rss_2.0Geochronometria FeedSciendo RSS Feed for Geochronometriahttps://sciendo.com/journal/GEOCHRhttps://www.sciendo.comGeochronometria 's Coverhttps://sciendo-parsed-data-feed.s3.eu-central-1.amazonaws.com/606af92a3999800867736d79/cover-image.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20220517T085618Z&X-Amz-SignedHeaders=host&X-Amz-Expires=604800&X-Amz-Credential=AKIA6AP2G7AKDOZOEZ7H%2F20220517%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Signature=7adb8f8d3a3b35d9f2d13f9bea581f02ff249963ae906635d9ca0dcab4594852200300Evaluating the Effect of Hydrofluoric Acid Etching on Quartz Grains using Microscope Image Analysis, Laser Diffraction and Weight Loss Particle Size Estimatehttps://sciendo.com/article/10.2478/geochr-2022-0001<abstract> <title style='display:none'>Abstract</title> <p>In this work we investigate the quartz etching process using hydrofluoric acid for trapped charge dating (TCD) applications. It is done using material collected from an active sand mine in Bełchatów Nowy Świat, central Poland. Approximately 20 kg of material was collected and prepared using routine procedures that are applied in TCD laboratories. The material was sieved using 180–200 μm meshes, and the selected fraction was etched for various time intervals. Sieved samples were etched for durations from 0 min up to 180 min and measured with microscope image analysis (IA), laser diffraction (LD), and mass loss which were used to estimate the depths of etching. Our results show statistical data on how non-uniform the etching process is. We estimate this as a function of etching time from IA, LD and mass loss. In our investigation, mass loss measurements with the assumption of spherical grains correspond to the decrease of radius of ca. 0.151 ± 0.003 μm · min<sup>−1</sup>. In case of LD, a rough etch depth estimation corresponds to a range 0.06–0.18 μm · min<sup>−1</sup> with median at 0.13 μm · min<sup>−1</sup>. Microscope IA gives a 0.03–0.09 μm · min<sup>−1</sup> with a median at 0.05 μm · min<sup>−1</sup>. Moreover, quartz grains are fractured into smaller pieces while etching. It means that assumptions that are used in etch depth estimation from mass loss are not correct. They incorrect not only because grains are not spheres but also because the number of grains is not constant. Therefore, the etch depth estimated from mass loss might be overestimated. Using microscope IA we report etch depth ranges that might be used to roughly estimate the etch depth uncertainty.</p> </abstract>ARTICLE2022-05-10T00:00:00.000+00:00Temporal variation of prehistoric human settlement recorded in the oxbow lake deposits of San river (Sandomierz Basin, SE Poland)https://sciendo.com/article/10.1515/geochr-2015-0119<abstract> <title style='display:none'>Abstract</title> <p>This study presents the sedimentological and pollen analysis, and radiocarbon dating of the palaeochannel fill deposits situated on the wide alluvial ridge on which 131 archaeological sites were discovered. The analyzed territory covers the right bank of the San river valley (in the area of the Leszno profile) with an area of 72.5 km<sup>2</sup>. Increase of fine-grain sand sediments, and the presence of redeposited fragments of clayey silts (soil aggregates) correlates well with the increase man’s activity in the 2<sup>nd</sup> and the 1<sup>st</sup> half of the 1 <sup>st</sup> millennia BC (the decline of the Mierzanowice culture, the Trzciniec culture, the Tarnobrzeg Lusatian culture) as well as in the 1<sup>st</sup> millennium AD (the Przeworsk culture and the early Medieval settlement) and with transformation of plant communities recorded in the palynological sequence. The layer of sediments at the depth of 85–69 cm with the highest proportion of the finest clay fraction may indicate the reduction of cultivation or abandonment of arable land (the pre-Roman (La Tène) period).</p></abstract>ARTICLE2020-03-06T00:00:00.000+00:00The Roman amphitheatre in Mérida, Spain ˗Augustan or Flavian? Radiocarbon dating results on mortar carbonatehttps://sciendo.com/article/10.2478/geochr-2020-0028<abstract><title style='display:none'>Abstract</title><p>Four lime mortar samples from the Mérida amphitheatre in Spain were dated in 2001 and re-dated in 2019 with refined dating methods and focus on carbon dioxide that was released in late CO<sub>2</sub> fractions when dissolved in phosphoric acid. The samples were difficult to date because they contained highly soluble, young carbonate contamination that dominated the carbon dioxide from the early stages of the reaction with the acid in the hydrolysis process. They were also rather hydraulic and rich in magnesium, which could have caused delayed hardening. However, there was very little dead carbon contamination so that late carbon dioxide fraction gave uniform <sup>14</sup>C ages, pointing to a late 1<sup>st</sup> c. AD Flavian, or later age of the amphitheatre.