Seabed environments and shallow geology of the Leveque Shelf, Browse Basin, Western Australia: seabed sediment laser measured grainsize data  

Authors / CoAuthors

Nicholas, W.A.

Abstract

In May 2013, Geoscience Australia, in collaboration with the Australian Institute of Marine Science, undertook a marine survey of the Leveque Shelf (survey number SOL5754/GA0340), a sub-basin of the Browse Basin. This survey provides seabed and shallow geological information to support an assessment of the CO2 storage potential of the Browse sedimentary basin. The basin, located on the Northwest Shelf, Western Australia, was previously identified by the Carbon Storage Taskforce (2009) as potentially suitable for CO2 storage. The survey was undertaken under the Australian Government's National CO2 Infrastructure Plan (NCIP) to help identify sites suitable for the long term storage of CO2 within reasonable distances of major sources of CO2 emissions. The principal aim of the Leveque Shelf marine survey was to look for evidence of any past or current gas or fluid seepage at the seabed, and to determine whether these features are related to structures (e.g. faults) in the Leveque Shelf area that may extend to the seabed. The survey also mapped seabed habitats and biota to provide information on communities and biophysical features that may be associated with seepage. This research, combined with deeper geological studies undertaken concurrently, addresses key questions on the potential for containment of CO2 in the basin's proposed CO2 storage unit, i.e. the basal sedimentary section (Late Jurassic and Early Cretaceous), and the regional integrity of the Heyward Formation (the seal unit overlying the main reservoir). The survey collected one hundred and eleven seabed sediment samples that were analysed for their grain size, textural composition and carbonate content. This dataset includes the results of grain size analysis measured by laser diffractometer.

Product Type

dataset

eCat Id

83637

Contact for the resource

Keywords

• Thematic Data

( Theme )

• marine survey

( Theme )

• sedimentology

( Theme )

• marine environmental baselines

( Theme )

• CCS

( Theme )

• geoscience

( Theme )

• Continental Shelf

( Theme )

• Data

• W A

Australian and New Zealand Standard Research Classification (ANZSRC)

• Surface Processes

• Published_External

Publication Date

2015-01-01T00:00:00

Creation Date

Security Constraints

Australian Government Security ClassificationSystem    

Classification - unclassified

Legal Constraints

Creative Commons Attribution 4.0 International Licence    

Access - license

Use - license

Status

Purpose

Maintenance Information

asNeeded

Topic Category

geoscientificInformation

Series Information

Lineage

A marine survey (GA0340/SOL5754) of the Leveque Shelf was undertaken in May 2013 as part of work investigating CO2 storage in Australia's offshore sedimentary basins. Seabed surface sediments were collected using either a Smith McIntyre or a Shipek grab sampler. Sediment grabs typically recovered about 0.1 cubic metres of undisturbed sediment, from which a 250 - 500 g sub-sample was taken to a depth of ~5 cm. Sub-samples were described from visual inspection, noting grain size, sorting, composition and Munsell colour then stored in plastic bags and refrigerated. In the laboratory, samples were used for grain size analysis and measurement of carbonate content on separate splits. Grain size measurement was undertaken by wet sieving to determine mud (<63 microns), sand (63-2000 microns) and gravel (>2000 microns) fractions as percentage of dry weight. A separate sub-sample (~1g) was used for laser diffraction measurement of the mud and sand fractions using a Malvern Mastersizer 2000, with results expressed as percentage of the total particle volume based on an average of three measurements on each sample. Summary statistics include arithmetic mean, standard deviation, skewness and kurtosis. Carbonate content was measured on the bulk fraction, sand fraction and mud fraction by acid digestion and measurement of resultant pressure, following Muller and Gastner (1979). The carbonate content of the gravel fraction was determined by visual assessment. Sediment data for the Leveque Shelf, Browse Basin, are a first generation product derived from the physical samples. No transformation of the data has been undertaken.

Parent Information

Extents

[-16.1, -15.45, 121.1, 121.75]

Reference System

WGS 84 / UTM zone 51S (EPSG:32751)

Spatial Resolution

Service Information

Associations

Downloads and Links

Link to Data package - Seabed environments and shallow geology of the Leveque Shelf  

Download the data (xlsx)  

Source Information

sediments from Leveque Shelf, offshore Broome, Western Australia