Levelled Gravity and Magnetic Data Covering the Southwest Margin of Australia  

Authors / CoAuthors

Hackney, R.

Abstract

A document briefly describing levelled ship-track gravity and magnetic data available for download from the Geophysical Archive Data Delivery System (GADDS) that cover the southwest margin of Australia in the region enclosing 106-120°E and 19-37°S. The document will be provided whenever the data are downloaded from GADDS. Note that the data is archived on the Corporate Data Store

Product Type

nonGeographicDataset

eCat Id

72700

Contact for the resource

Keywords

• External PublicationExplanatory Notes

( Theme )

• gravity

( Theme )

• magnetics

( Theme )

• marine survey

( Theme )

• data

( Theme )

• marine

Australian and New Zealand Standard Research Classification (ANZSRC)

• Geophysics

• Published_Internal

Publication Date

2011-01-01T00:00:00

Creation Date

Security Constraints

Australian Government Security ClassificationSystem    

Classification - unclassified

Legal Constraints

Creative Commons Attribution 4.0 International Licence    

Access - restricted

Use - license

Status

Purpose

Maintenance Information

irregular

Topic Category

geoscientificInformation

Series Information

Lineage

The source data used to generate a levelled dataset for the southwestern margin of Australia includes: 1) a dataset of gravity and magnetic data for the Australian region sourced internally from Geoscience Australia holdings of ship-track data and levelled by Desmond Fitzgerald and Associates Pty Ltd (now Intrepid Geophysics) in the late 1990s under contract to the Australian Geological Survey Organisation (now Geoscience Australia); 2) gravity and magnetic data from Geoscience Australia seismic survey GA-310 (2008/2009); and 3) gravity and magnetic data from Geoscience Australia marine survey GA-2476 (2008/2009). The processing steps applied to gravity data include: 1) re-computation of free-air gravity anomalies to ensure consistent computation of gravity anomalies between the different datasets; 2) splitting ship-tracks into relatively straight line segments to avoid multiple cross-overs between any pair of lines; 3) line filtering of the previously-levelled Australia-wide dataset to reduce noise and improve cross-over computations; 4) merge the individual datasets into a single master dataset for levelling; 5) editing to remove lines or line segments with spurious data - lines that were too short or too close to other line segments were also removed in order to improve levelling results; 6) line levelling - gravity data were levelled using a loop levelling technique referenced to a satellite radar altimetry-derived dataset (DNSC08GRA); 7) computation of complete Bouguer gravity anomalies (ie. with terrain corrections) using a spherical-cap Bouguer correction and a density contrast between water and sediment of 970 kilograms per cubic metre and water depths interpolated at each data point from the 2009 Bathymetry and Topography Grid of Australia; 8) combination with onshore data from the 2010 release of the Australian National Gravity Database. The processing steps applied to magnetic data include: 1) splitting ship-tracks into relatively straight line segments to avoid multiple cross-overs between any pair of lines; 2) line filtering of the previously-levelled Australia-wide dataset to reduce noise and improve cross-over computations; 3) merge the individual datasets into a single master dataset for levelling; 4) editing to remove lines or line segments with spurious data - lines that were too short or too close to other line segments were also removed in order to improve levelling results; 5) line levelling - magnetic data were loop levelled (minmising misclosures around closed loops formed by ship tracks); 6) merging with onshore data from the 5th Edition of the Magnetic Anomaly Map of Australia. The data processing and levelling were conducted using the INTREPID software from Intrepid Geophysics (versions 4.2.2). The resulting gravity and magnetic data for the southwest margin of Australia are available for download from the Geophysical Archive Data Delivery System (GADDS) at www.geoscience.gov.au/gadds.

Parent Information

Extents

[-37.0, -19.0, 106.0, 120.0]

Reference System

Spatial Resolution

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