Browsing by Author "Ulm, S"

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    Environmental context for late holocene human occupation of the South Wellesley Archipelago, Gulf of Carpentaria, northern Australia
    (Elsevier, 2015-10-22) Moss, PT; Mackenzie, LL; Ulm, S; Sloss, CR; Rosendahl, D; Petherick, LM; Steinberger, L; Wallis, LA; Heijnis, H; Petchey, F; Jacobsen, GE
    A 2400 year record of environmental change is reported from a wetland on Bentinck Island in the southern Gulf of Carpentaria, northern Australia. Three phases of wetland development are identified, with a protected coastal setting from ca. 2400 to 500 years ago, transitioning into an estuarine mangrove forest from ca. 500 years ago to the 1940s, and finally to a freshwater swamp over the past +60 years. This sequence reflects the influence of falling sea-levels, development of a coastal dune barrier system, prograding shorelines, and an extreme storm (cyclone) event. In addition, there is clear evidence of the impacts that human abandonment and resettlement have on the island's fire regimes and vegetation. A dramatic increase in burning and vegetation thickening was observed after the cessation of traditional Indigenous Kaiadilt fire management practices in the 1940s, and was then reversed when people returned to the island in the 1980s. In terms of the longer context for human occupation of the South Wellesley Archipelago, it is apparent that the mangrove phase provided a stable and productive environment that was conducive for human settlement of this region over the past 1000 years. © 2015 Published by Elsevier Ltd.
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    Extended residence times for foraminifera in a marine-influenced terrestrial archaeological deposit and implications for palaeoenvironmental reconstruction
    (Elsevier, 2016-02-01) Nagel, T; Rosendahl, D; Hua, Q; Moss, PT; Sloss, CR; Petchey, F; Ulm, S
    Accelerator Mass Spectrometry (AMS) radiocarbon dating and taphonomic grading was undertaken on foraminifera preserved in the archaeological shell matrix site of Thundiy, Bentinck Island, southern Gulf of Carpentaria, Australia. Foraminifera were assigned to one of six taphonomic grades ranging from pristine to severely abraded. AMS dating demonstrates a weak relationship between preservation status and age. Foraminifera ages are inconsistent with multiple ages on marine shell from the same deposit implying significant sediment transport system residence ages (the time between death of the organism and final deposition) for foraminifera in the deposit. Results demonstrate that foraminifera cannot be assumed to be contemporary with other components of the sedimentary context in which they occur, indicating that caution is required in interpreting chronologies and palaeoenvironmental records based on foraminifera recovered from highly dynamic depositional settings. Findings point to the potential of foraminifera AMS dating of coastal archaeological deposits to contribute to evaluations of site integrity and chrono-stratigraphic analyses. © 2015, Elsevier Ltd.
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    Fire and fuel in Holocene northern Australian tropical savannas
    (International Union for Quaternary Research (INQUA), 2019-07-26) Rehn, E; Bird, MI; Rowe, C; Ulm, S; Woodward, C; Jacobsen, GE
    Fire has a long history of interaction with Australian ecosystems but poses a growing risk as future climate change is predicted to lengthen fire seasons and increase extreme fire weather. Tropical savannas cover almost one quarter (1.9 million km2) of the Australian land mass, and fire occurs here almost annually. A greater understanding of past fire regimes, and their environmental context, is essential for management and planning in an increasingly fire-prone landscape. Despite the central importance of fire in savanna ecosystems, the region remains understudied in Australian palaeofire research. In light of this knowledge gap, this study combines established and emerging optical and chemical methods for charcoal analysis in the context of northern Australian tropical savannas. This study presents three new Holocene palaeofire records from tropical savanna wetland sites in far northern Australia, each with diverse land-use histories. Three methods were applied to achieve a more comprehensive understanding of fire and fuels over time in tropical savannas. Charcoal abundance is presented for four size classes covering a local signal (>250 µm and 250-125 µm) and surrounding regional signal (125-63 µm and <63 µm). Particle morphology and aspect ratio are proposed indicators of fuel type (e.g. grass, leaf, wood). However, this technique derives primarily from temperate environments, notably from experimental burns and sites in the Northern Hemisphere. Our study tests methods developed in temperate, Northern Hemisphere settings on charcoal from the Australian tropical savanna. Fuel type data are discussed using a morphotype classification system, and a length-width ratio of ≥3.6 is used to identify macroscopic grass particles. We demonstrate the application of chemical quantification of pyrogenic carbon (PyC) as well as isotopic identification of fuel type. PyC abundance determined using hydrogen pyrolysis and δ13C composition (contribution of C3 versus C4 plants) are presented for the three sites and combined with the data generated using optical methods. All records are supported by 210Pb and 14C chronologies and XRF core scanner data on elemental composition. Preliminary results show negligible variations in fuel composition through time at each site, with broad correspondence between fuel type determined by morphology and isotope composition. Variations are apparent between different charcoal size classes (macroscopic and microscopic) in both abundance and fuel composition at all sites, reflecting differences in local and regional fire signals and highlighting the importance of size differentiation during analysis. This study is a step towards filling the palaeofire knowledge gap represented by northern Australia and is an important assessment of the application of existing palaeofire techniques to this unique context. © The Authors.
