Chronological Model Research Articles

Bayesiansk kronologisk modellering som redskab i den lovpligtige arkæologi

Bayesiansk kronologisk modellering som redskab i den lovpligtige arkæologi

First high-resolution luminescence dating of loess in Western Siberia

The south of Western Siberia is an important part of the Eurasian loess belt, containing an extensive record of Quaternary landscape and climate evolution in up to 100 m thick loess deposits with as many as 10 pedocomplexes. However, this important Quaternary archive lacks a reliable absolute chronology, and this has prevented the linking of the widely accepted regional chronostratigraphic correlations with those of other parts of the Eurasian loess belt. Here we present the first results of detailed luminescence dating of the Late Pleistocene loess-palaeosol sequence at the Western Siberian stratotype section of Lozhok. According to the classical regional chronostratigraphic scheme, this sequence records the main stages of the environmental evolution of the region, including three palaeosols correlated with the warming stages of MIS 5e, MIS 5c and MIS 3. Our absolute chronology is based on 38 new luminescence ages (OSL, IR 50 , pIRIR 290 ). Good agreement between the OSL and pIRIR 290 ages suggests sufficient bleaching before deposition. The resulting chronology reveals that, rather than being only Upper Pleistocene in age, the loess-palaeosol sequence at Lozhok actually formed in the Middle and Upper Pleistocene. The ages of individual horizons do not correspond to the previously accepted stratigraphic units and morphological features of pedocomplexes. Our Bayesian chronological model reveals remarkable variation in dust accumulation and preservation at the site. The new results unambiguously identify the presence of an erosional boundary with a hiatus lasting ∼90 ka. The upper pedocomplex, immediately below this discontinuity, formed in sediment deposited between 131 ± 9 ka and 122 ± 11 ka and clearly corresponds to MIS 5. The lower pedocomplex is found in sediment deposited between 240 ± 12 and 199 ± 9 ka, and correlates closely with MIS 7. These new findings demonstrate the urgent need for a wider programme to date the main stratotypes of loess-palaeosol sections in Western Siberia. Only then can the global implications of the regional climate record in this important continental-scale archive be correctly interpreted.

Introduction to Special issue

Introduction to Special issue

Searching for buried craters on Mars based on gravity potential field separation method

There are many buried craters on Mars invisible in imaging or topographic data; however, the residual gravity anomaly separated from the Mars Bouguer gravity anomaly by minimum curvature separation method can reveal these buried craters. In our research, gravity separation results exposed 39 residual gravity anomaly highs (RGAHs), which may represent deeply buried impact craters with 300–500 ​km diameter. The RGAHs are widely distributed across the surface of Mars, but are especially concentrated in volcanic areas like Tharsis and Elysium, which indicates that there might be more craters buried in these regions. Older craters in volcanic regions were likely buried by subsequent volcanism coming from surrounding volcanoes, so the retention age of craters in all areas where RGAHs are located will be older than reported in the existing research based on topographic data alone. This study will help improve the chronological model of Mars. • The impact craters of Mars with diameter of 300–500 km appear central positive residual gravity anomalies. • The gravity separation results exposed 39 anomaly highs, that is inferred to be buried impact craters. • The most RGAHs are concentrated in volcanic areas just like Tharsis and Elysium.

ABSOLUTE CHRONOLOGY AT THE WATERLOGGED SITE OF LA DRAGA (LAKE BANYOLES, NE IBERIA): BAYESIAN CHRONOLOGICAL MODELS INTEGRATING TREE-RING MEASUREMENT, RADIOCARBON DATES AND MICRO-STRATIGRAPHICAL DATA

ABSTRACTSixty-two 14C dates are analyzed in combination with a recently established local floating tree-ring sequence for the Early Neolithic site of La Draga (Banyoles, northeast Iberian Peninsula). Archaeological data, radiometric and dendrochronological dates, as well as sedimentary and micro-stratigraphical information are used to build a Bayesian chronological model, using the ChronoModel 2.0 and OxCal 4.4 computer programs, and IntCal 2020 calibration curve. The dendrochronological sequence is analyzed, and partially fixed to the calendrical scale using a wiggle-matching approach. Depositional events and the general stratigraphic sequence are expressed in expanded Harris Matrix diagrams and ordered in a temporal sequence using Allen Algebra. Post-depositional processes affecting the stratigraphic sequence are related both to the phreatic water level and the contemporaneous lakeshore. The most probable chronological model suggests two main Neolithic occupations, that can be divided into no less than three different “phases,” including the construction, use and repair of the foundational wooden platforms, as well as evidence for later constructions after the reorganization of the ground surface using travertine slabs. The chronological model is discussed considering both the modern debate on the Climatic oscillations during the period 8000–4800 cal BC, and the origins of the Early Neolithic in the western Mediterranean region.

