Authors / CoAuthors
Radke, L.C. | Trafford, J. | 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 mineraology of the upper 2cm of seabed sediment. The mineral assemblage includes quartz, aragonite, calcite and high-Mg calcite expressed as mol %.
Product Type
dataset
eCat Id
78815
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
Samples were collected using a Smith McIntyre grab. Dried, ground samples were scanned from 2o to 70o 2, at a speed of 2o per minute and a step size of 0.02o, using a SiemensTM D500/501 series X-ray diffractometer. Mineral identification software (EVATM) was used to identify the d-spacings of a series of peaks corresponding to individual minerals. The relative abundances of the different minerals in the XRD trace were determined using SiroQuantTM. To quantify mol%MgCO3, firstly the d-space for magnesium calcite was determined with reference to a ZnO standard, then mol%MgCO3 was determined using the calibration coefficient of Goldsmith et al. (1955). Analytical errors are good to moderate: <5% for major elements and <10% for trace elements. Goldsmith, J.R., Graf, D.L. and Joensuu, O.I., 1955. The occurrence of magnesian calcites in nature. Geochimica et Cosmochimica Acta, 7: 212-230. Thanks to the crew of the RV Southern Surveyor for help with sample collection and Ashleigh Taylor and Tara Lidgard for lab support.
Parent Information
Extents
[-29.4508, -27.3208, 112.7662, 114.74]
Reference System
Spatial Resolution
Service Information
Associations
Source Information
Unknown