Age of the Mt. Ortles ice cores, the Tyrolean Iceman and glaciation of the highest summit of South Tyrol since the Northern Hemisphere Climatic Optimum

In 2011 four ice cores were extracted from the summit of Alto dell'Ortles (3859 m), the highest glacier of South Tyrol in the Italian Alps. This drilling site is located only 37 km southwest from where the Tyrolean Iceman, similar to 5.3 kyrs old, was discovered emerging from the ablating ice field of Tisenjoch (3210 m, near the Italian-Austrian border) in 1991. The excellent preservation of this mummy suggested that the Tyrolean Iceman was continuously embedded in prehistoric ice and that additional ancient ice was likely preserved elsewhere in South Tyrol. Dating of the ice cores from Alto dell'Ortles based on Pb-210, tritium, beta activity and C-14 determinations, combined with an empirical model (COPRA), provides evidence for a chronologically ordered ice stratigraphy from the modern glacier surface down to the bottom ice layers with an age of similar to 7 kyrs, which confirms the hypothesis. Our results indicate that the drilling site has continuously been glaciated on frozen bedrock since similar to 7 kyrs BP. Absence of older ice on the highest glacier of South Tyrol is consistent with the removal of basal ice from bedrock during the Northern Hemisphere Climatic Optimum (6-9 kyrs BP), the warmest interval in the European Alps during the Holocene. Borehole inclinometric measurements of the current glacier flow combined with surface ground penetration radar (GPR) measurements indicate that, due to the sustained atmospheric warming since the 1980s, an acceleration of the glacier Alto dell'Ortles flow has just recently begun. Given the stratigraphic-chronological continuity of the Mt. Ortles cores over millennia, it can be argued that this behaviour has been unprecedented at this location since the Northern Hemisphere Climatic Optimum

Low-Level Liquid Scintillation Counting in an Underground Laboratory

A commercial liquid scintillation counter (LSC) was tested for its ability of low level counting (LLC) in two underground laboratories (70m of water equivalent cover). Reduction of total background and background components compared to the normal counting laboratory (5m we. cover) up to a factor of 9 depending on the energy range and the shielding of counting cell and laboratory walls were obtained. First experiments with a large volume cell (50cc) led to a modern 14C net effect of 425cpm and a corresponding background of 1.6cpm.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

Etude des caractérisitques structurales et hydrodynamiques des aquifères karstiques par leurs réponses naturelles et provoquées

Les premiers résultats du Programme National sur le cycle de l'eau en pays calcaires ont été résentés el discutés lors de la réunion du 5 juin 1981 du Groupe suisse de l'Association Internationale des Hydrogéologues à Neuchâtel. Ce programme de recherche, financé par le Fonds National Suisse de la Recherche Scientifique, fait appel à des méthodes d'investigations indirectes, géochimiques, géophysiques, isotopiques, pour explorer les propriétés hydrogéologiques des aquifères calcaires. Il ouvre des voies nouvelles pour la mise en valeur, la gestion et la protection de ces réservoirs. La réunion s'est terminée par la visite de la source de l'Areuse et du synclinal de la Brévine

Die im Eis gespeicherte Information über die Geschichte von Naturvorgängen

Im Firn und Eis der Gletscher unserer Erde ist in Form von Niederschlägen vergangener Zeiten unter anderem Information über die Entwicklung der Atmosphäre gespeichert. Der Beurteilung des steigenden Einflusses menschlicher Tätigkeit auf Klima und Umwelt liefert die Entzifferung dieser Information unentbehrliche Basisdaten. Das Material der erbohrten Kerne überdeckt beispielsweise so unterschiedliche Zeitabschnitte wie die sogenannte Kleine Eiszeit und die industrielle Entwicklung (Schweizer Alpen), oder die ganze letzte Eiszeit und Teile des vorangegangen Interglazials (Grönland). Bei der Interpretation der Informationsträger, den Gasen und Spurenstoffen im Eis. ist eine präzise zeitliche Einordnung notwendig und neue analytische Methoden, wie die auf Schwerionenbeschieuniger abstützende Massenspektrometrie. sollen hier einen wesentlichen Beitrag liefern. Darüber hinaus muss die Strategie dieser Interpretation von der Konfrontation mit physikalischen Modellen bestimmt werden, die in der Lage sind, das Geschehen im System Atmosphäre-Biosphäre-Ozean zu erfassen

Glacier mass balance reconstruction by sublimation induced enrichment of chemical species on Cerro Tapado (Chilean Andes)

A 36 m long ice core down to bedrock from the Cerro Tapado glacier (5536 m a.s.l, 30°08' S, 69°55' W) was analyzed to reconstruct past climatic conditions for Northern Chile. Because of the marked seasonality in the precipitation (short wet winter and extended dry summer periods) in this region, major snow ablation and related post-depositional processes occur on the glacier surface during summer periods. They include predominantly sublimation and dry deposition. Assuming that, like measured during the field campaign, the enrichment of chloride was always related to sublimation, the chemical record along the ice core may be applied to reconstruct the history of such secondary processes linked to the past climatic conditions over northern Chile. For the time period 1962–1999, a mean annual net accumulation of 316 mm water equivalent (weq) and 327 mm weq loss by sublimation was deduced by this method. This corresponds to an initial total annual accumulation of 539 mm weq. The annual variability of the accumulation and sublimation is related with the Southern Oscillation Index (SOI): higher net-accumulation during El-Niño years and more sublimation during La Niña years. The deepest part of the ice record shows a time discontinuity; with an ice body deposited under different climatic conditions: 290 mm higher precipitation but with reduced seasonal distribution (+470 mm in winter and –180 mm in summer) and –3°C lower mean annual temperature. Unfortunately, its age is unknown. The comparison with regional proxy data however let us conclude that the glacier buildup did most likely occur after the dry mid-Holocene

Radiocarbon reservoir effect and the timing of the late-glacial/early holocene humid phase in the Atacama Desert (Northern Chile)

We revise substantially the regional chronology of lake-level fluctuations from the late-glacial/early Holocene humid phase along a high altitude transect (3500 to 4500 m) between 18°S and 28°S in the Southwestern Altiplano of Northern Chile. Radiocarbon dates and 210Pb profiles for limnic and terrestrial materials allow us to estimate and justify reservoir correction values for conventional 14C dates. Our chronology suggests that the latest Pleistocene/early Holocene humid phase started between 13,000 and 12,000 14C yr B.P., and that maximum lake levels were reached between 10,800 and 9200 14C yr B.P. This is significantly younger than what has been established so far for the Titicaca–Uyuni Basin in Bolivia. The paleolakes disappeared sometime between 8400 and 8000 14C yr B.P. Our revised chronology agrees with the regional history of human occupation, and is broadly synchronous with vegetation changes in subtropical continental South America, and with the onset of wetland expansion in the northern hemisphere tropics