Citation

Geoscience Australia provides most of its products for free under a Creative Commons Attribution 3.0 Australia Licence. We only require that you reference the use of our data or information using the following citation:
Radke, L.C., Trafford, J. & Carey, M., 2014. Geoscience Australia Marine Survey GA0332 (SS05/2011): Natural hydrocarbon seepage survey of the offshore northern Perth Basin - Total sediment metabolism and porewater pH and salinity of seabed sediments.. Geoscience Australia, Canberra.

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 total sediment metabolism (CO2 production) and porewater pH and salinity measurments of seabed sediments.
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 - Marine Data

Constraints

license
Creative Commons Attribution 3.0 Australia Licence

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

2014

Product Type

dataset

Topic Category

oceans

Keywords

Marine Data
geochemistry
seabed
continental margins
marine survey
marine
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

Bottom sediments were collected using a Smith McIntyre grab. Surface sediment (0-2 cm) was syringed into falcon vials. Pore waters were removed within 20 minutes of collection, and salinity, temperature and pH measurements were taken. The pore waters were then filtered (0.45 ┬Ám) into 3 ml gas-tight vials (pre-charged with 0.025 HgCl2). The procedure was repeated on pore waters from a second bulk sample that was incubated for ~24 hrs at sea surface temperatures. Dissolved inorganic carbon (DIC) concentrations were determined using a DIC analyser and infrared-based CO2 detector. (Geoscience Australia). CO2 production rates were calculated by concentration differences over the incubation period, after correction for CaCO3 fluxes. The average %RSD of the precisions and accuracies of the dissolved inorganic carbon measurements were 0.25% and 0.5% respectively. The accuracy of the wet/dry weight used in the calculations were better than 1%. Thanks to the crew of the RV Southern Surveyor for help with sample collection.

Digital Transfer Options

onLine

DISTRIBUTION Format

xlsx

Distributor

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

Metadata File Identifier

efe7a28f-a705-2674-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

2014-01-14

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 Geoscience Australia Client Services via:

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