Abstract

The established deformation paradigm for the Eastern Yilgarn Craton (EYC) has largely been developed from observations of overprinting relationships in the greenstone belts (Swager, 1989, 1997; Swager et al., 1992; Williams, 1993). Broadly, the recognised deformation (compressional history) involved early D1 recumbent folding and thrusting during N-S shortening, followed by E-W shortening through large-scale upright D2 folding and thrusting, then a period of strike-slip D3 faulting with associated folding, followed by continued regional D4 transpressive oblique and reverse faulting. Some authors have proposed early, intermediate, and late periods of extension throughout parts of this compressive history (Table 1). This study is aimed at providing a new deformation framework for the granites of the EYC. Granites form >60% of the surface expression of the province, so a more thorough understanding of their tectonic history is critical to our understanding of the evolution of the province. There are advantages of using deformed granites for establishing a time-space-event history. Granites have: 1. a well defined chrono-chemical framework across the entire province (pseudo-stratigraphy) (Champion & Sheraton, 1997); 2. a ductile mineralogy of quartz and feldspar that readily 'accepts' deformation; 3. multiple phases of granite, as sheets and dykes, which provide excellent markers for defining the subtleties of many of the events (especially the later ones); 4. exposure at various structural levels in the upper crust; and 5. a good U-Pb zircon geochronological database as a reference framework (Nelson, 1997; Fletcher, et al., 2001; Dunphy et al., 2003; Black et al., 2004). The scope of the study is to systematically describe the overprinting relationships of structures in granites for a range of structural levels and geographical positions (sites) for the major structural domains or terranes (Southern Cross, Kalgoorlie, Gindalbi-Kurnalpi-Laverton, and Merolia). The area chosen was the central EYC exposed in the area of the 1:250 000 scale map sheets of Leonora, Laverton, Menzies and Edjudina. This study area was chosen because new solid geology mapping (Whitaker and Blewett; 2002), new seismic reflection profiling (Goleby et al., 2002), and the available comprehensive geochronological database. The area also provided a different perspective for the regional deformation history to that determined from the better studied Kalgoorlie region (Swager, 1989). The approach was to systematically study the various structural elements for a range granite ages, with the granite age to be used as a time marker at each site. At each site, the structural elements before (cut by the dated phase) and after (overprint the dated phase) were systematically mapped and described. These structural elements form the data (available as separate data sheets) that were used to correlate events with adjacent sites in the same domain. These domain-wide event histories were also correlated to construct a new EYC deformation framework. Each stage of correlation becomes more interpretative. However, the original site data have been 'preserved' for evaluation and further testing.
Google map showing geographic bounding box with values North bound -30.0 East bound 126.0 West bound 120.0 South bound -34.0
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Product Type/Sub Type

nonGeographicDataset

Constraints

Creative Commons Attribution 4.0 International Licence

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

2004-01-01T00:00:00

Product Type

nonGeographicDataset

Topic Category

geoscientificInformation

GA Catalogue Number

47616 Product http://www.ga.gov.au/metadata-gateway/metadata/record/47616/

Keywords

GA Publication
Record
structural geology
AU-WA
Earth Sciences

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Geographic Extent

North bound
-30.0
East bound
126.0
West bound
120.0
South bound
-34.0

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Unknown

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onLine

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distributor
Organisation Name
Commonwealth of Australia (Geoscience Australia)
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
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Metadata File Identifier

a05f7892-c1a2-7506-e044-00144fdd4fa6

Metadata Standard Name

ANZLIC Metadata Profile: An Australian/New Zealand Profile of AS/NZS ISO 19115:2005, Geographic information - Metadata

Metadata Standard Version

1.1

METADATA SECURITY CLASSIFICATION

unclassified

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pointOfContact
Organisation Name
Commonwealth of Australia (Geoscience Australia)
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address
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