Accelerator Mass Spectrometry Dates Research Articles

Dietary Habits and Freshwater Reservoir Effects in Bones from a Neolithic NE German Cemetery

Within a project on Stone Age sites of NE Germany, 26 burials from the Ostorf cemetery and some further Neolithic sites have been analyzed by more than 40 accelerator mass spectrometry (AMS) dates. We here present the results of stable isotope and radiocarbon measurements together with reference 14C dates on grave goods from terrestrial animals such as tooth pendants found in 10 of the graves. Age differences between human individuals and their associated grave goods are used to calculate 14C reservoir effects. The resulting substantial reservoir effects have revealed misleadingly high 14C ages of their remains, which originally indicated a surprisingly early occurrence of graves and long-term use of this Neolithic burial site. We demonstrate that in order to 14C date the human bones from Ostorf cemetery, it is of utmost importance to distinguish between terrestrial- and freshwater-influenced diet. The latter may result in significantly higher than marine reservoir ages with apparent 14C ages up to ∼800 yr too old. The carbon and nitrogen isotopic composition may provide a basis for or an indicator of necessary corrections of dates on humans where no datable grave goods of terrestrial origin such as tooth pendants or tusks are available. Based on the associated age control animals, there is no evidence that the dated earliest burials occurred any earlier than 3300 BC, in contrast to the original first impression of the grave site (∼3800 BC).

Dating North Asian surface assemblages with ostrich eggshell: implications for palaeoecology and extirpation

East Asian ostrich ( Struthio anderssoni Lowe) was thought to have become extinct sometime in the Late Pleistocene. Petroglyphs portray ostrich with Pleistocene animals, and ostrich eggshell (OES) fragments and ornaments from Holocene sites were considered to be older fossils. Here we summarize previous radiometric dates for ostrich eggshell (OES) and present 15 new calibrated accelerator mass spectrometry (AMS) dates, indicating that ostrich survived in Mongolia and northern China until at least 8.9 ka BP. The dates in our sample population suggest a correlation between Struthio and warm steppe environments, with extirpation probably related to essential changes in Holocene steppe ecosystems including human expansion. This study assesses the usefulness of Asian OES for archaeological dating by AMS, constrains the date of Asian ostrich extirpation, and investigates palaeoenvironmental implications of ostrich survival and extinction.

Fluxes of Heavy Metals from a Highly Polluted Watershed During Flood Events: A Case Study of the Litavka River, Czech Republic

The Litavka River (length 56 km, watershed area 630 km2, average flow at the outlet to the Berounka River 2.57 m3 s−1) drains the historical mining, ore processing, and smelting region of Přibram. This Ag–Pb–Zn±Sb ore district (production from the thirteenth century to 1978, locally to 1980) is known for extensive heavy metal contamination. Recent contamination of the Litavka River system is mostly related to the erosion of contaminated soils and fluvial floodplains sediments, especially from a low-gradient river section located immediately below the ore district, where the fine-grained floodplain sediments are from 1.0 to 1.7 m thick. Radiocarbon accelerator mass spectrometry dating of charcoal fragments separated from one floodplain profile showed calibrated 14C age in the range AD 1220–1284 at a depth of 1.2 m below the surface, while depths of 0.4 and 0.8 m yielded ages in the range AD 1680–1939. Formation of this floodplain was related to disturbance of the river equilibrium resulting from deforestation and the influx of fine-grained material from ore processing, including historical failures of settling ponds. Fluxes of heavy metals during flood events in the Litavka River were studied 35 km downstream below the ore district. Metals are transported here mostly (more than 99% for Pb) in the form of suspended particulate matter (SPM), which at the outlet of the Litavka River contains 2,016 mg kg−1 Zn, 918 mg kg−1 Pb, and 25.5 mg kg−1 Cd on average. During a snowmelt-related minor flood event between March 25 and 29, 2006 (peak flow 36.6 m3 s−1), the river transported 2,400 tonnes of SPM during 4 days, containing 74 kg of Cd, 2,954 kg of Pb, and 5,811 kg of Zn. During larger floods (water flows above 55 m3 s−1 have occurred here 27 times during the last 77 years), the contamination is more diluted by material eroded in the floodplain along the middle and lower river course.

Geochemical reconstruction of Pacific decadal variability from the eastern North Pacific during the HoloceneThis article is one of a series of papers published in this Special Issue on the themePolar Climate Stability Network.