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00Chronology of seafloor massive sulfides formation within the Pobeda hydrothermal cluster (Mid-Atlantic Ridge)https://sciendo.com/article/10.2478/geochr-2020-0019<abstract><title style='display:none'>Abstract</title><p>A geochronological and mineralogical study on the seafloor massive sulfides from the Pobeda hydrothermal cluster at the Mid-Atlantic Ridge was carried out. To improve the reliability of geochronological data, the 230Th/U ages were measured for both the bulk samples and monomineral separates. The oldest age ca. 52 kyr within Pobeda-1 and ca. 107 kyr within Pobeda–2 fields have been obtained. Then, several episodes of hydrothermal activity were identified within both fields up to ca. 0.3 kyr ago and up to ca. 4.3 kyr ago, respectively.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00A new quartz for 𝛾-transfer calibration of radiation sourceshttps://sciendo.com/article/10.2478/geochr-2020-0020<abstract><title style='display:none'>Abstract</title><p>Quartz grains extracted from aeolian sand (<italic>LexCal2014</italic>) are tested for suitability as transfer material for radiation source calibration. After thermal pre-treatment, this quartz exhibits luminescence and dose-response properties which appear appropriate for transfer calibration purposes with little dependence of recovered β-dose on preheat temperature in the single aliquot (SAR) procedure and satisfying performance in β-dose recovery (0.98−1.00 given/measured β-dose for various experiments). Additional support is obtained by SARA and interpolation procedures, where OSL-data from γ-dosed <italic>LexCal2014</italic> is interpolated on data obtained for zeroed <italic>LexCal2014</italic> quartz, which is β-irradiated by the source to be calibrated. Initial results on fine-grain material agree with the coarse grain results presented.</p><p>The γ-dose of 3.00 ± 0.07 Gy is administered in a scatter-free geometry at the IAEA/WHO Secondary Standard Dosimetry Laboratory (SSDL) of the Helmholtz Zentrum München, with absorbed dose calculations obtained by Monte Carlo simulations.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00Increase in C dating accuracy of prehistoric skeletal remains by optimised bone sampling: Chronometric studies on eneolithic burials from Mikulin 9 (Poland) and Urziceni-Vada Ret (Romania)https://sciendo.com/article/10.2478/geochr-2020-0026<abstract><title style='display:none'>Abstract</title><p>In this research, sampling optimisation and modelling based thereon follow from the assumption that each human skeleton can be treated as a set of heterochronous carbon reservoirs capable of supplying at least an elementary sequence consisting of two <sup>14</sup>C dates corresponding to the moment of birth (otic capsule) and that of demise (ribs), as well as an anthropologically defined lag between them. Two case studies demonstrate that the approach can raise the precision of <sup>14</sup>C dates related to the death of the individuals. The benefits and main issues of this sampling strategy as well as the involved bioarchaeological conflict potential are taken under discussion.</p></abstract>ARTICLE2021-01-29T00:00:00.000+00:00Interaction between stem damage, crown vitality and growth performance of European yew in Central–East Europehttps://sciendo.com/article/10.2478/geochr-2020-0029<abstract><title style='display:none'>Abstract</title><p>As long-lived, slow-growing tree species, European yew (<italic>Taxus baccata</italic> L.) has considerable potential for dendrochronological use. The increasing probability of decline and the worsening of yew health status endanger the species diversity of temperate forests. In 2015–2017, we sampled adult yew populations with scattered occurrence in limestone beech forests (<italic>Fagetum dealpinum</italic>), in which yew trees exhibit the top growth performance. Altogether, 150 trees were sampled (294 cores) at four localities. By using the general linear model, we investigated the interactions between stem and crown status, sex and growth performance of yew trees. Based on the previous results and innovative measures of competition and canopy closure, we explored the promotion of silviculture care for female over the male trees and formulated exact release cutting rules. The results demonstrate divergent growth trends between male and female trees and the pronounced negative effects of crown and stem damage on growth performance of European yew. Expected decreases in radial growth of damaged female trees in comparison with male ones is less confirmed. Despite this, making silvicultural treatments for females as a priority is recommendable. Our findings can improve the effectiveness of forest management and restoration activities in European temperate forests, where yew adults are threatened by the higher degree of shading and herbivory pressure.