩崩地震成因的标准。树木年代学上获得的岩崩突然强化的日期可以被认为是过去地震的假定日期，应该用替代的代理数据加以验证。所得结果表明，全新世下半叶区域地震活动性较高。强烈的地震发生在公元1532年，600-700年，1300-1500年，2400-2700年，3400-3700年，3800-4200 cal BP。这些资料澄清了阿尔泰东南部地震事件的年代学。在近4000年中，强震的指定重复周期约为400年。
{"title":"Recurrence interval of strong earthquakes in the se Altai, Russia revealed by tree-ring analysis and radiocarbon dating","authors":"R. Nepop, A. Agatova","doi":"10.1515/geochr-2015-0083","DOIUrl":"https://doi.org/10.1515/geochr-2015-0083","url":null,"abstract":"Abstract This paper presents the results of paleoseismogeological investigations including tree-ring analysis and radiocarbon dating in pleistoseist zone of the 2003 Chuya earthquake, SE Altai, Russia. Twenty-five radiocarbon dates of previously unknown evidences of prehistoric earthquakes along the fault bounders of the Chagan-Uzun massif, North Chuya and South Chuya ranges are reported. Perspectives of applying dendroseismological approach within the high mountainous seismically active southeastern part of Russian Altai are demonstrated. In addition to estimating the germination ages of trees growing on the bare surfaces of seismically triggered landslides, analysis of wood penetrating injuries in the individual tree ring series was applied for dating paleorock-falls. Analysis of distribution patterns of tree-ring anomalies and injured trees suggests a criterion of recognizing seismic origin of past rock-falls. Dendrochronologically obtained dates of abrupt intensifications of rock-falls can be considered as supposed dates of past earthquakes, which should be verified by alternative proxy data. Obtained results argue for the high regional seismicity in the second half of the Holocene. Strong earthquakes occurred here AD 1532, and 600–700, 1300–1500, 2400–2700, 3400–3700, 3800–4200 cal BP. This data clarifies the chronology of seismic events within the SE Altai. The specified recurrence interval of strong earthquakes is about 400 years during the last 4000 years.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":"45 1","pages":"20 - 33"},"PeriodicalIF":1.2,"publicationDate":"2018-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/geochr-2015-0083","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46085173","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 : 2018-01-24DOI: 10.1515/geochr-2015-0085
Caroline W. Maina, J. Sang, B. Mutua, J. Raude
Abstract Soil erosion is one of the main soil degradation phenomena that threaten sustainable use of soil productivity thus affecting food security. In addition, it leads to reservoir storage capacity loss because of sedimentation. This not only affects water quantity but also water quality. Worldwide, annual loss in reservoir storage capacity due to sedimentation is 0.5 to 1%. Similarly, about 27% of land in Africa is largely degraded by erosion. As a result, there is need to minimize soil erosion and deposition through site specific estimation of soil erosion and deposition rates in the reservoirs. To achieve this, Fallout RadioNuclides (FRNs) are some of the methods in use. The most common radionuclides include; 137Cs, 210Pb and 7Be. Only few countries in Africa have exploited these FRNs. In these countries, 137Cs has been largely exploited but in some regions, it has been reported to be below minimum detection limit. Using 137Cs and 210Pb, maximum reference inventory in Africa is found to be 1450 and 2602 Bq/m2, respectively. However, there is minimal application of 7Be within the continent. Also, very little has been done in Africa to assess chronology and sedimentation rates of reservoirs using FRNs measured from sediment cores. In conclusion, a gap still exists on FRNs application in Africa in assessing soil erosion, deposition and reservoir sedimentation.
{"title":"A review of radiometric analysis on soil erosion and deposition studies in Africa","authors":"Caroline W. Maina, J. Sang, B. Mutua, J. Raude","doi":"10.1515/geochr-2015-0085","DOIUrl":"https://doi.org/10.1515/geochr-2015-0085","url":null,"abstract":"Abstract Soil erosion is one of the main soil degradation phenomena that threaten sustainable use of soil productivity thus affecting food security. In addition, it leads to reservoir storage capacity loss because of sedimentation. This not only affects water quantity but also water quality. Worldwide, annual loss in reservoir storage capacity due to sedimentation is 0.5 to 1%. Similarly, about 27% of land in Africa is largely degraded by erosion. As a result, there is need to minimize soil erosion and deposition through site specific estimation of soil erosion and deposition rates in the reservoirs. To achieve this, Fallout RadioNuclides (FRNs) are some of the methods in use. The most common radionuclides include; 137Cs, 210Pb and 7Be. Only few countries in Africa have exploited these FRNs. In these countries, 137Cs has been largely exploited but in some regions, it has been reported to be below minimum detection limit. Using 137Cs and 210Pb, maximum reference inventory in Africa is found to be 1450 and 2602 Bq/m2, respectively. However, there is minimal application of 7Be within the continent. Also, very little has been done in Africa to assess chronology and sedimentation rates of reservoirs using FRNs measured from sediment cores. In conclusion, a gap still exists on FRNs application in Africa in assessing soil erosion, deposition and reservoir sedimentation.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":"45 1","pages":"10 - 19"},"PeriodicalIF":1.2,"publicationDate":"2018-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/geochr-2015-0085","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42901504","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 : 2018-01-24DOI: 10.1515/geochr-2015-0073
P. Moska, G. Adamiec, Z. Jary, A. Bluszcz, G. Poręba, N. Piotrowska, M. Krawczyk, J. Skurzyński
Abstract Loess formations in Poland display a close relationship with cooling and warming trends of the Northern Hemisphere during the Pleistocene. Loess sequences sensitively record regional palaeoclimatic and palaeoecological changes. The Złota loess profile (21°39’E, 50°39’N) provides a unique opportunity to reconstruct climate conditions in the past in this part of Poland. This continuous sequence of loess and palaeosol deposits allows to distinguish between warmer and more humid climate which is favourable for soil development and much colder and dry periods which are conducive to loess accumulation. The silty and sandy aeolian material originates mainly from weathered rock surfaces affected by frost shattering or from glaciofluvial/fluvial deposits of river flood plains. In Poland, loess and loess-like formations occur in the southern part of the country, mostly in the south polish uplands, i.e. in the Lublin, Sandomierz, and Cracow Uplands. We used different techniques to establish a chronological framework for this site. 21 samples for luminescence dating were collected from the investigated loess profile in Złota. Infrared post-IR IRSL dating method was applied to the polymineral fine grains (4–11µm). The dating results are accompanied by detailed analyses of the geochemical composition, organic carbon and carbonate. Also, analysis of magnetic susceptibility and grain-size distribution were investigated. Based on such a large stratigraphic dataset an age-depth model using OxCal has also been constructed for this site.
