Radiocarbon Age Determinations Research Articles

Verification of the age of 10- and 20-year-old Tawny Port wines using Radiocarbon

Port is a famous sort of fortified wine, exclusively produced in the Douro region of Portugal. Among the various types of Port wines, the Tawny types with stated maturation ages of 10 or 20 years are among the higher quality and more expensive ones. Fraudulently producing those with a shorter maturation time than claimed, along with additions or treatments to mask this, would make production of those wines cheaper. Here, we present a method, based on Radiocarbon (14C) age determination of the ethanol and the sugar residue, to verify the maturation time of such Port wines. We successfully verified the method using single harvest year “Vintage” Port wines. We then analyzed a total of twenty 10- and 20-year-old Tawny Port wines, bought at various retail stores in the Netherlands. We found that seven of those had a significantly shorter maturation age than claimed on the label.

The paleo-community of the Sciacca red coral

The sub-fossil red coral deposits of Sciacca (Sicily Channel) have attracted scientific attention for nearly 150 years. Their origin and formation have been long questioned and investigated, given the fact that they represent one of the most intriguing geobiological events ever to occur in the Mediterranean basin. Less attention was given to the paleo-community associated with the sub-fossil coral. Radiocarbon age determinations, in particular, were provided only for red coral, neglecting the possibility of understanding which species were simultaneously present in the coralline paleo-community and which was their role. The study of cemented coral rubble pieces revealed that Corallium rubrum covered the largest time interval (more than 3000 years) and was contemporary to many secondary epibionts over two millennia and to Madrepora oculata for about 500 years; this last finding suggested that an uncommon co-dominance between the two structuring species occurred in the nearby living communities. The lack of Fe–Mg deposits on the cemented coral rubbles coupled with the low bioerosion rate of the red coral skeletons by the demosponge Siphonodictyon coralliirubri (assessed through the analysis of the erosive paleo-scars) suggested that the deposits met with a rapid sediment cover-up. Moreover, for the first time, the analysis of a piece of cemented coral rubble of sub-fossil red coral coming from Sardinian waters confirmed that, albeit to a lesser extent, the conditions favouring the preservation of dead corals can occur also in different localities far from Sciacca.

Dry, leeward regions support Colonization Period sites: Stratigraphy, dating, and geomorphological setting of one of the earliest habitations in the Hawaiian Islands

The earliest archaeological sites anchor discussions of the timing, speed, and direction of colonization of continents, single archipelagos, and individual islands, and new discoveries of the oldest sites often cause reevaluations of settlement models and culture-histories at various scales. Consequently, the oldest sites have continued to garner great interest amongst archaeologists worldwide. Here we report a suite of 21 AMS radiocarbon age determinations from a deeply stratified sandy mound habitation situated at an environmentally diverse “hot-spot” along the south-central leeward shore of Moloka‘i, Hawaiian Islands. Despite its ecological position in a dry leeward region – what some have called “high risk zones” – the ease of access and concentration of vital resources, including potable water, nutrient-rich gardening soils, and marine and freshwater biota was a magnet for early colonists. The faunal content, site stratigraphy, and geomorphological context of the Kawela Mound is described documenting rapid change in the dynamic landscape over several centuries. A Bayesian analysis of the Kawela Mound radiocarbon dates places earliest habitation at a modeled age of AD 1121–1262 (median AD 1210) making it one of the earliest habitations in the Hawaiian Islands. We provide a model for discovering early sites on leeward coastal Moloka‘I, which should be applicable elsewhere.

