187 research outputs found

    Anomalous radiocarbon ages found in Campanian Ignimbrite deposit of the Mediterranean deep-sea core CT85-5

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    A detailed radiocarbon chronology has been established for the deep-sea core CT85-5 from the Tyrrhenian Sea. This chronology, which is based on the analysis of foraminifera shells, shows a set of reversed 14C ages for sediments deposited during the eruption of the Campanian Ignimbrite (~40 ka cal BP). The anomalous young 14C ages coincide with elevated concentrations of 10Be measured in the same core. Although reversals in 14C ages have been previously found in other records at 40 ka cal BP, such extreme changes have not been observed elsewhere. The enhancement in 14C concentration in CT85-5 sediments associated with the Campanian Ignimbrite is equivalent to an apparent age ~15 ka younger than the age for the sediments deposited shortly before the eruption. Here, we present consistent results of repeated measurements showing no analytical problems that can explain the observed rapid changes in 14C of this particular record.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

    An Impacting Descent Probe for Europa and the other Galilean Moons of Jupiter

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    We present a study of an impacting descent probe that increases the science return of spacecraft orbiting or passing an atmosphere-less planetary body of the solar system, such as the Galilean moons of Jupiter. The descent probe is a carry-on small spacecraft (< 100 kg), to be deployed by the mother spacecraft, that brings itself onto a collisional trajectory with the targeted planetary body in a simple manner. A possible science payload includes instruments for surface imaging, characterisation of the neutral exosphere, and magnetic field and plasma measurement near the target body down to very low-altitudes (~1 km), during the probe's fast (~km/s) descent to the surface until impact. The science goals and the concept of operation are discussed with particular reference to Europa, including options for flying through water plumes and after-impact retrieval of very-low altitude science data. All in all, it is demonstrated how the descent probe has the potential to provide a high science return to a mission at a low extra level of complexity, engineering effort, and risk. This study builds upon earlier studies for a Callisto Descent Probe (CDP) for the former Europa-Jupiter System Mission (EJSM) of ESA and NASA, and extends them with a detailed assessment of a descent probe designed to be an additional science payload for the NASA Europa Mission.Comment: 34 pages, 11 figure

    Evolution of carbon fluxes during initial soil formation along the forefield of Damma glacier, Switzerland

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    Soil carbon (C) fluxes, soil respiration and dissolved organic carbon (DOC) leaching were explored along the young Damma glacier forefield chronosequence (7-128years) over a three-year period. To gain insight into the sources of soil CO2 effluxes, radiocarbon signatures of respired CO2 were measured and a vegetation-clipping experiment was performed. Our results showed a clear increase in soil CO2 effluxes with increasing site age from 9±1 to 160±67gCO2-Cm−2year−1, which was linked to soil C accumulation and development of vegetation cover. Seasonal variations of soil respiration were mainly driven by temperature; between 62 and 70% of annual CO2 effluxes were respired during the 4-month long summer season. Sources of soil CO2 effluxes changed along the glacier forefield. For most recently deglaciated sites, radiocarbon-based age estimates indicated ancient C to be the dominant source of soil-respired CO2. At intermediate site age (58-78years), the contribution of new plant-fixed C via rhizosphere respiration amounted up to 90%, while with further soil formation, heterotrophically respired C probably from accumulated ‘older' soil organic carbon (SOC) became increasingly important. In comparison with soil respiration, DOC leaching at 10cm depth was small, but increased similarly from 0.4±0.02 to 7.4±1.6gDOCm−2year−1 over the chronosequence. A strong rise of the ratio of SOC to secondary iron and aluminium oxides strongly suggests that increasing DOC leaching with site age results from a faster increase of the DOC source, SOC, than of the DOC sink, reactive mineral surfaces. Overall, C losses from soil by soil respiration and DOC leaching increased from 9±1 to 70±17 and further to 168±68gCm−2year−1 at the <10, 58-78, and 110-128year old sites. By comparison, total ecosystem C stocks increased from 0.2 to 1.1 and to 3.1kgCm−2 from the young to intermediate and old sites. Therefore, the ecosystem evolved from a dominance of C accumulation in the initial phase to a high throughput system. We suggest that the relatively strong increase in soil C stocks compared to C fluxes is a characteristic feature of initial soil formation on freshly exposed rock

    40Ar/39Ar and 14C geochronology of the Albano maar deposits: Implications for 2 defining the age and eruptive style of the most recent explosive activity at Colli 3 Albani Volcanic District, Central Italy

