Archaeomagnetic study of ceramics from the El Molon archaeological monument (Spain

Data on the geomagnetic field intensity in the first millennium BC and the 8th–10th centuries AD are obtained from the study of materials from the El Molon archaeological monument (Spain). A 75-yr averaged curve of the variation in the geomagnetic field intensity in the area of the zero meridian over the last three millennia is constructed from a set of new and previously obtained data on the geomagnetic intensity variations in Spain and France. The field intensity smoothly decreases in the time interval studied, and variations a few centuries long are superimposed on this trend. Unlike the present-day relationship, the average level of the geomagnetic field intensity in Spain in the first millennium BC was higher than in the Caucasus.     

Archaeomagnetic study of ceramics from the Neolithic Los Castillejos multilayer monument (Montefrio,Spain)

The geomagnetic intensity variation from the middle of the 4th millennium BC to the beginning of the 2nd millennium BC is reconstructed from the archaeomagnetic study of ceramic material taken from 24 layers of the Los Castillejos monument (Montefrio, Spain). The general patterns of the geomagnetic intensity variation reconstructed by studying materials from the Cendres Cave and Los Castillejos monuments (Spain) are similar. The intensity level is revised in the time interval including the minimum of the “fundamental” oscillation of the geomagnetic field; the characteristics of geomagnetic intensity variations whose superposition can provide the intensity variation observed in the study time interval are determined. Constraints on the climate humidity variation over the settlement lifetime are obtained from heating-induced variations in the magnetic susceptibility of the ceramics.     

Archaeomagnetic secular variation in the UK during the past 4000 years and its application to archaeomagnetic dating

This paper examines the limitations and deficiencies of the current British archaeomagnetic calibration curve and applies several mathematical approaches in an attempt to produce an improved secular variation curve for the UK for use in archaeomagnetic dating. The dataset compiled is the most complete available in the UK, incorporating published results, PhD theses and unpublished laboratory reports. It comprises 620 archaeomagnetic (directional) data and 238 direct observations of the geomagnetic field, and includes all relevant information available about the site, the archaeomagnetic direction and the archaeological age. A thorough examination of the data was performed to assess their quality and reliability. Various techniques were employed in order to use the data to construct a secular variation (SV) record: moving window with averaging and median, as well as Bayesian statistical modelling. The SV reference curve obtained for the past 4000 years is very similar to that from France, most differences occurring during the early medieval period (or Dark Ages). Two examples of dating of archaeological structures, medieval and pre-Roman, are presented based on the new SV curve for the UK and the implications for archaeomagnetic dating are discussed.     

Testing the application of post IR IRSL dating to Iron- and Viking-age ceramics and heated stones from Denmark

In this study we test, for the first time, the potential of an elevated temperature post-IR IR (pIRIR₂₉₀) SAR protocol for the dating of young heated artefacts. Seven heated stones and seven potshards were collected from three different archaeological sites in Denmark: one site from the early Pre-Roman Iron Age 200 BC to AD 100, and two from the Viking period between AD 800 and 1200.We first derive quartz OSL ages for these samples, to support the archaeological age control. The luminescence characteristics of the pIRIR₂₉₀ signal are then investigated; in particular the dose recovery ratios are shown to be close to unity. The performance of the feldspar pIRIR₂₉₀ protocol is then examined by comparing the pIRIR₂₉₀ ages with those based on the quartz OSL signal; the average ratio of pIRIR₂₉₀ to OSL ages is 1.14 ± 0.05 (n = 14) and there is some suggestion that the possible overestimation of the feldspar ages compared to quartz is only of significance for the heated stone samples. Nevertheless, there is no indication of incomplete heating of the stones; the ratios of D_e derived from the IR₅₀ and pIRIR₂₉₀ signals are independent of sample type, and consistent with complete resetting by heating. Comparison with the archaeological age control is not able to identify whether quartz or feldspar provides the most reliable dating signal.     