Impacts of Large-Scale Climate Oscillations on Fluvial Sediments in Central Poland: Evidence from Geochronological Analysis

Abstract The article presents the results of a collective analysis of 181 radiocarbon and 38 luminescence dating results from the time range 50–11.7 cal kBP for samples originating in fluvial sedimentary environment in Łódź region (central Poland), south of the last glacial maximum (LGM) line. Four sites were selected for a general of fluvial deposits and the obtained dating results Struga Żłobnicka, Parchliny, Warenka, and Swędów regions. Based on the summed probability density function (PDF) curves, the study demonstrates the response of the fluvial sedimentary environment to events of overregional scale. The collective analysis of the radiocarbon age determinations from the Łódź region allows for observing the correlation between local environmental changes and large-scale changes recorded in the NGRIP core. The warming periods Greenland interstadials (GI)-3, GI-4, and GI-5.1, the cooling event GI-1b within the warming GI-1, as well as the transition between GI-1a and Greenland stadials (GS)-1, were most prominently recorded in the PDF curves. The collective analysis of the luminescence age determinations reflects a change in the river valleys, expressed by a strong aggradation during the cold maximum of the studied period.

Aboriginal earth mounds of the Calperum Floodplain (Murray Darling Basin, South Australia): New radiocarbon dates, sediment analyses and syntheses, and implications for behavioural change

This paper presents the results of an archaeological investigation into anthropogenic earth (oven) mounds located on the Murray River floodplain at Calperum Station in the Renmark region of South Australia. Six mounds were excavated and their contents examined. Sediment analyses were also conducted to assess magnetic susceptibility, grain size and loss on ignition. Radiocarbon age estimates were obtained on shell and charcoal. Mound contents primarily included anthropogenically burnt clay (heat retainers), charcoal, fragments of mussel shell as well as very minor quantities of other faunal material and stone artefacts (which were consistent with previous lithic assessments for the region). The radiocarbon age determinations from 15 samples indicate that mounds were formed by Aboriginal people on the Calperum floodplain from at least 3981–3723 cal BP and utilised up to the time of European invasion. The very minimal amount of faunal remains (other than mussel shell), artefacts and a general lack of other material evidence apart from clay heat retainers, confirms that these features were single purpose and not used as living areas. Sediment analyses and radiocarbon dates indicate a high degree of homogeneity within mounds but provide insights into an economic transition on the Calperum floodplain, at around 4000 cal BP involving a food-production procurement strategy based on heat retainer technology and the exploitation of emergent macrophytes.

A radiocarbon chronology for Sanamere Lagoon, Cape York Peninsula, using multiple organic fractions

The selection and pre-treatment of reliable organic fractions for radiocarbon age determination is fundamental to the development of accurate chronologies. Sampling from tropical lakes is particularly challenging given the adverse preservation conditions and diagenesis in these environments. Our research is the first to examine and quantify the differences between radiocarbon ages from different carbon fractions and pretreatment protocols from tropical lake sediments. Six different organic fractions (bulk organics, pollen concentrate, cellulose, stable polycyclic aromatic carbon (SPAC), macrocharcoal >250 μm and microcharcoal >63 μm) were compared at six different depths along a 1.72 m long core extracted from Sanamere Lagoon, Cape York Peninsula, northern Australia. Acid-base-acid (ABA), modified ABA (30% hydrogen peroxide + ABA), 2chlorOx (a novel cellulose pre-treatment method) and hydrogen pyrolysis (hypy) were used to pre-treat the organic fractions. The oldest date is ∼31,300 calibrated years before present (cal yr BP) and the youngest is ∼2800 cal yr BP, spanning ∼28,500 years. The smallest offset between the minimum and the maximum age for different fractions and across pretreatment methods at a given depth was found to be 832 years (between SPAC and pollen) and the largest ∼16,750 years (between pollen concentrate and SPAC). The SPAC fractions pre-treated with hypy yielded older ages compared to all other fractions in most cases, while bulk organics yielded consistently younger ages. The magnitude and consistency of the offsets and the physical and chemical properties of the tested organic fractions suggest that SPAC is the most reliable fraction to date in tropical lake sediments and that hypy successfully removes exogenous carbon contamination. • Stable polycyclic aromatic carbon is the most reliable fraction to date tropical lake sediments. • Hydrogen pyrolysis (hypy) successfully removes contamination sourced from exogenous carbon. • The age-depth model from the peroxide+ABA pretreated bulk organics samples agrees with the hypy pretreated samples.

