Authors / CoAuthors
Radke, L.C. | Carey, M.
Abstract
In September and October of 2011 Geoscience Australia surveyed part of the offshore northern Perth Basin in order to map potential sites of natural hydrocarbon seepage. The primary objectives of the survey were to map the spatial distribution of seepage sites and characterise the nature of the seepage at these sites (gas vs oil, macroseepage vs microseepage; palaeo vs modern day seepage) on the basis of: acoustic signatures in the water column, shallow subsurface and on the seabed; geochemical signatures in rock and sediment samples and the water column; and biological signatures on the seabed. Areas of potential natural hydrocarbon seepage that were surveyed included proven (drilled) oil and gas accumulations, a breached structure, undrilled hydrocarbon prospects, and areas with potential signatures of fluid seepage identified in seismic, satellite remote sensing and multibeam bathymetry data. Within each of these areas the survey acquired: water column measurements with the CTD; acoustic data with single- and multi-beam echosounders, sidescan sonar and sub-bottom profiler (sidescan not acquired in Area F as it was too deep in places); and sediment and biological samples with the Smith-McIntyre Grab. In addition, data were collected with a remotely operated vehicle (ROV), integrated hydrocarbon sensor array, and CO2 sensor in selected areas. Sampling with the gravity corer had limited success in many of the more shallow areas (A-E) due to the coarse sandy nature of the seabed sediments. This dataset comprises organic carbon and nitrogen concentrations and isotopes of seabed sediments.
Product Type
dataset
eCat Id
78807
Contact for the resource
Custodian
Owner
Custodian
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Digital Object Identifier
Keywords
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- Marine Data
- ( Theme )
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- marine survey
- ( Theme )
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- continental shelf
- ( Theme )
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- seabed
- ( Theme )
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- geochemistry
- ( Theme )
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- marine
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- AU-WA
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Marine Geoscience
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- Published_External
Publication Date
2014-01-01T00:00:00
Creation Date
Security Constraints
Legal Constraints
Status
Purpose
Maintenance Information
asNeeded
Topic Category
oceans
Series Information
Lineage
Bottom sediments were collected using a Smith Macintyre grab. Surface sediments (~0-2 cm) within the grab were spooned into falcon vials and the porewaters were removed by centrifugation. The samples were then frozen for transport to the laboratories at Geoscience Australia where they were freeze-dried, ground in a tungsten carbide mill and decarbonated. The decarbonated powders were sent to Environmental Isotopes Pty Ltd (Sydney) for isotopic analysis by mass spectrometry. Samples were back-corrected to account for the carbonate removal, using carbonate concentrations derived from the bomb method. Thanks to the crew of the RV Southern Surveyor for help with sample collection and to M. Carey for field support. Analyses were undertaken at Environmental Isotopes Pty Ltd (Sydney) with administrative support by J. Chen.
Parent Information
Extents
[-29.4508, -27.3208, 112.7662, 114.7662]
Reference System
Spatial Resolution
Service Information
Associations
Source Information
Unknown