Pub Date : 2018-11-22DOI: 10.1515/geochr-2015-0098
M. Wistuba, I. Malik, M. Krąpiec
Abstract The aim of our study was to compare patterns of tree-ring eccentricity developed in Norway spruce trees as a result of landsliding with the one caused by the prevailing wind (in 2 study sites), and with the normal growth of trees (in 2 reference sites). We sampled 20 trees per study site and 10 per reference site. Two cores were taken from each tree (120 cores in total) from the upslope and downslope, windward and leeward sides of stems. Ring widths measured on opposite sides of stems were compared using the method of percent eccentricity index. Graphs of the index obtained for individual trees were analysed. Statistical indicators were calculated for a percent eccentricity index. Disturbance events were dated and the response index was calculated. The results show that the patterns of eccentricity developed as a result of the prevailing winds and due to landsliding differ from one another and from the reference sites. The results suggest that the impact of the prevailing wind on tree growth is more severe than the impact of landsliding. The difference may result from the slow-moving character of the landslide under study. The results, however, indicate that wind impact should be taken into account in dendrogeomorphic research and that the impact of mass movements should be considered in dendroecological studies on wind.
{"title":"Can we distinguish between tree-ring eccentricity developed as a result of landsliding and prevailing winds? consequences for dendrochronological dating","authors":"M. Wistuba, I. Malik, M. Krąpiec","doi":"10.1515/geochr-2015-0098","DOIUrl":"https://doi.org/10.1515/geochr-2015-0098","url":null,"abstract":"Abstract The aim of our study was to compare patterns of tree-ring eccentricity developed in Norway spruce trees as a result of landsliding with the one caused by the prevailing wind (in 2 study sites), and with the normal growth of trees (in 2 reference sites). We sampled 20 trees per study site and 10 per reference site. Two cores were taken from each tree (120 cores in total) from the upslope and downslope, windward and leeward sides of stems. Ring widths measured on opposite sides of stems were compared using the method of percent eccentricity index. Graphs of the index obtained for individual trees were analysed. Statistical indicators were calculated for a percent eccentricity index. Disturbance events were dated and the response index was calculated. The results show that the patterns of eccentricity developed as a result of the prevailing winds and due to landsliding differ from one another and from the reference sites. The results suggest that the impact of the prevailing wind on tree growth is more severe than the impact of landsliding. The difference may result from the slow-moving character of the landslide under study. The results, however, indicate that wind impact should be taken into account in dendrogeomorphic research and that the impact of mass movements should be considered in dendroecological studies on wind.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2018-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42798401","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 : 2018-11-05DOI: 10.1515/geochr-2015-0097
J. Jevšenak, S. Džeroski, T. Levanič
Abstract Climate-growth relationships in Quercus robur chronologies for vessel lumen area (VLA) from two oak stands (QURO-1 and QURO-2) showed a consistent temperature signal: VLA is highly correlated with mean April temperature and the temperature at the end of the previous growing season. QURO-1 showed significant negative correlations with winter sums of precipitation. Selected climate variables were used as predictors of VLA in a comparison of various linear and nonlinear machine learning methods: Artificial Neural Networks (ANN), Multiple Linear Regression (MLR), Model Trees (MT), Bagging of Model Trees (BMT) and Random Forests of Regression Trees (RF). ANN outperformed all the other regression algorithms at both sites. Good performance also characterised RF and BMT, while MLR, and especially MT, displayed weaker performance. Based on our results, advanced machine learning algorithms should be seriously considered in future climate reconstructions.
