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Southern Hemisphere Radiocarbon Calibration - Radiocarbon Dating Laboratory: University of Waikato

Radioactive Dating

Research focused upon the causes, timing, duration, geographic extent and impact on hunter-gatherer groups of this important cooling episode, has been hampered by inconsistencies in radiocarbon, ice core and varve time scales. The Younger Dryas cold event, represents an abrupt Northern Hemisphere cooling episode, punctuating the general warming trend from the Last Glacial Maximum LGM; 22, years ago to the Holocene 11, years ago. The timing of cooling leading into the YD and its duration are still incompletely understood. These chronological discrepancies undermine the calibration of all Lateglacial 14 C dates and are hindering determination of the synchronicity of climate change between regions and archives, which is urgently needed to help elucidate the mechanisms of abrupt global climate change. The Northland sub-fossil kauri resource represents one of the world's foremost archives of atmospheric records during the last 60, yrs. Kauri logs are buried in bogs scattered over a km stretch of northern New Zealand, with the acid conditions resulting in a remarkable state of preservation of the wood. Some of the buried trees are of enormous proportions, with diameters greater than 4 m and individual ages of more than 2, yr.

This means that 14 C dates do not equate directly with calendar time and therefore must be corrected using a calibration curve constructed by 14 C dating of samples of known calendar age. The material of choice for construction of a calibration curve is wood whose calendar age has been determined precisely by tree ring counting dendrochronology.

What is less widely known is that Southern Hemisphere samples have a lower 14 C content than contemporaneous Northern Hemisphere material — referred to as the 14 C interhemispheric offset. Early studies suggested a constant offset but recent research led by Waikato's own Dr Alan Hogg has demonstrated that over the last years the offset in fact varies.

This obviously has important ramifications for any Southern Hemisphere carbon dating, particularly for studies of climate change, the timing of natural disasters and anthropogenic effects. Radiocarbon53 3 p Journal of the Royal Society of.

New Zealand — Evidence of a significant relationship. Journal of the Royal Society of New. Zealand — New Zealand. Nature Climate Change 2 3 —6. The 12, Radiocarbon 46 3 11— Hogg AG. Performance and design of 0. In: Noakes. Liquid Scintil. Tucson: Radiocarbon. R, Baillie MGL. Dating ancient wood by high.

Robust radiocarbon dating of wood samples. Radiocarbon 49 2 —9 1. Evaluation of wood pretreatments on oak. Radiocarbon 40 1 — Atmospheric 14 C variations derived from tree. Quaternary Sci. Kaiser KF. Jahrringen und Mollusken schalen aus verschiedenen. V ereisungsgebieten. W interthur: Ziegler Druck- und. V erlags-AG. Challenging process to make the.

The New Zealand kauri (Agathis australis) research project: A radiocarbon dating intercomparison of Younger Dryas wood and implications for IntCal The New Zealand kauri (Agathis australis) research project: a radiocarbon dating intercomparison of Younger Dryas wood and implications for INTCAL PDF | We describe here the New Zealand kauri (Agathis australis) Younger RADIOCARBON DATING INTERCOMPARISON OF YOUNGER.

Late-glacial tree-ring chrono logies from Europe abso. Quaternary Science Reviews Lateglacial 14 C. The late Quaternary history of kauri Agathis. Journal of Biogeography — Extension of New Zealand kauri Agathis aus. Stage OIS 3. Journal of Quaternary Science 21 7 :. IntCal04 terrestrial radiocarbon age calibra. Radiocarbon 46 3 — IntCal09 and Marine09 ra diocarbon age calibration.

The New Zealand Kauri (Agathis australis) Research Project: A Radiocarbon Dating Intercomparison of Younger Dryas Wood and Implications. The New Zealand Kauri (Agathis australis) Research Project: A Radiocarbon Dating Intercomparison of Younger Dryas Wood and Implications for IntCal And by radiocarbon dating the wood, ancient kauri is providing unparalleled new insights into how the planet's carbon cycle behaves during periods of abrupt.