Znaczenie kalibracji radiowęglowej skali czasu dla chronostratygrafii późnego vistulianu

Znaczenie kalibracji radiowęglowej skali czasu dla chronostratygrafii późnego vistulianu

Sand Ridges on Rocky Coastal Platforms as Markers of Tsunami Impact: A Multi-Disciplinary Analysis along the Ionian Coast of Southern Apulia (Italy)

Along the Ionian coast of Southern Apulia, a sand ridge has been detected at the inner border of a wide, low-elevated rocky platform. A multi-disciplinary analysis was carried out to define the main geomorphological and sedimentological features of this dune-like coastal deposit, to clarify its nature as well as to obtain chronological constraints for its development. The geomorphological survey reveals that the sand ridge is about 40–60 m wide, reaching a maximum elevation of 3.9 m above m.s.l., whereas its thickness can be estimated between 1.0 and 2.8 m. The sand ridge is in some places associated with large-size boulders. Grain size analysis shows that it is made up of poorly sorted coarse-medium sands with a gravelly fraction, without significant sedimentary structures, as confirmed by Ground Penetrating Radar survey. The micro and macro-faunal assemblage sampled in the sand ridge can be related to shallow-water environments with Posidonia oceanica meadows occurring offshore. The development of the studied sand ridge can be ascribed to a tsunami event able to mix up very coarse bioclastic sands placed at submerged platforms, storm beach deposits covering the low-elevated coastal platform in patches, and possibly older tsunami deposits. Accelerator Mass Spectometry radiocarbon age determinations on mollusc shells sampled from the sand ridge span from 929–1168 AD to 1707–1950 AD and cluster around the 18th–19th centuries, suggesting a possible association with a recent tsunami event. Data reported in the Euro-Mediterranean Tsunami Catalogue would indicate as the most likely event that one of the 25th April 1836, produced by a strong earthquake with its epicenter near Rossano village, on the Ionian coast of the Calabria region.

Structural Characterization and Thermal Decomposition of Lime Binders Allow Accurate Radiocarbon Age Determinations of Aerial Lime Plaster

ABSTRACTRadiocarbon (14C) dating of anthropogenic carbonates (CaCO3) such as ash, lime plaster and lime mortar, has proven a difficult task due to the occurrence of a number of contaminants embedded within the CaCO3 pyrogenic binder. These include 14C-free geologic components and/or secondary phases bearing an unknown amount of 14C, and thus the alteration of the original pyrogenic isotopic signature of the material results in major age offsets when carbon recovery is performed through acid hydrolysis. Here we present a characterization/quantification approach to anthropogenic carbonates that includes Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thin section petrography, thermogravimetric analysis and scanning electron microscopy coupled with high-resolution cathodoluminescence, with which we identified the pyrogenic CaCO3 fraction in an aerial lime plaster and two hydraulic mortars. The preserved pyrogenic component was then isolated by density separation and its purity checked again using FTIR. Carbon was recovered through thermal decomposition in vacuum. The resulting 14C age matches the expected age of the lime plaster, whereas hydraulic mortars are slightly offset due to the carbonation of calcium hydroxide lumps. This approach highlights the importance of a dedicated characterization strategy prior to dating and may be applied to aerial lime plasters to obtain accurate ages.

Initial results and observations on a radiocarbon dating program in the Riverland region of South Australia

This paper presents a preliminary occupation chronology for the Riverland region of South Australia, based on 31 radiocarbon age determinations. This region has represented a significant geographic gap in understanding occupation chronologies for the broader Murray-Darling Basin. The dating forms part of an ongoing research program exploring the long-term engagements of Aboriginal people with the habitat mosaics of the central River Murray corridor. Dating targets were selected on the basis of their landscape context. Results relate occupation evidence to an evolving riverine landscape through the period extending from approximately 29 ka to the late Holocene. These results include the first pre-Last Glacial Maximum ages returned on the River Murray in South Australia and extend the known Aboriginal occupation of the Riverland by approximately 22,000 years.

