Crustal architecture of Central Victoria: results from the 2006 deep crustal reflection seismic survey  

Authors / CoAuthors

Cayley, R.A. | Korsch, R.J. | Moore, D.H. | Costelloe, R.D. | Nakamura, A.

Abstract

A ~400 km long deep crustal reflection seismic survey was carried out in Central Victoria, Australia, in 2006. It has provided information on crustal architecture across the western Lachlan Orogen and has greatly added to the understanding of the tectonic evolution. The east-dipping Moyston Fault is confirmed as the suture between the Delamerian and Western Lachlan orogens and is shown to extend down to Moho. The Avoca Fault, which is the boundary between the Stawell and Bendigo zones, is a west-dipping listric fault that intersects the Moyston Fault at a depth of about 22 km, forming a V-shaped geometry. Both the Stawell and Bendigo structural zones can be broadly divided into a lower crustal region of interlayered and imbricated metavolcanic and metasedimentary rocks and an upper crustal region of tightly-folded metasedimentary rocks. The Stawell Zone was probably part of a Cambrian accretionary system along the eastern Gondwana margin and mafic rocks may have been partly consumed by Cambrian subduction. Much of the Early Cambrian oceanic crust beneath the Bendigo Zone has not been subducted but is preserved as a crustal-scale imbricate thrust stack. The seismic data have shown that the 'thin-skinned' structural model appears to be valid for much of the Melbourne Zone whereas the Stawell and Bendigo zones have a 'thick-skinned' structural style. Internal faults in the Stawell and Bendigo zones are mostly west-dipping listric faults, which extend from the surface, with listric geometries, to near the base of the crust. The Heathcote Fault Zone, which forms the boundary between the Bendigo and Melbourne zones, extends to at least 20 km, and possibly to the Moho. A striking feature in the seismic data is the markedly different seismic character of the mid to lower crust of the younger Melbourne Zone. The deep seismic reflection data for the Melbourne have revealed a multilayered crustal structure that supports the Selwyn Block model.

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nonGeographicDataset

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69410

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• External PublicationScientific Journal Paper

( Theme )

• seismic sections

( Theme )

• gold

( Theme )

• structural geology

( Theme )

• geodynamics

• AU-VIC

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

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2009-08-12T00:00:00

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