Determining climate variations over the Holocene requires high-resolution records with well-developed age models. A 40 m long marine sediment core raised from Effingham Inlet, an anoxic fjord on the west coast of Vancouver Island, British Columbia, Canada, yields such a record. Forty six14C accelerator mass spectrometry (AMS) dates determined from terrestrial plant material form the age model. Downcore sampling at both 5 cm (20 year) and 1.5 cm (7 year) resolution indicates that high-frequency oceanographic variability has prevailed at this site over the last 10 000 years. Spectral analysis of wt.% opal, a proxy for diatom productivity in the basin, reveals the bidecadal and pentadecadal periods of the Pacific decadal oscillation (PDO) – North Pacific index (NPI) that are related to changes in the strength of the Aleutian Low. Coherence analysis between the Effingham Inlet data and δ18O records from Jellybean Lake (a high elevation site in southwest Yukon) indicates regional coherence at periods of 45, 70, and 510 years between productivity in Effingham Inlet and changes in the Aleutian Low strength. Over the entire Holocene, the strength of decadal variability has changed. Both 20- and 50-year periods are present to some degree in the early Holocene, and only the 50 year period is evident in the late Holocene. These data imply that regime shifts would have been more frequent in the early Holocene relative to the last several thousand years.

Symbolic Use of Terrestrial Gastropod Opercula during the Middle Stone Age at Porc‐Epic Cave, Ethiopia

The Middle Stone Age site of Porc‐Epic in southeastern Ethiopia has produced hundreds of opercula of the terrestrial gastropod Revoilia guillainopsis. Each of these opercula has a central perforation, and the unbroken specimens resemble disc beads. Microscopic examination could not unequivocally confirm their manufacture or use as beads. Their archaeological context indicates that their presence at the site was not the result of natural processes. Direct accelerator mass spectrometry dating of three opercula from different stratigraphic levels has produced ages ranging from about 33,000 to more than 43,000 years old. The opercula do not represent human food refuse but appear to have been collected by the Middle Stone Age occupants of the site for symbolic reasons.

Detecting Vertical Faulting Event Horizons from Holocene Synfaulting in Shallow Marine Sediments on the Western Margin of the Nobi Plain, Central Japan

Abstract Holocene activity of the Kuwana fault was reconstructed on the basis of 82 accelerator mass spectrometry (AMS) dates and stepwise changes in the depositional rates of shallow marine sediments in four cores drilled to examine the regularity of the recurrence interval of ruptures of this active intraplate fault. In our model, depositional rates on the footwall and hanging wall are nearly equal during interseismic periods, but depositional rates on the footwall become markedly larger than those on the hanging wall just after vertical displacement of the fault. To detect the timing of each faulting event more precisely, we compared changes in the depositional rates in cores from both the downthrown (footwall) and uplifted (hanging-wall) sides of the fault. As a result, six probable and one possible paleoseismic events, including the last two historical earthquakes, were inferred to have occurred during the last 7000 yr on the basis of stepwise changes in the depositional rate on the two sides of the fault. The timing of the faulting events was estimated from depositional rate curves of four cores. Probable ages of seismic events were approximately 6200, 5700, 4000, 3600, and 2100 calendar years before present and A.D. 745 and 1586. The average earthquake recurrence interval on the Kuwana fault calculated from these data is about 1000 yr. The average vertical slip rate of the fault has been at least 1 mm/yr during the last 7000 yr.

A New Chronology for Pololu Valley, Hawai'i Island: Occupational History and Agricultural Development

A reanalysis of the chronology of Pololu Valley, located in the district of Kohala on Hawai'i Island, is presented using standard radiocarbon and accelerator mass spectrometry (AMS) dating. Using curated materials from the 1970s, Pololu is reassessed and found to have the earliest coastal occupations in this part of Hawai'i, beginning about AD 1300. Occupations at the dunes and in the valley interior are investigated, as are dryland and wetland field agricultural systems. These data provide a refined model for expansion and intensification of agricultural production in the 15th–17th centuries, and link this remote valley to demographic and sociopolitical trends that were occurring in the rest of Hawai'i.

Symbolic Use of Terrestrial Gastropod Opercula during the Middle Stone Age at Porc-Epic Cave, Ethiopia

The Middle Stone Age site of Porc‐Epic in southeastern Ethiopia has produced hundreds of opercula of the terrestrial gastropod Revoilia guillainopsis. Each of these opercula has a central perforation, and the unbroken specimens resemble disc beads. Microscopic examination could not unequivocally confirm their manufacture or use as beads. Their archaeological context indicates that their presence at the site was not the result of natural processes. Direct accelerator mass spectrometry dating of three opercula from different stratigraphic levels has produced ages ranging from about 33,000 to more than 43,000 years old. The opercula do not represent human food refuse but appear to have been collected by the Middle Stone Age occupants of the site for symbolic reasons.