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00C Dating of mortar from ruins of an early medieval church Hohenrätien GR, Switzerlandhttps://sciendo.com/article/10.2478/geochr-2020-0027<abstract><title style='display:none'>Abstract</title><p>Numerous ruins around the world lack the radiometric dating due to the scarcity of organic carbon. Here, we present results of radiocarbon dating of mortar samples from an early Medieval church Hohenrätien GR, Switzerland, which was dated to the early 6<sup>th</sup> century, based on typology. The method of dating mortars, which is currently applied at the ETH laboratory, involves sieving the crushed mortar, selection of grain size 45−63 μm and sequential dissolution resulting in four fractions of CO<sub>2</sub> collected in a 3-second interval each. Two mortar samples, which were analyzed using sequential dissolution and one by dating a bulk of lime lump, resulted in a combined radiocarbon age of 1551±21 BP translating to the calendar age of 427−559 AD.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00Tree-ring reconstruction of June-July mean temperatures in the northern Daxing’an Mountains, Chinahttps://sciendo.com/article/10.2478/geochr-2020-0007<abstract><title style='display:none'>Abstract</title><p>In this study, the mean temperature of June to July was reconstructed for the period of 1880 to 2014 by using the <italic>Larix gmelinii</italic> tree-ring width data for the Mangui region in the northern Daxing’an Mountains, China. The reconstruction accounts for 43.6% of the variance in the temperature observed from AD 1959–2014. During the last 134 years, there were 17 warm years and 17 cold years, which accounted for 12.7% of the total reconstruction years, respectively. Cold episodes occurred throughout 1887–1898 (average value is 14.2°C), while warm episodes occurred during 1994–2014 (15.9°C). Based on this regional study, the warmer events coincided with dry periods and the colder events were consistent with wet conditions. The spatial correlation analyses between the reconstructed series and gridded temperature data revealed that the regional climatic variations were well captured by this study and the reconstruction represented a regional temperature signal for the northern Daxing’an Mountains. In addition, Multi-taper method spectral analysis revealed the existence of significant periodicities in our reconstruction. Significant spectral peaks were found at 29.7, 10.9, 2.5, and 2.2 years. The significant spatial correlations between our temperature reconstruction and the El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and Solar activity suggested that the temperature in the Daxing’an Mountains area indicated both local-regional climate signals and global-scale climate changes.</p></abstract>ARTICLE2020-07-17T00:00:00.000+00:00Radiocarbon dating of organic-rich deposits: Difficulties of paleogeographical interpretations in highlands of Russian Altaihttps://sciendo.com/article/10.2478/geochr-2020-0018<abstract><title style='display:none'>Abstract</title><p>The high mountainous southeastern part of Russian Altai is characterized by complicated sedimentation history. As a result of tectonic movements, Paleogene, Neogene, and even more old Carboniferous and Jurassic organicrich deposits had been partly uplifted and exhumed on the ridge’s slopes, where during the Pleistocene, they were affected by various exogenous processes including glaciation, glacio-fluvial erosion, winnowing activity of ice-dammed lakes, sliding during lake-draining events, followed by further intensive Holocene erosion, pedogenesis, and permafrost formation/degradation.</p><p>Remobilized ancient organic matter had been involved into geomorphic and pedogenesis processes and affected the results of radiocarbon dating. Numerous radiocarbon ages obtained revealed several typical problems in interpretation of dating results, which was confirmed by multidisciplinary investigations of associated sediments in a wider regional context.</p><p>This article presents a discussion on obtained apparent radiocarbon dates of organic material from ten sections of the SE Altai. In addition to radiocarbon analysis, in each case multidisciplinary study was carried out in order to properly interpret obtained dates, as well as to explain the inability of directly using apparent <sup>14</sup>C ages as a geochronological basis for paleogeographical reconstruction. The analysis presented is of vital importance for establishing the chronology of formation of large ice-dammed lakes and their cataclysmic draining; revealing chronology and paleoenvironmental conditions of pedogenesis in the highlands of the SE Altai; and estimating the range and magnitude of the tectonically driven topography rebuilding in the post-Neogene time.