{"title":"Predicting the vessel lumen area tree-ring parameter of Quercus robur with linear and nonlinear machine learning algorithms","authors":"J. Jevšenak, S. Džeroski, T. Levanič","doi":"10.1515/geochr-2015-0097","DOIUrl":"https://doi.org/10.1515/geochr-2015-0097","url":null,"abstract":"Abstract Climate-growth relationships in Quercus robur chronologies for vessel lumen area (VLA) from two oak stands (QURO-1 and QURO-2) showed a consistent temperature signal: VLA is highly correlated with mean April temperature and the temperature at the end of the previous growing season. QURO-1 showed significant negative correlations with winter sums of precipitation. Selected climate variables were used as predictors of VLA in a comparison of various linear and nonlinear machine learning methods: Artificial Neural Networks (ANN), Multiple Linear Regression (MLR), Model Trees (MT), Bagging of Model Trees (BMT) and Random Forests of Regression Trees (RF). ANN outperformed all the other regression algorithms at both sites. Good performance also characterised RF and BMT, while MLR, and especially MT, displayed weaker performance. Based on our results, advanced machine learning algorithms should be seriously considered in future climate reconstructions.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2018-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48245136","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 : 2018-10-30DOI: 10.1515/geochr-2015-0099
M. Horvat, U. Klötzli, D. Jamičić, G. Buda, Eva Klötzli, C. Hauzenberger
Abstract Detailed cathodoluminescence (CL) and back scattered electron (BSE) imaging of zircon crystals, coupled with in-situ U-Pb zircon dating by Laser Ablation Multi-Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) were used to develop new insights into the evolution of a monzogranite from Omanovac Quarry (Psunj Mt.), and of monzogranites from Šandrovac Quarry and Kišeljevac Creek (Papuk Mt.), both located in the Slavonian Mountains (Croatia). U-Pb isotopic data yielded a concordia age of 380 ± 4 Ma for the monzogranite from Omanovac Quarry, and 382 ± 2 Ma and 383 ± 5 Ma for monzogranites from Šandrovac Quarry and Kišeljevac Creek. The results suggest Late Devonian magmatic activity.
{"title":"Geochronology of granitoids from Psunj and Papuk Mts., Croatia","authors":"M. Horvat, U. Klötzli, D. Jamičić, G. Buda, Eva Klötzli, C. Hauzenberger","doi":"10.1515/geochr-2015-0099","DOIUrl":"https://doi.org/10.1515/geochr-2015-0099","url":null,"abstract":"Abstract Detailed cathodoluminescence (CL) and back scattered electron (BSE) imaging of zircon crystals, coupled with in-situ U-Pb zircon dating by Laser Ablation Multi-Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) were used to develop new insights into the evolution of a monzogranite from Omanovac Quarry (Psunj Mt.), and of monzogranites from Šandrovac Quarry and Kišeljevac Creek (Papuk Mt.), both located in the Slavonian Mountains (Croatia). U-Pb isotopic data yielded a concordia age of 380 ± 4 Ma for the monzogranite from Omanovac Quarry, and 382 ± 2 Ma and 383 ± 5 Ma for monzogranites from Šandrovac Quarry and Kišeljevac Creek. The results suggest Late Devonian magmatic activity.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2018-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45577876","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 : 2018-08-21DOI: 10.1515/geochr-2015-0093
Katarzyna Łuszczyńska, M. Wistuba, I. Malik, M. Krąpiec, Bartłomiej Szypuła
Abstract Most landslide hazard maps are developed on the basis of an area’s susceptibility to a landslide occurrence, but dendrochronological techniques allows one to develop maps based on past landslide activity. The aim of the study was to use dendrochronological techniques to develop a landslide hazard map for a large area, covering 3.75 km2. We collected cores from 131 trees growing on 46 sampling sites, measured tree-ring width, and dated growth eccentricity events (which occur when tree rings of different widths are formed on opposite sides of a trunk), recording the landslide events which had occurred over the previous several dozen years. Then, the number of landslide events per decade was calculated at every sampling site. We interpolated the values obtained, added layers with houses and roads, and developed a landslide hazard map. The map highlights areas which are potentially safe for existing buildings, roads and future development. The main advantage of a landslide hazard map developed on the basis of dendrochronological data is the possibility of acquiring long series of data on landslide activity over large areas at a relatively low cost. The main disadvantage is that the results obtained relate to the measurement of anatomical changes and the macroscopic characteristics of the ring structure occurring in the wood of tilted trees, and these factors merely provide indirect information about the time of the landslide event occurrence.