Preliminary study on radiocarbon AMS dating of pollen

17 samples were collected from aeolian and lacustrine profiles within the environment sensitive zone of the Loess Plateau, and an experimental method was established which is suitable for pollen extraction from aeolian sediment. A comparative study of pollen dating was carried out using the accelerator mass spectrometry (AMS)¹⁴C dating of known age samples, and then an experiment with the pollen concentrates was performed. The results indicate that pollen that has been deposited simultaneously with sediment in a stable environment can provide reliable ages. This technique will provide a way of improving the chronological framework for the Loess Plateau since the late Pleistocene. The^I4c dating was combined with field investigations, and from the geological record within this zone, evidence was extracted of four major monsoon precipitation changes during the transition from the late Pleistocene to Holocene. Project supported by the National Natural Science Foundation of China (Grant Nos. 49894170, 49725308), Chinese Academy of Sciences (Nos. KZ-951-A1-402& KZ-952-S1-419), and State Committee of Science and Technology of China.     

地质定年方法综述与地球物理定年

年代确定在地学中得到广泛应用.而作为地史学中重要的组成部分，年代确定为地质时期中地球岩石圈在时间上发展和演变提供了重要的时间约束.本文综述了四种定年方法：即古生物法；古地磁法；同位素法和地球物理法.随着地球物理的探测技术的发展，地球内部精细结构得到揭示.我们认为，应用地球物理资料确定年龄将可以弥补其它方法的缺陷，可能为地球内部三维岩石定年提供支撑.     

The minimum extraction technique: A new sampling methodology for optically stimulated luminescence dating of museum ceramics

This paper introduces a novel optically stimulated luminescence (OSL) sampling protocol, referred to as the minimum extraction technique (MET), which assists in the OSL dating of museum ceramics. Here we outline how to extract a sample using this technique, as well as offering a discussion on the preparation protocols used for the method, and the calculation of the internal and external dose rates. A major benefit of MET is the minute sample size required, resulting in minimal damage to the museum object.MET permits OSL dating of material which would otherwise be usually off-limits for conventional OSL dating, for example, those housed in museum collections. In particular, MET can be used on objects which originate from regions where scientific analysis is currently not permitted on archaeological material, often owing to heritage laws.     

Single-grain optically stimulated luminescence dating of quartz temper from prehistoric Intermountain Ware ceramics,northwestern Wyoming,USA

This study applies single-grain optically stimulated luminescence (SG OSL) dating of quartz sand temper to Intermountain Ware ceramics recovered from four archaeological sites in northwestern Wyoming, USA. We show that SG OSL dating can strengthen and further refines existing archaeological site chronologies in certain settings. The SG OSL results are compared to multi-grain infrared stimulated luminescence (IRSL) dating of the polymineral (feldspar and quartz) silt fraction in the ceramic paste of the same sherds. Results from the two methods are statistically indistinguishable, although coarse-grained quartz SG OSL ages have consistently lower standard error terms due to higher relative sensitivity and avoidance of anomalous fading calculations. Moreover, the SG OSL results produced precision at two-sigma standard error greater than or equal to associated calibrated radiocarbon ages. SG OSL dating of quartz temper from Intermountain Ware ceramics provides more reliable site occupation timing than radiocarbon dating, which can be conditioned by incorporation of old wood and contamination from young soil carbon. This study highlights the importance of SG OSL dating on sherds from buried contexts when exposure to wildfires may have occurred, as ceramics recovered from the ground surface of one site after a high-intensity fire produced near-modern apparent ages, suggesting they were thermally reset during the fire. We suggest SG OSL should be applied to date similar ceramics with quartz temper to determine site age and bolster regional chronologies.     

Archaeomagnetic studies of materials from the Gorelyi Les and Ust-Khaita monuments (Eastern Siberia)

Archaeomagnetic studies of materials from archaeological monuments of the Irkutsk and Baikal regions provided new constraints on the geomagnetic intensity variation in Eastern Siberia for the interval from the 5th millennium BC through the 1st millennium AD. Material from the Gorelyi Les and Ust-Khaita multilayer archaeological monuments of the Irkutsk region is dated according to layer depths of deposits. Data on the geomagnetic intensity obtained from archaeomagnetic studies corroborate the validity of this method of dating. It is established that the average level of the geomagnetic intensity smoothly rose in the interval from the 5th millennium BC through the 1st millennium AD, with faster variations being superimposed on this trend. The pattern of the geomagnetic intensity variation is similar to those in other Eurasian regions.     

