Browsing by Author "Prebble, M"

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    A holocene pollen and diatom record from Vanderlin Island, Gulf of Carpentaria, lowland tropical Australia
    (Cambridge University Press, 2017-01-20) Prebble, M; Sim, R; Finn, J; Fink, D
    Sedimentary, palynological and diatom data from a dunefield lake deposit in the interior of Vanderlin Island in the Gulf of Carpentaria are presented. Prior to the formation of present perennial lake conditions, the intensified Australian monsoon associated with the early Holocene marine transgression allowed Cyperaceae sedges to colonise the alluvial margins of an expansive salt flat surrounded by an open Eucalyptus woodland. As sea level stabilised between 7500 and 4500 cal yr B.P. coastal dunes ceased to develop allowing dense Melaleuca forest to establish in a Restionaceae swamp. Dune-sand input into the swamp was diminished further as the increasingly dense vegetation prevented fluvial and aeolian transported sand arriving from coastal sources. This same process impounded the drainage basin allowing a perennial lake to form between 5500 and 4000 cal yr B.P. Myriophyllum and other aquatic taxa colonised the lake periphery under the most extensive woodland recorded for the Holocene. The palynological data support an effective precipitation model proposed for northern Australia that suggests more variable conditions in the late Holocene. A more precise measure of effective precipitation change is provided by diatom-based inferences that indicate few changes in lake hydrology. Such interpretations are explained in terms of palynological sensitivity to adjustments in local fire regimes where regional precipitation change may only be recorded indirectly through fire promoting mechanisms, including intensified ENSO periodicity and human impact. © University of Washington
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    Late Holocene environmental change of Te Whakaraupō | Lyttelton Harbour, New Zealand
    (Australasian Quaternary Association Inc., 2022-12-06) Hanson, J; Reid, C; Prebble, M; Shulmeister, J; Moy, CM; Zawadzki, A; Hua, Q
    Due to the increasing impacts of climate change, global sea levels and ocean temperatures have been rapidly increasing. One region which will be affected by these increased sea levels are the bays of Horomaka | Banks Peninsula on the east coast of the South Island, New Zealand. Horomaka is a poorly understood landscape that has been highly modified by human land management in both Māori and European times. This research will investigate the interactions between changes in the coastal system and the surrounding catchments which are deeply incised valleys in the flanks of an old volcanic complex. The work focusses on three locations: Te Whakaraupō | Lyttelton Harbour, Kawatea | Okains Bay and Te Wairewa | Lake Forsyth and uses a combination of micro-fossil, geochemical and sedimentological proxies to decipher ecological, hydrological and anthropomorphic changes in these catchments. Here we present our preliminary findings from Te Whakaraupō | Lyttelton Harbour, where a 3.4 m shallow marine sediment core was collected from the mudflats of the innermost harbour. Foraminiferal records indicate a rapid infilling of the harbour with a shift in conditions from low intertidal to high intertidal to present day salt marsh. This change in sedimentation is reflected in our X-ray Fluorescence results, which show increased variability in terrigenous sediment and organic content at the top of the record. This research presents the first of its kind in Horomaka to reconstruct past environmental conditions over time. Future research will include pollen and micro-charcoal analyses and grain size analysis to amplify the palaeoenvironmental data. This research will develop key information on changes in both marine and terrestrial environmental change and sedimentation rates over the late Holocene, which will help inform the management response to enhanced climate change and urban development in the harbour.