Zur Entwicklung der jungquartären Tieflandstäler im Saale-Elbe-Raum unter besonderer Berücksichtigung von 14C-Daten

Erstmalig wurden für den Saale-Elbe-Raum — als geologisch gut erschlossenes Untersuchungsgebiet Mitteleuropas — systematisch gesammelte Proben durch Radiokarbon datiert. Somit ist es möglich, das weichseiszeitliche Alter der intakten und gekappten Niederterrasse zu bestätigen sowie die stark differenzierte holozäne Flußdynamik chronostratigraphisch zu erfassen. Die in der nacheiszeitlichen Flußgeschichte innerhalb eines komplexen Wirkungsgefüges ablaufenden Sedimentationsprozesse wurden in bestimmten Einzugsgebieten durch mittelbare anthropogene Eingriffe bereits seit neolithischer Zeit stark beeinflußt. Dies zeigt sich vor allem im Beginn und Verlauf der Auelehmakkumulation. Durch die radiometrische Datierung subfossiler Hölzer aus holozänen Flußschottern konnte ebenfalls für den mitteldeutschen Raum die Verdrängung der Kiefer durch die Eiche aus den Flußtälern bereits für das Boreal (ältestes 14C-Datum 8790 ± 140 BP) festgestellt werden. Dies stimmt gut mit Befunden aus anderen Flußgebieten vor allem des südlichen Mitteleuropas überein.researc

Ungewöhnliche Probleme bei der 14C-Datierung organischer Komponenten und Fraktionen fluviatiler Sedimente aus der Aue der Weißen Elster bei Leipzig

Aus Paläorinnensedimenten und fossilen Bodenhorizonten in der Weißen Elsteraue wurden konventionelle und AMS 14C-Altersbestimmungen der organischen Substanz durchgeführt. Die Ergebnisse liefern z.T. sehr große Altersdifferenzen der verschiedenen Komponenten einer Probe bis über 20.000 14C-Jahre, die der Beimischung von umgelagertem tertiären Material zuzuschreiben ist. Die Resultate belegen, dass bei der Interpretation von 14C-Altersbestimmungen an organischem Material aus fluviatilen Sedimenten große Vorsicht geboten ist, wenn nicht die Altershomogenität des Probenmaterials bewiesen werden kann oder weitere Absicherungen durch unabhängige absolute Datierungsmethoden vorliegen.researc

An Extended Prehistoric Well Field in the Opencast Mine Area of Zwenkau, Germany

From the 16th International Radiocarbon Conference held in Gronigen, Netherlands, June 16-20, 1997.In the opencast mine area of Zwenkau, Germany, many prehistoric wells and pits have recently been excavated. In this region there is generally no bone preservation and charred seeds are rare, seldom encountered in a reliable archaeological context, whereas charcoal is frequently found. From an archaeological point of view, however, charcoal from wood is not as reliable for radiocarbon dating as short-lived materials. Fortunately, many deep features were found where wood has been preserved. Over a dozen structures turned out to be prehistoric wells, some of them typologically dated by ceramics to between Early Bronze Age and Early Middle Ages. For other features without archaeological finds, 14C dating was the only way to get an age. Analysis showed that different types of wells were constructed by the same culture. On the other hand, the same constructions are not characteristic for a defined cultural period and were applied over a time span of three millennia.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Influence of Chromium Endowment and Surface Area of Silica-Alumina Catalysts and of Reaction Conditions on Benzene Synthesis

Radiocarbon laboratories using liquid scintillation counting depend on the availability of a catalyst for benzene synthesis. One of the two commonly used is a commercially available chromium-activated silica-alumina catalyst, PKN/D1. As this catalyst will no longer be produced, we have tested similar catalysts as possible replacements. We measured benzene purity by gas chromatography and mass spectrometry, and found that chromium endowment was crucial for a proper catalyst function. The surface area of the catalyst also significantly affected benzene yield and purity. We also studied the effects of different reaction conditions of acetylene absorption and benzene desorption on benzene purity. A catalyst with half of the Cr endowment and doubled specific surface area created yield and purity comparable to PKN/D1.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Radiocarbon dating of mumiyo samples from Antarctica

Radiocarbon dating is a nimportant tool for reconstructing Late Quaternary paleoenvironmental history of the Antarctic continent. Because of the scarcity of datable material, new suitable substances are welcomed. We present here novel paleoenvironmental records subfosil stomach oil deposits (mumiyo). This waxy organic material is found in petrel breeding colonies, especialy in those of snow petrels, Pagodroma nivea. The substance is formed by acumulation and solidifica tion of stomach oil regurgitated for the purpose of defense. We demonstrate and outline the usefulnes and limitations of 14C dating mumiyo for determining dates of local ice retreat, moraines and petrel ocupation history