Browsing by Author "Hua, Q"
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- ItemA 1,000 year rainfall record for SE Australia using speleothem hydrological proxies(Geological Society of Australia, 2010-07-04) McDonald, J; Drysdale, RN; Hodge, E; Hua, Q; Fischer, MJ; Treble, PC; Greig, A; Hellstrom, JCCave drip water studies at Wombeyan Caves (34°19’S, 149°59’E) demonstrated a marked hydrochemical response to wet/dry (McDonald et al., 2004; 2007). Three 20th Century coeval active speleothems (WM4, WM6 and WM20) were geochemically analysed and changes in trace element and stable isotope values were related to the instrumental record. These climate‐geochemical relationships were interpolated to two longrecord speleothems (WM7 and WM9) which grew deeper within the same cave system. Two major difficulties were encountered. Unlike other sub‐annual/annual climate records derived from speleothems using trace elements (Treble et al., 2003; Johnson et al., 2006); stable isotopes (Treble et al., 2005; Johnson et al., 2006) and annual laminae (Borsato et al., 2007) where annual cycles were shown to be consistent, at Wombeyan frequent droughts perturb predicted rainfall patterns and rainfall variability is high. Here, droughts can span several years, or extend over winter, diminishing or obliterating the expected winter recharge signal. Alternatively, wet summers can sustain ‘unseasonal’ high discharge and lessen the expected prior calcite precipitation (PCP) signal. Thus an annual wet/dry geochemical signal is often absent. Secondly, due to the young age of the speleothems and very low uranium concentrations (~10 ppb) the use of U‐series disequilibrium dating was ineffective to produce a robust chronology. Trace element cycle counting only gave the minimum age due to the non‐expression of many cycles. The 14C bomb pulse was successfully defined in two modern stalagmites (WM4 and WM6) and maximum 14‐C activity was around 134 per cent modern carbon (pMC) for both speleothems, indicating rapid transfer of 14‐C from atmosphere, to soil, to drip water during the bomb‐pulse period. A dampened 14C bomb pulse was detected in WM7 (where pMCmax was 112 per cent modern carbon) reflecting the greater degree of mixing within the thicker bedrock. Carbon‐14 AMS analyses were utilised together with trace element cycle counting to obtain preliminary chronological control. Despite these difficulties, palaeohydrological records using multiple proxies: Mg/Ca (aridity), P and Y (wet), δ18O (dominant air mass and rainfall amount signals), and based on 14C ages were constructed for the longerrecord, slower growing stalagmites. Over the last 1,000 years there have been several sustained episodes of wet/arid or highly variable phases. A sustained wet phase occurred ~ 900–1300 AD and followed by ~ 200 years of highly variable wet/dry conditions. From ~ 1500 to 1800 AD a dry phase is indicated. The last 150 years support a drying phase, but the negative IPO (1944–1978 [wettest period in 20thC]) is not indicated by a negative anomaly and further, sustained positive δ18O anomalies in this period suggest that other factors maybe influencing this part of the record (temperature?). The δ18O record indicates changing frequency from ~ centennial to pentadecadal time‐scales in the longer‐time scale oscillations. Within the longer‐time scale oscillations, higher resolution (~ 2–5 years) variability is evident replicating the trend shown by modern annually resolved stalagmites at this site.
- ItemA 1,500 year south Australian rainfall record based on speleothem hydrological proxies(AMOS National Conference, 2013-02-11) McDonald, J; Drysdale, RN; Hua, Q; Hodge, E; Treble, PC; Greig, A; Fallon, SJ; Lee, S; Hellstrom, JCCave drip water studies at Wombeyan Caves (34°19’S, 149°59’E) demonstrated a marked hydrochemical response to wet/dry phases (McDonald Et al. 2004; 2007). Geochemical Variations in three 20th Century coeval active Speleothems were able to be linked to the instrumental record. Subsequently geochemical relationships were investigated in a long record speleothem(WM7) which grew deeper within the same cave system. Obtaining a robust chronology proved to be challenging, due to the young age of the speleothem and very low uranium concentrations (~10 ppb) the use of U‚Aeseries disequilibrium dating was ineffective to produce a robust chronology. Chronology for WM7 was based on a dense sequence of DCF corrected ages using three different age-‐depth models: Clam (Classical method), and Bacon and OxCal (Bayesian statistical approach) (Hua et al. 2012).The new chronology indicated that WM7 began growth around 4400 cal BP(171 mm). However, since sampling from 0-‐50mm was most intensive, the model is based on this part of the stalagmite and indicates that the top 50 mm of WM7 grew during the past 1360 and 1740 years. An aridity index based on Sr,P, Y, La, and Ba shows that over the last 1,500 years several sustained episodes of wet/arid and otherwise variable phases have occurred. Two sustained wet phases ~ 700-‐880 AD and ~ 900-‐ 1250 AD were followed by ~ 400 years of variable wet/dry conditions, although from ~1300 to 1600 AD a drying trend is indicated, but punctuated by several wetter episodes. The last 200 years indicate sustained drying phases. The OE¥13C record is anomalous from ~ 1880 to present and attributed to the stalagmite’s recording of increasing contribution of fossil fuel to CO2 concentrations. Within the longer-‐time scale oscillations, higher resolution (~ 2-‐5 years) variability is evident, replicating the trend shown by modern annually resolved stalagmites at this site.