Radiocarbon 51 4 :. IntCal13 and Marine13 ra diocarbon age calibration. Radiocarbon 55 4this. The IAEA. Stuiver M, Polach H. Discussion: reporting of 14 C. Radiocarbon 19 3 — Towards a radiocarbon calibration for Oxygen. Isotope Stage 3 using New Zealand kauri Agathis. Radiocarbon 49 2 — Jones R. The potential of New Zealand kauri. Agathis australis for testing the synchronicity of. Quaternary Science Re. Journal of Quaternary Sci. On the average. Journal of.

Climate and Applied Meteorology —1 3. Is the consensus value of ANU sucrose. IAEA C-6 too high? Radiocarbon 52 2—3 — Citations References Kauri logs were extracted from two geographic locations for this study. The first location was a farm site near Towai 35? S, ? E; Figure 1 in Northland where a cohort of 37 subfossil kauri logs of YD age has recently been discovered Hogg et al.

The yr Towai floating subfossil kauri chronology compiled from 91 radial strips derived from 37 trees is well replicated and securely cross-dated with an average cross-correlation coefficient between all series of 0. The chronology has only 0. The Last Glacial—Interglacial Transition LGIT; 15,—11, cal BP was characterized by complex spatiotemporal patterns of climate change, with numerous studies requiring accurate chronological control to decipher leads from lags in global paleoclimatic, paleoenvironmental, and archaeological records.

However, close scrutiny of the few available tree-ring chronologies and radiocarbon-dated sequences composing the IntCal13 14C calibration curve indicates significant weakness in 14C calibration across key periods of the LGIT. The new kauri record and repositioned NH pine 14C series offer a refinement of the international 14C calibration curves IntCal13 and SHCal13, providing increased confidence in the correlation of global paleorecords.

Scott et al.

Waikato Radiocarbon Dating Laboratory

Accurate calibration is also dependent upon accurate, precise and reproducible component data sets. Tree-ring series with weak dendrochronological linkages can result in serious calibration curve errors. For example, the beginning of the "absolute tree-ring chronology" Friedrich et al. Wood pretreatment procedures can vary significantly and range from more rapid acid-baseacid ABA processes to intensive alpha-cellulose extraction.

The influence of calibration curve construction and composition on the accuracy and precision of radiocarbon wiggle-matching of tree rings, illustrated by Southern Hemisphere atmospheric data sets from ad — Hogg Timothy J. It presents a new Bayesian spline method for calibration curve construction and tests it on extant and new Southern Hemisphere SH data sets also examining their dendrochronology and pretreatment for the post-Little Ice Age LIA interval AD — The new method of construction allows calculation of component data offsets, permitting identification of laboratory and geographic biases.

Data sets with individual offsets larger than this need to be carefully assessed before selection for calibration purposes. We identify a potential geographical offset associated with the Southern Ocean high latitude Campbell Island data. We test the new methodology for wiggle-matching short tree-ring sequences and use an OxCal simulation to assess the likely precision obtainable by wiggle-matching in the post-LIA interval.

This was the first time glacial-age swamp kauri has been found, and the collection at that site represents a single cohort of trees. A well-replicated floating tree-ring chronology was built from that material Palmer et al.

The scientific value and potential of New Zealand swamp kauri. New Zealand swamp kauri Agathis australis are relic trees that have been buried and preserved in anoxic bog environments of northern New Zealand for centuries through to hundreds of millennia.

Kauri are massive in proportion to other native New Zealand trees and they can attain ages greater than years. The export market for swamp subfossil kauri has recently been driven by demand for a high-value workable timber, but there are concerns about the sustainability of the remaining resource, a situation exacerbated in recent years by the rapid extraction of wood.

Economic exploitation of swamp kauri presents several unique opportunities for Quaternary science, however the scientific value of this wood is not well understood by the wider research community and public.

Here, we summarise the history of scientific research on swamp kauri, and explore the considerable potential of this unique resource. Swamp kauri tree-ring chronologies are temporally unique, and secondary analyses such as radiocarbon and isotopic analyses have value for improving our understanding of Earth's recent geologic history and pre-instrumental climate history.