Blind dates: Exploring uncertainty in the radiocarbon evidence on the emergence of animal husbandry in the Dutch wetlands

The emergence of animal husbandry in the Netherlands remains the subject of much speculation. Challenges in identifying domesticated animals among the faunal remains, inconsistent excavation documentation, and flawed radiocarbon analysis have resulted in questionable chronologies. This paper examines the available radiocarbon evidence from selected sites which are the mainstay of early examples of domesticated animals in the Netherlands, between 5000 and 4000 BCE.1All radiocarbon dates given in this paper, denoted as BCE, are calibrated unless stated otherwise.1 We approach the legacy data in two ways: by employing principles of chronometric hygiene to reassess the radiocarbon datasets of selected sites and by exploring the use of such data for future studies in chronology by means of Bayesian chronological modelling. The latter is demonstrated with a case study, whereby we employ legacy data from Hardinxveld-Giessendam De Bruin in Bayesian models to demonstrate that, despite their shortcomings, such dates remain a valuable resource for much needed future chronological analysis.

Mainland-coastal interactions in East Borneo: Inter-site comparison and Bayesian chronological models of two Late Pleistocene–Holocene sequences (Liang Abu and Kimanis rock shelters)

In recent decades, East Borneo has become an increasingly important archaeological “hot-spot” in Island Southeast Asia as a result of early dates for rock art ca. 38,000 BP and the greater number of excavated sites that support a much longer period of human occupation. However, the chronology of settlement and adaptation to environmental changes during the Pleistocene–Holocene transition is still poorly known. Here we report on an excavation at the Liang Abu rock shelter which has contexts dating from the Late Pleistocene (12,660 ± 58 uncal. BP) to the present day, indicating a terminus ante quem (TAQ) for human occupation at 23,790 BP. We present the results of an attempt to systematically integrate and compare data from Liang Abu and Kimanis, a geographically close site with a previously published sequence. Particular attention is paid to post-depositional issues in tropical settings and to data compatibility, reuse, and reproducibility, relying on open-source software for data processing (R scripts) and Bayesian chronological modeling. Two Bayesian models are built and compared using the ChronoModel software, which can handle outliers and uncertainty (e.g., freshwater reservoir effect). This first inter-site comparison for Borneo results in a new chronology of human settlement and mainland–coastal interactions in East Borneo and paves the way for future regional synthesis.

Social and chronological aspects of the Late Bronze age burial site of Kokcha 3 (Uzbekistan)

The Amu-Darya Delta (ancient Khwarazm, modern Uzbekistan) was a borderland between northern steppe-based Andronovo-Srubnaya groups and southern oasis cultures in the Late Bronze Age. The local sites are known as the Tazabag'yab culture, of which Kokcha 3 is the largest excavated burial site. As such, Kokcha 3 provides the largest representative record of the local burial customs for this era. Scholars have documented a complex burial ritual for males, females and two types of double burials and reconstructed two chronological phases at the site. However, a study incorporating these different sources is still missing.In this paper, the anthropological and archaeological record of Kokcha 3 is studied using multivariate statistical approaches and spatial distribution patterns. The burial ritual was most likely divided according to gender. Double burials are distinguished between simultaneous and consecutive burials, which include different demographics and are likely to be used in different contexts. On the excavation plan, three separate areas for males, females and double burials can be reconstructed. The two-phase chronology model is verified using correspondence analysis, establishing the funeral pottery as chronological marker at Kokcha 3. Conclusions about the prehistoric landscape are drawn from the results and a hypothesis on the social structure of the Kokcha 3 community is proposed considering the context of a borderland situation. The results presented may also be relevant for the interpretation of the archaeological record of the Late Bronze Age in other regions in south Central Asia.

Long eccentricity forcing Asian dust input into the northwestern Pacific during the early Pleistocene

