Integrated geophysical appraisal of crustal architecture in the eastern Lachlan Orogen

Direen, Nicholas G.; Lyons, Patrick G.; Korsch, R. J.; Glen, R. A.

doi:10.1071/aseg2001ab030

Cited by 4 publications

(11 citation statements)

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“…The crustal structure is constrained in few locations from passive seismic experiment: receiver function (RF) studies (Shibutani et al 1996;Clitheroe et al 2000;Kennett et al 2011). An anisotropic upper, middle and lower crust was well imaged in previous seismic reflection data (Direen et al 2001;Glen et al 2002) and the seismic interface between the crust and the mantle was interpreted as not flat Glen et al 2002).…”

Section: Introductionmentioning

confidence: 67%

“…The V P /V S ratio is around 1.7 at CAN and CNB and 1.75 at YNG compatible with the presence of granite-gneiss beneath CAN and CNB and biotite gneiss beneath YNG. At SO01 this would be the down dip extension of mafic rocks imaged and modelled in Direen et al (2001), (Figure 4a, b). At CAN and CNB stations, the V P /V S values are compatible with mafic orthogneisses or mafic granulite inferred in the lower crust from a wide-angle seismic profile in the southern Lachlan Orogen .…”

Section: P /V S Ratiosmentioning

confidence: 99%

“…Indeed, only a few deep seismic refraction and reflection profiles have been conducted in the region (e.g. Finlayson et al 1980Finlayson et al , 2002Direen et al 2001;Glen et al 2002). Most onshore refraction profiles date from the 1960s to 1980s (see e.g.…”

Section: Introductionmentioning

confidence: 99%

“…LTZ is the Lachlan Transverse Zone. Seismic lines show the location of reflection profiles (Direen et al 2001;Glen et al 2002). A and B are the location of the extremities of the refraction profile from Finlayson et al (2002).…”

Section: Introductionmentioning

confidence: 99%

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Crustal complexity in the Lachlan Orogen revealed from teleseismic receiver functions

Fontaine¹,

Tkalčić²

2013

Australian Journal of Earth Sciences

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There is an ongoing debate about the tectonic evolution of southeast Australia, particularly about the causes and nature of its accretion to a much older Precambrian core to the west. Seismic imaging of the crust can provide useful clues to address this issue. Seismic tomography imaging is a powerful tool often employed to map elastic properties of the Earth's lithosphere, but in most cases does not constrain well the depth of discontinuities such as the Mohorovi ci c (Moho). In this study, an alternative imaging technique known as receiver function (RF) has been employed for seismic stations near Canberra in the Lachlan Orogen to investigate: (i) the shear-wave-velocity profile in the crust and uppermost mantle, (ii) variations in the Moho depth beneath the Lachlan Orogen, and (iii) the nature of the transition between the crust and mantle. A number of styles of RF analyses were conducted: H-K stacking to obtain the best compressional-shear velocity (V P /V S ) ratio and crustal thickness; nonlinear inversion for the shear-wave-velocity structure and inversion of the observed variations in RFs with backazimuth to investigate potential dipping of the crustal layers and anisotropy. The thick crust (up to 48 km) and the mostly intermediate nature of the crustÀmantle transition in the Lachlan Orogen could be due to the presence of underplating at the base of the crust, and possibly to the existing thick piles of Ordovician mafic rocks present in the mid and lower crust. Results from numerical modelling of RFs at three seismic stations (CAN, CNB and YNG) suggest that the observed variations with back-azimuth could be related to a complex structure beneath these stations with the likelihood of both a dipping Moho and crustal anisotropy. Our analysis reveals crustal thickening to the west beneath CAN station which could be due to slab convergence. The crustal thickening may also be related to the broad Macquarie volcanic arc, which is rooted to the Moho. The crustal anisotropy may arise from a strong N-S structural trend in the eastern Lachlan Orogen and to the preferred crystallographic orientation of seismically anisotropic minerals in the lower and middle crust related to the paleo-Pacific plate convergence.

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Section: Introductionmentioning

confidence: 67%

Section: P /V S Ratiosmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Crustal complexity in the Lachlan Orogen revealed from teleseismic receiver functions

Fontaine¹,

Tkalčić²

2013

Australian Journal of Earth Sciences

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“…Geophysical support for an oceanic middle crust was cited by Glen et al (2002), from two lines of evidence: a seismic refraction interpretation indicated a layer from about 15 to about 30 km depth with V p = 6.4-6.6 kms -1 , interpreted to represent mafic lithologies (Finlayson et al, 2002); and a cross-section derived from a potential field model showing an equivalent layer as MORB volcanic rocks. However, the range of velocities for this layer corresponds to the average crustal velocity reported for both continental arcs and shields over the equivalent depth range (Christensen and Mooney, 1995), and the original potential field model, as shown in Direen et al (2001), identifies this layer as simply mid-crust, and assigns a magnetic susceptibility of zero, inconsistent with a mafic composition.…”

Section: Discussionmentioning

confidence: 99%

Long-wavelength magnetic anomalies as a guide to the deep crustal composition and structure of eastern Australia

Musgrave

2013

ASEG Extended Abstracts

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Geochemistry and age of magmatic rocks in the unexposed Narromine, Cowal and Fairholme Igneous Complexes in the Ordovician Macquarie Arc, New South Wales

Crawford

Cooke

2007

Australian Journal of Earth Sciences

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Integrated geophysical appraisal of crustal architecture in the eastern Lachlan Orogen

Cited by 4 publications

References 10 publications

Crustal complexity in the Lachlan Orogen revealed from teleseismic receiver functions

Crustal complexity in the Lachlan Orogen revealed from teleseismic receiver functions

Long-wavelength magnetic anomalies as a guide to the deep crustal composition and structure of eastern Australia

Geochemistry and age of magmatic rocks in the unexposed Narromine, Cowal and Fairholme Igneous Complexes in the Ordovician Macquarie Arc, New South Wales

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