The Quaternary History of Cumberland Sound, Southeastern Baffin Island: The Marine Evidence

Acoustic and core data from Cumberland Sound show that glacial ice derived from the Foxe Sector (Amadjuak Dome) of the Laurentide Ice Sheet advanced to the continental shelf at the mouth of the sound during a late phase of the Foxe Glaciation. The basal lithofacies/acoustic unit (Ai/BUD) in the sound is a massive, black diamicton. On the basis of strati-graphic, acoustic, lithologie and faunal evidence, this unit is interpreted as till. The till is overlain by an ice proximal to ice distal glacial-marine sediment sequence termed the Davis Strait Silt (DSS). The influence of ice retreat is reflected in the foraminiferal assemblages of the DSS. Rapid sedimentation rates in the sound prevailed during deposition of the DSS as shown by the conformable geometry of the DSS. Accelerator Mass Spectrometry dates on molluscs and foraminifera and a single conventional 14C date on disseminated organic material from ice proximal sediment of the DSS (lithofacies B and lower lithofacies C) indicate that the ice retreated rapidly from its probable maximum position on the shelf no earlier than ca. 13,400 BP and into the fiords along the coast of the sound by ca. 8900 BP. Deposition of ice-distal glacial marine sediments (lower lithofacies D) continued in the sound until ca. 7600 BP as the ice margin rapidly retreated into the fiords. Between ca. 8900 BP and ca. 8000 BP, the foraminiferal fauna show that the influence of glacial ice is remote and that "Atlantic Water" impinges on the seafloor. Postglacial sedimentation began in the sound at ca. 7600 BP. Retreat of the ice margin onto land made the fiord basins available as sediment catchments. The reduced sedimentation rates in the sound during this interval are indicated by the change to onlapping basin fill geometry of the Tiniktartuq Silt and Clay (TS&C). Calcareous foraminifera disappear from the sediments by ca. 6300 BP and are replaced by agglutinated foraminifera reflecting "Arctic Water" conditions at the seafloor. The TS&C is presently being deposited in the sound.

A ∼25 ka Indian Ocean monsoon variability record from the Andaman Sea

Recent paleoclimatic work on terrestrial and marine deposits from Asia and the Indian Ocean has indicated abrupt changes in the strength of the Asian monsoon during the last deglaciation. Comparison of marine paleoclimate records that track salinity changes from Asian rivers can help evaluate the coherence of the Indian Ocean monsoon (IOM) with the larger Asian monsoon. Here we present paired Mg/Ca and δ 18O data on the planktic foraminifer Globigerinoides ruber (white) from Andaman Sea core RC12-344 that provide records of sea-surface temperature (SST) and δ 18O of seawater (δ 18O sw) over the past 25,000 years (ka) before present (BP). Age control is based on nine accelerator mass spectrometry (AMS) dates on mixed planktic foraminifera. Mg/Ca-SST data indicate that SST was ∼3 °C cooler during the last glacial maximum (LGM) than the late Holocene. Andaman Sea δ 18O sw exhibited higher than present values during the Lateglacial interval ca 19–15 ka BP and briefly during the Younger Dryas ca 12 ka BP. Lower than present δ 18O sw values during the BØlling/AllerØd ca 14.5–12.6 ka BP and during the early Holocene ca 10.8–5.5 ka BP are interpreted to indicate lower salinity, reflect some combination of decreased evaporation–precipitation (E–P) over the Andaman Sea and increased Irrawaddy River outflow. Our results are consistent with the suggestion that IOM intensity was stronger than present during the BØlling/AllerØd and early Holocene, and weaker during the late glaciation, Younger Dryas, and the late Holocene. These findings support the hypothesis that rapid climate change during the last deglaciation and Holocene included substantial hydrologic changes in the IOM system that were coherent with the larger Asian monsoon.

Dating Paleosol and Animal Remains in Loess Deposits

Accurate and reliable dating of paleosols, animal remains, and artifacts is of crucial importance in reconstructing environmental change and understanding the interrelationship between human activities and natural environments. Dating different materials in the same sample can help resolve problems such as soil carbon sources and carbon storage state. Conventional radiocarbon dating of soil (inorganic and organic matter) and accelerator mass spectrometry (AMS) dating of animal remains (fossil bones and teeth) result in different ages for materials from the same sample position in a typical loess section at Xinglong Mountain, Yuzhong County, Gansu Province in NW China. Inorganic matter is ∼3400 yr older than organic matter, 4175 ± 175 cal BP to 3808 ± 90 cal BP. A 1610-yr difference between the 14C ages of fossils (animal bones and teeth) and soil organic matter suggests that a depositional hiatus exists in the studied profile. The varying 14C ages of fossils and soil organic and inorganic matter have important implications for paleoclimate reconstructions from loess sections. It is critical to consider the meaning of the variable 14C ages from different material components from the same sample position in terms of soil organic and inorganic carbon storage, vegetation history reconstruction, archaeology, and the study of ancient civilizations.