Asian dust deposition in the northwestern Pacific is generally linked to high-latitude paleoclimate evolution during the Quaternary. However, whether low-latitude tropical Pacific processes, such as El Niño-Southern Oscillation (ENSO), influence Asian dust input into the northwestern Pacific remains uncertain. Here, we present clear periodic variations in potassium content (K (wt%)) and gamma-ray attenuation (GRA) bulk density, which are closely linked to the variations in Asian dust, in a sediment core recovered at Site U1438 in the Amami Sankaku Basin (ASB), northwestern Philippine Sea. Based on the shipboard age-depth model, we tuned the GRA to the mass accumulation rate curve on the Chinese Loess Plateau and the 8-kyr-lagged obliquity curve, and established the astronomical timescale. The K (wt%) content and GRA were higher during glacials and lower during interglacials, as driven by the variability in the Northern Hemisphere ice sheet (NHIS) during the Quaternary. In addition, strong long eccentricity 405-kyr cycles were observed in the dust records (K (wt%) content and GRA) during the early Pleistocene. The 405-kyr filter results showed that increased (decreased) Asian dust corresponded to the La Niña-like (El Niño-like) state, suggesting that Asian dust input into the northwestern Pacific was modulated by ENSO on 405-kyr cycles in the early Pleistocene. Our study illustrated the possible link between long eccentricity 405-kyr cycles in the Asian interior and low-latitude forcing, including potential modulation by ENSO. • K (wt%) and GRA from Site U1438 are related to input of Asian dust. • Dust signals were used to reconstruct the orbital chronological model. • Dust signals have clear 405-kyr cycles during the early Pleistocene. • Long eccentricity forcing Asian dust input into the northwestern Pacific.

The Appearance of Contracting Stem Dart Points in the Western United States, Diffusion or Migration?

Contracting stem dart points are assigned to various named types and are considered Archaic temporal markers, but their dating and geographic distribution remain somewhat variable and uncertain. Bayesian chronological modeling indicates contracting stem dart points were in use in the Colorado Plateau and Great Basin from 2210 cal BC through 710 cal BC. Comparative dating indicates contracting stem dart points did not arrive with farmers from Mexico, but rather, the dates and geographic distribution of the contracting stem points indicate this hafting style diffused rapidly throughout the western US.

How reliable is µXRF core scanning at detecting tephra layers in sedimentary records? A case study using the Lake Suigetsu archive (central Japan)

AbstractHere, we evaluate the ability of micro X‐ray fluorescence (µXRF) core scanning to identify non‐visible volcanic ash (cryptotephra) layers in sedimentary records. Its suitability is assessed using the annually resolved lacustrine sediments of Lake Suigetsu (Japan) for which there is high‐resolution ITRAX µXRF core scanning data, and a detailed crypto‐tephrostratigraphy (formerly established via density separation techniques). The studied core sections contain 10 visible and 30 cryptotephra markers that span a range of glass concentrations (from 1000 to >20 000 shards per gram of dried sediment) and compositions (basalts, trachy‐andesites, phonolites, trachytes and rhyolites), thus providing an ideal case study. The ITRAX core scanner produced recognisable µXRF elemental responses for the visible ash layers, including those just 1 mm thick. However, just 10% of the cryptotephra layers could be unequivocally identified. Although this study demonstrates that µXRF core scanning should not be used as an independent method within a similar geological setting, we show it can provide a powerful tool alongside traditional techniques. Where detected, µXRF profiles can verify and refine cryptotephra positions (here to a sub‐millimetre resolution), and help establish reworking signatures. These insights create possibilities for ultra‐precise synchronisation of records, improved chronological modelling and help generate more complete eruption histories.

Age-depth modelling and the effect of including – or not – shared errors across sets of OSL samples: The case study of Beg-er-Vil (Brittany, France)

The coastal site of Beg-er-Vil (Brittany, France) has yielded remains of a dwelling site from the Mesolithic period, dating back to ca. 8000 years ago. These archaeological remains were covered by a marine sand dune. Among the research questions raised by recent excavations, the timing of the dune formation with respect to the human occupations is of particular interest: how much time elapsed between these two events? To resolve this question, we employed radiocarbon dating to infer the timing of human occupations and OSL dating to date the dune aggradation. We combined radiocarbon and OSL data in a Bayesian framework, including stratigraphic constraints and measurement errors shared across OSL samples, to build a robust and precise chronological model of the site. We then built an age-depth model for the dune to determine the onset of dune formation. We conclude that we cannot detect a time gap between the latest human occupations and dune aggradation. Finally, we demonstrate how stratigraphic constraints and shared errors affect – and improve – the precision of the chronology inferred from our measurements.

