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Bones of three human individuals, found at the Upper Palaeolithic site of Sungir (central European Russia) in graves with unique adornments and other rich burial goods, have recently been 14C-dated at the NSF-Arizona AMS Facility. Collagen for dating was extracted using slow demineralization of whole bone fragments in weak hydrochloric acid. For the Sungir 1 burial, a 14C value of ≈19 200 BP was obtained; for the double burial Sungir 2 and 3, 14C values of ≈26 200–27 200 BP (average ≈26 400 BP) were obtained. This contradicts earlier 14C dates made at the Oxford AMS Lab, with collagen extracted following Longin's technique: ≈22 900 BP for Sungir 1; and ≈23 800–24 100 BP (average ≈23 900 BP) for Sungir 2 and 3. The use of two different techniques of collagen extraction for the Tucson and Oxford dates might be the cause of the age differences. Additional studies need to be conducted to resolve these 14C age differences. [Copyright &y& Elsevier]

Examines the possible tektite strewn field of glass at the Pampean Plain in Argentina. Association of impact glass with 11 elongate depressions; Identification of 400 additional elongate features; Origins of the depressions.

What remains of a 30 g sample, first recognized as a meteorite in 1989 during characterization of metalworking debris from Danebury, an Iron Age hillfort, in Hampshire, England, has been classified as an H5 ordinary chondrite. Its arrival on Earth has been dated as 2350 ± 120 yr BP, making it contemporary with the period of maximum human activity at the recovery site. Despite its considerable terrestrial residence age, the interior of the specimen is remarkably fresh with a weathering index of W1/2. There is, however, no evidence of human intervention in its preservation. Its near-pristine state is explained in terms of its serendipitous burial during the back-fill of a pit dug into chalk by prehistoric people for the storage of grain. This chance discovery has interesting ramifications for the survival of meteorites in areas having a high pH because of a natural lime content arising as a result of the local geology. [ABSTRACT FROM AUTHOR]

Rapid shifts in past climate recorded in polar ice sheets have elicited various explanations relating to either thermohaline circulation changes by ice-rafting or natural greenhouse gas concentrations modulated by climatic conditions in the tropics. To compare the tropical paleoclimate record with the polar record, one must choose sediment cores from highly productive ocean regions. Necessarily, such regions reflect the wind records in the tropics, because high productivity is associated with upwelling driven by winds. Comparing tropical precipitation records with high-latitude records is, however, a more difficult task because sediments recording paleoprecipitation usually have low sedimentation rates, and offer coarser resolution relative to polar ice cores. Here, we present δ 18O data of three planktonic species of Foraminifera (a proxy for precipitation) from such a sediment core, spanning the past 35 ka for the equatorial Indian Ocean, which falls under the southwest monsoon (SWM) realm. Results show that minimum SWM precipitation occurred at the Last Glacial Maximum, with a subsequent increase at Termination IA. During the Holocene, SWM precipitation intensified uniformly up to the core top (∼2.2 ka b. p.), as revealed by generally decreasing δ 18O values. Variations in precipitation are consistent with climate changes recorded in polar ice sheets. Although the different resolutions of the two records preclude a rigorous comparison, abrupt cooling/warming events appear to be accompanied by sudden reduction/enhancement in (SWM) rainfall. Thus, mechanisms with time scales much shorter than a millennium, such as natural greenhouse warming (e.g., CH4 concentration), controlled by emissions from the tropics, could have played a major role in high-latitude climate change. [ABSTRACT FROM AUTHOR]

Whatever the cause, it is extraordinary that dozens of genera of large mammals became extinct during the late Quaternary throughout the Western Hemisphere, including 90% of the genera of the xenarthran suborder Phyllophaga (sloths). Radiocarbon dates directly on dung, bones, or other tissue of extinct sloths place their "last appearance" datum at ≈11,000 radiocarbon years before present (yr BP) or slightly less in North America, ≈10,500 yr BP in South America, and ≈4,400 yr BP on West Indian islands. This asynchronous situation is not compatible with glacial-interglacial climate change forcing these extinctions, especially given the great elevational, latitudinal, and longitudinal variation of the sloth-bearing continental sites. Instead, the chronology of last appearance of extinct sloths, whether on continents or islands, more closely tracks the first arrival of people. [ABSTRACT FROM AUTHOR]

The new results of AMS 14C dating of the earliest pottery from the Russian Far East, Osipovka, Gromatukha and Novopetrovka cultural complexes (Amur River basin), are presented. Pottery temper (represented by sedge grass) was chosen for dating; pottery-associated charcoal was also dated. The earliest pottery from the Amur River basin nowadays may be dated to ca. 13 000 BP (ca. 16 000 cal BP), and this is one of the oldest potteries in East Asia, and in Old World in general. [Copyright &y& Elsevier]