- Item14.30 An introduction to dating techniques: a guide for geomorphologists(Elsevier, 2013-01-01) Sloss, CR; Westaway, KE; Hua, Q; Murray-Wallace, CVThis chapter provides researchers with a guide to some of the types of dating techniques that can be used in geo- morphological investigations and issues that need to be addressed when using geochronological data, specifically issues relating to accuracy and precision. This chapter also introduces the ‘types’ of dating methods that are commonly used in geomorphological studies. This includes sidereal, isotopic, radiogenic, and chemical dating methods. © 2013 Elsevier Inc.
- Item14C AMS measurements of the bomb pulse in N- and S- hemisphere tropical trees(Elsevier, 1997-03-02) Murphy, JO; Lawson, EM; Fink, D; Hotchkis, MAC; Hua, Q; Jacobsen, GE; Smith, AM; Tuniz, CThe 14C bomb-pulse signature has been measured by AMS on cross-dateable teak samples from N- and S-hemisphere locations in the tropics. Excellent agreement is found with the atmospheric 14C content in the period 1955 to 1980 for the respective hemispheres. These results demonstrate that 14C measurements can be used to facilitate growth rate determinations in tropical trees. © 1997 Elsevier B.V.
- Item14C in uranium and thorium minerals: a signature of cluster radioactivity?(Springer Nature, 1999-06-01) Bonetti, R; Guglielmetti, A; Poli, G; Sacchi, E; Fink, D; Hotchkis, MAC; Jacobsen, GE; Lawson, EM; Hua, Q; Smith, AM; Tuniz, CVarious uranium and thorium minerals have been analysed with accelerator mass spectrometry to determine their 14C content. It is found that, whenever the contribution from secondary reactions such as the 11B(α,p)14C is sufficiently low, the 14C concentration is consistent with that expected from 14C (spontaneous) cluster radioactivity from radium isotopes of the uranium and thorium natural series. © Springer-Verlag 1999
- Item14CH4 measurements in Greenland ice: investigating last glacial termination CH4 sources(American Association for the Advancement of Science (AAAS), 2009-04-24) Petrenko, VV; Smith, AM; Brook, EJ; Lowe, DC; Riedel, K; Brailsford, G; Hua, Q; Schaefer, H; Reeh, N; Weiss, RF; Etheridge, DM; Severinghaus, JPThe cause of a large increase of atmospheric methane concentration during the Younger Dryas-Preboreal abrupt climatic transition (~11,600 years ago) has been the subject of much debate. The carbon-14 (14C) content of methane (14CH4) should distinguish between wetland and clathrate contributions to this increase. We present measurements of 14CH4 in glacial ice, targeting this transition, performed by using ice samples obtained from an ablation site in west Greenland. Measured 14CH4 values were higher than predicted under any scenario. Sample 14CH4 appears to be elevated by direct cosmogenic 14C production in ice. 14C of CO was measured to better understand this process and correct the sample 14CH4. Corrected results suggest that wetland sources were likely responsible for the majority of the Younger Dryas-Preboreal CH4 rise. © 2009, American Association for the Advancement of Science (AAAS)
- Item15th International Conference on Accelerator Mass Spectrometry(Australian Nuclear Science and Technology Organisation, 2021-11-15) Bertuch, F; Child, DP; Fink, D; Fülöp, RH; Hotchkis, MAC; Hua, Q; Jacobsen, GE; Jenkinson, A; Levchenko, VA; Simon, KJ; Smith, AM; Wilcken, KM; Williams, AA; Williams, ML; Yang, B; Fallon, SJ; Wallner, TOn behalf of the AMS-15 Organising committee, we would like to thank you for attending the 15th International Conference on Accelerator Mass Spectrometry. Held as an online event for the first time, the 2021 conference attracted over 300 attendees with presentations delivered by colleagues and professionals from around the globe.Applications of AMS to the world’s most pressing problems/questions: A-1 : Earth’s dynamic climate palaeoclimate studies, human impacts on climate, data for climate modelling. A-2 : Water resource sustainability groundwater dating, hydrology, water quality and management A-3 : Living landscapes soil production, carbon storage, erosion, sediment