Browsing by Author "Zoppi, U"

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    AMS at ANTARES – the first 10 years
    (Elsevier, 2000-10) Lawson, EM; Elliott, G; Fallon, J; Fink, D; Hotchkis, MAC; Hua, Q; Jacobsen, GE; Lee, P; Smith, AM; Tuniz, C; Zoppi, U
    The status and capabilities of the ANTARES AMS facility after 10 years are reviewed. The common AMS radioisotopes, 10Be, 14C, 26A1, 36C1 and 129I, are routinely analysed. A capability for the detection of 236U and other actinide isotopes has been developed. The measurement program includes support to Quaternary science projects at Australian universities and to ANSTO projects in global climate change and nuclear safeguards. © 2000 Elsevier Science B.V.
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    AMS radiocarbon dating of micro samples from the rock paintings of Malakula (Vanuatu)
    (Oxford University School of Archaeology, 2002-04-09) Zoppi, U; David, B; Wilson, M; Hua, Q; Williams, AA; Watchman, A
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    ANSTO’s accelerators
    (Australian Institute of Physics, 2005-01-31) Zoppi, U; Cohen, DD; Garton, D
    Throughout its history, ANSTO demonstrated sustained excellence in accelerator-based science and technology. The 40 years old KN3000 Van de Graaff accelerator provided more than 110 000 running hours. The 10 MV ANTARES Tandem Accelerator is delivering leading edge Accelerator Mass Spectrometry (AMS) and Ion Beam Analysis (IBA) services. An additional HVEE 2 MV Tandetron accelerator has been recently commissioned and is expected to be applied across a very wide range of applications utilising IBA and AMS techniques. After a short review of the technical aspect of the 3 ANSTO accelerators, we will present a summary of the most exciting accelerator applications across a wide variety of scientific fields including air pollution, radiocarbon dating of precious artefacts and global climate change studies. © (2005) Australian Institute of Physics.
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    The ANTARES AMS facility at ANSTO
    (Elsevier, 2004-08) Fink, D; Hotchkis, MAC; Hua, Q; Jacobsen, GE; Smith, AM; Zoppi, U; Child, DP; Mifsud, C; van der Gaast, H; Williams, A; Williams, M
    This paper presents an overview of ANTARES operations, describing (1) technical upgrades that now allow routine 0.3–0.4% 14C precision for 1 mg carbon samples and 1% precision for 100 micrograms, (2) proficiency at 236U measurements in environmental samples, (3) new developments in AMS of platinum group elements and (4), some major application projects undertaken over the period of the past three years. Importantly, the facility is poised to enter into a new phase of expansion with the recent delivery of a 2 MV 14C tandem accelerator system from High Voltage Engineering (HVE) and a stable isotope ratio mass spectrometer from Micromass Inc. for combustion of organic samples and isotopic analysis. © 2004 Elsevier B.V.
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    Atmospheric 14C variations derived from tree rings during the early Younger Dryas
    (Elsevier, 2009-12) Hua, Q; Barbetti, M; Fink, D; Kaiser, KF; Friedrich, M; Kromer, B; Levchenko, VA; Zoppi, U; Smith, AM; Bertuch, F
    Atmospheric radiocarbon variations over the Younger Dryas interval, from ~13,000 to 11,600 cal yr BP, are of immense scientific interest because they reveal crucial information about the linkages between climate, ocean circulation and the carbon cycle. However, no direct and reliable atmospheric 14C records based on tree rings for the entire Younger Dryas have been available. In this paper, we present (1) high-precision 14C measurements on the extension of absolute tree-ring chronology from 12,400 to 12,560 cal yr BP and (2) high-precision, high-resolution atmospheric 14C record derived from a 617-yr-long tree-ring chronology of Huon pine from Tasmania, Australia, spanning the early Younger Dryas. The new tree-ring 14C records bridge the current gap in European tree-ring radiocarbon chronologies during the early Younger Dryas, linking the floating Lateglacial Pine record to the absolute tree-ring timescale. A continuous and reliable atmospheric 14C record for the past 14,000 cal yr BP including the Younger Dryas is now available. The new records indicate that the abrupt rise in atmospheric Δ14C associated with the Younger Dryas onset occurs at ~12,760 cal yr BP, ~240 yrs later than that recorded in Cariaco varves, with a smaller magnitude of ~40‰ followed by several centennial Δ14C variations of 20–25‰. Comparing the tree-ring Δ14C to marine-derived Δ14C and modelled Δ14C based on ice-core 10Be fluxes, we conclude that changes in ocean circulation were mainly responsible for the Younger Dryas onset, while a combination of changes in ocean circulation and 14C production rate were responsible for atmospheric Δ14C variations for the remainder of the Younger Dryas. © 2009, Elsevier Ltd.
