1887
Volume 49, Issue 4
  • ISSN: 0812-3985
  • E-ISSN: 1834-7533

Abstract

[

The Gilmore Fault Zone (GFZ) marks a distinct geophysical contrast between metasediments of the Wagga Metamorphic Belt (high gravity and low magnetic intensity) and the Macquarie Arc and Silurian rift basins (low gravity and high magnetic intensity) in the Eastern Lachlan Orogen, Australia. This study uses a geologically constrained inversion of magnetic and gravity data to provide a revised model of the GFZ.

This model results in a significant improvement in fit to all previous models of the same profiles and involves repeated two-way exchange between geologists and geophysicists.

Two profiles corresponding to the seismic reflection lines 99AGSL1-L2 and 99AGSL3, and extending for more than 80 km, were simultaneously inverted by forward modelling of total magnetic intensity and gravity data. This was done through iterative modification of body geometry correlating to mapped geology. Profiles were further constrained by reflection seismics and physical property contrasts.

This model is used to clearly define the dip direction of the GFZ (west-dipping) and suggests a separate classification of the Barmedman Fault (east-dipping). The Barmedman Fault is a shallow fault flake, previously considered part of the GFZ, which has contributed to the confusion around the regional extent of the GFZ. This new work also has the potential to inform future tectonic interpretations of this area.

,

The Gilmore Fault Zone marks a distinct geophysical and complex geological boundary. This work improves on existing models of this fault zone and presents a revised potential field model. These models of the subsurface morphology of this major thrust and/or strike-slip fault system are being used to refine tectonic models for the evolution of the Eastern Lachlan Orogen.

]
ASEG
Loading

Article metrics loading...

/content/journals/10.1071/EG16148
2018-08-01
2026-01-25

  • From This Site

    /content/journals/10.1071/EG16148
    dcterms_title,dcterms_subject,pub_keyword
    -contentType:Journal -contentType:Contributor -contentType:Concept -contentType:Institution
    10
    5
Loading full text...

Full text loading...