Society Islands (Central Eastern Polynesia) Chronology: 11 Radiocarbon Dates for the Late Prehistoric Expansion and Proto-Historic Periods in the ‘Opunohu Valley, Mo'Orea

The chronology of residential site construction and occupation in the upper reaches of the ‘Opunohu Valley, Mo'orea, Central Eastern Polynesia, has been debated over the last 15 yr. This paper reports a suite of 11 radiocarbon age determinations from excavations at 5 house sites and a simple temple structure (marae). Direct accelerator mass spectrometry (AMS) dating of wood charcoal identified to short-lived taxa confirms site construction and occupation during the mid-15th to 17th centuries, supporting that maximal population density was in the centuries immediately prior to European contact. The study demonstrates that targeted dating of multiple structures within residential complexes allows for multiple phases of site construction and use to be discriminated. These data are critical for adequately assessing site contemporaneity and the development, maintenance, and expansion of residential groups and their house clusters through time.

Intrashell Radiocarbon Variability in Marine Mollusks

We demonstrate variable radiocarbon content within 2 historic (AD 1936) and 2 prehistoric (about 8200 BP and 3500 BP)Mytilus californianusshells from the Santa Barbara Channel region, California, USA. Historic specimens from the mainland coast exhibit a greater range of intrashell variability (i.e. 180–24014C yr) than archaeological specimens from Daisy Cave on San Miguel Island (i.e. 12014C yr in both shells). δ13C and δ18O profiles are in general agreement with the up welling of deep ocean water depleted in14C as a determinant of local marine reservoir correction (ΔR) in the San Miguel Island samples. Upwelling cycles are difficult to identify in the mainland specimens, where intrashell variations in14C content may be a complex product of oceanic mixing and periodic seasonal inputs of14C-depeleted terrestrial runoff. Though the mechanisms controlling ΔR at subannual to annual scales are not entirely clear, the fluctuations represent significant sources of random dating error in marine environments, particularly if a small section of shell is selected for accelerator mass spectrometry (AMS) dating. For maximum precision and accuracy in AMS dating of marine shells, we recommend that archaeologists, paleontologists, and14C lab personnel average out these variations by sampling across multiple increments of growth.

Reassessing Coxcatlan Cave and the early history of domesticated plants in Mesoamerica

Reanalysis and direct accelerator mass spectrometry radiocarbon dating of the cucurbit assemblage from Coxcatlan Cave provide information on the timing and sequence of the initial appearance of three domesticated plants in the Tehuacán Valley (Puebla, Mexico) and allow reassessment of the overall temporal context of plant domestication in Mexico. Cucurbita pepo is the earliest documented domesticate in the cave, dating to 7,920 calibrated calendrical (cal) years B.P. The bottle gourd (Lagenaria siceraria) is dated at 7,200 cal years B.P. Cucurbita argyrosperma does not appear until 2,065 cal years B.P. The earlier identification of Cucurbita moschata specimens is not confirmed. Seventy-one radiocarbon dates, including 23 accelerator mass spectrometry dates on cucurbits, provide ample evidence of postdepositional vertical displacement of organic materials in the western half of Coxcatlan Cave, but they also indicate that the eastern half of the cave was largely undisturbed.

AMS Radiocarbon Dates of Kurgans Located On the Ust'-Yurt Plateau, Uzbekistan

Recent osteological analyses of archaeological human skeletal remains from the Ust'-Yurt Plateau, Uzbekistan, provided the opportunity to obtain samples for radiocarbon dating. The results of 18 accelerator mass spectrometry (AMS) dates are presented in this paper and provide the first absolute dates for late prehistoric and early historic archaeological sites in Uzbekistan. The AMS dates suggest that most sites are earlier than have been traditionally thought based on relative dating using artifact typologies.