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00Status of the AMS graphitization system in the dendrochronological laboratory at AGH-UST, Krakówhttps://sciendo.com/article/10.2478/geochr-2020-0024<abstract><title style='display:none'>Abstract</title><p>A new system for the preparation of graphite samples for radiocarbon (<sup>14</sup>C) measurement using an accelerator mass spectrometer (AMS) has been built in the Dendrochronological Laboratory at AGH-UST, Kraków. This system consists of three independent components. The first is the equipment for mechanical and chemical sample pre-treatment. The second is the vacuum line for sample sealing and the purification of CO<sub>2</sub>. The third and central part of this system is a graphitization line, where graphite is produced from CO<sub>2</sub>. In the first stage, chemical sample preparation was carried out to remove impurities. IAEA and NIST OxII standard materials were converted to CO<sub>2</sub> without pre-treatment. In the next step, samples were combusted to CO<sub>2</sub>. The resulting CO<sub>2</sub> was released under vacuum and cryogenically purified for subsequent graphitization. The performance of the system was tested with NIST OxII, IAEA standards (IAEA C5, C6 and C7) and background samples. The test confirms good reproducibility of results obtained for the samples prepared using this system. The results of the 49 samples of NIST Ox-II, IAEA standards and blank samples were presented in this article.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00Oxygen isotopic fractionation in rat bones as a result of consuming thermally processed water – bioarchaeological applicationshttps://sciendo.com/article/10.2478/geochr-2020-0001<abstract><title style='display:none'>Abstract</title><p>Stable isotope analyses of oxygen are used in anthropology for such purposes as determination of origin of individuals, tracking migration routes or dynamics of human community relocation. The methodology related to oxygen isotope analysis has been founded on the relationship between its isotopic composition within phosphate groups of bone tissue (δ<sup>18</sup>O<sub>p</sub>) in individuals being analysed and the water consumed by such individuals (δ<sup>18</sup>O<sub>w</sub>). Such a relationship has been observed in many species of mammals, including humans. However, the influence of culinary practices on the isotopic delta values of apatite phosphates of individuals has not yet been researched. The present study, which was conducted using laboratory rats, is an investigation of the influence of the thermal processing of water drank by such rats on the isotopic composition (δ<sup>18</sup>O<sub>p</sub>) of bone apatite. Increasing the value of the isotopic composition of water by about 6.1 ‰ during boiling resulted in an increase in the oxygen isotopic value δ<sup>18</sup>O<sub>p</sub> of rats drinking the water by about 4 ‰ (29%). It can be expected that regular consumption of heavily isotopic drinks and foods by humans may cause the δ<sup>18</sup>O<sub>p</sub> of individuals to exceed the range of isotopic environmental variability, even by a few per mille.</p></abstract>ARTICLE2020-05-04T00:00:00.000+00:00Schmidt hammer exposure dating for brick masonryhttps://sciendo.com/article/10.2478/geochr-2020-0030<abstract><title style='display:none'>Abstract</title><p>This research investigates the validity of the Schmidt hammer exposure dating (SHED) technique as a complementary means to date monuments according to the evaluation of the brick decay from masonry exposed to climatic conditions. The degree of surface weathering, I<sub>5</sub> (%) is calculated as an indicator of the ageing effect and compared to the absolute age of the churches constructed between 1600 and 1795. This paper discusses the results obtained with such a method and the use of the technique within the framework of historical research. Tests were done on exterior church walls built between the 17<sup>th</sup> and 19<sup>th</sup> centuries. All the churches were located within the limited geographical area of Hainaut, in the south of Belgium. Results indicate that SHED provides encouraging results for buildings constructed between 1790 and 1895, with a linear correlation (R<sup>2</sup>&gt;0.8) between surface weathering of brick façades and their ages. However, the weathering indices show high variability of values for the period 1750−1790, which may confirm that the variable qualities of bricks were in use during this period of time because of the different production techniques. As such, the results highlight the probable influence of the entire manufacturing and construction process and technical improvements in traditional brick-making.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00Estimation of the durations of breaks in deposition – Speleothem case studyhttps://sciendo.com/article/10.2478/geochr-2020-0022<abstract><title style='display:none'>Abstract</title><p>Speleothems provide one of the most continuous terrestrial archives. However, due to changing conditions in temperature/humidity or the chemistry of percolating water, sedimentation breaks (hiatuses) and erosional events are possible and are commonly recorded in speleothems. Sedimentation breaks with durations longer than the resolution of the studied record should be considered in potential speleothem age-depth models. The most classic and reliable solution to the problem is the independent construction of age-depth models for the parts of speleothems separated by the hiatuses. However, in some cases, it is not possible to obtain a sufficient number of dating results for reliable age-depth model estimation. In such cases, the problem can be solved by the application of other sources of chronological information. Here, based on a few speleothem examples, an alternative approach – oxygen isotopic stratigraphy – is used to estimate the chronology for the parts of speleothems where there is not enough chronological information for classic age-depth models. As a result, the deposition break duration can be estimated.