Radiocarbon

High-precision radiocarbon dating of swamp kauri chronologies can improve the resolution of the global radiocarbon calibration curve, while testing age modelling and chronologic alignment of other independent long-term high-resolution proxy records.

Swamp kauri also has the potential to facilitate absolute dating and verification of cosmogenic events found in long Northern Hemisphere tree-ring chronologies. Future efforts to conserve these identified values requires scientists to work closely with swamp kauri industry operators, resource consent authorities, and export regulators to mitigate potential losses to science as this precious material is progressively extracted from the ground and utilized.

Each ring directly reflects the atmospheric D 14 C at its time of growth and can be absolutely and accurately dated via dendrochronology. The current framework of absolutely dated tree-ring extends back to 12, cal BP calibrated before present, CE,Friedrich et al.

Radiocarbon calibration uncertainties during the last deglaciation: Insights from new floating tree-ring chronologies. Florian Adolphi. These data are necessary for acquiring rates of change and understanding the associated mechanisms, causes and consequences. Annual tree-ring data are ideal for obtaining the high-resolution temporal data, but Lateglacial wood suitable for dendrochronological analysis is sparse e. Guyette et al. Full-text available.

A year period of higher year-to-year ring-width variability dates to around 11 cal a BP, infers strong regional climatic perturbations and may represent the end of the YD. Tamarack and spruce were dominant species throughout the YD—EH interval at the site, indicating that boreal conditions persisted into the EH, in contrast to geographical regions immediately south and east of the lowlands, but consistent with the Great Lakes interior lowlands.

This infers that Bell Creek was at the eastern boundary of a boreal ecotone, perhaps a result of its lower elevation and the non-analog dynamics of the Laurentide Ice Sheet. This finding suggests that the ecotone boundary extended farther east during the YD—EH transition than previously thought.

How to Date a Dead Thing

Radiocarbon ages presented below were all calibrated using OxCal v4. Built structures in rockshelters of the Pilbara, Western Australia.

Jan Built structures in rockshelters are relatively common archaeological features in the Pilbara that have been neglected in the published literature. Drawing primarily on grey literature, coupled with new data from recent investigations, this paper provides a review of current knowledge about these enigmatic structures. Results show that these features are found across the Hamersley Plateau, although are especially abundant in the Packsaddle Range, and in the Chichester Ranges.

Most are likely to be late Holocene features, concurrent with a suite of other changes that occurred during that period. The current practice of grouping all built structures in rockshelters into a single site type i. A typology is suggested based on morphological and contextual features to allow better characterisation of these features, thereby improving understandings of their distribution and functions, and facilitating more adequate assessments of their signi cance in management contexts.

Walled structures in rockshelters of the Pilbara, Western Australia. Conference Paper. Dec While some studies of these structures have been undertaken, very few have been published. This paper draws primarily on information in the grey literature to provide a review of the current state of knowledge about this particular type of archaeological feature. Results indicate walled structures are found across the Hamersley Plateau, though they are more common in the east, as originally posited by Brown The current practice of grouping of all walled structures that occur in rockshelters into a single site type category conceals the wide variation amongst these features.

Two other types of walled structures are not walls per se, but are instead essentially self-standing structures that can be separated into two types: 4 Cairns, which have a cavity or chamber within the rocks; and 5 Piles, which do not have a cavity or chamber within.

It is strongly suggested that, during recording, these features be systematically categorised according into defined sub-types to help develop a better understanding of their distribution, significance and possible function s. While this is theoretically the case back to 12 cal BP calibrated before present, AD, Friedrich et al.

Hence, we limit our analysis to the Holocene where both dendrochronological and 14 C-data replication is 20 high and most robust Reimer et al. Synchronizing the Greenland ice core and radiocarbon timescales over the Holocene — Bayesian wiggle-matching of cosmogenic radionuclide records Synchronizing the Greenland ice core and radiocarbon timescales.

Jul CPD. Investigations of past climate dynamics rely on accurate and precise chronologies of the employed climate reconstructions. Here we use common variations in the production rates of 14 C and 10 Be recorded in tree-rings and ice cores, respectively, to assess the differences between both timescales during the Holocene. We employ a novel statistical approach which leads to strongly reduced and yet, more 10 robust, uncertainty estimates in comparison to earlier work.