The Gursky peatbog contains the most complete terrestrial record of environmental changes for the last 13 000 14C years in the Lower Amur River basin. Pollen and AMS 14C data were obtained from a 340 cm long section, represented by peat and sapropel deposits. Several Late Glacial climatic events, such as Bølling, Older Dryas, Allerød and Younger Dryas, were securely identified for the first time in the Russian Far East; the main Holocene climatic events were also revealed. The Gursky peatbog looks promising as a case study for construction of paleoclimatic curve of the Late Glacial and the Holocene of whole Northeast Asia. [Copyright &y& Elsevier]

A sediment core recovered from the vicinity of Vladivostok on Peter the Great Gulf (northwestern Sea of Japan coast), represents one of the most complete records of pollen, diatom and microfauna of the Holocene marine shallow-water sediments of this region. Until recently, there were no 14C-dates on this core. Three bulk foraminifera samples were AMS 14C-dated, and reservoir-corrected using value as ≈370 yr. This allows us to pinpoint the most important Holocene climatic and oceanographic events in this part of the Sea of Japan, such as warm Tsushima current invasions. [Copyright &y& Elsevier]

Studies the paleoclimate and paleoenvironment changes from a river terrace profile between Xi'an and Xianyang cities in Guanzhong Area, Shaanxi Province during the last glacial maximum. Qilipu stratigraphy in Xianyang; Climate and environment record from mammalian fossils; Discussion.

The annual 14 C data in tree rings is an outstanding proxy for uncovering extreme solar energetic particle (SEP) events in the past. Signatures of extreme SEP events have been reported in 774/775 CE, 992/993 CE, and ∼660 BCE. Here, we report another rapid increase of 14 C concentration in tree rings from California, Switzerland, and Finland around 5410 BCE. These 14 C data series show a significant increase of ∼6‰ in 5411-5410 BCE. The signature of 14 C variation is very similar to the confirmed three SEP events and points to an extreme short-term flux of cosmic ray radiation into the atmosphere. The rapid 14 C increase in 5411/5410 BCE rings occurred during a period of high solar activity and 60 years after a grand 14 C excursion during 5481-5471 BCE. The similarity of our 14 C data to previous events suggests that the origin of the 5410 BCE event is an extreme SEP event., (© 2021. The Authors.)

Tree ring series were collected from the vicinity of a Hungarian radioactive waste treatment and disposal facility and from a distant control background site, which is not influenced by the radiocarbon discharge of the disposal facility but it represents the natural regional (14)C level. The (14)C concentration of the cellulose content of tree rings was measured by AMS. Data of the tree ring series from the disposal facility was compared to the control site for each year. The results were also compared to the (14)C data of the atmospheric (14)C monitoring stations at the disposal facility and to international background measurements. On the basis of the results, the excess radiocarbon of the disposal facility can unambiguously be detected in the tree from the repository site., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The source and nature of carbon on Mars have been a subject of intense speculation. We report the results of confocal Raman imaging spectroscopy on 11 martian meteorites, spanning about 4.2 billion years of martian history. Ten of the meteorites contain abiotic macromolecular carbon (MMC) phases detected in association with small oxide grains included within high-temperature minerals. Polycyclic aromatic hydrocarbons were detected along with MMC phases in Dar al Gani 476. The association of organic carbon within magmatic minerals indicates that martian magmas favored precipitation of reduced carbon species during crystallization. The ubiquitous distribution of abiotic organic carbon in martian igneous rocks is important for understanding the martian carbon cycle and has implications for future missions to detect possible past martian life.

There are many diverse uses of accelerator mass spectrometry (AMS). Carbon-14 studies at our laboratory include much research related to paleoclimate, both with 14C as a tracer of past changes in environmental conditions as observed in corals, marine sediments and many terrestrial records. Terrestrial records such as forest fires can also show the influence of oceanic oscillations, whether they are short-term such as ENSO, or on the millennial time scale. In tracer applications, we have developed the use of 129I as well as 14C as tracers for nuclear pollution studies around radioactive waste dump sites, in collaboration with IAEA. We discuss some applications carried out in Tucson for several of these fields and hope to give some idea of the breadth of these studies.

There are many diverse uses of accelerator mass spectrometry (AMS). 14C studies at our laboratory include much research related to paleoclimate, with 14C as a tracer of past changes in environmental conditions as observed in corals, marine sediments, and many terrestrial records. Terrestrial records can also show the influence of oceanic oscillations, whether they are short term, such as ENSO (El Niño/Southern Oscillation), or on the millennial time scale. In tracer applications, we have developed the use of 129I as well as 14C as tracers for nuclear pollution studies around radioactive waste dump sites, in collaboration with IAEA. We discuss some applications carried out in Tucson, AZ, for several of these fields and hope to give some idea of the breadth of these studies.