{"title":"Dendrochronological dating as the basis for developing a landslide hazard map – An example from the Western Carpathians, Poland","authors":"Katarzyna Łuszczyńska, M. Wistuba, I. Malik, M. Krąpiec, Bartłomiej Szypuła","doi":"10.1515/geochr-2015-0093","DOIUrl":"https://doi.org/10.1515/geochr-2015-0093","url":null,"abstract":"Abstract Most landslide hazard maps are developed on the basis of an area’s susceptibility to a landslide occurrence, but dendrochronological techniques allows one to develop maps based on past landslide activity. The aim of the study was to use dendrochronological techniques to develop a landslide hazard map for a large area, covering 3.75 km2. We collected cores from 131 trees growing on 46 sampling sites, measured tree-ring width, and dated growth eccentricity events (which occur when tree rings of different widths are formed on opposite sides of a trunk), recording the landslide events which had occurred over the previous several dozen years. Then, the number of landslide events per decade was calculated at every sampling site. We interpolated the values obtained, added layers with houses and roads, and developed a landslide hazard map. The map highlights areas which are potentially safe for existing buildings, roads and future development. The main advantage of a landslide hazard map developed on the basis of dendrochronological data is the possibility of acquiring long series of data on landslide activity over large areas at a relatively low cost. The main disadvantage is that the results obtained relate to the measurement of anatomical changes and the macroscopic characteristics of the ring structure occurring in the wood of tilted trees, and these factors merely provide indirect information about the time of the landslide event occurrence.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2018-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44786394","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 : 2018-08-21DOI: 10.1515/geochr-2015-0096
M. Błaszczyk, H. Hercman, J. Pawlak, M. Gąsiorowski, Šárka Matoušková, Marta Aninowska, Ditta Kicińska, A. Tyc
Abstract The quality of paleoenvironmental reconstruction based on speleothem records depends on the accuracy of the used proxies and the chronology of the studied record. As far as the dating method is concerned, in most cases, the best solution is the use of the U-series method to obtain a precise chronology. However, for older periods (i.e., over 0.5 Ma), dating has become a serious challenge. Theoretically, older materials could be dated with the U-Pb dating method. However, that method requires a relatively high uranium content (minimum of several ppm), whereas typical speleothems from Poland (and all of Central Europe) have uranium concentrations below 0.1 ppm. Because the materials in Polish caves are problematic, we applied oxygen isotope stratigraphy (OIS) as a tool for speleothem dating. By using OIS as an alternative tool to create a chronology of our flowstone, it was found that the studied flowstone crystallized from 975 to 470 ka with three major discontinuities, so obtained isotopic record can be correlated with oxygen isotopic stages from MIS 24 to MIS 12. The observed isotopic variability was also consistent and confirmed with the petrographic observations of the flowstone.
{"title":"Low to middle Pleistocene paleoclimatic record from the Kraków-Częstochowa Upland (Poland) based on isotopic and calcite fabrics analyses","authors":"M. Błaszczyk, H. Hercman, J. Pawlak, M. Gąsiorowski, Šárka Matoušková, Marta Aninowska, Ditta Kicińska, A. Tyc","doi":"10.1515/geochr-2015-0096","DOIUrl":"https://doi.org/10.1515/geochr-2015-0096","url":null,"abstract":"Abstract The quality of paleoenvironmental reconstruction based on speleothem records depends on the accuracy of the used proxies and the chronology of the studied record. As far as the dating method is concerned, in most cases, the best solution is the use of the U-series method to obtain a precise chronology. However, for older periods (i.e., over 0.5 Ma), dating has become a serious challenge. Theoretically, older materials could be dated with the U-Pb dating method. However, that method requires a relatively high uranium content (minimum of several ppm), whereas typical speleothems from Poland (and all of Central Europe) have uranium concentrations below 0.1 ppm. Because the materials in Polish caves are problematic, we applied oxygen isotope stratigraphy (OIS) as a tool for speleothem dating. By using OIS as an alternative tool to create a chronology of our flowstone, it was found that the studied flowstone crystallized from 975 to 470 ka with three major discontinuities, so obtained isotopic record can be correlated with oxygen isotopic stages from MIS 24 to MIS 12. The observed isotopic variability was also consistent and confirmed with the petrographic observations of the flowstone.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2018-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42283060","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 : 2018-08-11DOI: 10.1515/geochr-2015-0095
Christoph Schmidt, J. Bösken, T. Kolb