Grave of the Corded Ware culture from Węgrzce, Kraków District

Grave 3/2016 from site 3 in Węgrzce, Comm. Zielonki, Kraków District was discovered during archaeological excavations preceding construction of a detached house. This was a niche grave, holding two burials: a male aged 38–47 years, and a child 4–5 years old. The recorded funeral rite is characteristic of a cluster of Corded Ware culture cemeteries on the lower Dłubnia River, near Kraków. A vessel recovered from the grave reveals local features characteristic of that cluster. One radiocarbon age determination was obtained for the burial, pointing to ca. 2470–2350 BC as the most likely range. Thus, the grave links with the younger phase of the Final Eneolithic in Lesser Poland.

Radiocarbon dating of groundwater from a PZ-2 piezometer located in the foreground of Wieliczka Salt Mine, Poland

Abstract A comparison of two methods of radiocarbon age determination of groundwater is presented. The simplest Pearson model and the “user-defined” option of the NETPATH program were considered. Both methods were used to determine the age of water from a PZ-2 piezometer that is situated in the foreground of chamber Z-32 in Wieliczka Salt Mine. Results of these calculations clearly demonstrate that 14C ages obtained by the Pearson model can be significantly overestimated in comparison with those determined by the NETPATH code. Without additional data, such as the stable isotope composition of the water, conclusions on the age of the groundwater based solely on the Pearson model may be highly inadequate.

Ancient and recent sponge assemblages from the Tyrrhenian coralligenous over millennia (Mediterranean Sea)

The demosponge siliceous spicules, entrapped in the Mediterranean coralligenous bioherms, are a good tool for reconstructing the sponge ancient communities across time, also allowing a comparison with the current biodiversity. The aim of this paper has been the description of the ancient sponge assemblages of the coralligenous bioherms grown up in the Tavolara-Capo Coda Cavallo Marine Protected Area (northeastern Sardinia, Tyrrhenian Sea) between 5800 and 3700 YBP and its comparison with the living sponge community. On the base of radiocarbon age determinations, it was possible to estimate that these bioherms cover a span of time ranging from the Holocene Climatic Optimum until the Bronze Age Crisis. Their growth rates, 0.21–0.24 mm year−1, were of the same order of estimations conducted around the Mediterranean. The Tavolara ancient sponge diversity was compared with those found in ancient accretions from Ligurian Sea and Ionian Sea. Our results supported the already-described general trend, supporting the hypothesis that the genus richness in the coralligenous bioherms was driven by climatic vicissitudes. Nevertheless, our data strongly indicated that the sponge diversity is also related to the conditions of the coralligenous structures: in the accretions characterized by an active growth of coralline algae the number of sponge genera is similar to those recorded in the ancient assemblages while in coralligenous where the accretion is stopped the number of sponge genera strongly decreases probably due to the competition with frondose macroalgae.

Corrigendum: Coastal occupation before the “Big Swamp”: Results from excavations at John Wayne Country Rockshelter on Barrow Island

Corrigendum: Coastal occupation before the “Big Swamp”: Results from excavations at John Wayne Country Rockshelter on Barrow Island

Geoarchaeological Study of Szálka and Vajda Kurgans (Great Hungarian Plain) Based on Radiocarbon and Geophysical Analyses

ABSTRACTTwo archaeologically unexplored mounds were studied in the area of the central Great Hungarian Plain. The age of the construction of the mounds was clarified on the basis of radiocarbon (14C) age determination of buried soil layers. Different, later-building phases of the mounds were detected by pedological and geo-electric analyses of the human-made layers. The age of the buried soils was corrected for the reservoir age of the recent soils found in the surroundings of the mounds. Radiocarbon ages of the carbon extracted from the soils at temperatures 400 and 800ºC were almost completely the same. Based on the calibrated ages of cal BP 4830–5270 (Szálka Mound) and cal BP 4880–5290 (Vajda Mound) of the buried soil layers, the identified kurgans were built by people of the Copper Age Yamnaya Culture. On the basis of the pedological and geophysical analysis of the layers, Szálka Mound and Vajda Mound were built in two and in three phases respectively from the chernozem-like humus-rich topsoil layers of the surrounding area. The former shallow quarry sites have been almost completely filled and cannot be identified at the foot of the mounds even using geodetic methods.

