Lithospheric Framework of Australia

Blewett, Richard

doi:10.18814/epiiugs/2012/v35i1/003

Cited by 27 publications

(15 citation statements)

References 52 publications

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“…The complex development of Australian lithosphere over more than 2 Ga has exerted fundamental influences on the overall tectonic stability and the character of the landscape, the distribution of earthquakes and associated seismic risk, the evolution of sedimentary basins, as well as heat flow and other resource endowment (Kennett and Blewett, 2012).…”

Section: Australian Structurementioning

confidence: 99%

Lg-wave attenuation in the Australian crust

Wei

Zhao

2017

Tectonophysics

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We estimate the Lg-wave quality factor (Q) across the Australian continent from vertical-component Lg waveforms. A tomographic inversion is performed to construct an Lg attenuation model for 58 frequencies between 0.05 and 10.0 Hz. The available spatial resolution is approximately 1.5°×1.5° for the 0.5-2.0 Hz band. At 1.0 Hz the Lg-wave Q over the whole island continent varies from 50 to 1250 with an average value of 850. Significant regional variations in the Lg-wave Q images tie well with many geological features and boundaries in Australia. The cratons in western, northern and southern parts of Australia usually have higher Q values (700-1250), while the volcanic regions, sedimentary basins and orogenic areas in eastern Australia are characterized by increased attenuation (lower Q values, 50-650). We determine the frequency-dependent Q of Lg waves for different blocks across Australia, and find the frequency dependence of Q is much more complex than the traditional single power law representation. When combined with the assumed geometrical spreading relation, the Lg Q maps provide a new way of assessing potential ground motion across the continent for any event location.

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Section: Australian Structurementioning

confidence: 99%

Lg-wave attenuation in the Australian crust

Wei

Zhao

2017

Tectonophysics

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“…Rocks older than 3.7 Ga have been reported in the Archean region of the WAC, especially the oldest known zircon crystals (4.4 Ga), which were discovered in the Yilgarn Craton (e.g., Kennett & Blewett, ). The Yilgarn Craton, which is located in the southern part of the WAC, consists of four geologic provinces: the southwestern Gneiss Terrane with ages of 3.7–3.0 Ga and the Murchison, Southern Cross, and Eastern Goldfields Provinces, the last three of which are greenstone belts with ages of 3.0–2.7 Ga (Gee et al, ).…”

Section: Introductionmentioning

confidence: 99%

Insights Into Layering in the Cratonic Lithosphere Beneath Western Australia

Sun

Saygin

et al. 2018

JGR Solid Earth

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The characteristics of internal lithospheric discontinuities carry crucial information regarding the origin and evolution of the lithosphere. However, the formation and mechanisms of the midlithosphere discontinuity (MLD) are still enigmatic and controversial. We investigate the midlithospheric discontinuities beneath the Archean Western Australian Craton, which represents one of the oldest continents on the globe, using a novel receiver‐based reflectivity approach combined with other geophysical information comprising tomographic P and S wave velocity, radial anisotropy, electrical resistivity, and heat flow data. The MLD is rather shallow with a depth of 68–82 km. Multiple prominent discontinuities are observed in the lithospheric mantle using constructed high‐frequency (0.5–4 Hz) P wave reflectivities. These multiple discontinuities coincide well with the broad‐scale reduction of relative P and SV wave velocities at the top of the graded transition zone from the lithosphere to the asthenosphere. Strong radial anisotropy in the upper lithosphere mantle tends to be weak across the MLD, which might reflect quasi‐laminar lithospheric heterogeneity behavior with a horizontal correlation length that is greater than its vertical correlation length. Broad‐scale electrical resistivity variations show little coherence with the MLD. Given these various geophysical observations, the upper lithosphere exhibits rigid and elastic properties above the MLD, while the lower lithosphere tends to be ductile and rheological or viscous. A model comprising quasi‐laminar lithospheric heterogeneity could effectively represent the MLD characteristics beneath the Archean continent.