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    Holocene sea-level change and coastal landscape evolution in the southern Gulf of Carpentaria, Australia
    (SAGE, 2018-09-01) Sloss, CR; Nothdurft, L; Hua, Q; O'Connor, SG; Moss, PT; Rosendahl, D; Petherick, LM; Nanson, RA; Mackenzie, LL; Sternes, A; Jacobsen, GE; Ulm, S
    A revised Holocene sea-level history for the southern Gulf of Carpentaria is presented based on new data from the South Wellesley Archipelago and age recalibration of previous research. Results confirm that rising sea levels during the most recent post-glacial marine transgression breached the Arafura Sill ca. 11,700 cal. yr BP. Sea levels continued to rise to ca. –30 m by 10,000 cal. yr BP, leading to full marine conditions. By 7700 cal. yr BP, sea-level reached present mean sea-level (PMSL) and continued to rise to an elevation of between 1.5 m and 2 m above PMSL. Sea level remained ca. + 1.5 between 7000 and 4000 cal. yr BP, followed by rapid regression to within ± 0.5 m of PMSL by ca. 3500 cal. yr BP. When placed into a wider regional context results from this study show that coastal landscape evolution in the tropical north of Australia was not only dependent on sea-level change but also show a direct correlation with Holocene climate variability. Specifically, the formation and preservation of beach-rock deposits, intertidal successions, beach and chenier ridge systems hold valuable sea-level and Holocene climate proxies that can contribute to the growing research into lower latitude Holocene sea-level and climate histories. © The Author(s) 2018
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    Holocene sea-level change and coastal landscape evolution in the southern Gulf of Carpentaria, Australia
    (International Union for Quaternary Research (INQUA), 2019-07-30) Sloss, CR; Northdurft, L; Hua, Q; O'Connor, SG; Moss, PT; Rosendahl, D; Petherick, LM; Nanson, RA; Mackenzie, LL; Sternes, A; Jacobsen, GE; Ulm, S
    A Holocene sea-level history for the southern Gulf of Carpentaria has been constructed based on a review of previously published data, combined with data collected for this study from a variety of sea-level proxies. These sea-level proxies include beach ridges, claypans, mangrove swamps, fossilized in situcoral reefs, beachrock and aeolinite deposits. Results confirm that rising sea-levels during the last Post-Glacial Marine transgression beached the Arafura Sill ca. 11,700 years ago (-53 m), resulting in a change from lacustrine to a marine environment. Sea levels continued to rise to ca. -30 m by 10,000 years ago. By 7,700 cal. yr BP sea-level reached PMSL and continued to rise an elevation of between 1.5 and 2 m above present mean sea-level by 7,000 years ago. Elevated sea levels resulted in the development of raised coral reefs, beach-rock and aeolinite deposits, and the initiation of chenier plains and beach ridges. Sea-level remained ca. +1.5 m above PMSL during the Holocene highstand, accompanied by distinct phases of beach-ridge and chenier plain development. The highstand was followed by arapid regression to within ±0.5 m of PMSL by ca. 3,500 cal. yr BP. When placed into a wider regional context results from this study show thatcoastal landscape evolution in the tropical north of Australia was not only dependenton sea-level change but also show a direct correlation with Holocene climatevariability. Specifically, the formation and preservation of beach-rock deposits,intertidal successions, beach and chenier ridge systems hold valuable sea-level and Holoceneclimate proxies that can contribute to the growing research into lowerlatitude Holocene sea-level and climate histories. ©2019 The Authors.
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    Marine carbon reservoir variability in Torres Strait: preliminary results of AMS dating of live-collected shell specimens.
