Radiocarbon chronology of occupation of the site Chicha and Bayesian statistics for the assessment of a discontinuous transition from Late Bronze to Early Iron Age (West Siberia)     

J. Schneeweiss  F. Becker  V.I. Molodin  H. Parzinger  Zh.V. Marchenko  S.V. Svyatko 《Russian Geology and Geophysics》2018,59(6):635-651

The Late Bronze to Iron Age transition in West Siberia involved significant cultural and political changes, which were reflected in the emergence of protourban settlements in the forest-steppe zone. The transition is roughly dated to the turn from the 2nd to the 1st mil. BC, mainly based on archaeological artefacts and on the general sociocultural development. A more precise radiocarbon dating for this transition was problematic mainly because of the general lack of data for West Siberia. This paper analyzes the chronology of the Late Bronze to Iron Age transition at Chicha, a reference site in the region for this period. The assessment of a possible hiatus between the Late Bronze Age and the following transitional period at Chicha is the key issue of our paper, as its presence may have far reaching cultural implications. To increase the precision of the radiocarbon chronology with focus on the possible hiatus, the samples from well-defined stratigraphic contexts were analyzed using Bayesian modeling incorporating stratigraphic information. The performed chronological modeling supports existing archaeological hypothesis of a hiatus at the very end of the 2nd mil. BC, just before the regular emergence of a new protourban settlement at the site of an abandoned Late Bronze settlement. A sensitivity analysis including the simulated hiatus confirms the reliability of the model. A complete population change seems to be plausible. The protourban settlement of Chicha, typical of the Transitional period, did not exist very long. With the emergence of the early nomadic cultures in the South Siberian steppes at the beginning of the 1st mil. BC, it most probably stopped functioning. The cultural development of that time, former believed to be continuous, was deeply interrupted several times.  相似文献   

Evidence for carbonate platform failure during rapid sea‐level rise; ca 14 000 year old bioclastic flow deposits in the Lesser Antilles     

JESSICA TROFIMOVS  JODIE K. FISHER  HEATHER A. MACDONALD  PETER J. TALLING  R. STEPHEN J. SPARKS  MALCOLM B. HART  CHRISTOPHER W. SMART  GEORGES BOUDON  CHRISTINE DEPLUS  JEAN‐CHRISTOPHE KOMOROWSKI  ANNE LE FRIANT  STEVEN G. MORETON  MELANIE J. LENG 《Sedimentology》2010,57(3):735-759

Bioclastic flow deposits offshore from the Soufrière Hills volcano on Montserrat in the Lesser Antilles were deposited by the largest volume sediment flows near this active volcano in the last 26 kyr. The volume of these deposits exceeds that of the largest historic volcanic dome collapse in the world, which occurred on Montserrat in 2003. These flows were most probably generated by a large submarine slope failure of the carbonate shelf comprising the south‐west flank of Antigua or the east flank of Redonda; adjacent islands that are not volcanically active. The bioclastic flow deposits are relatively coarse‐grained and either ungraded or poorly graded, and were deposited by non‐cohesive debris flow and high density turbidity currents. The bioclastic deposit often comprises multiple sub‐units that cannot be correlated between core sites; some located just 2 km apart. Multiple sub‐units in the bioclastic deposit result from either flow reflection, stacking of multiple debris flow lobes, and/or multi‐stage collapse of the initial landslide. This study provides unusually precise constraints on the age of this mass flow event that occurred at ca 14 ka. Few large submarine landslides have been well dated, but the slope failures that have been dated are commonly associated with periods of rapid sea‐level change.  相似文献   

Understanding the dynamics and contamination of an urban aquifer system using groundwater age (14C, 3H,CFCs) and chemistry          下载免费PDF全文

Jürgen Mahlknecht  Arturo Hernández‐Antonio  Christopher J. Eastoe  Carol Tamez‐Meléndez  Rogelio Ledesma‐Ruiz  José A. Ramos‐Leal  Nancy Ornelas‐Soto 《水文研究》2017,31(13):2365-2380

The quality of the groundwater supplying drinking water to the Guadalajara metropolitan area has deteriorated due to both endogenic and exogenic processes. Previous studies of this complex neotectonic volcanic environment suggest that the sources of contamination here are underground fluids derived from an active volcanic center and surface wastewater derived from regional land‐use intensification. This study uses isotopic, gaseous, and chemical signatures to more comprehensively characterize this groundwater flow and its contamination paths. Groundwater is mainly recharged at the La Primavera Caldera to the west and is discharged into the Santiago River to the east. The exception to this trend is the Toluquilla area, where groundwater most likely represents rainfall originating from outside the basin limits. Evaporation affects groundwater in these areas, especially waters that have been affected by recycling below urban areas in the Atejamac area and by intensive agricultural activity in the Toluquilla area. Additionally, we present evidence that groundwater flow through alluvial sediments and tuffs in deeper wells mixes with a lower aquifer unit in basaltic‐andesitic rocks, which are in contact with hydrothermal fluids. Groundwater ages range from postbomb in the western and northwestern regions of the study area (i.e., the Atemajac aquifer unit) to Late Pleistocene in the southern and southeastern regions (i.e., the Toluquilla aquifer unit). Recently recharged water records little mixing and is located mostly in or near the La Primavera volcanic system. As groundwater undergoes gravitational flow towards discharge areas, it mixes with older water components. Chloride and sodium concentrations above natural background levels are primarily related to volcanic activity, nitrate is associated with human activities, and sulfate originates from both anthropogenic sources and water–rock interactions. Nitrate originating from land‐use activities (such as sewers, septic tanks, landfills, and agricultural fields) that is introduced into the deeper part of the groundwater system is expected to travel with the groundwater to the discharge areas because oxidizing conditions will prevent microbial reduction. See Supplementary Information.  相似文献   