transport, geomorphology. A-4 : Catastrophic natural events volcanoes, cyclones, earthquakes, tsunamis, space weather, mass extinctions. A-5 : Advancing human health metabolic and bio-kinetic studies, bomb-pulse dating, diagnostics and bio-tracing. A-6 : Challenges of the nuclear age nuclear safeguards, nuclear forensics, nuclear waste management, nuclear site monitoring, impacts of nuclear accidents. A-7 :Understanding the human story archaeology, human evolution and migration, history, art and cultural heritage A-8 : Understanding the cosmos fundamental physics, nuclear astrophysics, nuclear physics AMS Research and Development: T-1 : Novel AMS systems, components and techniques T-2 : Suppression of isobars and other interferences T-3 : Ion sourcery T-4 : New AMS isotopes T-5 : Advances in sample preparation T-6 : Data quality and management T-7 : Facility Reports (Poster Presentation only)
- ItemActive sediment generation on coral reef flats contributes to recent reef island expansion(American Geophysical Union (AGU), 2020-11-20) Ford, MR; Kench, PS; Owen, SD; Hua, QThe ongoing development of Jeh Island in the Marshall Islands was investigated using aerial photographs, high-resolution satellite imagery, and radiometric dating of island sediments. Remote sensing observations show the present-day island of Jeh is the product of two or more smaller islands merging together between 1943 and 2006 which are continuing to expand despite local sea-level rise (SLR). Remote sensing observations show modern island development involving a complex multistage merging of smaller islands on a linear atoll rim. Radiometric ages of sediments demonstrate that island development is occurring through the active generation and delivery of modern sediments. Results highlight that at sites where sediment production regimes are in a healthy state, island building under conditions of SLR is possible. The findings have implications for interpreting island evolution from morphostratigraphic studies and understanding future island behavior with further SLR. ©2020 American Geophysical Union
- ItemAge and growth of a fire prone Tasmanian temperate old-growth forest stand dominated by Eucalyptus regnans, the world's tallest angiosperm.(Elsevier, 2010-07-15) Wood, SW; Hua, Q; Allen, KJ; Bowman, DMJSForests are key components of the global carbon cycle, with deforestation being an important driver of increased atmospheric carbon dioxide. Temperate old-growth forests have some of the highest above ground stores of carbon of any forest types on Earth. Unlike tropical forests, the ecology of many temperate forests is dominated by episodic disturbance, such as high intensity fire. An exemplar of a particularly carbon dense temperate forest system adapted to infrequent catastrophic fires is the Eucalyptus regnans forests of south eastern Australia. Knowledge of the growth and longevity of old-growth trees is crucial to understanding the carbon balance and fire regimes of these forest systems. In an old-growth E. regnans stand in the Styx Valley in southern Tasmania we used dendrochronological techniques and radiocarbon dating to determine the age and stem growth of E. regnans and Phyllocladus aspleniifolius, an understorey rainforest conifer. Our analysis revealed that an even-aged cohort of E. regnans and P. aspleniifolius established in 1490–1510AD, apparently after a stand-replacing fire. The stem growth rates of E. regnans in the first 100 years were very rapid compared to the co-occurring P. aspleniifolius. That the longevity of E. regnans is >500 years challenges the suggested 350–450 year timeframe proposed for the widely held model of succession from eucalypt to rainforest. These forests not only have the potential to store vast amounts of carbon, but can also maintain these high carbon densities for a long period of time. Estimates of the capacity of these forests to sequester and store carbon should explicitly consider past harvesting and fire regimes and the potential increases in the risk of fire associated with climate change. © 2010, Elsevier Ltd.