Abstract Dating of polymineral silt-sized samples by use of post-infrared infrared stimulated luminescence (pIRIR) protocols at elevated temperature has recently gained attraction due to assumed lower rates of anomalous fading. The α-efficiency (or a-value) associated with the pIRIR signals as an integral part of age calculation has, however, not yet been sufficiently constrained. Here we present a set of 65 a-values determined for 47 samples collected across Europe with two different IRSL protocols in two laboratories. By testing the basic preconditions for application of the single-aliquot regeneration (SAR) procedure to constrain a-values and by comparing SAR results to a-values obtained by multiple-aliquot protocols, we demonstrate that SAR-derived a-values are reliable for the majority of samples. While aliquot size and signal resetting mode prior to α-regeneration do not appear to affect the resulting a-value, we detected significant differences in mean a-values measured in the two laboratories. For the pIRIR290 signal, a-values average to 0.085 ± 0.010 (Bayreuth) and 0.101 ± 0.014 (Cologne), while a modified SAR protocol yields 0.081 ± 0.008 (Bayreuth). Whereas provenance-specific differences in a-values might be masked by overall scatter, systematic offsets between laboratories are attributed to technical issues such as heater and source calibration. Based on the present data set, use of the same routine dating equipment is strongly advised for both dose and a-value measurements.
{"title":"Is there a common alpha-efficiency in polymineral samples measured by various infrared stimulated luminescence protocols?","authors":"Christoph Schmidt, J. Bösken, T. Kolb","doi":"10.1515/geochr-2015-0095","DOIUrl":"https://doi.org/10.1515/geochr-2015-0095","url":null,"abstract":"Abstract Dating of polymineral silt-sized samples by use of post-infrared infrared stimulated luminescence (pIRIR) protocols at elevated temperature has recently gained attraction due to assumed lower rates of anomalous fading. The α-efficiency (or a-value) associated with the pIRIR signals as an integral part of age calculation has, however, not yet been sufficiently constrained. Here we present a set of 65 a-values determined for 47 samples collected across Europe with two different IRSL protocols in two laboratories. By testing the basic preconditions for application of the single-aliquot regeneration (SAR) procedure to constrain a-values and by comparing SAR results to a-values obtained by multiple-aliquot protocols, we demonstrate that SAR-derived a-values are reliable for the majority of samples. While aliquot size and signal resetting mode prior to α-regeneration do not appear to affect the resulting a-value, we detected significant differences in mean a-values measured in the two laboratories. For the pIRIR290 signal, a-values average to 0.085 ± 0.010 (Bayreuth) and 0.101 ± 0.014 (Cologne), while a modified SAR protocol yields 0.081 ± 0.008 (Bayreuth). Whereas provenance-specific differences in a-values might be masked by overall scatter, systematic offsets between laboratories are attributed to technical issues such as heater and source calibration. Based on the present data set, use of the same routine dating equipment is strongly advised for both dose and a-value measurements.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2018-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42837434","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 : 2018-08-11DOI: 10.1515/geochr-2015-0092
V. Anechitei-Deacu, A. Timar-Gabor, D. Constantin, O. Trandafir-Antohi, L. D. Valle, J. Fornós, L. Gómez‐Pujol, A. Wintle
Abstract SAR-OSL dating studies of Romanian, Serbian and Chinese loess using fine and coarse quartz have previously resulted in a series of controversial issues. We extend here the investigations using fine (4–11 μm) and different coarse quartz (>63 μm) grains extracted from aeolianites from a site on Eivissa Island (southwestern Mediterranean). Aeolianites were chosen since they contain quartz from a different geological context and have significantly lower environmental dose rates. The dose response curves of the OSL signals for fine and coarse quartz are similar to those for loess and are also represented by the sum of two saturating exponential functions. For doses up to ~200 Gy, the dose response curves of fine and coarse grains from aeolianites can be superimposed and the ages obtained for the different grain sizes are in agreement up to ~250 ka, increasing our confidence in the accuracy of the ages obtained for samples with such doses, irrespective of the magnitude of the environmental dose rate. Particularly for the fine quartz fraction, a mismatch between the SAR dose response curve and the dose response curve obtained when doses are added to the natural is reported, indicating that the application of the SAR protocol in the high dose range is problematic. This dose dependent deviation is much less pronounced for coarse grains. Thus, it seems reasonable to infer that the dose response curves for the coarse grains, although saturating earlier can be regarded as more reliable for equivalent dose calculation than those for the fine grains.