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    Beginning of the early Bronze Age in the north Jordan Valley: new C-14 determinations from Pella in Jordan
    (University of Arizona, 2009-06-01) Bourke, S; Zoppi, U; Meadows, J; Hua, Q; Gibbins, S
    This article reports on 10 new accelerator mass spectrometry (AMS) radiocarbon dates from early phases of the Early Bronze Age at the long-lived settlement of Pella (modern Tabaqat Fahl) in the north Jordan Valley. The new AMS dates fall between 3400 and 2800 cal BC, and support a recent Suggestion that all Chalcolithic period occupation had ceased by 3800/3700 cal BC at the latest (Bourke et al. 2004b). Other recently published Early Bronze Age C-14 data strongly supports this revisionist scenario, Suggesting that the earliest phase of the Early Bronze Age (EBA I) occupied much of the 4th millennium cal BC (3800/3700 to 3100/3000 cal BC). As this EB I period in the Jordan Valley is generally viewed as the key precursor phase in the development Of urbanism (Joffe 1993), this revisionist chronology has potentially radical significance for understanding both the nature and speed of the move from village settlement towards a complex urban lifeway. © 2009 by the Arizona Board of Regents on behalf of the University of Arizona
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    The chronology of the Late Neolithic and Early Chalcolithic periods in the north Jordan Valley: new 14C determinations from Pella in Jordan
    (Oxford University School of Archaeology, 2002-04-09) Bourke, S; Lawson, EM; Hua, Q; Zoppi, U
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    Forensic applications of 14C bomb-pulse dating
    (Elsevier, 2004-08-01) Zoppi, U; Skopec, Z; Skopec, J; Jones, G; Fink, D; Jacobsen, GE; Tuniz, C; Williams, AA
    After a brief review of the basics of 14C bomb-pulse dating, this paper presents two unique forensic applications. Particular attention is dedicated to the use of the 14C bomb-pulse to establish the time of harvest of illicit drugs such as heroin and opium. Preliminary measurements of 14C concentrations in milligram samples taken from seized drugs are presented. 14C bomb-pulse dating can determine whether drug distribution originates from stockpiles or recent manufacture, and support the action of law enforcement authorities against criminal organisations involved in drug trafficking. In addition, we describe the dating of wine vintages for a number of authenticated single label vintage red wines from the Barossa Valley – South Australia. Our results show that radiocarbon dating can be used to accurately determine wine vintages and therefore reveal the addition of unrelated materials of natural and synthetic origin. © 2004 Elsevier B.V.