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00Dendrochronological dating of St. George’s Orthodox Church in Drohobych, Ukrainehttps://sciendo.com/article/10.2478/geochr-2020-0023<abstract><title style='display:none'>Abstract</title><p>St. George’s Orthodox Church in Drohobych is a wooden monument of sacral architecture, recently registered in the UNESCO World Heritage List. However, clear, unequivocal written sources about the origins of the structure are lacking. Absolute dating was attempted with the dendrochronological method, and it was carried out in a noninvasive way due to the status and value of the object. Construction elements of the church were documented with over 40 macrophotographs. The studies were made for selected elements, displaying distinct perpendicular or tangential cross sections. Most of the elements examined represented fir wood. It turned out that the wood used for the construction of this church was contemporaneous and most likely represented a single construction phase. The 124-year chronology based on correlated curves covers the period 1464–1598 AD. Construction elements with the outermost rings retained indicate that the timber was harvested in the 1590s. In most cases, the outermost rings were lacking, which allowed only for dating terminus post quem. The youngest preserved rings (1598 AD) from the church wood apparently reveal the dates of both the wood harvesting and the structure’s construction. Such a dating may indicate that the church mentioned in the sources as purchased in Nadiyevo in 1657 AD could be the basis for the rebuilding of Drohobych St. George’s Orthodox Church, only adapted to the new conditions. The church later underwent renovation, consisting in reconstruction of the dome in 1821 AD.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00Age of sediments on Danube terraces of the Pest Plain (Hungary) based on optically stimulated luminescence dating of quartz and feldsparhttps://sciendo.com/article/10.2478/geochr-2020-0021<abstract><title style='display:none'>Abstract</title><p>The numerical ages available for the sediments on the Danube terraces in the Pest Plain are scarce. In this study, we present quartz OSL and K feldspar post-IR IRSL<sub>290</sub> ages for the sandy fluvial, aeolian and slope sediments collected from Danube terraces IIb, III and V.</p><p>The feldspar post-IR IRSL<sub>290</sub> ages without residual dose subtraction are older than the quartz OSL ages, except for one sample, but the two sets of ages are overlapping within one or two sigma errors.</p><p>In the bleaching experiment under natural sunlight during summer, an unbleachable component ranging from 2.5±0.7 Gy to 5.2±0.3 Gy after 30 h exposure to bright sunshine is observed and it corresponds to 3−8% of the measured K feldspar post-IR IRSL<sub>290</sub> equivalent doses. These facts indicate that residual dose subtraction would be necessary before age calculation, in most cases.</p><p>The saturated fluvial gravelly sand of terrace V of the Danube is older than ~ 296 ka based on feldspar post-IR IRSL<sub>290</sub> measurements. This age does not contradict the traditional terrace chronology and the earlier published age data of this terrace. The other studied sediments on the surface of the terraces V, III and IIb deposited much later than the formation of these terraces. They infer aeolian activity and fluvial sedimentation of small streams during the MIS 3 and MIS 2 periods. The age of the dated dune sands with coeval aeolian sediments in Hungary indicate the cold and dry periods with strong wind activity of the Late Weichselian.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00Chronostratigraphy of Late Glacial aeolian activity in SW Poland – A case study from the Niemodlin Plateauhttps://sciendo.com/article/10.2478/geochr-2020-0015<abstract><title style='display:none'>Abstract</title><p>The stratigraphy of Late Pleniglacial and Late Glacial fluvio-to-aeolian succession was investigated in two sites located at the Niemodlin Plateau, SW Poland. Lithofacial analysis was used for the reconstruction of sedimentary environments. An absolute chronology for climatic change and the resulting environmental changes were determined based on optically stimulated luminescence (OSL – nine samples) and radiocarbon (three samples) dating methods. Four phases of changes in sedimentary environments were established. The first depositional phase correlates with the Last Permafrost Maximum (24−17 ka) based on the type and size of the periglacial structures, which aggraded under continuous permafrost conditions. During 17.5−15.5 ka (upper Late Pleniglacial), a stratigraphic gap was detected, owing to a break in the deposition on the interfluve area. The second depositional phase took place during 15.5−13.5 ka. During this phase, the first part of the dune formation (Przechód site) and fluvio-aeolian cover (Siedliska site) was deposited. The sedimentary processes continued throughout the entire Bølling interstadial and Older Dryas. In the third phase (Allerød interstadial), soil formation took place. At the Siedliska site, palaeosol represented Usselo soil type, whereas at the Przechód site, there was a colluvial type of soil. The last phase (Younger Dryas) is represented by the main phase of dune formation in both sites. After the Younger Dryas, no aeolian activity was detected. High compliance with both absolute dating methods was noticed.