Geoscience Australia LEI Products from the Honeysuckle Creek TEMPEST AEM Survey, Victoria  

Authors / CoAuthors

Fisher, A.G. | Brodie, R.C.

Abstract

This report describes the geophysical inversion of the Honeysuckle Creek TEMPEST airborne electromagnetic (AEM) survey data (Geoscience Australia Airborne Geophysics Project # 903) to produce subsurface electrical conductivity predictions using a layered earth inversion algorithm developed by Geoscience Australia (GA-LEI). It also describes the products that were derived from the GA-LEI subsurface electrical conductivity predictions. The GA-LEI algorithm has significantly improved on previous conductivity predictions generated by inversion and conductivity depth transform methods, as shown by comparisons between conductivity predictions and ground truth data (measurements of conductivity acquired down boreholes). While this comparison is best shown graphically, statistically speaking the correlation between the GA-LEI predictions and borehole measured conductivities (R2 = 0.77) is better than for previous predictions from inversions (R2 = 0.05 and 0.47), and conductivity depth transforms (R2 = 0.04 and 0.47). This improvement is attributed to the GA-LEI methodology, which solved for three unmeasured components of the system geometry as well as the ground conductivity model, and was guided by downhole conductivity and geological knowledge. In addition, the GA-LEI method used both the X and Z components of the measured response, and used minimally processed data which have fewer introduced assumptions than data previously used. Being an inversion, it compared the calculated response from the subsurface conductivity predictions with the measured response data, ensuring the conductivity predictions results are consistent with measured data, which was not done with previous transform methods. The subsurface electrical conductivity predictions produced by the GA-LEI were post-processed to produce a variety of derivative products. These products were designed to be used without specialised geophysical knowledge, however, they should only be considered depictions of the data, and the methods used in their generation have instilled their own biases. The main products derived from the GA-LEI results are: layer conductivities; conductivity depth slices; vertical conductivity sections; a conductance distribution; and, an estimate of the depth of the basement rocks beneath the regolith. These products have been enhanced, producing colour images stored in either the JPEG or PDF format. All products are available from the Geoscience Australia website (www.ga.gov.au).

Product Type

nonGeographicDataset

eCat Id

66170

Contact for the resource

Keywords

• GA PublicationRecord

( Theme )

• AEM

( Theme )

• Airborne Electromagnetics

( Theme )

• geophysics

• AU-VIC

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

Publication Date

2008-01-01T00:00:00

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

unknown

Topic Category

geoscientificInformation

Series Information

Record 2008/012

Lineage

Unknown

Parent Information

Extents

[-36.743, -36.42, 145.383, 145.886]

Reference System

Spatial Resolution

Service Information

Associations

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Source Information

Source data not available.