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    In search of in-situ radiocarbon in Law Dome ice and firn
    (Elsevier, 2000-10-01) Smith, AM; Levchenko, VA; Etheridge, DM; Lowe, DC; Hua, Q; Trudinger, CM; Zoppi, U; Elcheikh, A
    Results of AMS radiocarbon measurements on CO and CO2 separated from firn air directly pumped from the ice sheet, and on CO2 separated from air extracted from ice cores by a dry grating technique, are presented. The firn air samples and ice cores used in this study were collected from the region of Law Dome, Antarctica. No evidence of in-situ 14CO2 was found in the firn air samples or the ice core air samples from one site although a slight enhancement of 14CO above expected polar atmospheric concentrations was observed for some firn air samples. A clear in-situ 14CO2 signal for ice pre-dating the radiocarbon bomb pulse was found, however, in air samples extracted from an ice core from a second site. We compare these results and propose an hypothesis to explain this apparent contradiction. The degree to which in-situ 14C is released from the ice crystals during trapping and bubble formation is considered and discussed. The selectivity of the dry grating technique for the extraction of trapped atmospheric gases from ice cores is also discussed and compared with other methods. © 2000 Elsevier Science B.V
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    Marine reservoir correction for the Cocos (Keeling) Islands, Indian Ocean
    (Cambridge University Press, 2004) Hua, Q; Woodroffe, CD; Barbetti, M; Smithers, SG; Zoppi, U; Fink, D
    Known-age corals from the Cocos (Keeling) Islands, Indian Ocean, have been analyzed by accelerator mass spectrometry (AMS) for radiocarbon to determine marine reservoir age corrections. The ΔR value for the Cocos (Keeling) Islands is 66 ± 12 yr based on the analyses undertaken for this study. When our AMS and previously published dates for Cocos are averaged, they yield a ΔR of 64 ± 15 yr. This is a significant revision of an earlier estimate of the ΔR value for the Cocos (Keeling) Islands of 186 ± 66 yr (Toggweiler et al. 1991). The (revised) lower ΔR for the Cocos (Keeling) Islands is consistent with GEOSECS 14C data for the Indian Ocean, and previously published bomb 14C data for the Red Sea, Gulf of Aden, and Cocos Islands. The revised ΔR is also close to values for the eastern Indian Ocean and adjacent seas. These suggest surface waters that reach the Cocos Islands might be partly derived from the far western Pacific, via the Indonesian throughflow, and might not be influenced by the southeast flow from the Arabian Sea. Copyright © The Arizona Board of Regents on behalf of the University of Arizona
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    New radiocarbon measurements from Tasmanian Huon pine: closing the current gap in tree-ring based calibration data for the early Younger Dryas
    (Eleventh International Conference on Accelerator Mass Spectrometry, 2008-09) Hua, Q; Barbetti, M; Fink, D; Levchenko, VA; Zoppi, U; Smith, AM; Bertuch, F
    The European absolute tree-ring chronologies have recently extended back to 12,594 cal BP [1], covering most of the Younger Dryas (YD). Radiocarbon data from these chronologies spanning the past 12,400 cal BP have been used to construct the younger part of the current internationally ratified calibration curve IntCal04 [2]. For the Late Glacial, radiocarbon data from a floating 1382-ring pine chronology are also available [3]. Here we present new high-precision, high-resolution radiocarbon measurements for the early YD chronozone derived from 4 sub-fossil logs of Huon pine with clearly defined annual tree rings. These logs were excavated from alluvial sediments along Stanley River in north-western Tasmania, Australia. A total of 137 samples, mostly decadal, were pretreated to alpha-cellulose, then converted to graphite and measured by AMS using the ANTARES facility at ANSTO [4], with a typical precision of 0.3-0.4%. A floating 617-ring Huon pine chronology has been constructed based on ring width and radiocarbon measurements. Our high-precision decadal 14C record, covering an age range from 10,350 to 10,760 14C years BP, has been linked to the European absolute tree-ring and floating Late Glacial Pine chronologies, bridging the current gap in the European tree-ring chronologies during the early YD and making a continuous and reliable atmospheric 14C record for the past 14,000 cal BP. Variations in atmospheric 14C during the YD recorded in tree rings and the possible mechanisms are also discussed. © The Authors
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    Radiocarbon dating of Kharosthi fragments from the Schøyen and senior manuscript collections
    (Hermes Publishing, 2006) Allon, M; Salomon, R; Jacobsen, GE; Zoppi, U
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    Radiocarbon in tropical tree rings during the Little Ice Age
    (Elsevier, 2004-08) Hua, Q; Barbetti, M; Zoppi, U; Fink, D; Watanasak, M; Jacobsen, GE
    Cross-dated tree-ring cores (Pinus merkusii) from north-central Thailand, spanning AD 1620–1780, were used to investigate atmospheric 14C for the tropics during the latter part of the Little Ice Age. In addition, a cross-dated section of Huon pine from western Tasmania, covering the same period of time, was investigated. A total of 16 pairs of decadal samples were extracted to alpha-cellulose for AMS 14C analysis using the ANTARES facility at ANSTO. The 14C results from Thailand follow the trend of the southern hemisphere, rather than that of the northern hemisphere. This is a surprising result, and we infer that atmospheric 14C for north-central Thailand, at 17° N, was strongly influenced by the entrainment of southern hemisphere air parcels during the southwest Asian monsoon, when the Inter-Tropical Convergence Zone moves to the north of our sampling site. Such atmospheric transport and mixing are therefore considered to be one of the principal mechanisms for regional 14C offsets. © 2004 Elsevier B.V.