Magma eruption ages and fluxes in the Rembrandt and Caloris interior plains on Mercury: Implications for the north-south smooth plains asymmetry

The MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) mission by the National Aeronautics and Space Administration revealed that ~27% of the surface of Mercury is occupied by smooth plains potentially formed by magma eruptions. Most of these smooth plain units are located on the floors of the impact basins; these plains occupy a surface area that is approximately seven times larger in the northern hemisphere than in the southern hemisphere. This suggests a difference in thermal conditions in the mantle and/or the ease of magma eruption between hemispheres. This study re-estimated magma eruption ages and volumes within the Rembrandt and Caloris basins; these are representative impact basins in the southern and northern hemispheres, respectively. The estimations of eruption ages and volumes were carried out by measuring crater size-frequency distributions and the diameters of partially buried craters. The formation and eruption ages of the Rembrandt and the Caloris basins were estimated by adopting the porous-target chronology model; the formation ages were estimated as 3.93 ± 0.06 and 3.94 ± 0.04 Gy, while their eruption ages were from 3.87 ± 0.04 to 3.76 ± 0.01 Gy and 3.88 ± 0.03 to 3.74 ± 0.01 Gy, respectively. The observed crater size-frequency distributions in both basins might show multiple resurfacing from episodic eruptions, as suggested by previous numerical simulations of Mercurian thermal evolution. The estimated magma eruption fluxes in the Caloris basin (9.3–15.1 km/Gy) were at most, three times larger than that in the Rembrandt basin (5.2–12.3 km/Gy). Given its larger diameter, the crust beneath the Caloris basin is likely to be ~1.8 times thinner than the crust beneath the Rembrandt basin. This will make it easier for magma to ascend to the surface beneath Caloris than beneath Rembrandt; as such, quantities of magma production in the mantle beneath the two basins should not differ by a factor of <3. These results suggest that there are no large spatial variations in the abundance of heat-producing elements in the mantle and lower crust of Mercury unlike the concentration of heat-production elements on the nearside of the Moon.

The intrusive nature of the Châtelperronian in the Iberian Peninsula.

Multiple factors have been proposed to explain the disappearance of Neandertals between ca. 50 and 40 kyr BP. Central to these discussions has been the identification of new techno-cultural complexes that overlap with the period of Neandertal demise in Europe. One such complex is the Châtelperronian, which extends from the Paris Basin to the Northern Iberian Peninsula between 43,760–39,220 BP. In this study we present the first open-air Châtelperronian site in the Northern Iberian Peninsula, Aranbaltza II. The technological features of its stone tool assemblage show no links with previous Middle Paleolithic technology in the region, and chronological modeling reveals a gap between the latest Middle Paleolithic and the Châtelperronian in this area. We interpret this as evidence of local Neandertal extinction and replacement by other Neandertal groups coming from southern France, illustrating how local extinction episodes could have played a role in the process of disappearance of Neandertals.

Radiocarbon dating and Hallstatt chronology: a Bayesian chronological model for the burial sequence at Dietfurt an der Altm\xfchl \u2018Tennisplatz\u2019, Bavaria, Germany

This study is first attempt to refine Early Iron Age absolute chronology, specifically the timing of the Hallstatt C-D transition in southern Germany, using Bayesian chronological modelling of radiocarbon (14C) dates. The Hallstatt period (c.800–450 BC) marks the transition from prehistory to proto-history in Central Europe. The relative chronological framework for Hallstatt burials developed by the mid-twentieth century is still used today, but absolute dating is limited by the scarcity of dendrochronological dates and the perception that 14C dating in the Hallstatt period (HaC-HaD) is futile, due to the calibration plateau between c.750 and 400 cal BC. We present new AMS 14C dates on 16 HaC-HaD burials from a stratified sequence at Dietfurt an der Altmühl ‘Tennisplatz’ (Bavaria, Germany). This sequence is situated entirely on the ‘Hallstatt plateau’, but by combining 14C dating with osteological, stratigraphic, and typological information, we demonstrate that the plateau is no longer the ‘catastrophe’ for archaeological chronology once envisaged. Taking into account dendrochronological dating elsewhere, we show that at Dietfurt, the HaC-HaD transition almost certainly occurred before 650 cal BC, and most likely between 685 and 655 cal BC (68.3% probability), several decades earlier than usually assumed. We confirm the accuracy and robustness of this estimate by sensitivity testing. We suggest that it is now possible, and essential, to exploit the increased precision offered by AMS measurement and the IntCal20 14C calibration curve to re-evaluate absolute chronologies in Early Iron Age Europe and equivalent periods in other regions.

Author Correction: Updated lunar cratering chronology model with the radiometric age of Chang’e-5 samples

Author Correction: Updated lunar cratering chronology model with the radiometric age of Chang’e-5 samples

Application of Representation Learning-Based Chronological Modeling for Network Intrusion Detection

An autoencoder has the potential to overcome the limitations of current intrusion detection methods by recognizing benign user activity rather than differentiating between benign and malicious activity. However, the line separating them is quite blurry with a significant overlap. The first part of this study aims to investigate the rationale behind this overlap. The results suggest that although a subset of traffic cannot be separated without labels, timestamps have the potential to be leveraged for identification of activity that does not conform to the normal or expected behavior of the network. The second part aims to eliminate dependence on visual-inspections by exploring automation. The trend of errors for HTTP traffic was modeled chronologically using resampled data and moving averages. This model successfully identified attacks that had orchestrated over HTTP within their respective time slots. These results support the hypothesis that it is technically feasible to build an anomaly-based intrusion detection system where each individual observation need not be categorized.