    (International Union for Quaternary Research, 2007-07) Ulm, S; Barham, AJ; David, B; Jacobsen, GE; McNiven, IJ; Petchey, F; Rowland, MJ
    Despite routine dating of marine shell by Quaternary scientists in the Torres Strait region, no systematic evaluation of the applicability of the recommended DeltaR value has been undertaken. This value can be shown to be problematic. It is based on only three samples from Torres Strait and two from the west coast of Cape York Peninsula, together spanning 125±60 to -14±60 years; the samples are from different oceanographic provinces; the dated taxa are not amongst those commonly dated by contemporary researchers; and all of the dates were obtained over 20 years ago before the advent of high precision AMS dating. This project attempts to address this deficiency through the dating of a suite of well-provenanced live-collected shell specimens using the high precision ANTARES AMS facilities at ANSTO. Dated samples are largely derived from a unique assemblage of well-documented live-collected shell specimens in the Australian Museum from Murray Island and Albany Passage collected by Charles Hedley in August-October 1907, supplemented by smaller collections from elsewhere in Torres Strait. Sample selection focused on suspension-feeders (Arcidae, Mesodesmatidae, Veneridae), although carnivores (Volutidae), herbivores/omnivores (Neritidae) and algae grazers (Trochidae) were included to examine inter-taxa variability. Preliminary results help establish more robust regional DeltaR values for the region based on shellfish commonly dated by Quaternary scientists and allow examination of localised variability in DeltaR values. These findings have broad implications for refining chronologies in coastal archaeology and geomorphology in the Torres Strait region, including studies of sea-level change, reef and coral cay development, coastal dune sequences, storm event frequency and archaeological trends.
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    A radiocarbon chronology for Sanamere Lagoon, Cape York Peninsula, using multiple organic fractions
    (Elsevier B. V., 2022-05) Rivera-Araya, M; Rowe, C; Levchenko, VA; Ulm, S; Bird, MI
    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. © 2022 Elsevier B.V.
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    Reliable AMS ages for Mayan Caches at Copán, Honduras based on spondylus sp. marine shells
    (GNS Science, 2011-03-24) Hua, Q; Ulm, S; Levchenko, VA; Fash, W; Ajurcia, R; Sharer, R; Traxler, L; Petchey, F
    Copán, located in western Honduras, is one of the most well-known of all ancient Mayan cities. Over a century of intensive archaeological research has revealed the development of Copán from its origins as a small agricultural village, to a major city state, followed by its decline or ‘collapse’ after AD 800. Copán’s chronology relies heavily on changes in ceramics dated by association with hieroglyphic dates on monuments. There are surprisingly few radiocarbon dates available for a site with such a long-term history of study and researchers have expressed a general reluctance to use radiocarbon dating (mainly on charcoal) at Copán because radiocarbon ages are often too old compared to associated hieroglyphic dates. Dating marine shell offers an alternative approach for radiocarbon-based chronology building at Copán. Spondylus sp. or spiny oyster shell is found in offering caches throughout the Copán valley. Caches are commonly associated with the dedication of buildings, altars and stelae. We have dated cached Spondylus sp. shells and compared their ages with calendrical dates derived from Maya hieroglyphs to obtain new information about Classic Maya caching behaviours and the chronology of contact with exchange partners in coastal areas from where the shell was sourced. A total of 17 Spondylus sp. shells collected from 9 independently dated contexts were analysed for 14C with AMS to high precision (0.30-0.35%) using the facilities at ANSTO and Waikato. Most of our AMS dates agreed well with structural/hieroglyphic dates indicating that Spondylus sp. can be reliably used for dating contexts. The results also showed there was very little time between death of the shellfish and placement within caches suggesting that shells may have been acquired for specific caching/dedication events rather than stored for long periods.