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    Radiocarbon variations from the Southern Hemisphere, 10,350–9700 cal BP
    (Elsevier, 2004-08) Barbetti, M; Hua, Q; Zoppi, U; Fink, D; Zhao, Y; Thomson, B
    We have made AMS measurements on a series of 10-ring samples from a subfossil Huon pine log found in western Tasmania (42°S, 145°E). The results show a pronounced rise in Δ14C over the first 200 years, and a decrease over the following 160 years. Tree-ring width measurements indicate that this log (catalogue SRT-447) can be cross-dated with another subfossil log (SRT-416) for which a series of high-precision radiometric 14C measurements have previously been made. When the two tree-ring series are thus aligned, SRT-447 is the older of the two logs, and there is a 139-year overlap. We then have a Huon pine floating chronology spanning 680 years, with 14C measurements attached. The 14C data sets agree well within the period of overlap indicated by the tree-rings. The 14C variations from Huon pine show excellent agreement with those from German oak and pine for the period 10,350–9670 cal BP. Aligning the Huon pine 14C series with that from German oak and pine allows us to examine the inter-hemispheric offset in 14C dates in the early Holocene. © 2004 Elsevier B.V.
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    Variations in tree-ring 14C for the younger dryas
    (GNS Science, 2009-05-15) Hua, Q; Barbetti, M; Fink, D; Levchenko, VA; Zoppi, U; Smith, AM; Bertuch, F
    Of all millennial-scale paleoclimate reversals during the Last Glacial Cycle, the Younger Dryas (YD), from ~13 to 11.6 cal kyr BP, has attracted the most attention and controversy. The debate centres on understanding the physical mechanisms for such an abrupt change in climate and radiocarbon, which are associated with small changes in solar output and/or major changes in earth-system interactions dealing with oceanic circulation and exchanges between the carbon reservoirs. The leads and lags between climatic proxy records of the YD event are at the heart of such research. Unfortunately, one of the problems is that there is no reliable, direct atmospheric 14C record based on tree-ring chronology for the whole YD period, thus negating any possibility of locking in the critical time marker of its initiation. Here we present new high-precision, high-resolution radiocarbon measurements for the early YD chronozone derived from 4 sub-fossil logs of Huon pine with clearly defined annual tree rings. These logs were excavated from alluvial sediments along Stanley River in north-western Tasmania, Australia. A floating 617-ring Huon pine chronology has been constructed based on ring width and AMS radiocarbon measurements. Our 14C record, covering an age range from 10,350 to 10,760 14C years BP, has been linked to the European absolute tree-ring and floating Late Glacial Pine chronologies, bridging the current gap in the European tree-ring 14C chronologies during the early YD. A continuous and reliable atmospheric 14C record for the past 14 cal kyr BP is now available. This allows a more precise determination of the timing in observed climatic and environmental parameters and allows for a critical evaluation of mechanisms of atmospheric 14C variations for the YD.