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    New 40Ar/39Ar and 14C ages have been found for the Albano multiple maar pyroclastic units and underlying 25 paleosols to document the most recent explosive activity in the Colli Albani Volcanic District (CAVD) near 26 Rome, Italy, consisting of seven eruptions (Albano 1 27 ^ = ^ oldest). Both dating methodologies have been applied on several proximal units and on four mid-distal fall/surge deposits, the latter correlated, according to two 28 current different views, to either the Albano or the Campi di Annibale hydromagmatic center. The 40Ar/39Ar 29 ages on leucite phenocrysts from the mid-distal units yielded ages of ca. 72 ka, 73 ka, 41 ka and 36 ka BP, 30 which are indistinguishable from the previously determined 40Ar/39Ar ages of the proximal Albano units 1, 2, 31 5 and 7, thus confirming their stratigraphic correspondence. 32 Twenty-one 14C ages of the paleosols beneath Albano units 3, 5, 6 and 7 were found for samples collected 33 from 13 proximal and distal sections, some of which were the same sections sampled for 40Ar/39Ar 34 measurements. The 14C ages were found to be stratigraphically inconsistent and highly scattered, and were 35 systematically younger than the 40Ar/39Ar ages, ranging 36 ^ from 35 ka ^ to 3 ka. Considering the significant consistence of the 40Ar/39Ar chronological framework, we interpret the scattered and contradictory 14C ages 37 to be the result of a variable contamination of the paleosols by younger organic carbon deriving from the 38 superficial soil horizons. 39 These results suggest that multiple isotopic systems anchored to a robust stratigraphic framework may need 40 to be employed to determine accurately the geochronology of the CAVD as well as other volcanic districts. 4

    Queen Nefertari, the royal spouse of pharaoh Ramses II: a multidisciplinary investigation of the mummified remains found in her tomb (QV66)

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    Queen Nefertari, the favourite Royal Consort of Pharaoh Ramses II (Ancient Egypt, New Kingdom, 19th Dynasty c. 1250 BC) is famous for her beautifully decorated tomb in the Valley of the Queens. Her burial was plundered in ancient times yet still many objects were found broken in the debris when the tomb was excavated. Amongst the found objects was a pair of mummified legs. They came to the Egyptian Museum in Turin and are henceforth regarded as the remains of this famous Queen, although they were never scientifically investigated. The following multidisciplinary investigation is the first ever performed on those remains. The results (radiocarbon dating, anthropology, paleopathology, genetics, chemistry and Egyptology) all strongly speak in favour of an identification of the remains as Nefertari's, although different explanations-albeit less likely-are considered and discussed. The legs probably belong to a lady, a fully adult individual, of about 40 years of age. The materials used for embalming are consistent with Ramesside mummification traditions and indeed all objects within the tomb robustly support the burial as of Queen Nefertari.Michael E. Habicht, Raffaella Bianucci, Stephen A. Buckley, Joann Fletcher, Abigail S. Bouwman, Lena M. Őhrström, Roger Seiler, Francesco M. Galassi, Irka Hajdas, Eleni Vassilika, Thomas Böni, Maciej Henneberg, Frank J. Rühl

    Центральная Азия в интересах Ирана, Китая, России и Турции: взгляд из США

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    Работа посвящена изучению реакции американских специалистов на внешнюю политику Ирана, Китая, России и Турции в Центральной Азии. В исследовании комплексно рассмотрена политика единственной сверхдержавы относительно отдельного региона в рамках общей стратегии США.Робота присвячена вивченню реакції американських фахівців на зовнішню політику Ірану, Китаю, Росії та Туреччини у Центральній Азії. У дослідженні комплексно розглянута політика єдиної наддержави щодо окремого регіону в рамках її загального стратегічного курсу.The thesis is focused on a study of the american specialists reactions toward foreign policy of China, Iran, Russia and Turkey in Central Asia. The research presents a complex investigation of the policy of the only superpower in the relation to a separate region in the frame of its general strategic course

    INTEGRATED DATING OF THE CONSTRUCTION AND RESTORATION OF THE MODENA CATHEDRAL VAULTS (NORTHERN ITALY): PRELIMINARY RESULTS

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    After the last damaging earthquake in 2012, an anti-seismic reinforcement project of the cathedral of Modena was designed giving us the opportunity to investigate and date the building materials. Radiocarbon (14C), optically stimulated luminescence (OSL), and thermoluminescence (TL) dating techniques were performed on the vaults with the aim to (1) clarify the construction timing, (2) define the history of the restorations, and (3) explore the possible correlation of the main restoration works to the earthquake chronology deduced from the historic catalog. Preliminary results show that medieval older bricks were reused for most of the original construction. Only lime and non-gypsum mortar was used for the original construction in the 15th century and for later repair of damage caused by earthquakes in the 16th and 17th centuries. Gypsum mortar was used for later repair in the 18th century. The results show much stronger damage due to earthquakes than previously thought

    Very high resolution paleosecular variation record for the last ∼ 1200 years from the Aral Sea

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    A record of geomagnetic paleosecular variation (PSV) spanning the last ∼1200 years has been obtained from two lacustrine sediment cores from the north part of Aral Sea (Kazakhstan). Magnetic susceptibility and NRM intensity have been used for correlating between cores and reconstructing composite core data. The main swings and fine details of declination and inclination records correlate well between both cores. A very high sedimentation rate (up to 25 mm per year) due to recent tectonic activity of the region provides a very high resolution PSV record for the interval from 450 ± 100 years BP to 655 ± 65 years BP. The results which have been dated by eight AMS radiocarbon age determinations, suggest that a 200-400 years secular variation period with amplitudes in declination and inclination up to 10-15° existed regularly during the time interval 0-1200 BP. Amplitudes of the PSV record from Aral Sea are not reduced and smoothed by postdetrital magnetization processes. They adjoin to the historical data model and are considered to represent a reliable paleosecular variation record for the Aral Sea region for the last ∼1200 years
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