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2020

62 record(s)
 
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    Ocean currents are strongly controlled by seafloor topography. Recent studies have shown that small-scale features with slopes steeper than 0.05° significantly affect subsurface eddy velocities and the vertical structure of ocean circulation patterns. Such slope gradients represent the majority of the present-day oceanic basins. Modeling past oceanographic conditions for key climate stages requires similarly detailed paleo seafloor topography grids, in order to capture ocean currents accurately, especially for ocean models with sufficient resolution (<0.1°) to resolve eddies. However, existing paleobathymetry reconstructions use either a forward modeling approach, resulting in global grids lacking detailed seafloor roughness, or a backward modeling technique based on sediment backstripping, capturing realistic slope gradients, but for a spatially restricted area. Both approaches produce insufficient boundary conditions for high-resolution global paleo models. Here, we compute high-resolution global paleobathymetry grids, with detailed focus on the Southern Ocean, for key Cretaceous and early Cenozoic climate stages. We backstrip sediments from the modern global bathymetry, allowing the preservation of present-day seafloor slope gradients. Sediment isopach data are compiled from existing seismo-stratigraphic interpretations along the Southern Ocean margins, and expanded globally using total sediment thickness information and constant sedimentation rates. We also consider the effect of mantle flow on long-wavelength topography. The resulting grids contain realistic seafloor slope gradients and continental slopes across the continent-ocean transition zones that are similar to present-day observations. Using these detailed paleobathymetry grids for high-resolution global paleo models will help to accurately reconstruct oceanographic conditions of key climate stages and their interaction with the evolving seafloor.

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    The AUStralian Tidal Energy (AUSTEn) project was a three year project (2018 - 2020) funded by the Australian Renewable Energy National Agency (agreement number G00902) led by the Australian Maritime College (University of Tasmania), in partnership with CSIRO and University of Queensland. The project had a strong industry support (Atlantis Resources Limited, MAKO Tidal Turbines Ltd, Spiral Energy Corporation Ltd). The aim of the project was to assess the technical and economic feasibility of tidal energy in Australia, based on the best understanding of resource achievable. For further information and output of the project, please visit the AUSTEn project website www.austen.org.au.

  • Trace element (TE) concentrations of juvenile Short-tailed Shearwaters collected on Great Dog Island, Tasmanian in 2017.

  • These files contain the metadata adopted and MATLAB code edited as well as visual plots generated in the Hongkun Honour's project. The data mainly includes the shipboard ADCP data and vertical cast type of Triaxus data collected from RV Investigator during the voyage IN2016V04 and IN2018T01 and satellite data (chlorophyll, sea level anomaly & sea surface temperature) collected from the IMOS website on the study region. The data was processed in MATLAB and then used to find visualization results, with the ultimate aim of exploring the potential of Triaxus in biogeochemistry.

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    This record describes an aggregated data product compiled from a number of different surveys of Macrocystis surface cover in Tasmanian waters, spanning 1950 to 2019. Some surveys represent a statewide census of Macrocystis cover, while others are targeted surveys of smaller regions. Methodology and data quality lso varies between surveys. Please see linked metadata records for specific methodologies and quality statements applying to individual surveys.

  • The Australian Coastal Restoration Network (ACRN) database collates information about coastal restoration projects in eight different ecosystems across Australia and New Zealand: shellfish, macroalgae, seagrass, mangrove, saltmarsh, coastal wetland and coral environments. This record represents a static snapshot of the database made in March 2020. The ACRN website (https://www.acrn.org.au) may contain more recent updates to the database.

  • The aim of the project was to determine the particulate organic carbon concentration in coastal polynyas and off-shelf sites south of the Polar Front. Data is collected from the CTD deployed at various stations. This record descripbes three datafiles. (1) POC_data: station, pressure, temperature, conductivity, salinity, PAR, total beam attenuation coefficients (c), attenuation by particles (cp), site, particulate organic carbon concentration (from optical measurements), rho, longitude and latitude. (2) Ammonium: station, pressure, site, ammonium, latitude, longitude (3) POC_PON_ratio: site, depth, particulate organic carbon concentration (measured) particulate organic nitrogen concentration (measured), C:N ratio.

  • This record provides an overview of the scope and research output of NESP Marine Biodiversity Hub Project A15 - "Conservation status of tropical inshore dolphins". No data outputs are expected for this project. -------------------- This project is solely for a desktop review of peer-reviewed publications, research projects, and reports (e.g. EIAs) associated with major port developments 2013-2019.

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    A numerical ocean model based on the Regional Ocean Modelling System (ROMS) framework was run for the Sorsdal ice shelf region and included modifications for ice/ocean thermodynamics and mechanical pressure, following (Dinniman et al., 2007). The model domain was discretised on a polar stereographic grid with a uniform 2 km horizontal resolution. The vertical terrain-following coordinate had 31 vertical layers with a sigmoidal layer distribution to provide higher vertical resolution at the surface and bottom regions.

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    The final lithospheric breakup of the Australian-Antarctic rift system remains controversial due to sparse geological constraints on the nature of the basement along the ocean-continent transition zones. We present new interpretations of multichannel seismic reflection transects, as well as new petrological data of dredged mantle rocks along the East Antarctic margin (Seamount B, offshore Terre Adélie). By combining both datasets, we show that a 50–100 km wide domain of cold (900°C), fertile subcontinental mantle was exhumed along the non-volcanic Antarctic margin. The dredged peridotites preserve characteristics similar to mantle xenoliths found in syn- to post-rift volcanism at the eastern end of the Australian margin (Victoria and Tasmania), indicating the sampling of a common fertile subcontinental mantle during rifting between Australia and Antarctica. Seamount B represents the initial stages of exhumation of cold subcontinental lithosphere along an ocean-continent transition during rifting. This thick mantle domain was likely affected by syn-rift melt impregnation at high-pressure (8 kbar), leading to the formation of plagioclase-pyroxenites. Overall, the combination of continental rifted blocks, a 50-100 km wide domain of volcanic-poor subcontinental mantle and (ultra)-slow spreading implies that ocean-continent transition zones along the Australian-Antarctic margins represent a recent analogue to ocean continent transition zones from the Jurassic Western Tethys. Additionally, evidence of syn-rift melt stagnation at high pressure suggests that magmatism along the Australian-Antarctic rifted margins was sufficient to form magnetic anomalies that can be used as isochrons despite their formation in lithosphere other than mature, steady-state ocean crust.