EARTH SCIENCE > OCEANS > BATHYMETRY/SEAFLOOR TOPOGRAPHY > CONTINENTAL MARGINS
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Acoustic sounder charts were collected at six locations during Australian Antarctic Division Voyage 6 1994/95 (BANGSS) using the Kongsberg EA200 Echo Sounder on the Aurora Australis. BANGSS is an acronym for Big ANtarctic Geological and Seismic Survey. The voyage began on 6 February 1995 and finished on 12 April 1995. Each chart is labelled with information about when and where the data was collected: date, time, latitude and longitude. The charts provide a profile of the sea floor and have a time axis with numbers in the following format. the first two digits are the day the next two digits are the month the next five digits are the time (UTC) the last ten digits are the maximum value on the depth axis eg 2402005 360000000500 means 24 February 5:36 UTC and the maximum value on the depth axis is 500 metres See a Related URL for a link to information about the voyage including the voyage report.
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This dataset comprises Digital Elevation Models (DEMs) of varying resolutions for the George V and Terre Adelie continental margin, derived by incorporating all available singlebeam and multibeam point depth data into ESRI ArcGIS grids. The purpose was to provide revised DEMs for Census of Antarctic Marine Life (CAML) researchers who required accurate, high-resolution depth models for correlating seabed biota data against the physical environment. The DEM processing method utilised all individual multibeam and singlebeam depth points converted to geographic xyz (long/lat/depth) ASCII files. In addition, an ArcGIS line shapefile of the East Antarctic coastline showing the grounding lines of coastal glaciers and floating ice shelves, was converted to a xyz ASCII file with 0 m as the depth value. Land elevation data utilised the Radarsat Antarctic Mapping Project (RAMP) 200 m DEM data converted to xyz ASCII data. All depth, land and coastline ASCII files were input to Fledermaus 3DEditor visualisation software for removal of noisy data. The cleaned point data were then binned into a gridded surface using Fledermaus DMagic software, resulting in a 0.001-arcdegree (~100 m) resolution DEM with holes where no input data exists. ArcGIS Topogrid software was used to interpolate across the holes to output a full-coverage DEM. ArcGIS was used to produce the additional 0.0025-arcdegree (~250 m) and 0.005-arcdegree (~500 m) resolution grids. Full processing details can be viewed in: Beaman, R.J., O'Brien, P.E., Post, A.L., De Santis, L., 2011. A new high-resolution bathymetry model for the Terre Adelie and George V continental margin, East Antarctica. Antarctic Science 23(1), 95-103. doi:10.1017/S095410201000074X
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A collaborative Italian/Australian marine geoscience research voyage to the George Vth Land sector of the East Antarctic continental margin was carried out between 11th February and 20th March, 2000, on board the of the RV Tangaroa. The cost of the expedition was shared jointly by the Italian and Australian National Antarctic Research Programs. Twenty four scientific personnel from 13 institutions participated in the expedition. The geophysical data collected includes a total of 1827 km of multi-channel seismic data and 562 km of Chirper sonar data. A total of 11 gravity cores, 28 piston cores, 18 surface grabs and 11 short trigger cores were collected on the voyage. Water profile (CTD) measurements and water samples were collected at nine stations and seabed bottom photographs were made at 11 stations. The expedition discovered and mapped a shelf sediment drift deposit covering about 400 km2 lying in an greater than 800m deep section of the George Vth basin west of the Mertz Glacier. It is a true 'drift' deposit, since these sediments exhibit a patchy distribution, large-scale bedforms, contain foreset bedding and display a depositional architecture indicative of contour-parallel sediment transport. A significant observation is that the drift thins to the north into an acoustically-transparent veneer; this observation implies that the drift is sourced from the outer continental shelf, with sediment being transported landwards, across the shelf and into an 850m deep inner shelf basin. The 'Mertz Drift' is over 35 m thick and core samples demonstrate that it is composed of laminated, anoxic, gelatinous