Radiocarbon dating and its applications in Quaternary studies

Dieser Beitrag gibt einen Überblick über die Herkunft von Radiokohlenstoff, den globalen Kohlenstoffkreislauf, anthropogene Einflüsse auf das atmosphärische 14C und die Grundlagen der Radiokohlenstoffmethode. Probenaufbereitung und das Messen der 14C Konzentration sind wichtige Aspekte im Zusammenhang mit der Radiokohlenstoffdatierung. Gegenwärtige Fortschritte in der Probenaufbereitung erlauben ein besseres Verstehen lang bekannter Probleme (z.B. die Kontamination von Knochen) und haben zu verbesserten Chronologien geführt. In diesem Überblick werden verschiedene Aufbereitungstechniken für typische Probengattungen beschrieben. Der letzte Schritt beim Erstellen einer Chronologie ist die Kalibration der Radiokohlenstoffalter. Die gegenwärtige auf Baumringzeitreihen basierende Kalibrationskurve wird stetig über das Holozän und Spätglazial hinaus erweitert. Eine zuverlässige Kalibrationkurve für die letzten 50.000–55.000 Jahre ist von herausragender Bedeutung sowohl für die Archäologie als auch die Geowissenschaften. In den letzten Jahren haben zahlreiche Studien an der Erweiterung der Radiokohlenstoff-Kalibrationskurve (INTCAL working group) und an der Rekonstruktion des Paläo-Reservoireffekts in marinen Archiven gearbeitet.researc

High-resolution radiocarbon chronologies and synchronization of records

It is now accepted that the precise dating of certain periods is complicated by extreme variability of atmospheric ¹⁴C content shown at times in the ¹⁴C calibration curve. This complication arises from variations in atmospheric ¹⁴C content and is known as wiggles in the calibration curve. Radiocarbon age ‘plateaus’, are caused by a decrease in the atmospheric ¹⁴C concentration and appear as a slowing down of the ¹⁴C clock such as occurred during the Younger Dryas (YD) chronozone. In effect, similar ¹⁴C ages apply across a range of up to 500 calendar years. The opposite is observed when atmospheric ¹⁴C levels increase so that the ¹⁴C clock appears to speed up. In such cases, which include the beginning of the YD and Pre-Boreal intervals, the true age of a sample, taking dating errors into account, may spread across a comparatively wide ¹⁴C age rang

Comparing analysis of pretreatment methods of wood and bone materials for the chronology of peripheral burials at Tunnug 1, Tuva Republic, Russia

Nine burials from Tunnug 1 site in Tuva Republic, which contained human and animal bones as well as remains of wood, were chosen for intercomparison study of preparation methods. Nine human bones, nine animal bones and 11 pieces of wood were prepared. Gelatin extracted from bones was purified using the UF method but the extraction from bones was modified with respect to acid and base treatment. Wood samples were treated as whole using acid-base-acid and cellulose was extracted for comparison. The results confirmed a highly consistent chronology of the sites centered at 200–400 CE, however, a few bones resulted in an offset between ages obtained by different methods. The extraction of cellulose was limited due to the poor preservation of wood. Our results highlight problems of dating poorly preserved bones and wood

Timing and mechanisms of sediment accumulation and pedogenesis: Insights from the Po Plain (northern Italy)

The relationships between pedogenetic processes and fluvial-coastal dynamics in the Po Plain have been reconstructed through sedimentological analysis and correlation of ca. 170 core data chronologically constrained by 376 radiocarbon dates. Vertically stacked, weakly developed paleosols within Upper Pleistocene and Holocene mud-prone strata testify to intermittent pedogenesis, periodically interrupted by overbank sedimentation. Individual paleosols are laterally traceable for tens of km and exhibit A-Bk-Bw, A-Bk or A-Bw profiles. Strati graphically ordered 14C calibrated ages from A organo-mineral horizons testify to slow aggradation during 4-6 thousand years-long exposure periods. Burial ages, with an error of few centuries, are provided by plant debris at the top of A horizons.Millennial-scale climate oscillations and glacio-eustasy are the main drivers of the pedo-sedimentary evolution of the area during the last 50 kyr. Upper Pleistocene paleosols (P1-P3) developed in well-drained floodplain environments, during relatively warm periods.Paleosol burial occurred during colder phases. High-sediment supply during the Last Glacial Maximum hindered pedogenesis and led to the accumulation of 3-10 m-thick overbank strata. Widespread soil development (paleosol PH) occurred at the end of Last Glacial Maximum, following the retreat of Alpine glaciers and the afforestation of Apennine drainage basins. At distal locations, paleosol PH was progressively buried under estuarine sediments during the Holocene phases of post-glacial sea level rise. Beyond the area of marine influence, burial ages of paleosol PH change from a place to another without specific spatial trends and reflect upstream fluvial sedimentation dominated by avulsions and deposition of spatially restricted alluvial units. Holocene (H1-H2) paleosols show a poor correlation potential and laterally variable degree of maturity that reflect avulsive sedimentation patterns and crevassing. This paper provides insights on the timing and mechanisms of formation and burial of weakly-developed paleosols. The outcomes of this research are applicable to similar Quaternary alluvial systems, and may help interpreting ancient paleosolbearing successions

The Equilibrium Line Altitude of isolated glaciers during the Last Glacial Maximum : New insights from the geomorphological record of the Monte Cavallo Group (south-eastern European Alps)

The authors would like to thank Francesco Ferrarese for providing spatial data that enabled the reconstruction of the Monte Grappa Glacier, and Renato R. Colucci for assisting with field sampling. This work was supported by the Royal Society [grant number: IEC\R2\202123].Peer reviewedPublisher PD

The polymorphism and tradition of funerary practices of medieval Turks in light of new findings from Tuva Republic.

The medieval Turks of the eastern Asian steppe are known for funerary finds exalting horsemanship and military heroism that thrived on intertribal warfare. Existing bodies of research on various categories of objects-which include architecture, stelae, grave goods and inhumations-are in depth but highly regionalized. As a result, our understanding of the archaeological culture of the Turks on a spatio-temporal scale commensurate with territorial shifts in their political dominion throughout the period of the Turk khaganates (mid-6th to mid-8th centuries CE) remains disjunct. The present paper addresses this problem of disparate data. We present a synthesis of the archaeological research of medieval Turks spanning Mongolia, southern Siberia, and Xinjiang in view of results of the excavation of medieval burials at Tunnug 1 in Tuva Republic-where Turkic remains are dispersed and not easily distinguishable from other funerary cultures of connecting time periods. We argue that Turkic funerary culture can be better characterized as polymorphic-the presence of different regional amalgams of burial traditions. The horse-and-human burials and commemorative ogradka known to be quintessentially Turkic are but one of the more dominant amalgams. This pattern of differential practices is congruent with the history of medieval Turks evolving as peoples of mixed lineages and political groupings, rather than people of a unitary culture

Cold Reversal on Kodiak Island, Alaska, Correlated with the European Younger Dryas by Using Variations of Atmospheric C-14 Content

High-resolution AMS (accelerator-mass-spectrometer) radiocarbon dating was performed on late-glacial macrofossils in lake sediments from Kodiak Island, Alaska, and on shells in marine sediments from southwest Sweden. In both records, a dramatic drop in radiocarbon ages equivalent to a rise in the atmospheric C-14 by approximately 70%. coincides with the beginning of the cold period at 11000 yr B.P. (C-14 age). Thus our results show that a close correlation between climatic records around the globe is possible by using a global signature of changes in atmospheric C-14 content