Archaeomagnetic Studies of Baked Clay Bricks in European Part of Russia: New Data

Izvestiya, Physics of the Solid Earth - Abstract—Reconstructing the evolution of the geomagnetic field in the European part of Russia has been an extremely challenging problem due to the...     

Archaeomagnetic determination of the ancient intensity of the geomagnetic field in Tamilnadu,India

A detailed study of the ancient intensity of the Earth's magnetic field in Tamilnadu, India is presented using pottery, bricks, tiles etc., obtained from the excavations that have been carried out at some of the important places of historical and archaeological interest. An attempt is made to reconstruct the secular variation of the geomagnetic field intensity. The results reported here reveal considerable changes in the Earth's magnetic field in this region during the past 2400 y. It is observed that the intensity of the geomagnetic field has been previously 57% greater than at present.     

A combined luminescence and radiocarbon dating study of the Ili loess,Central Asia

Similar to the loess in the Chinese Loess Plateau (CLP), the loess deposits in the Ili basin of Central Asia arid area play an important role in understanding the climate and environmental changes. However, in contrast to the intensively investigated loess deposits in the CLP, the Ili loess is still insufficiently known and poorly understood. The geochronology study of the Ili loess remains controversial. In order to examine the potential of optically stimulated luminescence (OSL) dating for the Ili loess, we carry out a combined luminescence and radiocarbon dating study on a 6.9 m loess section in the south margin of the Ili basin. Polymineral fine grains were investigated by post infrared (IR) OSL using a Multiple-Aliquot Regenerative-dose (MAR) protocol. Radiocarbon dating of organic carbon were carried in a 3 Megavolt (MV) multi-element Accelerator Mass Spectrometry (AMS). The results indicate that the OSL ages are in agreement with the observed stratigraphy in the field, which is well correlated with that of the CLP, but the AMS ¹⁴C ages are much younger than the OSL and assumed stratigraphical ages. Thus, the OSL dating technique may provide an absolute chronology in this loess section. Further methodological approaches and more samples analysis will lead to the improvement of this chronology for high-resolution paleoclimatic interpretation.     

Optical dating of drowned landscapes: A case study from the English Channel

Drowned landscapes are important archives documenting palaeoenvironmental response to abrupt climate and sea-level changes characteristic of the Quaternary. Analysis of high resolution geophysical and core data has revealed preservation of fluvial, coastal, shallow marine and periglacial deposits on the continental shelf in the eastern English Channel, thus providing an ideal field site to test the application of optical dating to a variety of depositional environments presently submerged beneath the sea. A stratigraphic model detailing the sequence and nature of sedimentary processes operating on the shelf in relation to post-glacial relative sea-level change is presented as a framework to test the reliability of optical ages. The single-aliquot regenerative-dose protocol was applied to 1 mm aliquots of fine quartz sand and individual aliquots were rejected following the criteria proposed by Wintle and Murray (2006). All samples demonstrate a range of intrinsic sensitivities with a sufficient number of grains giving enough light to enable reliable estimation of D_e. Different age models, CAM and MAM-3, were used to establish palaeodose and the robustness of these age models was tested using a bootstrapping technique. Coastal sediments show evidence of incomplete bleaching limiting confidence in age estimates. Quartz deposited in fluvial, periglacial and shallow marine environments is suitably bleached and OSL sensitive to enable reliable estimates of D_e. Changes in environmental dose must be considered when interpreting ages from sediments that have experienced repeated relative sea-level cycles. Ages in the range of 107.8 ka to 5.3 ka were calculated that are remarkably consistent with the stratigraphic model, thus demonstrating the successful applicability of optical dating to drowned landscapes.     