- ItemAge-growth relationships, temperature sensitivity and palaeoclimate-archive potential of the threatened Altiplano cactus Echinopsis atacamensis(Oxford University Press & the Society for Experimental Biology, 2021-01-27) English, NB; Dettman, DL; Hua, Q; Mendoza, JM; Muir, D; Hultine, KR; Williams, DGThe tall (>4 m), charismatic and threatened columnar cacti, pasacana [Echinopsis atacamensis (Vaupel) Friedrich & G.D. Rowley)], grows on the Bolivian Altiplano and provides environmental and economic value to these extremely cold, arid and high-elevation (~4000 m) ecosystems. Yet very little is known about their growth rates, ages, demography and climate sensitivity. Using radiocarbon in spine dating time series, we quantitatively estimate the growth rate (5.8 and 8.3 cm yr−1) and age of these cacti (up to 430 years). These data and our field measurements yield a survivorship curve that suggests precipitation on the Altiplano is important for this species’ recruitment. Our results also reveal a relationship between night-time temperatures on the Altiplano and the variation in oxygen isotope values in spines (δ18O). The annual δ18O minimums from 58 years of in-series spine tissue from pasacana on the Altiplano provides at least decadal proxy records of temperature (r = 0.58; P < 0.0001), and evidence suggests that there are longer records connecting modern Altiplano temperatures to sea-surface temperatures (SSTs) in the Atlantic Ocean. While the role of Atlantic SSTs on the South American Summer Monsoon (SASM) and precipitation on the Bolivian Altiplano is well described, the impact of SSTs on Altiplano temperatures is disputed. Understanding the modern impact of SSTs on temperature on the Altiplano is important to both understand the impact of future climate change on pasacana cactus and to understand past climate changes on the Altiplano. This is the best quantitative evidence to date of one of the oldest known cactus in the world, although there are likely many older cacti on the Altiplano, or elsewhere, that have not yet been sampled. Together with growth, isotope and age data, this information should lead to better management and conservation outcomes for this threatened species and the Altiplano ecosystem. © The Author(s) 2021
- ItemAMS 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, UThe 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.
- ItemAMS radiocarbon analysis of microsamples(Australian Institute of Nuclear Science and Engineering, Australian Nuclear Science & Technology Organisation and Australian Museum, 1997-02-12) Jacobsen, GE; Hua, Q; Tarshishi, J; Fink, D; Hotchkis, MAC; Lawson, EM; Smith, AM; Tuniz, CThe ANTARES AMS Centre has two chemistry laboratories dedicated to preparing targets for measurement. Target preparation encompasses a variety of activities ranging from the curation of incoming samples to the numerous steps involved in the purification and processing of dissimilar samples. One of the two laboratories is set up for the physical and chemical pretreatment of 14C samples. Treatments include cleaning by sonification, sorting, grinding and sieving, and chemical treatments such as the standard AAA treatment, and solvent extraction. Combustion and graphitisation are also carried out in this laboratory. The second laboratory is a clean room and is dedicated to the combustion, hydrolysis and graphitisation of 14C samples as well as processing targets for the other isotopes. Combustion is achieved by heating the sample to 900 deg C in the presence of CuO, the resulting gas is purified by passing over Ag and Cu wire at 600 deg C. Graphitisation is carried out by reducing the CO{sub 2} with an iron catalyst (600 deg C) in the presence of zinc (400 deg C) and a small amount of hydrogen. Samples such as charcoal, shell, bone, wood, sediment, seawater and groundwater, containing 0.3-1 mg or more of original carbon, are processed routinely for radiocarbon analysis. The current 14C chemistry background for 1 mg carbon is approx. 0.3 percent of modern carbon (pMC) enabling materials` dating up to 45 000 BP.