Re-Dating Mid-Holocene Betelnut (Areca Catechu L.) and Other Plant Use at Dongan, Papua New Guinea

Direct accelerator mass spectrometry (AMS) dating of anaerobically preserved plant remains from the Dongan site in New Guinea, combined with assessment of preservation condition, confirms earlier doubts about the antiquity of betelnut (Areca catechu L.) found at the site. A possible sago leaf fragment is also identified as a modern contaminant. The mid-Holocene age of other fruit and nut remains is verified using these methods. The utility of AMS dating in combination with detailed archaeobotanical assessment is demonstrated, thus improving chronometric hygiene and with it knowledge of past plant use in Oceania.

Drowning of the −150 m reef off Hawaii: A casualty of global meltwater pulse 1A?

We present evidence that the drowning of the 2150 m coral reef around Hawaii was caused by rapid sea-level rise associated with meltwater pulse 1A (MWP-1A) during the last deglaciation. New U/Th and 14 C accelerator mass spectrometry dates, combined with reinterpretation of existing radiometric dates, constrain the age of the coral reef to 15.2-14.7 ka (U/Th age), indicating that reef growth persisted for 4.3 k.y. following the end of the Last Glacial Maximum at 19 ka. The drowning age of the reef is roughly synchronous with the onset of MWP-1A between 14.7 and 14.2 ka. Dates from coralline algal material range from 14 to 10 cal ka (calibrated radiocarbon age), 1-4 k.y. younger than the coral ages. A paleoenvironmental reconstruction incorporating all available radiometric dates, high-resolution bathymetry, dive observations, and coralgal paleobathymetry data indicates a dramatic rise in sea level around Hawaii ca. 14.7 ka. Paleowater depths over the reef crest increased rapidly above a critical depth (30-40 m), drowning the shallow reef-building Porites corals and causing a shift to deep- water coralline algal growth, preserved as a crust on the drowned reef crest.

The End of the Chalcolithic Period in the South Jordan Valley: New 14C Determinations from Teleilat Ghassul, Jordan

This article reports on 12 new accelerator mass spectrometry (AMS) dates from the latest phases of the Chalcolithic period occupation (late 5th millennium cal BC) at Teleilat Ghassul, type site for the south Levantine Ghassulian Chalcolithic culture. The new AMS dates from Teleilat Ghassul favor an amendment to a previous suggestion (Bourke et al. 2001), that all significant occupation at the site had ceased by 4000/3900 cal BC. This end-date should now be amended to 3900/3800 cal BC. Follow-up statistical modelling sourced to published 14C data drawn from a wide selection of south Levantine Chalcolithic period sites (Bourke 2001; Burton and Levy 2001) raises the possibility that Chalcolithic period occupation had ceased at virtually all major centers by 3800/3700 cal BC. This, in turn, suggests that the new data bearing on the end-date for occupation at Teleilat Ghassul may reflect a more widespread horizon of abandonment in the southern Levant.

A Pretreatment Procedure for the AMS Radiocarbon Dating of Sub-Fossil Insect Remains

Two pretreatment methods for accelerator mass spectrometry (AMS) dating of insect remains were explored. One method involves a simple acid wash that removes carbonate, while the other is based on the industrial purification of chitin and results in isolation of polymeric chitosan. No contamination is observed from Maillard reactions during the deacetylation reaction used to isolate the chitosan. The methods were tested on Coleoptera samples from two Roman Britain sites. Our results demonstrate that both methods produce acceptable AMS dates that correspond well to the expected age of the deposits from which they came.

Paleoecology of a Middle Wisconsin Deposit from Southern California

Analysis of a buried deposit in the Diamond Valley of southern California has revealed well-preserved pollen, wood, and diatom remains. Accelerator mass spectrometry dates of 41,200±2100 and 41,490±1380 14C yr B.P. place this deposit in marine isotope stage 3. Diatoms suggest a shallow lacustrine environment. Pollen data suggest that several plant communities were present near the site, with grassland, scrub, chaparral, forest, and riparian communities represented. Comparison with modern pollen suggests similarities with montane forests in the nearby San Bernardino and San Jacinto ranges, indicating vegetation lowering by at least 900 m elevation and temperatures 4°–5°C cooler than today. An increase in high-elevation conifer pollen documents climatic cooling near the profile top. Early-profile diatoms are typical of warm water with high alkalinity and conductivity, whereas later diatoms suggest a higher flow regime and input of cooler water into the system. We suggest that the sequence is part of the cooling phase of an interstadial Dansgaard–Oeschger cycle. Records of the middle Wisconsin period are rare in southern California, but the Diamond Valley site is similar to records from Tulare Lake in the San Joaquin Valley and the ODP Site 893A record from Santa Barbara Basin. It is probable that the Diamond Valley assemblage is a local expression of a vegetation type widespread in the ranges and basins of southwestern California during the middle Wisconsin.