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“…For example, white mica Tschermak substitution has shown apparently conflicting patterns for different mineral deposits at similar pressure-temperature conditions [165]. Thermodynamic modelling research is now helping to resolve this complexity [166,167], which may ultimately explain even larger patterns, such as whether the apparent relationship between the thickness of the Australian crust (~depth to MOHO) [137] and the surface (top 100 µm) mineralogy (e.g., Figure 16b) is related to the vertical migration of reduced, alkaline mantle fluids [168,169].…”

Section: Discussionmentioning

confidence: 99%

“…(a) ASTER V1 Ferric Oxide Composition map of Australia[135] with similarly processed field validation ASD measurements of the field NGSA surface samples (0-10 cm depth)[136] (colored dots); (b) Oblique view from south of the Australian ASTER ferric composition and Mohorovičić Discontinuity (MOHO) maps[137]. The edge of a high in the MOHO is marked by a magenta line which mirrors a change in the surface iron oxide information; (c) ASTER V1 Al-clay content map of Australia together with rainfall and field validation NGSA %clay data; (d) ASTER false color image of the Mt Carbine area, NE Queensland.…”

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confidence: 99%

Mineral Mapping for Exploration: An Australian Journey of Evolving Spectral Sensing Technologies and Industry Collaboration

Cudahy

2016

Geosciences

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This paper describes selected results from over a dozen collaborative projects led by Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia spanning a 30-year history of developments in satellite, airborne, field and drill core sensing technologies and how these can assist explorers to measure and map valuable mineral information. The exploration case histories are largely from Australian test sites and describe how spectral sensing technologies have progressed from early "niche creation" systems, such as the field PIMA-II (Portable Field Mineral Analyzer) and airborne Geoscan, HyMap™ and OARS-TIPS (Operational Airborne Remote Sensing-Thermal Infrared Profiling Spectrometer) systems and drill-core HyLogger™ systems, to the current expanding array of pubic and commercial mineral mapping sensors, including the ASTER (Advanced Spaceborne Thermal Emission and Reflectance Radiometer) satellite system which has acquired imagery spanning the entire Earth's land surface (<83 • latitude). These sensors are delivering voluminous spectral data from different parts of the visible to the thermal infrared (400 to 14,000 nm) spectrum at different spectral, radiometric and spatial resolutions. Two critical exploration challenges are central to the case histories, namely: (i) can surface cover, such as vegetation, regolith or transported materials, be characterized and accounted for so that the target geology is accurately revealed; and (ii) does this revealed geology show evidence of alteration footprints to potential economic mineralization. Spectrally measurable minerals important to solving these challenges include white micas, kaolinite and garnets, with measurement of their respective physicochemistries being key. For example, kaolin disorder is useful for mapping transported versus weathered in situ materials, while the chemical substitution in white micas and garnets provide vectors to potential economic mineralization. Importantly, appropriate selection of the optimum sensor/data type for a given geological application depends primarily on the level of detail/accuracy of the mineral information required by the user. A major opportunity is to now harness the many sensor/data types and deliver to users consistent, accurate mineral information products, that is, creation of a number of valuable global mineral product standards. As part of this vision, CSIRO has been developing improved sensor/data calibration processes and information extraction methods that for example, unmix the target mineralogy from green and dry vegetation cover in remote sensing data sets. Emphasis to date has been on generating public spectral-mineral product standards, especially at ASTER's limited but geologically-valuable spectral resolution. The results are showing that scalable, global, three-dimensional (3D) mineral maps are achievable which will only improve our ability to more accurately characterize regolith and geological architecture, increase our understanding of formative processes and assist the discovery of ...

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Lithospheric Framework of Australia

Abstract: has exerted fundamental control on the overall tectonic stability and consequent landscape evolution, the distribution of earthquakes and associated seismic risk, the evolution of sedimentary basins, as well as heat flow and other resource endowment.

Cited by 27 publications

References 52 publications

Lg-wave attenuation in the Australian crust

Lg-wave attenuation in the Australian crust

Insights Into Layering in the Cratonic Lithosphere Beneath Western Australia

Mineral Mapping for Exploration: An Australian Journey of Evolving Spectral Sensing Technologies and Industry Collaboration

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