Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/110567
Type: Thesis
Title: Evolution of shear-enhanced compaction bands and pure compaction bands: an example from the Willunga Basin, South Australia
Author: White, S. R. S.
Issue Date: 2014
School/Discipline: School of Physical Sciences
Abstract: Shear-enhanced compaction band (SECB) and pure compaction band (PCB) evolution was constrained at Sellicks Beach, analysing measurements from 247 deformation bands recorded at 12 field locations, from outcrop of the Port Willunga Formation and Heatherdale Shale in the Willunga Basin, South Australia. Three distinct deformation band sets were identified with dominant strike orientations of NW-SE, and subordinate strike orientations of NNW-SSE and WNW-ESE. Sets one and two are defined as two sub-sets of SECBs, forming conjugate sets in outcrops of the Port Willunga Formation. Set three was defined as PCB by definition, forming perpendicular to the maximum principal shortening direction. Deformation bands were further characterised by deformation band style; i) sharp; ii) gradual, and; iii) diffuse, and deformation band fills; i) reorientated bioclasts fill (normal fill); ii) black lithic fill, and; iii) micrite fill. Deformation band conjugate set dihedral angles, band interactions, microstructural and petrophysical properties were used to define the three generations of deformation bands and their temporal evolution. They were formed in response to rotation of stress orientations during basin formation and reactivation, and inversion of the large-scale Willunga Fault at Sellicks Beach during the Middle Eocene and Pliocene. Thin sections revealed increasing cataclastic failure in deformation bands analysed, enabling identification of an evolutionary sequence of; i) diffuse, to; ii) gradual, to; iii) sharp, and finally; iv) black lithic. This sequence demonstrates progressively higher amounts of cataclasis and shear. Thin sections were further used, as well as core samples, to produce porosity values of deformation band types, with reductions of porosity values coinciding with higher amounts of cataclasis and shear. Thus, the Port Willunga Formation at Sellicks Beach provides insight into deformation band characteristics and evolution in carbonate rocks, which have not previously been studied in detail.
Dissertation Note: Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2014
Where: Willing Basin, South Australia
Keywords: Honours; Geology; shear-enhanced compaction band; pure compaction band; Willunga Basin; Port Willunga Formation
Description: This item is only available electronically.
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the author of this thesis and do not wish it to be made publicly available, or you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals
Appears in Collections:School of Physical Sciences

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