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00A Tree-Ring chronology from Allerød–YD transition from Koźmin (Central Poland)https://sciendo.com/article/10.2478/geochr-2020-0025<abstract><title style='display:none'>Abstract</title><p>Subfossil trunks of pine (<italic>Pinus sylvestris</italic> L.) from the Late Weichselian were discovered in the site Koźmin in the Koło Basin, central Poland (<xref ref-type="bibr" rid="j_geochr-2020-0025_ref_011_w2aab3b7d181b1b6b1ab2b1c11Aa">Dzieduszyńska et al., 2014a</xref>). Another part of organic sediments with trunks was excavated in the frame of the research project. Altogether 224 samples from Koźmin were analysed dendrochronologically; they represented generally young trees, 40 to 70 years old. Based on the most convergent sequences, the chronology 2KOL_A1 was produced, 210 years in length. With the wiggle-matching method, it was dated to ca. 13065–12855 cal BP. Dendrochronological dating of trunks buried in organic sediments, most of which occurred <italic>in situ</italic>, revealed that tree deaths occurred successively, over more than 100 years. That could have been due to unfavourable climatic conditions, as well as extreme events, e.g. strong winds.</p></abstract>ARTICLE2020-12-31T00:00:00.000+00:00A 333-year record of the mean minimum temperature reconstruction in the Western Tianshan Mountains, Chinahttps://sciendo.com/article/10.1515/geochr-2015-0104<abstract> <title style='display:none'>Abstract</title> <p>In this paper, a fragile ecological area in the Western Tianshan National Nature Reserve of China was selected as the research region, and <italic>Picea schrenkiana</italic>, which is sensitive to climate change, was selected as the research object. The mean minimum temperature in the growing season of the previous year (May to September) was the main limiting factor for tree radial growth based on an analysis of the relationship between chronological series and climatic factors during 1959–2012 (<italic>r</italic> = –0.792, <italic>p</italic> &lt; 0.05). Moreover, the relationship was stable, which showed that tree rings can be used as alternative materials for climate reconstruction. Therefore, the mean minimum temperature of the previous year in 1680–2012 was reconstructed, and the explained variance of the reconstruction equation was 62.7% (<italic>R<sup>2</sup><sub>adj</sub></italic> = 62.0%, F = 85.8). The 31 dramatically altered years were found via characteristic year analyses, and extreme changes occurred most often under relatively warm conditions. The mean minimum temperature in the reconstruction shows a clear warming trend by the 11-year moving average of the reconstructive series since the 1950s (the temperature increase: 0.341°C/decade). The driving factors of the mean minimum temperature were influenced mainly by the interaction of solar activity and large-scale atmospheric–oceanic variability, especially the westerly circulations.</p></abstract>ARTICLE2019-04-11T00:00:00.000+00:00Application of long time artificial optical bleaching of the E’ centre to sediment ESR datinghttps://sciendo.com/article/10.1515/geochr-2015-0106<abstract> <title style='display:none'>Abstract</title> <p>Three quartz samples extracted from different origins were collected for ESR evaluation to appreciate the optical bleaching characteristics of the <italic>E<sub>1</sub></italic>’ centre in a long time scale. After exposure of about 400 hours to artificial sunlight, the <italic>E<sub>1</sub></italic>’ centre were bleached to a steady increasing level, about 2.5 times of its natural level, and the increase level also exhibit a small variability among different sample origins. The constant increasing level provide a significantly evidence for the potential use of the natural signal intensities of quartz <italic>E<sub>1</sub></italic>’ centre in tracing sediment provenance. The results show that the signal intensity of <italic>E<sub>1</sub></italic>’ centre increased within beginning 84 h and decreased after 202 h as previous researches have partly predicted. After long time exposed to sunlight, there is no correlation between irradiated samples’ dose rate and its <italic>E<sub>1</sub></italic>’ centre ESR signal intensity. Thus, no new convenient indication shed light on the possible use of the <italic>E<sub>1</sub></italic>’ centre for ESR sediment dating.</p></abstract>ARTICLE2019-05-17T00:00:00.000+00:00en-us-1