{"title":"Luminescence chronostratigraphy for the loess deposits in Złota, Poland","authors":"P. Moska, G. Adamiec, Z. Jary, A. Bluszcz, G. Poręba, N. Piotrowska, M. Krawczyk, J. Skurzyński","doi":"10.1515/geochr-2015-0073","DOIUrl":"https://doi.org/10.1515/geochr-2015-0073","url":null,"abstract":"Abstract Loess formations in Poland display a close relationship with cooling and warming trends of the Northern Hemisphere during the Pleistocene. Loess sequences sensitively record regional palaeoclimatic and palaeoecological changes. The Złota loess profile (21°39’E, 50°39’N) provides a unique opportunity to reconstruct climate conditions in the past in this part of Poland. This continuous sequence of loess and palaeosol deposits allows to distinguish between warmer and more humid climate which is favourable for soil development and much colder and dry periods which are conducive to loess accumulation. The silty and sandy aeolian material originates mainly from weathered rock surfaces affected by frost shattering or from glaciofluvial/fluvial deposits of river flood plains. In Poland, loess and loess-like formations occur in the southern part of the country, mostly in the south polish uplands, i.e. in the Lublin, Sandomierz, and Cracow Uplands. We used different techniques to establish a chronological framework for this site. 21 samples for luminescence dating were collected from the investigated loess profile in Złota. Infrared post-IR IRSL dating method was applied to the polymineral fine grains (4–11µm). The dating results are accompanied by detailed analyses of the geochemical composition, organic carbon and carbonate. Also, analysis of magnetic susceptibility and grain-size distribution were investigated. Based on such a large stratigraphic dataset an age-depth model using OxCal has also been constructed for this site.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":"45 1","pages":"44 - 55"},"PeriodicalIF":1.2,"publicationDate":"2018-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46171114","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 Forty-one living larch (Larix principis-rupprechtii) trees collected from two sampling sites in 1310–1530 m a.s.l. in the southern Greater Higgnan Mountains in the northeastern China are used to develop a regional tree-ring width chronology. The credible chronology spans 185 years from 1830 to 2014. The results of correlation analyses indicate that moisture is the main climatic factor controlling radial growth of larch trees in this mountainous area. Spatial correlation proves that the regional tree-ring width chronology contains climatic signals representative for a large area including the eastern Mongolian Plateau and Nuluerhu Mountains. A comparison between the newly developed chronology and a May–July Palmer Drought Severity Index (PDSI) reconstruction for the Ortindag Sand Land reveals similar variations, particularly in the low-frequency domain. The tree-ring records also capture a severe and sustained drying trend recorded in the 1920s across a wide area of northern China.
{"title":"Development of a Larix principis-rupprechtii tree-ring width chronology and its climatic signals for the southern Greater Higgnan Mountains","authors":"Tongwen Zhang, Shulong Yu, Yu-jiang Yuan, Liping Huang, Shengxia Jiang","doi":"10.1515/geochr-2015-0082","DOIUrl":"https://doi.org/10.1515/geochr-2015-0082","url":null,"abstract":"Abstract Forty-one living larch (Larix principis-rupprechtii) trees collected from two sampling sites in 1310–1530 m a.s.l. in the southern Greater Higgnan Mountains in the northeastern China are used to develop a regional tree-ring width chronology. The credible chronology spans 185 years from 1830 to 2014. The results of correlation analyses indicate that moisture is the main climatic factor controlling radial growth of larch trees in this mountainous area. Spatial correlation proves that the regional tree-ring width chronology contains climatic signals representative for a large area including the eastern Mongolian Plateau and Nuluerhu Mountains. A comparison between the newly developed chronology and a May–July Palmer Drought Severity Index (PDSI) reconstruction for the Ortindag Sand Land reveals similar variations, particularly in the low-frequency domain. The tree-ring records also capture a severe and sustained drying trend recorded in the 1920s across a wide area of northern China.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":"45 1","pages":"1 - 9"},"PeriodicalIF":1.2,"publicationDate":"2018-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/geochr-2015-0082","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45200779","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}
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