- Title
- Subsurface modelling of the Gilmore Fault Zone: implications for Lachlan tectonic reconstructions
- Creator
- Venkataramani, Deepika
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2017
- Description
- Masters Research - Master of Philosophy (MPhil)
- Description
- This study considers the tectonic evolution of the Lachlan Orogen by modelling the subsurface morphology of the Gilmore Fault Zone (GFZ). The GFZ marks a distinct geophysical contrast between (high gravity, low magnetic intensity) high-grade metamorphic rocks found in the Wagga Metamorphic Belt (WMB) to the west, and the (low gravity, uniformly high magnetic intensity) low-grade metavolcanic rocks found in the Macquarie Arc and Silurian rift basins to the east. Subsurface structure around the GFZ in the vicinity of Barmedman (34°8'33.94"S 147°23'11.39"E) has been inverted by iterative 2.5D potential-field modelling of gravity and magnetics, constrained by pre-existing reflection seismic profiles, potential-field interpretations by previous workers, and physical properties data collected on representative lithologies. My findings show that the surface structure mapped as the Gilmore Fault is an east-dipping, shallow thrust fault, and does not correspond to the major crustal ‘suture’ envisaged in regional tectonic studies. This shallow east-dipping fault should be renamed the Barmedman fault. The Barmedman Fault flake (as opposed to the GFZ) is curved, and terminates abruptly to the north, indicating the Barmedman Fault flake is the base of a series of thrust flakes imposed on the pre-existing main fault in the GFZ. The GFZ is best described as a steep west-dipping fault zone constituting the eastern flank of the Silurian Tumut Trough. I conclude that the modelled structure of the GFZ is not consistent with the terrane accretion model since the GFZ does not mark a suture between significantly different geological units. The modelled structure of the GFZ shows evidence of multiple contractional and extensional events which are the main characteristics of the accretionary orogen tectonic model. However, steep faults are observed as well, indicating that significant lateral slip, a characteristic of the orocline tectonic model, is mechanically possible.
- Subject
- geophysics; potential field modelling; Gilmore Fault Zone; Barmedman Fault; 3D modelling; geoscience
- Identifier
- http://hdl.handle.net/1959.13/1352309
- Identifier
- uon:30852
- Rights
- Copyright 2017 Deepika Venkataramani
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 4 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 268 KB | Adobe Acrobat PDF | View Details Download |