{"title":"Assessing the maximum limit of SAR-OSL dating using quartz of different grain sizes","authors":"V. Anechitei-Deacu, A. Timar-Gabor, D. Constantin, O. Trandafir-Antohi, L. D. Valle, J. Fornós, L. Gómez‐Pujol, A. Wintle","doi":"10.1515/geochr-2015-0092","DOIUrl":"https://doi.org/10.1515/geochr-2015-0092","url":null,"abstract":"Abstract SAR-OSL dating studies of Romanian, Serbian and Chinese loess using fine and coarse quartz have previously resulted in a series of controversial issues. We extend here the investigations using fine (4–11 μm) and different coarse quartz (>63 μm) grains extracted from aeolianites from a site on Eivissa Island (southwestern Mediterranean). Aeolianites were chosen since they contain quartz from a different geological context and have significantly lower environmental dose rates. The dose response curves of the OSL signals for fine and coarse quartz are similar to those for loess and are also represented by the sum of two saturating exponential functions. For doses up to ~200 Gy, the dose response curves of fine and coarse grains from aeolianites can be superimposed and the ages obtained for the different grain sizes are in agreement up to ~250 ka, increasing our confidence in the accuracy of the ages obtained for samples with such doses, irrespective of the magnitude of the environmental dose rate. Particularly for the fine quartz fraction, a mismatch between the SAR dose response curve and the dose response curve obtained when doses are added to the natural is reported, indicating that the application of the SAR protocol in the high dose range is problematic. This dose dependent deviation is much less pronounced for coarse grains. Thus, it seems reasonable to infer that the dose response curves for the coarse grains, although saturating earlier can be regarded as more reliable for equivalent dose calculation than those for the fine grains.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2018-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42042169","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 : 2018-07-19DOI: 10.1515/geochr-2015-0094
B. Sensuła, S. Wilczyński
Abstract Scots pine (Pinus sylvestris L.) growing in 16 sites in three industrial regions in Poland was analysed to delineate dendroclimatologically uniform areas. A dendrochronological and mass spectrometric analysis revealed the following: a dry and sunny previous September, low winter temperature, and moisture supply in July limit the radial growth of the pines in all the regions. The weather conditions of the current growing season have been the most strongly reflected in the isotopic ratio. Positive relationships were noted between δ13C and temperature and δ13C and sunshine. A negative relationship was observed between δ13C and precipitation and δ13C and humidity. At the same time, a positive relationship was noted between δ18O and sunshine and δ18O and temperature, but negative between δ18O and humidity. The climate signal recorded in the stable isotope composition was temporally unstable and only for a few of the climatic parameters did we find temporally stable climate signals. However, variability in the strength and direction of the relationships between variables has been observed. In general, the weather in July and August is important for determining the δ13C and δ18O signals. Instability can reflect the physiological adaptation of the plants to changes in the ecosystem.