黑龙江省小南山遗址受热历史的考古磁学证据

考古磁学技术为考古遗址的受热历史研究提供了重要的定性/定量分析方法.黑龙江省东北部的小南山是中国东北地区重要的史前遗址之一,该遗址记录的最早人类活动可以追溯到更新世末期.遗址揭露了距今约16 ka以来序列性的人类生活遗物及遗迹,包括大量的石制品和少量的陶片,以及与当时人类生活方式相关的疑似用火遗迹.本文对小南山遗址内疑似用火区及周边的散土样品进行了一系列岩石磁学测试,包括低频磁化率、逐步磁化率随温度变化曲线（χ-T）、磁滞回线、等温剩磁获得曲线、反向场退磁曲线和一阶反转曲线（FORC）等,旨在通过磁学指标为遗址受热温度、受热范围等信息提供定量化证据.实验结果显示,采样区域内两处疑似用火区（ZB、ZC）磁化率普遍偏高、逐步χ-T曲线在400~600℃之间表现出较好的热稳定性、饱和等温剩磁偏强、FORC信号偏强;而表层烧土被清理后的疑似用火区（ZA）和非疑似用火区磁化率普遍偏低、逐步χ-T曲线显示样品在加热过程中逐渐发生热变化、饱和等温剩磁和FORC信号偏弱.这些磁学特征意味着ZB、ZC两处疑似用火区曾受过加热烘烤,而从ZA采集到的样品和疑似用火区外的样品则可能没有受热.逐步χ-T曲线结果显示疑似用火区高磁化率样品在400~600℃之间表现出较好的热稳定性,而当温度达到700℃时则发生明显的热转化,指示样品历史最高受热温度应该在600~700℃之间.

     

Soil radiocarbon analysis and soil dating

Based on¹⁴C dating principles, techniques of measuring¹⁴C concentrations in pedogenic organic materials have been well established. Basic lines of soil sample pretreatment for radiocarbon analysis by liquid scintillation are shown. Possible influences of lithogenic carbon on the results obtained are discussed.Soil organic matter¹⁴C analysis results can-according to the radiocarbon dating formula-be interpreted as minimum ages of the soil under investigation if strong evidence for autochthonous pedogenic origin of the material is given. In case of fossil soils, minimum age is maximum estimate for period of burial. The gap existing between minimum age and true age can be reduced by special techniques of fractionation, as well as by taking account of additional pedological information on turnover features of the material. Discussion of possible soil organic matter turnover mechanisms leads to a theory of rates of decomposition high in the initial stages and slowing down to nearly zero with time.Application of¹⁴C techniques to humus dynamics until now yielded apparently contradictory results on relative ages of different humic matter fractions., Enrichment of old material in the HCl hydrolysis residue fraction, however, has been observed in all instances.Mathematical modelling of soil radiocarbon response on varying turnover parameters results in estimates of turnover time and migration speed of soil organic matter in total as well as fractions thereof.

