Citation

Heggie, D.T., Lane, J.L. & Veeh, H.H., 1993. Geochemistry of Surface Sediments from the Southern Australian Continental Margin Including Offshore West Tasmania, South Australia and Victoria. Record  1993/087. Australian Geological Survey Organisation, Canberra.

Abstract

As part of Bureau of Mineral Resources (BMR) survey 67 using Rig Seismic offshore South Australia, Victoria and West Tasmania, many gravity cores were sampled and analysed for light hydrocarbons as part of the Continental Margins surface geochemistry project. Eight of those cores were analysed, both at sea and in Canberra, for a variety ofcomplementary geochemical data. This Record provides a summary of the geochemical analyses subsequently conducted on those cores. The data presented here include (i) porewater metabolites (ii) geochemical analyses of major and trace element abundances (iii) radiochemical data and select palaeoceanographic indicators. Some of these data have been used to assist in the interpretation of the light hydrocarbon data, while much of theother data has applications to a variety of environmental and resource issues in southern Australia. These data (i) provide a data-base which can be used to assess long-termenvironmental change associated with anthropogenic discharges to the southern marginsof Australia (ii) allow assessment of Late Quaternary and natural climatic change and (iii) provide clues to geochemical processes operating in the sediments which are important inidentifying formation of some seafloor minerals including marine phosphorites and manganese crusts and nodules. This Record and these data also form part of ageochemical data-base which includes data from other parts of the Australian continental margin. These data will be used to systematically develop the basis for an understanding of the controls on the geochemical compositions of sediments from around Australia. The pore water data indicate that the outer-shelf/upper-slope cores are probably sub-oxicto anoxic in character within the top few centimetres as a result of organic carbon burialand recycling in the core-tops. In contrast the lower-slope sediments are more oxic (oxicto sub-oxic) and these reflect generally lower rates of organic matter input into these sediments. Pore water silicate data in some cores suggest uptake of silica into the solid phases at depth, which may be indicative of glauconite formation in the sediments. Glauconite is often associated with modern phosphorite accumulations in sediments, although these data provide no direct clues to phosphorite formations in these sediments. The inventory of sedimentary manganese in the outer-shelf/upper-slope cores is generally significantly lower than that measured in lower-slope cores. This observation, and the pore water data which shows manganese remobilisation andrecycling between pore waters and sediments, may help explain an important processcontributing to the formation of abundant manganese crusts and nodules in the deepwaters off West Tasmania including the South Tasman Rise. The down-core distributions of some radiochemical species, including authigenicuranium and excess thorium 230 are being used to both determine sedimentation ratesand assess Late Quaternary paleoceanography in the region. These data and several other potential palaeoceanographic indicators indicate down-core trends which may beindicative of natural palaeoceanographic and palaeochemcial changes between glacialand interglacial periods, but these cannot be assessed until these sediments have been dated. This dating is in progress at the Flinders University of South Australia.
Google map showing geographic bounding box with values North bound -37.0 East bound 146.0 West bound 138.0 South bound -43.0
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Product Type/Sub Type

dataset - GA Publication - Record

Constraints

license
Creative Commons Attribution 3.0 Australia Licence

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

1993

Product Type

dataset

Topic Category

geoscientificInformation

Keywords

GA Publication
Record
marine
marine survey
geochemistry
Earth Sciences

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Geographic Extent

North bound
-37.0
East bound
146.0
West bound
138.0
South bound
-43.0

Lineage

Legacy product, lineage not available

Digital Transfer Options

onLine

DISTRIBUTION Format

pdf

Distributor

Role
distributor
Organisation Name
Geoscience Australia
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address

Metadata File Identifier

a05f7892-9999-7506-e044-00144fdd4fa6

Metadata Standard Name

ANZLIC Metadata Profile: An Australian/New Zealand Profile of AS/NZS ISO 19115:2005, Geographic information - Metadata

Metadata Standard Version

1.1

Metadata Date Stamp

1996-10-30

METADATA SECURITY CLASSIFICATION

unclassified

Metadata Contact

Role
pointOfContact
Organisation Name
Geoscience Australia
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address
Downloads
For information on acquiring this product,
please contact the Geoscience Australia Sales Centre via:

fax:
+61 2 6249 9960; or
phone:
1800 800 173 (within Australia);
 
+61 2 6249 9966 (outside Australia).

Please note that support hours are 9 am to 5 pm weekdays