{"title":"Tree-ring widths and the stable isotope composition of pine tree-rings as climate indicators in the most industrialised part of Poland during CO2 elevation","authors":"B. Sensuła, S. Wilczyński","doi":"10.1515/geochr-2015-0094","DOIUrl":"https://doi.org/10.1515/geochr-2015-0094","url":null,"abstract":"Abstract Scots pine (Pinus sylvestris L.) growing in 16 sites in three industrial regions in Poland was analysed to delineate dendroclimatologically uniform areas. A dendrochronological and mass spectrometric analysis revealed the following: a dry and sunny previous September, low winter temperature, and moisture supply in July limit the radial growth of the pines in all the regions. The weather conditions of the current growing season have been the most strongly reflected in the isotopic ratio. Positive relationships were noted between δ13C and temperature and δ13C and sunshine. A negative relationship was observed between δ13C and precipitation and δ13C and humidity. At the same time, a positive relationship was noted between δ18O and sunshine and δ18O and temperature, but negative between δ18O and humidity. The climate signal recorded in the stable isotope composition was temporally unstable and only for a few of the climatic parameters did we find temporally stable climate signals. However, variability in the strength and direction of the relationships between variables has been observed. In general, the weather in July and August is important for determining the δ13C and δ18O signals. Instability can reflect the physiological adaptation of the plants to changes in the ecosystem.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2018-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48370488","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 : 2018-07-04DOI: 10.1515/geochr-2015-0089
G. Stella, L. Almeida, L. Basilio, S. Pasquale, J. Dinis, M. Almeida, A. Gueli
Abstract Cross-dating of bricks and mortars from historical building, through thermal (TL) and optically stimulated (OSL) luminescence have achieved good accuracy and precision. However this approach is, in many cases, not exhaustive especially for buildings with different construction phases closely temporally spaced to each other. The uncertainties of experimental data added to the reuse of old bricks and/or the presence of mortars applied on restorations represent the main limits to obtain the complete chronology. In the case of the Convento de S. Francisco (Coimbra, Portugal), the dating results were crossed with the stratigraphic study of the building, mineralogical characterization by XRD and colorimetric data of the mortar samples. Thanks to luminescence ages, mineralogical composition and color specification, two phases of construction were identified: the first from the 17th century and the first half of the 18th century and the second from the second half of the 18th century to the first half of the 19th century. These results were confirmed by mineralogical characterization and colorimetric measurements of mortars that identify two different types of materials in aggregate/binder ratio terms and superficial optical characteristics.
摘要利用热释光和光激发光法对历史建筑砖浆进行交叉测年，取得了较好的准确性和精密度。然而，在许多情况下，这种方法并不详尽，特别是对于具有不同施工阶段的建筑物，它们在时间上彼此紧密间隔。实验数据的不确定性，加上旧砖的再利用和/或修复中使用的砂浆的存在，是获得完整年表的主要限制。在convto de S. Francisco(葡萄牙科英布拉)的案例中，测年结果与建筑物的地层学研究、XRD矿物学表征和砂浆样品的比色数据相交叉。根据发光年龄、矿物成分和颜色规格，确定了两个建设阶段:第一个阶段从17世纪到18世纪上半叶，第二个阶段从18世纪下半叶到19世纪上半叶。这些结果通过矿物学表征和砂浆的比色测量得到证实，砂浆在骨料/粘合剂比和表面光学特性方面识别出两种不同类型的材料。
{"title":"Historical building dating: A multidisciplinary study of the Convento de São Francisco (Coimbra, Portugal)","authors":"G. Stella, L. Almeida, L. Basilio, S. Pasquale, J. Dinis, M. Almeida, A. Gueli","doi":"10.1515/geochr-2015-0089","DOIUrl":"https://doi.org/10.1515/geochr-2015-0089","url":null,"abstract":"Abstract Cross-dating of bricks and mortars from historical building, through thermal (TL) and optically stimulated (OSL) luminescence have achieved good accuracy and precision. However this approach is, in many cases, not exhaustive especially for buildings with different construction phases closely temporally spaced to each other. The uncertainties of experimental data added to the reuse of old bricks and/or the presence of mortars applied on restorations represent the main limits to obtain the complete chronology. In the case of the Convento de S. Francisco (Coimbra, Portugal), the dating results were crossed with the stratigraphic study of the building, mineralogical characterization by XRD and colorimetric data of the mortar samples. Thanks to luminescence ages, mineralogical composition and color specification, two phases of construction were identified: the first from the 17th century and the first half of the 18th century and the second from the second half of the 18th century to the first half of the 19th century. These results were confirmed by mineralogical characterization and colorimetric measurements of mortars that identify two different types of materials in aggregate/binder ratio terms and superficial optical characteristics.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2018-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44732360","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 : 2018-06-02DOI: 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":null,"pages":null},"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}
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