New age controls on the tephrochronology of the southernmost Andean Southern Volcanic Zone, Chile

AbstractThe chronology of over 50 tephra layers preserved in a lake sediment core from Laguna La Trapananda (LLT) in the southern portion of the Andean Southern Volcanic Zone (SSVZ), Chile, is constrained by new radiocarbon age determinations, which span the period from late Pleistocene glacial retreat to the late Holocene. The tephra are correlative with tephra previously described from other lake cores in the region and are attributed to explosive eruptions of the SSVZ volcanoes Mentolat, Hudson, Macá, and potentially Cay. The new age determinations are used to estimate the ages of the >50 tephra in the LLT core, as well as those from the other previously described lake cores in the area, by a Bayesian statistical method. The results constrain the frequency of explosive eruptions of the volcanic centers in the southernmost SSVZ. They indicate that there was essentially no increase in the rate of eruptions from late-glacial to recent times due to deglaciation. They also provide isochrones used to constrain the depositional histories of the small lacustrine systems within which they were deposited and they provide a tephrochronologic tool for other paleoclimatic, paleoecologic, archaeologic and tephrochronologic studies in central Patagonia.

Holocene Paleointensity of the Island of Hawai `i From Glassy Volcanics

AbstractThis study presents new high‐quality paleointensity records and 14C radiocarbon age determinations from the Island of Hawai `i during the Holocene. Previous studies on Hawai `i use experimental methods and statistical selection criteria that may produce inaccurate geomagnetic field strength estimates. Additional high‐quality paleointensity results can be used to evaluate the existing Hawaiian data set and investigate Holocene geomagnetic field behavior. New paleointensity sites from 22 lava flows were calculated using the IZZI‐Thellier laboratory technique and a strict set of selection criteria. Rapidly cooled, glassy volcanic material was collected for all sites. Isotopic age determinations range from 270 to >10, 000 years before present (nine new 14C ages are also presented as part of this study). The median intensity for the 22 flows is 47.5 μT, with a median absolute deviation uncertainty of 5.6 μT; substantially greater than the present‐day field strength at Hawai `i (~36 μT). These new results are comparable to previously published data from this location and are consistent with global paleointensity models. There is no evidence of an intensity “spike” at 3,000 years before present, as seen in the Levant and elsewhere. Previously published data vary in intensity by experimental technique relative to data using glassy material and strict selection criteria. Non‐Thellier‐type data are biased low, a result of these techniques estimating intensity from possibly nonsingle domain magnetic carriers. Thellier‐Thellier data are biased high, the reasons for which remain unclear as no cooling rate effect was demonstrated, and we were unable to reproduce the high bias with different selection criteria.

