Dataset DOI

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 %.
Google map showing geographic bounding box with values North bound -27.3208 East bound 114.74 West bound 112.7662 South bound -29.4508
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Product Type/Sub Type

dataset

Constraints

Creative Commons Attribution 4.0 International Licence

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

2014-01-01T00:00:00

Product Type

dataset

Topic Category

oceans

GA Catalogue Number

78815 Product http://www.ga.gov.au/metadata-gateway/metadata/record/78815/

Keywords

Marine Data
marine survey
continental shelf
seabed
geochemistry
marine
AU-WA
Marine Geoscience

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Geographic Extent

North bound
-27.3208
East bound
114.74
West bound
112.7662
South bound
-29.4508

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.

Digital Transfer Options

onLine

Distributor

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

Source Description

Unknown

Metadata File Identifier

efe74af7-383d-12cb-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 SECURITY CLASSIFICATION

unclassified

Metadata Contact

Role
pointOfContact
Organisation Name
Commonwealth of Australia (Geoscience Australia)
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address
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