We demonstrate that the inferred timescale differences are robust independent of i the applied ice core 10 Be records, ii assumptions of the mode of 10 Be deposition, as well as iii carbon cycle effects on 14 C, and in agreement with independent estimates of the timescale differences.

Our results imply that the GICC05 counting error is likely underestimated during the 15 most recent years leading to a dating bias that propagates throughout large parts of the Holocene. Nevertheless, our analysis indicates that the GICC05 counting error is generally a robust uncertainty measurement but care has to be taken when treating it as a nearly Gaussian error distribution. The proposed IntCalGICC05 transfer function facilitates the comparison of ice core and radiocarbon dated paleoclimate records 20 at high chronological precision.

SHCal13 southern hemisphere calibration, We present the WD chronology for the upper part 0— m, The chronology is based on counting of annual layers observed in the chemical, dust and electrical conductivity records. These layers are caused by seasonal changes in the source, transport, and deposition of aerosols. The measurements were interpreted manually and with the aid of two automated methods. We validated the chronology by comparing to two high-accuracy, absolutely dated chronologies.

The New Zealand Kauri (Agathis Australis) Research Project: A Radiocarbon Dating Intercomparison of Younger Dryas Wood and Implications. Some of the NZ kauri YD research project team members standing on a 12, yr old kauri log. From left: Dr Jonathan Palmer, Gondwana Tree Ring Laboratory, . The New Zealand Kauri (Agathis Australis) Research Project: A Radiocarbon Dating Intercomparison of Younger Dryas Wood and Implications for IntCal

WD has consistently younger ages than Greenland ice-core chronologies during most of the Holocene. Given its high accuracy, WD can become a reference chronology for the Southern Hemisphere, with synchronization to other chronologies feasible using high quality proxies of volcanism, solar activity, atmospheric mineral dust, and atmospheric methane concentrations.

Show more. Dendroclimatic interpretation of tree-rings in Agathis australis kauri. Climate correlation functions and master chronology. Sep Brendan M.

In this paper we analyse nine existing Agathis australis kauri chronologies for their response to climate, and compare our results with those of previous studies. We update the southernmost chronology, from Katikati, which now extends to the growth ring growing season in Southern Hemisphere. We also employ recent standardisation procedures that have been demonstrated to eliminate the chance of biasing the chronology indices.

Climate correlation functions are generated for all nine kauri chronologies, by correlating chronology indices with meteorological datasets. In an earlier study only a 12 month response window was analysed, combined with lagging the growth year in order to account for prior-season growth response. Our expanded dendroclimatic response window covers the 21 months from May of the year of growth tback to the previous September year t - 1.

There are consistent significant correlations with climate for all nine kauri sites, most pronounced in the form of a positive response in season t to precipitation in the previous season t - 1and an inverse response to temperature in the year of growth.

The most robust climate signal comes from the Katikati chronology, which has been updated by 16 years to the growth ring. The additional years allow for more degrees of freedom and a better estimate of the climate correlation functions. Correlation and Principal Component Analyses validate the combining of eight of the nine chronologies into one regional time series.

Radiocarbon dating kauri

The results presented in this paper are encouraging for future dendroclimatic research with Agathis australis, towards the goal of long-term reconstruction of climate. The combined oak and pine tree-ring chronologies of Hohenheim University are the backbone of the Holocene radiocarbon calibration for central Europe. Here, we present the revised Holocene oak chronology HOC and the Preboreal pine chronology PPC with respect to revisions, critical links, and extensions.

Oaks affected by cockchafer have been identified and discarded from the chronology. The formerly floating PPC has been cross-matched dendrochronologically to the absolutely dated oak chronology, which revealed a difference of only 8 yr to the published 14 C wiggle-match position used for IntCal The 2 parts of the PPC, which were linked tentatively at 11, BP, have been revised and strengthened by new trees, which enabled us to link both parts of the PPC dendrochronologically.

Including the 8-yr shift of the oak-pine link, the older part of the PPC pre, BP needs to be shifted 70 yr to older ages with respect to the published data Spurk In addition, the PPC was extended significantly by new pine chronologies from other regions.