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Zusammenfassung Ausgehend von den Grundlagen der¹⁴C Datierung wird das Verfahren der¹⁴C Messung an organischem Bodenmaterial mit Hilfe der Flüssigkeits Szintillations Methode kurz erläutert. Ernste meßtechnische Probleme liegen heute nicht mehr vor. Als Mangel wird die uneinheitliche Probenvorbereitung bei CaCO₃ haltigen und CaCO₃ freien Proben empfunden.Die bodendynamisch bedingte altersmäßige, Inhomogenität der Proben ermöglicht es nicht, das wahre Alter einer Probe, d. h. das Alter des ältesten Teils der in der Probe enthaltenen organischen Stoffe nach der Datierungsformel zu berechnen. Eine genaue Analyse zeigt vielmehr, daß der nach der Formel berechnete Wert nur als Minimalabschätzung für das Alter der Probe gesichert ist. Das so ermittelte Minimalalter der untersuchten organischen Substanz ist gleichzeitig ein Minimalalter für den zugehörigen Boden, falls feststeht, daß das erfaßte Material autochthon pedogen ist und weder aus dem Ausgangsmaterial stammt noch durch Lateraltransport in den Boden gelangte. Das Minimalalter fossiler Böden ist gleichzeitig eine Maximalabschätzung, ihrer Überdeckungszeit.Durch Isolierung einer an älterem Material angereicherten Fraktion der organischen Substanz und ihre gesonderte Untersuchung kann ein Minimalalter für den untersuchten Boden gewonnen werden, das dem wahren Alter näher kommt. Erfolge wurden bisher mit der Rückstandsfraktion von HCl Hydrolysen erzielt. Die Frage nach der Fraktion höchsten Alters ist noch offen.Über das durch Fraktionierungsmethoden gewonnene Maß hinaus kann Aufschluß über die Größe der Differenz zwischen Minimalalter und wahrem Alter im wesentlichen nur durch bodenkundlich theoretische Information über Turnover und Abbauverhalten der organischen Substanz gewonnen werden. Zwei Ansätze werden vorgestellt und diskutiert. ¹⁴C Analysen der klassischen Fraktionen der organischen Substanz haben keine, für alle Böden, ja nicht einmal eine für alle Profilbereiche desselben Bodens gleiche Rangfolge der Fraktionen bezüglich ihres¹⁴C Gehaltes erbracht. Die aus dieser Ergebnislage erwachsenden Schwierigkeiten für ein Verständnis der biochemischen Humusdynamik werden unter Verweis auf die Literatur angedeutet.Versuche, mit mathematischen Modellen die Wechselbeziehungen zwischen der Dynamik der organischen Substanz des Bodens und seiner¹⁴C Konzentrationen in verschiedenen Profiltiefen zu erhellen, werden vorgestellt. Fortschritte auf diesem Gebiet könnten sowohl die Genauigkeit der Altersschätzung mit der¹⁴C Methode erhöhen als auch zu einer konsistenten Interpretation der¹⁴C Ergebnisse in der Erforschung der Humusdynamik führen.

     

Rare-gas dating,III. Evaluation of a double-spiking procedure for potassium-argon dating

A double-spike method for KAr dating is described. Use of long-lived³⁹Ar in addition to the usual³⁸Ar in the spike permits argon isotopic discrimination occurring after insertion of the spike to be monitored at the same time as ages are determined. A “bootstrap” (self-contained) method of calibrating the spike for isotopic composition is described which, when used appropriately, gives final ages which are independent of the published isotopic composition of the terrestrial atmospheric argon used as a comparison gas. The method calls for a mass spectrometer which resolves adjacent isotopes to a high degree. We have tested the method nevertheless with a mass spectrometer of relatively low resolving power, the AEI MS-10, and found it to be successful in part and without any disadvantages with respect to conventional techniques in those instances where the method fails because of insufficient resolution. That is, we find the discrimination factor inferred in runs on young rocks and blanks to be valid and useful. That factor changes by as much as 1.3% over the life of a filament in the ion source of the MS-10, proving that close control of the discrimination factor is essential for analytical precision with the instrument. These assertions are documented graphically with a compilation of data which represents more than two years experience with the method. We also report measurements of the mass discrimination of the MS-10 and its linearity with mass which indicate that the latter quantity is acceptable when the repeller voltage for the ion source is close to +1 V and is unacceptable otherwise. The spike material is available, upon request, to those laboratories which decide firmly to undertake further testing of the method.     

High-resolution dating of Co-rich crusts: A comparative study using the methods of orbital pacing and ~(230)Th_(ex)/~(232)Th dating

Due to their slow growth rates, seamount Co-rich crusts are very difficult to date with high resolution and precision. This paper is to test the use of orbital pacing on the growth profile of crusts to determine high-resolution age and growth rate. Crust CB14 from the central Pacific Ocean was selected for this study. We first examined the growth pattern in detail under a reflected-light microscope and ascertained that the growth environment was stable for the sub-layer 1 (0-3 mm). We then used electron mic...