olive green, silicious mud and diatom ooze (SMO). Preliminary shipboard counts of the laminae suggest a thickness of from 4 to 20mm, with a mean of about 7mm. While the lower sediments are laminated, there is a 20 to 50cm thick sandy drape at the surface over the whole of the drift. This suggests that a recent (late Holocene) change in the depositional environment has occurred, possibly related to changes in the extent of the nearby Mertz Glacier tongue, current regime and/or to the persistence of sea ice over the shelf area. Multi-channel seismic data show the occurrence of foreset beds at the shelf break, interpreted as having been deposited by ice streams that grounded on the outer shelf during glacial maxima. On the shelf, the seismic character of the seafloor exhibits highly reflective, parabolic reflectors suggestive of crystalline basement, cropping out at the seafloor. Northwards of these basement outcrops, the water depth increases to over 1,100 m which is the George Vth Basin. The basin coincides with an abrupt transition in seismic character from acoustic basement in the south to seaward (northeasterly) dipping reflectors. On the continental rise, seismic sections were taken across a contourite drift deposit and submarine canyon system in 2500 to 3500 m water depth. Piston cores were collected along the profile of one drift deposit which gave a preliminary Mid-Pliocene age to truncated strata that crop out on the drift's steeper lee side. These data will provide useful site-survey information in support of a proposal sent to the Ocean Drilling Program under the auspices of the SCAR-ANTOSTRAT project for drilling key sites along the Antarctic margin.
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Antarctic sediments and sea-ice are important regulators in global biogeochemical and atmospheric cycles. These ecosystems contain a diverse range of bacteria whose biogeochemical roles remains largely unknown and which inhabit what are continually low temperature habitats. An integrated molecular and chemical approach will be used to investigate the coupling of microbial biogeochemical processes with community structure and cold adaptation within coastal Antarctic marine sediments and within sea-ice. Overall the project expects to make an important contribution to our understanding of biological processes within low temperature habitats. DATA SET ORGANISATION: The dataset is organised on the basis of publication and is organised on the basis of the following sections: 1. SEDIMENT SAMPLES and ISOLATES Samples collected are described in terms of location, type and where data were obtained chemical features. The designation, source, media used for cultivation and isolation and availability of sediment and other related isolates are provided. Samples included are from the following locations: Clear Lake, Pendant Lake, Scale Lake, Ace Lake, Burton Lake, Ekho Lake, Organic Lake, Deep lake and Taynaya Bay (Burke Basin), Vestfold Hills region; and the Mertz Glacier Polynya region. 2. BIOMASS and ENZYME ACTIVITY DATA Biomass, numbers and extracellular enzyme activity data are provided for Bacteria and Archaea populations from Mertz Glacier Polynya shelf sediments. 3. FATTY ACID and TETRAETHER LIPID DATA Phospholipid and tetraether lipid data are provided for Mertz Glacier Polynya shelf sediments. Whole cell fatty acid data are provided for various bacterial isolates described officially as new genera or species. 4. RNA HYBRIDISATION DATA RNA hybridisation data for Mertz Glacier Polynya sediment samples is provided, including data for oligonucleotide probes specifc for total Bacteria, Archaea, the Desulfosarcina group (class Deltaproteobacteria, sulfate reducing bacterial clade), phylum Planctomycetes, phylum Bacteroidetes (Cytophaga-Flavobacterium-Bacteroides), class Gammaproteobacteria, sulfur-oxidizing and related bacteria (a subset of class Gammaproteobacteria) and Eukaryota. 5. PHYLOGENETIC DATA 16S rRNA gene sequence data are indicated including aligned datasets for three clone libraries derived from the Mertz Glacier Polynya including GenBank accession numbers. Sequence accession numbers are provided for Vestfold Hills lake sediment samples. In addition GenBank numbers are provided for denaturing gradient gel electrophoresis band sequence data from Mertz Glacier Polynya shelf sediment. Other forms of this DGGE data (banding profile analysis) are available in reference Bowman et al. 2003 (AAD ref 10971).