- ItemAMS 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, ANot available
- ItemAnomalous tree-ring identification facilitated by AMS 14C analysis in subtropical and tropical Australian Araucariaceae samples enables development of a long-term, high-resolution climate reconstruction(Australian Nuclear Science and Technology Organisation, 2021-11-17) Haines, HA; Palmer, JG; Hua, Q; English, NB; Hiscock, W; Turney, CSM; Marjo, CE; Gadd, PS; Kemp, J; Olley, JMIn Australia the majority of tropical and subtropical regions lack long-term instrumental climate records. Paleoclimate reconstructions from tree rings provide one alternative but very few dendrochronological investigations have so far been undertaken. Early assessments of mainland Australian tree species were discouraging due to the high prevalence of anomalous ring boundaries. Some species, however, were seen as more favourable than others including those in the Araucariaceae family which is common along the subtropical-tropical Australian east coast. These trees are longer lived than many other species in the region and contain growth rings known to be annual in nature and responsive to climatic conditions. There is however, a heavy prevalence of anomalous ring boundaries in species from this family which must be accounted for when dating these species. Here we describe the tree-ring characteristics and growth response from two stands of Hoop pine (Araucaria cunninghamii) trees located in subtropical and tropical Queensland, Australia (regions known for experiencing extreme hydroclimatic events). Confirmation of annual growth driven by moisture sensitivity was determined using radius dendrometers on four trees in Lamington National Park (c. 28º S). Tree cores were collected from both the Lamington stand as well as a stand at Hidden Valley near Paluma, Queensland (c. 19º S). Ring-width assessment showed the presence of false, faint, locally absent, and wedging rings in both sites. Results of bomb-pulse radiocarbon dating of selected single tree rings demonstrated that trees from this species can fall into one of three categories: A – those with locally-absent rings around the circumference of the trees, B – those where false rings were observed, and C – those with many wedging and locally-absent rings. Only trees in the first two categories were able to be included in the master chronologies. Traditional dendrochronological analysis with age validation by bomb-pulse radiocarbon dating allowed for a robust ring-width chronology from 1805-2014 CE to be developed for the Lamington National Park site. Growth-climate analysis of the master tree-ring chronology determined that the strongest environmental correlation was to wet season drought conditions. The strength of this response was compared to local and regional drought indices as well as to a long-term drought reconstruction. The combined analysis led to the development of a 200-year drought reconstruction for the region which shows influences from both the El Niño Southern Oscillation and the Interdecadal Pacific Oscillation. © The Authors
- ItemANSTO AMS facility sample processing and target preparation: an update(20th International Radiocarbon Conference, 2009-06-01) Jacobsen, GE; Barry, LA; Bertuch, F; Hua, Q; Mifsud, C; Pratap, P; Reilly, N; Varley, S; Williams, AGThe ANSTO AMS Facility has been operating for the past 17 years, and comprises two accelerators complemented with a suite of chemistry laboratories dedicated to the processing of samples for carbon, beryllium, aluminium, iodine, and actinide analyses. The facility performs and supports a wide range of research in the areas of paleoclimate change, water resource sustainability, archaeology, geomorphology, and nuclear safeguards. As a result, the chemistry laboratories are called upon to process a large variety of sample types and increasing numbers of samples. The radiocarbon laboratories process charcoal, wood, sediments, pollen, carbonates, waters, textiles, and bone though the pretreatment stages, combustion or hydrolysis, and graphitization. Over the years, we have continually worked to improve pretreatment methods, reduce sample size, and reduce background. Construction of a dedicated low-background combustion and graphitization system is underway. The cosmogenic laboratories process quartz-bearing rocks and sediments through cleaning, dissolution, separation, and purification of Be and Al and preparation of targets as oxides. In this poster, we will summarize the current methods and developments in the radiocarbon and cosmogenic chemistry laboratories.
- ItemANSTO Radiocarbon Laboratory: developments to meet the needs of our community(Australian Nuclear Science and Technology Organisation, 2021-11-17) Bertuch, F; Williams, AA; Yang, B; Nguyen, TH; Varley, S; Jacobsen, GE; Hua, QThe radiocarbon chemistry laboratories in the Centre for Accelerator Science at the Australian Nuclear Science and Technology Organisation (ANSTO) have a role providing support to AMS measurements for government organisations, industry, and academia in Australia and overseas. Over recent years the radiocarbon laboratories at ANSTO have expanded to support projects that address unique challenges which include environmental issues, the sustainable management of water resources, climate variability, ecological studies, and research into Indigenous heritage. The increase of work in these areas has seen a growing demand for processing samples of groundwater, rock art, ice cores, tree rings and Antarctic mosses. Here we will present an update of our procedures for processing a diverse range of sample types. We will also describe developments such as an automated dissolved organic carbon (DIC) extraction system for water samples, and our automated AAA pretreatment system. We will also outline our range of graphitisation systems which include a set of 24 Fe/H2 graphitisation units, 6 microconventional furnace (MCF) Fe/H2 graphitisation lines, a laser heated furnace (LHF) graphitisation system, and an Ionplus AGE-3 graphitisation system (owned by UNSW). Our MCF and conventional graphitisation lines have been designed to handle and reliably produce graphite targets containing as little as 5 μg and 10ugC of carbon respectively), making the graphitisation of minute carbon samples from rock art and ice cores possible.