A multi-proxy assessment of the impact of environmental instability on Late Holocene (4500-3800 BP) Native American villages of the Georgia coast.

Circular shell rings along the South Atlantic Coast of North America are the remnants of some of the earliest villages that emerged during the Late Archaic (5000–3000 BP). Many of these villages, however, were abandoned during the Terminal Late Archaic (ca 3800–3000 BP). We combine Bayesian chronological modeling with mollusk shell geochemistry and oyster paleobiology to understand the nature and timing of environmental change associated with the emergence and abandonment of circular shell ring villages on Sapelo Island, Georgia. Our Bayesian models indicate that Native Americans occupied the three Sapelo shell rings at varying times with some generational overlap. By the end of the complex’s occupation, only Ring III was occupied before abandonment ca. 3845 BP. Ring III also consists of statistically smaller oysters harvested from less saline estuaries compared to earlier occupations. Integrating shell biochemical and paleobiological data with recent tree ring analyses shows a clear pattern of environmental fluctuations throughout the period in which the rings were occupied. We argue that as the environment became unstable around 4300 BP, aggregation at villages provided a way to effectively manage fisheries that are highly sensitive to environmental change. However, with the eventual collapse of oyster fisheries and subsequent rebound in environmental conditions ca. post-3800 BP, people dispersed from shell rings, and shifted to non-marine subsistence economies and other types of settlements. This study provides the most comprehensive evidence for correlations between large-scale environmental change and societal transformations on the Georgia coast during the Late Archaic period.

Landscapes for Neolithic People in Mainland, Orkney

Neolithic occupation of the Orkney Islands, in the north of Scotland, probably began in the mid fourth millennium cal BC, culminating in a range of settlements, including stone-built houses, varied stone-built tombs and two noteworthy stone circles. The environmental and landscape context of the spectacular archaeology, however, remains poorly understood. We applied the Multiple Scenario Approach (MSA) to Neolithic pollen records from Mainland, Orkney, in order to understand land cover and landscape openness across the timespan 4200–2200 cal BC. Interpreted within a framework provided by Bayesian chronological modelling, 406 radiocarbon dates from archaeological contexts and a further 103 from palaeoenvironmental samples provide the basis for the first detailed reconstruction of the spatio-temporal patterns of Neolithic people and their environment. Major alterations to the land cover of Mainland took place from 3400 cal BC (reduction in woodland from 20% to 10%) and from 3200 cal BC (increase in disturbed land from 3% to 30%). The dramatic increase in disturbed land coincided with the Grooved Ware phenomenon and the establishment of settlements at Skara Brae and Ness of Brodgar. The upturn in the signal for disturbance communities in the pollen record may indicate an increase in the amount of land used as pasture. This accords with the archaeological record, since the Neolithic Orcadian economy probably relied heavily on cattle for subsistence. By 2800 cal BC in the core of the Orkney Mainland, most settlements appear to have been ending, with people dispersing into the wider landscape, as the MSA modelling indicates a maintenance of disturbed land, and indeed a subsequent slight increase, implying persistence of human activity elsewhere in Mainland. People exhausted themselves rather than their land; that and its varied resources endured, while the intensive social relationships and practices of the peak of late Neolithic Orkney could not be maintained.

Stages, Periods, and Radiocarbon: 14C Dating in the Archaeology of the Central Andes

Some of the earliest archaeological materials radiocarbon-dated were from the Central Andes, and archaeologists from the region were also involved in early efforts at meta-analysis of assemblages of radiocarbon dates and Bayesian chronological modeling. Nevertheless, regional chronological schema still vary surprisingly little from their pre-radiocarbon antecedents. As a result, significant scope for increasing the impact of radiocarbon dates, as well as making their use more robust and transparent, remains. Improved use of radiocarbon dates has the potential to reconfigure Central Andean chronologies, suiting them better to addressing many of the questions that archaeologists wish to ask. With this in mind, I here review the history of use of 14C dating in the archaeology of the Central Andes, before focusing on practical issues that confront archaeologists working in the region as they both employ 14C dates and seek to be informed and critical consumers of published 14C dates and chronologies.