The absolutely dated tree-ring chronology now extends back to 12, cal BP 10, BC. Therefore, the tree-ring-based 14 C calibration now reaches back into the Central Younger Dryas. With respect to the Younger Dryas-Preboreal transition identified in the ring width of our pines at 11, BP, the absolute tree-ring chronology now covers the entire Holocene and yr of the Younger Dryas.

Precision and accuracy in accelerator mass spectrometry AMS dating relies on the systematic reduction of errors at all stages of the dating process, from sampling to AMS measurement. With new AMS systems providing much better precision and accuracy for the final stage of the process, we need to review the process as a whole to test the accuracy of reported results.

Since then, the system has been in routine use for AMS dating and here we report on our experiences during the first year. The AMS system itself is known to be capable of making measurements on single targets to a precision of better than 0.

In routine operation, we measure known-age wood to a precision of just above 0. This provides a test of all parts of the process for a particular material in a particular state of preservation. More generally, sample pretreatment should remove as much contamination as feasible from the sample while adding as little laboratory contamination as possible.

For more complex materials, such as bone, there is clearly more work needed to prove good reproducibility and insignificant offsets in all circumstances. Reporting of 14C data. The best means for correcting Southern Hemisphere SH radiocarbon measurements, which are significantly influenced by temporal variations in the interhemispheric offset, is by the construction of a SH-specific calibration curve from dendrochronologically dated wood.

We present here decadal 14C measurements on dendrochronologically secure New Zealand kauri Agathis australiscovering the period BC-ADextending the range of calibration measurements from New Zealand tree rings to more than 2 millennia. Recently published Tasmanian huon pine Lagarostrobos franklinii data for the interval BC to AD measured at the Center for Accelerator Mass Spectrometry CAMS have underestimated standard errors, which need to be re-assessed before the data can be considered for a Southern Hemisphere calibration curve update.

Although these data points are being checked, it is unlikely this represents a temporal geographic location-dependent offset. This SH offset is lower than the modeled offset of yr used in the construction of SHCal04, and we recommend the lower value be used in future SHCal updates. Although there is an apparent increase in higher frequency events in the SH offset NZ kauri plus Tasmanian huon from BC-ADthe reason for this remains unclear. Discussion-Reporting of Count rates, representing the rate of 14 C decay, are the basic data obtained in a 14 C laboratory.

The conversion of this information into an age or geochemical parameters appears a simple matter at first.

However, the path between counting and suitable 14 C data reporting table 1 causes headaches to many. Minor deflections in pathway, depending on personal interpretations, are possible and give end results that are not always useful for inter-laboratory comparisons. This discussion is an attempt to identify some of these problems and to recommend certain procedures by which reporting ambiguities can be avoided.

Wood growth rates in interstadial samples, compared to modern trees, suggest that kauri was stressed by lower temperatures and a wetter environment. With further temperature reduction in the late Otiran stadial last glacial maxium growth may have been limited to four summer months. The scarcity of kauri pollen from stratigraphic samples and the rarity of wood dating from this period support the contention that kauri was much reduced in abundance during the last glacial maximum.

Kauri expansion in the early Holocene may have been delayed by moist cloudy summer conditions, and by lack of suitable regeneration opportunities in the more equable climate of that period. In the mid to late Holocene, after BP, kauri spread southwards at rates of up to m yr- 1, reaching its southern limit by BP.

This apparent southwards migration probably represents the expansion of small populations on favourable north-facing slopes or ridge-top sites scattered throughout the area to the north of Auckland, rather than a simple wave-like migration from a hypothetical northern refuge.

It imples a change in the disturbance regime, with greater frequency of landscape-scale forest destruction by fire or windstorm, favouring regeneration of kauri, and drier sunnier summers enhancing tree growth rates. Kauri remained abundant at the southern limits in the Waikato from BP. Mar Nat. The instrumental record is too short to discern centennial-scale trends and modelling results are inconclusive. Proxy reconstructions indicate that ENSO activity was relatively high during the late twentieth century, but whether this was unusual in the millennial context remains uncertain.

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