- ItemAntarctic mosses reveal high resolution records of local microclimates(Australian Nuclear Science and Technology Organisation, 2021-11-17) Waterman, MJ; Bramley-Alves, J; Casanova-Katny, A; Zúñiga, GE; Hua, Q; Robinson, SAIntroduction Life in Antarctica is living in the extreme. To survive there, life must be resilient to sub-zero temperatures, high levels of damaging ultraviolet and solar radiation, strong winds and waterlimiting environments. In this harsh continent where water is locked up as snow and ice for most of the year, mosses are the dominant plant form. Like many living things, these small plants rely on liquid water to survive. The amount of potential water that is available to drive growth, distribution and survival of Antarctic flora is strongly influenced by the changing climate, especially temperature, precipitation and winds. However, meteorological climate records in most of the biologically diverse regions in Antarctica are sparse and limited to a few decades or less. In these areas, there is an increasing need for local climate proxies. We show that Antarctic moss species can be used as living proxies for local water availability through preserved stable carbon isotopes captured in cellulose. Methods and Results Using accelerator and isotope ratio mass spectrometry techniques, we obtained radiocarbon ages and δ¹³C signatures along 26 cores of long shoots of moss collected from the Windmill Islands, East Antarctica and South Shetland Islands in the Maritime Antarctic. AMS radiocarbon results showed that these once living cores are up to 500 years old. The five moss species studied grew at different rates; the slowest species grew at less than 1 mm/year while the fastest achieved 8 mm/year. These moss cores provide a high-resolution record, at annual to decadal scales, of their microclimate. Our results also reveal that growth patterns of these Antarctic plants are dependent on local moisture environments. Trends in δ¹³C signatures indicate microclimates in these regions are drying. Conclusion This work suggests that mosses have considerable potential as climate proxies by providing a temporal and spatial history of microclimate in Antarctica. Applying these measures will allow us to determine which terrestrial sites are at risk of the negative impacts of climate change in order to inform critical conservation efforts in a rapidly changing environment. © The Authors
- ItemThe ANTARES AMS Centre : a status report(Cambridge University Press, 2016-07-18) Tuniz, C; Fink, D; Hotchkis, MAC; Jacobsen, GE; Lawson, EM; Smith, AM; Hua, Q; Drewer, P; Lee, P; Levchenko, VA; Bird, R; Boldeman, JW; Barbetti, M; Taylor, G; Head, JThe ANTARES accelerator mass spectrometry facility at Lucas Heights Research Laboratory is operational and AMS measurements of 14C, 26Al and 36Cl are being carried out routinely. Measurement of 129I recently commenced and capabilities for other long-lived radioisotopes such as 10Be are being established. The overall aim of the facility is to develop advanced programs in Quaternary science, global climate change, biomedicine and nuclear safeguards. © the Department of Geosciences, The University of Arizona
- ItemThe 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, MThis 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.
- ItemArchaeological implications of a widespread 13th Century tephra marker across the central Indonesian Archipelago(Elsevier, 2016-01-01) Alloway, BV; Andreastuti, S; Setiawan, R; Miksic, JN; Hua, QDespite the occurrence of exceptionally large eruptions in the Indonesian Archipelago in recent historic times (i.e. Krakatoa 1883, Tambora 1815), no historic tephra beds have been widely identified in the terrestrial realm that could facilitate the correlation of equivalent aged sequences and/or archaeological remains. This study has identified one such tephra bed of 13th Century age that can be correlated throughout central-east Java and now can be unequivocally correlated with the Samalas 1257 A.D. tephra recently described from Lombok. The occurrence of this historic tephra marker extending ≥650 km west from its eruptive source provides the first opportunity to effect inter-regional correlation over large swathes of central Indonesia. It remains entirely conceivable that in the aftermath of this exceptionally large eruptive event there was considerable westward disruption to subsistence agriculture and trade, food shortages and famine, dislocation of affected populations and socio-political unrest on a scale that equalled or exceeded the catastrophic effects documented from the more recent Tambora 1815 A.D. eruption. Indeed the effects of this mid-13th Century eruption can be registered globally in a variety of records from Antarctica, Europe, Middle East and the Americas. Unfortunately, archaeological evidence indicating such disruption in mid-13th Century Indonesia is yet to be deciphered from the so-far sparse accounts and inscriptions of that time. However, this paucity of evidence does not diminish the utility of this widespread tephra bed as a unique chronostratigraphic marker for archaeological studies across large areas of central Indonesia. © 2016, Elsevier Ltd.