Drumlinized tunnel valleys in south-central Ontario

A network of Late Wisconsin valleys deeply incise thick successions (up to 200 m) of Quaternary sediment and Paleozoic bedrock across south-central Ontario. The valleys have previously been interpreted as an integrated network of tunnel channels recording catastrophic releases of subglacial meltwater across the bed of the Laurentide Ice Sheet (LIS). Recent geologic investigations in the western part of the valley network integrate information gained from surficial sediment and landform mapping, continuously-cored boreholes that penetrate the entire Quaternary sediment succession in valleys as well as intervening uplands, and both water-borne and land-based geophysical surveys. Together, these data provide new insights and a refined interpretation of the genesis, timing and paleoglaciological significance of these valleys.Valleys within the study area are some of the largest observed within the regional network – up to 30 km long, 7 km wide and >175 m deep. They are oriented both north-south and in a radial pattern, varying from NE-SW in the southern part of the study area, to ESE-WNW in the north. An undulating Late Wisconsin till sheet (Newmarket Till) caps the regional uplands and is commonly observed along the flanks and floors of the valleys – all of which show evidence of a drumlinization phase that postdates excavation of most of the valleys. At least two generations of valleys are interpreted from cross-cutting relationships, with abrupt heads and locally perched downflow ends of some valley forms. Radiocarbon age determinations of organic material from both below and above the Newmarket Till constrain the timing of valley excavation to between 28.05 and 12.81 14C kyr BP. Borehole and outcrop data within the valleys reveal four stratigraphic units (SU1-SU4) that form the floor and sediment infill of the valleys. The Newmarket Till (SU1) is commonly underlain by deformed substrates. The till is absent in parts of some valleys and the lowermost parts of the valley fill commonly consist of coarse-grained gravels (SU2) that pass upwards into sands (SU3). The bulk of the sediment infill consists of glaciolacustrine silt-clay rhythmites (SU4) that pass upwards into organic- and mollusk-bearing nearshore and fluviodeltaic deposits that record drainage of proglacial lakes from the study area during deglaciation.It is proposed that these features are a previously unrecognized type of tunnel valley that developed subglacially during Late Wisconsin ice cover. Meltwater surpluses would be generated at the ice-bed interface due to the low-transmissivity substrate in the study area with flow preferentially routed into lows on the bed. Downward incision into confined and pressurized aquifers likely facilitated rapid headward erosion of the valleys enhanced by piping. Waning meltwater flow velocities/discharges allowed ice creep to re-occupy newly-formed valleys permitting renewed till deposition and subsequent drumlinization of the valleys. The valleys also provided efficient routing for meltwater draining the retreating ice marginal zone during deglaciation and allowed localised sand and gravel deposition as eskers and ice-proximal subaquatic fans in the Oak Ridges Moraine and within proglacial lakes that developed during ice retreat. However, there is no evidence for regional-scale catastrophic release of subglacial meltwater in the valley infills. This integrated dataset represents one of the most complete characterizations of subglacial valleys in a terrestrial setting in North America.

Late Glacial-Holocene tephra from southern Patagonia and Tierra del Fuego (Argentina, Chile): A complete textural and geochemical fingerprinting for distal correlations in the Southern Hemisphere

Explosive volcanoes from the southern Andes are able to disperse ash over wide areas of the Southern Hemisphere, potentially as far as Antarctica. With the aim of improving correlations between sources and tephra in southernmost South America and, possibly, Antarctica, this work presents new field, textural and geochemical data on tephra layers from southern Patagonia and Tierra del Fuego (Argentina and Chile). Major- and trace-element data, obtained on single glass shards allowed to identify tephra sources in Late Glacial-Holocene eruptions from Hudson, Reclus and Mt Burney volcanoes, located in the Southern and Austral Volcanic Zone of the Andean Cordillera. Twelve new radiocarbon age determinations of charcoals, peats and soils have further constrained the correlations between the studied tephra layers and known eruptions from Hudson, Mt Burney and Reclus volcanoes. Therefore, this study contributes to expand the geochemical dataset on volcanic glasses valuable for tephra correlations in South America, and improves the current tephrostratigraphic framework of this region. Furthermore, we revised literature data by compiling a database including Neogene-Quaternary volcanic tephra found in Antarctic ice cores, marine sediments, blue ice and continental outcrops as well as tephra produced by volcanic sources located in Antarctica and circum-Antarctic areas. This revision shows that Antarctic tephra can be correlated with confidence to Antarctic and circum-Antarctic (South Shetlands and South Sandwich Islands) volcanic sources, whereas correlations with South American sources are arguable, and a complete geochemical fingerprinting is needed for validation.

Misunderstandings Concerning the Significance of AMS Background 14C Measurements

ABSTRACTWe consider one misconception of those who currently reject the general validity of radiocarbon (14C) age determinations older than, at most, 10,000 BP. There is an allegation that the presence of 14C reported by accelerator mass spectrometry (AMS) laboratories in their measurements of 14C infinite age (>100,000 years) organics used to define background levels, support their point of view. This article has been written for a general audience, primarily for those who have questions about the validity of these arguments. However, they may not be familiar with the literature relevant to providing a clear response to the claims of these individuals. We conclude that, in our view, of all of the possible explanations for the reports of the presence of 14C in these background samples, the least probable explanation has been advanced by those rejecting the validity of the 14C time scale in excess of, at most, 10,000 BP.