Evidence for the occurrence of Vedde Ash in Sweden: radiocarbon and calendar age estimates     

Stefan Wastegrd  Svante Bjrck  Gran Possnert  Barbara Wohlfarth 《第四纪科学杂志》1998,13(3):271-274

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Pitfalls in the AMS radiocarbon-dating of terrestrial macrofossils     

B. Wohlfarth  G. Skog  G. Possnert  B. Holmquist 《第四纪科学杂志》1998,13(2):137-145

The AMS ¹⁴C technique has the advantage that small samples of Late Quaternary age can be dated with high accuracy, and that errors due to reservoir effects can be avoided if specifically determined terrestrial micro- and macrofossils are measured. However, to obtain such high-accuracy measurements, it is important how small samples are handled prior to treatment in the radiocarbon laboratories. Here we present a set of 51 AMS ¹⁴C measurements, of which 31 dates gave expected ages and 20 dates resulted in anomalously young ages, despite the fact that all samples consisted of clearly identified Late Weichselian terrestrial plant macrofossils. To evaluate possible sources of error, we compared these samples in respect to preparation methods, sample storage and sample weight. Our results show that the long-term storage of wet macrofossil samples appears to have a significant effect on the radiocarbon age obtained, even when the samples are kept cool. Fungi or micro-organisms may easily be incorporated into a sample during preparation and identification, and can easily contribute to the contamination of a sample, if stored cool and wet for several months. © 1998 John Wiley & Sons, Ltd.  相似文献   

The new 14C chronology for the Palaeolithic site of La Ferrassie,France: the disappearance of Neanderthals and the arrival of Homo sapiens in France     

S. Talamo  V. Aldeias  P. Goldberg  L. Chiotti  H. L. Dibble  G. Guérin  J.-J. Hublin  S. Madelaine  R. Maria  D. Sandgathe  T. E. Steele  A. Turq  S. J. P. Mcpherron 《第四纪科学杂志》2020,35(7):961-973

The grand abri at La Ferrassie (France) has been a key site for Palaeolithic research since the early part of the 20th century. It became the eponymous site for one variant of Middle Palaeolithic stone tools, and its sequence was used to define stages of the Aurignacian, an early phase of the Upper Palaeolithic. Several Neanderthal remains, including two relatively intact skeletons, make it one of the most important sites for the study of Neanderthal morphology and one of the more important data sets when discussing the Neanderthal treatment of the dead. However, the site has remained essentially undated. Our goal here is to provide a robust chronological framework of the La Ferrassie sequence to be used for broad regional models about human behaviour during the late Middle to Upper Palaeolithic periods. To achieve this goal, we used a combination of modern excavation methods, extensive geoarchaeological analyses, and radiocarbon dating. If we accept that Neanderthals were responsible for the Châtelperronian, then our results suggest an overlap of ca. 1600 years with the newly arrived Homo sapiens found elsewhere in France.  相似文献   

The Late Pleistocene megafauna of the Chulym River basin,southeastern West Siberian Plain: chronology and stable isotope composition     

Yaroslav V. Kuzmin  Andrei V. Shpansky 《第四纪科学杂志》2023,38(1):2-7

New data were obtained for the Chulym River basin in the southeastern part of the West Siberian Plain, one of the understudied parts of Siberia in terms of age and composition of carbon and nitrogen stable isotopes for Late Pleistocene megafauna. The ¹⁴C dates from the Sergeevo outcrop, the most complete section of Late Quaternary deposits in the region, are mostly greater than ~30 550 bp. Other localities yielded ¹⁴C values in the range from >44 500 to ~19 300 bp. The finite date of ~42 270 bp for the Khozarian steppe elephant (Mammuthus trogontherii chosaricus) from Asino is intriguing because previously it was not detected in the Late Pleistocene of Siberia after the last interglacial (Marine Isotope Stage 5e), ~115 000–130 000 years ago. Stable isotope data show both similarities and differences compared to the pre-Last Glacial Maximum megafaunal species in other parts of Siberia.  相似文献