References

  1. Bosch M. Meza R. Jiménez R. Hönig A. 2006 Joint gravity and magnetic inversion in 3D using Monte Carlo methods: Geophysics 71 G153 G156 10.1190/1.2209952
    https://doi.org/10.1190/1.2209952 [Google Scholar]
  2. Chopping R. Kennett B. 2015 Maximum depth of magnetisation of Australia, its uncertainty, and implications for Curie depth: GeoResJ 7 70 77 10.1016/j.grj.2015.06.003
    https://doi.org/10.1016/j.grj.2015.06.003 [Google Scholar]
  3. Crawford A. Glen R. Cooke D. Percival I. 2007 Geological evolution and metallogenesis of the Ordovician Macquarie Arc, Lachlan Orogen, New South Wales: Australian Journal of Earth Sciences 54 137 141 10.1080/08120090701221615
    https://doi.org/10.1080/08120090701221615 [Google Scholar]
  4. Direen N. 1998 The palaeozoic Koonenberry Fold and Thrust Belt, Western NSW: a case study in applied gravity and magnetic modelling: Exploration Geophysics 29 330 339 10.1071/EG998330
    https://doi.org/10.1071/EG998330 [Google Scholar]
  5. Direen N. Lyons P. Korsch R. Glen R. 2001 Integrated geophysical appraisal of crustal architecture in the eastern Lachlan Orogen: Exploration Geophysics 32 252 262 10.1071/EG01252
    https://doi.org/10.1071/EG01252 [Google Scholar]
  6. Fisher R. A. 1953 Dispersion on a sphere: Proceedings of the Royal Society of London. Series A 217 295 305 10.1098/rspa.1953.0064
    https://doi.org/10.1098/rspa.1953.0064 [Google Scholar]
  7. Glen R. Korsch R. Direen N. Jones L. Johnstone D. Lawrie K. Finlayson D. Shaw R. 2002 Crustal structure of the Ordovician Macquarie Arc, Eastern Lachlan Orogen, based on seismic‐reflection profiling: Australian Journal of Earth Sciences 49 323 348 10.1046/j.1440‑0952.2002.00925.x
    https://doi.org/10.1046/j.1440-0952.2002.00925.x [Google Scholar]
  8. Glen, R. A., Dawson, M. W., and Colquhoun, G. P., 2007, Eastern Lachlan Orogen Geoscience Database (on DVD-ROM) Version 2. Geological Survey of New South Wales, Department of Primary Industries, Maitland, NSW, Australia.
  9. Koenigsberger J. 1938 Natural residual magnetism of eruptive rocks: Journal of Geophysical Research 43 119 130 10.1029/TE043i002p00119
    https://doi.org/10.1029/TE043i002p00119 [Google Scholar]
  10. Lane R. FitzGerald D. Guillen A. Seikel R. McInerney P. 2007 Lithologically constrained inversion of magnetic and gravity data sets: Preview 129 11 17
    [Google Scholar]
  11. Musgrave R. J. Dick S. 2017 A 3D model for the Koonenberry Belt from geologically constrained inversion of potential field data: Geological Survey of New South Wales, Quarterly Notes 149 1 13
    [Google Scholar]
  12. Oldenburg, D., and Pratt, D., 2007, Geophysical inversion for mineral exploration : a decade of progress in theory and practice, in B. Milkereit, ed., Proceedings of Exploration 07: Fifth Decennial International Conference on Mineral Exploration, 61–95.
  13. Percival, I. G., and Glen, R. A., 2001, Correlation of successions within the Ordovician Macquarie Arc, central New South Wales: Geological Survey of New South Wales, 47–60.
  14. Scheibner E. 1985 Suspect terranes in the Tasman Fold Belt System, east Australia: Tectonostratigraphic Terranes of the Circum-Pacific Region 1 493 514
    [Google Scholar]
  15. Scheibner, E., and Basden, H. (eds.) 1998, Geology of New South Wales — Synthesis. Volume 1, Structural Framework: Geological Survey of New South Wales, Memoir Geology 13(1).
  16. Stuart-Smith P. G. 1991 The Gilmore Fault Zone—the deformational history of a possible terrane boundary within the Lachlan Fold Belt New South Wales: BMR Journal of Australian Geology and Geophysics 12 35 49
    [Google Scholar]
  17. Suppel D. W. Warren A. Y. E. Watkins J. J. Chapman J. Tenison Woods K. Barron L. 1986 A reconnaissance study of the geology and gold deposits of the west Wyalong-Temora-Adelong District: New South Wales Geological Survey, Quarterly Notes 64 1 23
    [Google Scholar]
  18. Venkataramani, D., 2017, Subsurface modelling of the Gilmore Fault Zone: implications for Lachlan Tectonic reconstructions: M.Ph. thesis, University of Newcastle, Newcastle, NSW, Australia.
  19. Warren, A. Y. E., Gilligan, L. B., and Raphael, N. M., 1995, Geology of the Cootamundra 1 : 250 000 map sheet. viii + 160 pp. Geological Survey of New South Wales, Sydney.
  20. Wormald R. J. Price R. C. 1990 The gabbro-qtz monzodiorite-alkai granite association in southern New South Wales: implications for intrusive related gold mineralisation: Geological Society of Australia Abstracts 25 265
    [Google Scholar]
  21. Wyatt B. W. Yeates A. N. Tucker D. H. 1980 A regional review of the geological sources of magnetic and gravity fields in the Lachlan Fold belt of NSW: BMR Journal of Australian Geology and Geophysics 5 289 300
    [Google Scholar]
/content/journals/10.1071/EG16148
Loading
Revised potential field model of the Gilmore Fault Zone
Exploration Geophysics 49, 572 (2018); https://doi.org/10.1071/EG16148
/content/journals/10.1071/EG16148
/content/journals/10.1071/EG16148
Loading

Data & Media loading...

  • Article Type: Research Article
Keyword(s): 3D modelling; faults; petrophysics; potential fields

Most Cited This Month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error