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    Temporal variability in the Holocene marine radiocarbon reservoir effect for the Tropical and South Pacific
    (Elsevier, 2020-12-01) Hua, Q; Ulm, S; Yu, K; Clark, TR; Nothdurft, LD; Leonard, ND; Pandolfi, JM; Jacobsen, GE; Zhao, JX
    Understanding the marine radiocarbon reservoir effect (i.e., marine radiocarbon reservoir age (R) and/or correction (ΔR)) is important for the construction of robust radiocarbon chronologies for marine archives for various research areas including archaeology, palaeoecology, paleoceanography, Quaternary research and climate change studies. In this study, we examined temporal ΔR variability for the South China Sea (SCS) and the Great Barrier Reef (GBR) during the past ∼8.1 ka based on 14C analysis of 230Th-dated corals. Results show large ΔR variations of ∼410 yr and ∼490 yr for the SCS and the northern GBR for ∼5.5–8.1 ka and ∼5.5–7 ka, respectively, and a smaller ΔR variability of ∼200 yr for the SCS for ∼2–3.5 ka. Our data, together with those previously published for the Tropical and South Pacific, indicate that variability in ocean upwelling bringing old subsurface waters to the surface and/or changes in the sources (or 14C level) of the upwelled waters are responsible for seeing large ΔR variations in coastal areas along the eastern Pacific and the Tropical East Pacific (TEP) of several hundred to a thousand years mostly during the Early to Middle Holocene. ΔR variations in the central and western Pacific of several and a couple of hundred years during the Middle and Late Holocene, respectively, might be due to variability in Pacific-wide ocean circulation associated with climatic changes controlling the spread of upwelled waters from the TEP to the west. This mechanism together with local/regional effects, such as changes in ocean upwelling in the SCS resulting from East Asian monsoon variability and changes in upwelling and/or horizontal advection in the northern GBR associated with variability in the El Niño Southern Oscillation, might be responsible for the observed ΔR variations in these areas. The results of our study also indicate the need for regional marine radiocarbon calibration curves for improved radiocarbon dating of marine samples as the observed Holocene ΔR values for the Tropical and South Pacific are not fully reproduced by a recent modelling work using a 3D ocean model, which takes into account climate change effects. Ocean circulation changes were included in the model for the period of 11.5–50 cal kyr BP but possibly not considered or not well represented for the Holocene, which might explain the differences between the observed and modelled ΔR values. Crown Copyright©2020 Published by Elsevier Ltd
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    Variability in the Holocene marine radiocarbon reservoir effect for the Tropical West Pacific
    (Australian Nuclear Science and Technology Organisation, 2021-11-17) Hua, Q; Ulm, S; Yu, K; Clark, T; Nothdurft, LD; Leondard, ND; Pandolfi, JM; Jacobsen, GE; Zhao, JX
    Reliable determination of the marine radiocarbon reservoir effect (e.g., marine radiocarbon reservoir correction (ΔR)) is important for the construction of robust radiocarbon chronologies for marine archives for various research areas including archaeology, palaeoecology, paleoceanography, Quaternary research and climate change studies. In this study, we examined temporal ΔR variability for the South China Sea (SCS) and the Great Barrier Reef (GBR) during the past ~8.1 ka based on ¹⁴ C analysis of ²³⁰ Th-dated corals. Coral samples, including Acropora sp., Cyphastrea sp., Favia sp. and Porites sp., were collected from Xisha (or Paracel) Islands and Yongshu Reef, Nansha (or Pratly) Islands in the SCS; Clerke Island, Gore Island, Haggerstone Island, Alexandra Reef and High Island in the northern GBR; and Great Keppel Island in the southern GBR. A total of 44 unaltered coral samples (based on SEM screening, δ²³⁴ U and initial ²³⁰ Th/²³²Th ratios) were analysed for ²³⁰ Th and ¹⁴ C. ²³⁰ Th dates were determined using a VG Sector-54 thermal ionization mass spectrometer (TIMS) or a Nu Plasma MC-ICP-MS in the Radiogenic Isotope Facility, The University of Queensland, with a precision better than 0.5% (2σ). Subsamples of these dated corals were then taken for radiocarbon analysis using the STAR AMS facility at ANSTO with a typical precision of ~0.3-0.4% (1σ). Results show large ΔR variations of ~410 yr and ~490 yr for the SCS and the northern GBR at ~5.5-8.1 ka and ~5.5-7 ka, respectively, and a smaller ΔR variability of ~200 yr for the SCS at ~2-3.5 ka. Changes in the sources (or ¹⁴ C level) of upwelled waters in the Tropical East Pacific, and variations in Pacific-wide and regional/local ocean circulation associated with climate change might be responsible for these observed ΔR variations [1]. The results of our study also indicate the need for regional marine radiocarbon calibration curves for improved radiocarbon dating of marine samples as the observed Holocene ΔR values for the Tropical Pacific are not fully reproduced by recent modelling work using a 3D ocean model [2], which takes into account climate change effects. Ocean circulation changes were included in the model for the period 11.5-50 ka but possibly not considered or not well represented for the Holocene, which might explain the differences between the observed and modelled ΔR values. © The Authors