Structure and evolution of the Amadeus, officer and Ngalia basins of central Australia

Lambeck, Kurt

doi:10.1080/08120098408729278

Cited by 72 publications

(81 citation statements)

References 33 publications

(45 reference statements)

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“…The deep structure of Central Australia is relatively well studied and the deformation at depth appears to be expressed continuously through the surface [62,63]. In other parts of the continent, however, the correct identi¢cation of the dominant strain directions from surface observations is more problematic.…”

Section: Discussionmentioning

confidence: 99%

Seismic and mechanical anisotropy and the past and present deformation of the Australian lithosphere

Simons

Hilst

2003

Earth and Planetary Science Letters

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We interpret the three-dimensional seismic wave-speed structure of the Australian upper mantle by comparing its azimuthal anisotropy to estimates of past and present lithospheric deformation. We infer the fossil strain field from the orientation of gravity anomalies relative to topography, bypassing the need to extrapolate crustal measures, and derive the current direction of mantle deformation from present-day plate motion. Our observations provide the depth resolution necessary to distinguish fossil from contemporaneous deformation. The distribution of azimuthal seismic anisotropy is determined from multi-mode surface-wave propagation. Mechanical anisotropy, or the directional variation of isostatic compensation, is a proxy for the fossil strain field and is derived from a spectral coherence analysis of digital gravity and topography data in two wavelength bands. The joint interpretation of seismic and tectonic data resolves a rheological transition in the Australian upper mantle. At depths shallower than V150^200 km strong seismic anisotropy forms complex patterns. In this regime the seismic fast axes are at large angles to the directions of principal shortening, defining a mechanically coupled crust^mantle lid deformed by orogenic processes dominated by transpression. Here, seismic anisotropy may be considered 'frozen', which suggests that past deformation has left a coherent imprint on much of the lithospheric depth profile. The azimuthal seismic anisotropy below V200 km is weaker and preferentially aligned with the direction of the rapid motion of the Indo-Australian plate. The alignment of the fast axes with the direction of present-day absolute plate motion is indicative of deformation by simple shear of a dry olivine mantle. Motion expressed in the hot-spot reference frame matches the seismic observations better than the no-net-rotation reference frame. Thus, seismic anisotropy supports the notion that the hot-spot reference frame is the most physically reasonable. Independently from plate motion models, seismic anisotropy can be used to derive a best-fitting direction of overall mantle shear. ß

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Section: Discussionmentioning

confidence: 99%

Seismic and mechanical anisotropy and the past and present deformation of the Australian lithosphere

Simons

Hilst

2003

Earth and Planetary Science Letters

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“…(35). Cloetingh and Burov (2011) compiled wavelengths of folded lithosphere, including crustal, mantle and whole lithosphere folding, for 17 regions worldwide, including Central Asia (Burov et al, 1993), central Australia (Lambeck, 1983b), the north-east European platform (Bourgeois et al, 2007), the Tibet/Himalayan syntaxes belt (Shin et al, 2015) and the Indian oceanic lithosphere (McAdoo and Sandwell, 1985;Krishna et al, 2001), and showed that all fold wavelengths are between 40 and 700 km. Not surprisingly, wavelengths for crustal folding are the smallest and wavelengths for whole lithosphere folding are the largest.…”

Section: Lithospheric Foldingmentioning

confidence: 99%

Folding and necking across the scales: a review of theoretical and experimental results and their applications

Schmalholz

Mancktelow

2016

Solid Earth

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Abstract. The shortening and extension of mechanically layered ductile rock generates folds and pinch-and-swell structures (also referred to as necks or continuous boudins), which result from mechanical instabilities termed folding and necking, respectively. Folding and necking are the preferred deformation modes in layered rock because the corresponding mechanical work involved is less than that associated with a homogeneous deformation. The effective viscosity of a layered rock decreases during folding and necking, even when all material parameters remain constant. This mechanical softening due to viscosity decrease is solely the result of fold and pinch-and-swell structure development and is hence termed structural softening (or geometric weakening). Folding and necking occur over the whole range of geological scales, from microscopic up to the size of lithospheric plates. Lithospheric folding and necking are evidence for significant deformation of continental plates, which contradicts the rigid-plate paradigm of plate tectonics. We review here some theoretical and experimental results on folding and necking, including the lithospheric scale, together with a short historical overview of research on folding and necking. We focus on theoretical studies and analytical solutions that provide the best insight into the fundamental parameters controlling folding and necking, although they invariably involve simplifications. To first order, the two essential parameters to quantify folding and necking are the dominant wavelength and the corresponding maximal amplification rate. This review also includes a short overview of experimental studies, a discussion of recent developments involving mainly numerical models, a presentation of some practical applications of theoretical results, and a summary of similarities and differences between folding and necking.

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“…The interested reader can find more comprehensive accounts in Lambeck (1983), Lindsay et al (1987), Korsch and Lindsay (1989), Lindsay and Korsch (1991), Shaw et al (1991), Walter and Gorter (1994), Walter et al (1995) and Q14:1 Sandiford et al (2002). In one of the earliest accounts (Lambeck 1983) the formation of the central Australia basins was attributed to long high amplitude (c.10 km) lithospheric-scale buckling, largely on the basis of the Nielsen & Hansen (2000). The locus of maximum inversion intensity typically occurs in the interior of the precursor rift basins.…”

Section: Styles Of Inversion In Naturementioning

confidence: 99%

Lower crustal rheological expression in inverted basins

Sandiford

Hansen

McLaren

2006

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Although lithospheric modelling has provided extraordinary insights into the processes that shape the continental crust, considerable uncertainty surrounds the basic rheology that governs behaviour at geological timescales. In part, this is because it has proved difficult to identify the geological observations that might discriminate, or unify, models of lithospheric rheology. In particular, the relative strength of lower crust and upper mantle remains a contentious aspect of continental lithospheric rheology. We show that various models for lower crustal rheology may produce distinct patterns of inversion in extensional sedimentary basins, consistent with some of the observed natural variability of inversion styles. Inversion of basin interiors, as is common in European Mesozoic basins, is favoured by a lithospheric rheology more sensitive to lateral thermal structure than to changes in the depth of the Moho, consistent with there being little strength contrast between the lower crust and upper mantle in these settings. In contrast, inversion of basin margins, particularly involving basinward verging structures, is consistent with a rheological sensitivity to the depth of Moho as would apply for a lower crust much weaker than the upper mantle. We use an example from central Australia to demonstrate this later response, together with thermochronologic data that suggests that a relatively weak lower crust in this setting may reflect abnormally high geothermal gradients.

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Structure and evolution of the Amadeus, officer and Ngalia basins of central Australia

Cited by 72 publications

References 33 publications

Seismic and mechanical anisotropy and the past and present deformation of the Australian lithosphere

Seismic and mechanical anisotropy and the past and present deformation of the Australian lithosphere

Folding and necking across the scales: a review of theoretical and experimental results and their applications

Lower crustal rheological expression in inverted basins

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